Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Mon, 12/11/2017 - 23:20

000
AXNT20 KNHC 120520
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1220 AM EST Tue Dec 12 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
0415 UTC.

...ITCZ/MONSOON TROUGH...
The monsoon trough extends from the African coast near 10N14W to
09N17W. The Intertropical Convergence Zone axis extends from
09N17W to 03N30W to 01N49W. Isolated moderate convection is from
02N-06N between 11W-15W...and from 05N-07N between 20W-26W.

...DISCUSSION...

GULF OF MEXICO...
A surface ridge extends across the entire basin anchored by a
1025 mb high centered offshore of southern Texas near 27N96W.
Light to moderate anticyclonic winds are noted across the basin
this evening with slightly stronger moderate to occasional fresh
W winds expected to materialize N of 27N by morning. The stronger
winds will be associated with a weak frontal trough emerging off
the SE CONUS coast Tuesday introducing a brief period of fresh
W-NW winds to the northern waters shifting eastward into the
eastern waters Tuesday afternoon into the evening. The troughing
will be quick to clear east of the basin by Wednesday with
moderate northerly winds prevailing through Thursday.

CARIBBEAN SEA...
The primary feature across the basin is the stationary front
extending from the Windward Passage SW to Jamaica then S to the
coast of western Panama near 09N81W. Widely scattered showers and
isolated tstms are occurring generally S of 19N between 75W-
83W. Much of this convection is supported aloft by a divergent
upper level pattern on the western periphery of an upper level
anticyclone anchored over northern Colombia near 08N75W. East of
the anticyclonic circulation...dry NW flow prevails providing
overall stability to the central and eastern Caribbean this
evening. A few isolated showers are noted on satellite imagery E
of 71W...but remain shallow and embedded within gentle to
moderate trades. The front is forecast to remain stationary across
the western Caribbean and gradually weaken through Thursday.

...HISPANIOLA...
Fair weather conditions prevail across the island this evening
while a stationary front remains analyzed across the Windward
Passage region to the NW. Isolated showers are possible within 60
nm either side of the front which is expected to remain
stationary and begin weakening through Thursday.

ATLANTIC OCEAN...
Water vapor imagery indicates broad middle to upper level
troughing over the eastern CONUS and western North Atlc waters
supporting a stationary front extending from 32N59W to the Turks
and Caicos near 22N72W to the Windward Passage and into the SW
Caribbean Sea. Isolated showers are occurring within 120 nm either
side of the front. Otherwise...the remainder of the SW North Atlc
waters are under the influence of a surface ridge anchored over
the Gulf of Mexico and portions of eastern Mexico. Farther east...
water vapor imagery indicates a middle to upper level low centered
near 25N51W. The associated surface trough extends from 14N57W to
29N54W with scattered showers and tstms occurring E of the
troughing from 14N-30N between 41W-51W.

For additional information please visit
http://www.hurricanes.gov/marine

$$
HUFFMAN

Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Mon, 12/11/2017 - 17:53

000
AXNT20 KNHC 112353
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
653 PM EST Mon Dec 11 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2330 UTC.

...SPECIAL FEATURES...

A nearly stationary frontal boundary extends southwestward over
the western Atlc from 32N61W across eastern Cuba, Jamaica, to end
over the southwestern Caribbean Sea near 10N81W. A band of
cloudiness and showers is found along and up to 180 n mi west of
the front. The slow motion of the boundary is conducive to heavy
rainfall accumulations. 2.32 inches of rainfall has been observed
at Montego Bay, Jamaica during the 24 hours ending at 12 UTC this
morning. The pressure gradient between the front and high pressure
ridging southward along the coast of Nicaragua remains strong
enough to produce gale force winds to the west of the boundary
over the Caribbean Sea. The ridge has begun to weaken and winds
are expected to subside below gale force this evening. See the
latest NWS High Seas Forecast under AWIPS/WMO headers
MIAHSFAT2/FZNT02 KNHC for more details.

A strong cold front is pushing southward along the coast of
Morocco. Meteo France has posted a gale warning for the Agadir and
Tarfaya zones for N to NE winds increasing to gale force on
Tuesday, especially in gusts. Winds are expected to remain near
gale force over the Agadir, Tarfaya and Canarias forecast zones as
well as the southeastern portion of the Madeira forecast zone
until Wed, then subside by Wed evening.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from Sierra Leone on the African coast
near 08N13W to 07N16W. The Intertropical Convergence Zone
continues from 07N16W to the coast of Brazil near 01S46W.
Isolated moderate convection is present from 03N to 05N between
37W and 40W.

GULF OF MEXICO...

Fair weather conditions continue across the entire Gulf of Mexico
due to a combination of strong surface high pressure centered
over Mexico ridging eastward over the Gulf and deep layer ridging
aloft. Surface winds are generally light to moderate over the
northern half of the Gulf and moderate to fresh over the southern
half. A weak cold front will introduce a reinforcing shot of cold
air into the Gulf on Tue. The coldest air will affect the
northeastern Gulf and bring a brief period of fresh to strong W to
NW winds to the northeastern waters. High pressure will rebuild
over the Gulf on Wed and Thu and maintain light to moderate winds
over the basin.

CARIBBEAN SEA...

The main weather maker across the region is a nearly stationary
front that crosses the basin from the eastern tip of Cuba to
Jamaica to the coast of Panama near 10N81W. Please refer to the
Special Features section regarding the gale force winds over the
SW Caribbean. West of the front, northerly flow and scattered
showers are occurring between the front and the coast of Nicaragua
as well as the eastern third of Cuba. Moderate to fresh winds are
continuing along the coast of Colombia. Otherwise, generally
tranquil conditions exist to the east of the front, with light to
moderate trade winds and scattered shallow showers covering much
of the eastern and central Caribbean Sea. The front is forecast to
remain stationary while gradually weakening through mid-week.

...HISPANIOLA...

Generally fair weather conditions prevail across the island this
evening as a frontal boundary remains nearly stationary just to
the west of the island across the Windward Passage and eastern
Cuba. The front is not expected to move much, so partly cloudy
skies and isolated showers are expected over the island during
the next day or two.

...ATLANTIC OCEAN...

A mid-to upper-level trough is pivoting northeastward from the
western Atlantic into the central Atlantic. This will reduce
support for the boundary that remains nearly stationary over the
western Atlantic from 32N61W to the eastern tip of Cuba. A band
of clouds and showers is seen along and up to 240 n mi of the
front. Farther east, an upper-level trough extends SSW to the
coast of Guyana from a low centered near 24N49W. The accompanying
surface trough extends SSW from 28N51W to 16N57W. Scattered
moderate and isolated strong convection is tasking place from 15N
to 30N between 42W and 50W. The remainder of the basin remains
under a fairly quiet weather regime maintained by a strong
subtropical ridge supported by 1030 mb high pressure centered SW
of the Azores near 37N35W.

For additional information please visit
http://www.hurricanes.gov/marine

$$
McElroy
Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 12:44
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1243 PM CST Mon Dec 11 2017 Valid 121200Z - 131200Z Elevated to locally critical fire weather conditions remain likely in portions of southern California - especially in terrain-favored areas where wind gusts will exceed 30 mph at times amidst a very dry and warm airmass. Additionally, portions of the northern and central High Plains will experience locally elevated fire weather conditions due to breezy westerly surface flow and areas of dry fuels. RH values in these areas should remain above critical thresholds in most areas, however, and the spatial extent of any elevated fire weather should be limited. See the previous discussion below for more information. ..Cook.. 12/11/2017 .PREV DISCUSSION... /ISSUED 0136 AM CST Mon Dec 11 2017/ ...Synopsis... The persistent mid-level, west-to-east ridge-trough pattern across the United States will be reinforced on Tuesday as a short-wave trough crests the ridge and quickly digs toward the base of the eastern trough during the afternoon and nighttime hours. This pattern will maintain/reinforce the dry airmass across the central Plains and the offshore flow across Southern California. The aforementioned short-wave trough may aid the strengthening of the surface-pressure gradient across Southern California late on Tuesday, which would increase wind speeds to near or above critical fire-weather thresholds. Will hold off on adding a critical area at this time owing to uncertainty in just how strong the winds end up being. Farther east, in the Plains, despite the very dry airmass in place, cooler temperatures and weaker winds on Tuesday will act to limit the overall fire-weather threat. However, if temperatures end up being warmer than forecast or winds are a bit stronger, elevated highlights will become necessary. ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 12:44
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1243 PM CST Mon Dec 11 2017 Valid 121200Z - 131200Z Elevated to locally critical fire weather conditions remain likely in portions of southern California - especially in terrain-favored areas where wind gusts will exceed 30 mph at times amidst a very dry and warm airmass. Additionally, portions of the northern and central High Plains will experience locally elevated fire weather conditions due to breezy westerly surface flow and areas of dry fuels. RH values in these areas should remain above critical thresholds in most areas, however, and the spatial extent of any elevated fire weather should be limited. See the previous discussion below for more information. ..Cook.. 12/11/2017 .PREV DISCUSSION... /ISSUED 0136 AM CST Mon Dec 11 2017/ ...Synopsis... The persistent mid-level, west-to-east ridge-trough pattern across the United States will be reinforced on Tuesday as a short-wave trough crests the ridge and quickly digs toward the base of the eastern trough during the afternoon and nighttime hours. This pattern will maintain/reinforce the dry airmass across the central Plains and the offshore flow across Southern California. The aforementioned short-wave trough may aid the strengthening of the surface-pressure gradient across Southern California late on Tuesday, which would increase wind speeds to near or above critical fire-weather thresholds. Will hold off on adding a critical area at this time owing to uncertainty in just how strong the winds end up being. Farther east, in the Plains, despite the very dry airmass in place, cooler temperatures and weaker winds on Tuesday will act to limit the overall fire-weather threat. However, if temperatures end up being warmer than forecast or winds are a bit stronger, elevated highlights will become necessary. ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Mon, 12/11/2017 - 12:08

000
AXNT20 KNHC 111808
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
105 PM EST Mon Dec 11 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1715 UTC.

...SPECIAL FEATURES...

A stationary frontal boundary over the western Atlantic from 30N 63W
extends southwestward across eastern Cuba, Jamaica, and into the
southwestern Caribbean Sea. A band of cloudiness and showers
extends about 120 n mi on either side of the front. Due to the
little motion of the boundary, there have been some reports of
notable rainfall accumulations, including 2.32 inches observed at
Montego Bay, Jamaica, during the last 24 hours. The strong pressure
gradient between this front and strong high pressure over Mexico is
still producing gale force winds on the west side of the boundary
over the Caribbean Sea. See the latest NWS High Seas Forecast under
AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast from Liberia near
07N11W to 7N16W to 7N18W. The Intertropical Convergence Zone axis
extends from 7N18W to 3N30W and crosses the Equator near 43W to
Brazil near 1S46W. Isolated moderate convection is from 2N-5N
between 10W-44W.

GULF OF MEXICO...

Fair weather conditions exist across the entire Gulf of Mexico due
to a combination of strong surface high pressure centered over
Mexico and a dry air mass aloft. Surface winds are generally light
and mostly out of the north for most of the region. By tomorrow, a
weak cold front will emerge off the southeastern U.S., which could
bring a brief period of fresh W-NW winds over the northern waters.
Otherwise, quiet conditions are expected to continue for the next
day or two.

CARIBBEAN SEA...

The main weather producer across the region is a stationary front
that is draped across the western portion of the region. Please read
the Special Features section for details about the gale-force winds
in the area. West of the front, northerly flow and a few showers
exist. Generally tranquil conditions exist to the east of the front,
with moderate trade winds and scattered shallow showers covering
much of the eastern and central Caribbean Sea. The front is forecast
to remain stationary while gradually weakening through mid-week.

...HISPANIOLA...

Generally fair weather conditions prevail across the island today,
while a stationary front remains just to the west of the island
across the Windward Passage and eastern Cuba. The front is not
expected to move much, so generally similar weather conditions are
expected over the island during the next day or two.

...ATLANTIC OCEAN...

A mid-to upper-level trough is lifting out of the western Atlantic
Ocean, providing less support for a boundary that is now stationary
over the western Atlantic from 30N 63W southwestern to eastern Cuba.
A band of clouds and showers is within 180 n mi of the front.
Farther east, an upper-level low and accompanying surface trough
from 27N 51W to 15N 55W are producing showers and thunderstorms to
the east of the surface boundary from 15N to 30N between 41W and
51W. The remainder of the basin is fairly quiet, supported by strong
subtropical ridging that is centered just north of the area near 36N
36W.


For additional information please visit
http://www.hurricanes.gov/marine

$$
Jc/mt
Categories: Weather

SPC Day 1 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 09:46
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0944 AM CST Mon Dec 11 2017 Valid 111700Z - 121200Z The ongoing forecast is on track with no changes needed. Gusty offshore winds will continue in southern California - especially in terrain-favored areas of Santa Barbara, Ventura, and Los Angeles counties where 30+ mph wind gusts are possible. Farther east, a broad area of elevated fire weather conditions will develop by mid-afternoon, with critical thresholds (25-35 mph and 12-15% RH) being exceeded briefly in northeastern Colorado and vicinity before sunset. See the previous discussion below for more information. ..Cook.. 12/11/2017 .PREV DISCUSSION... /ISSUED 0136 AM CST Mon Dec 11 2017/ ...Synopsis... Mid-level ridging will persist across the western United States, with a deep trough found across the East. A short-wave trough moving through the mid-level flow across the East will help drive a surface cold front south through the Plains. ...Southern California... Offshore winds will continue through Monday and Monday night, albeit not as strong as in previous days. Coincident with this, warm temperatures and a dry airmass will support minimum relative-humidity values falling into the single digits and teens across much of the area. Additionally, overnight recovery should remain poor, leaving little reprieve from the low relative humidity. The result will be elevated fire-weather conditions. ...Central United States... Temperatures will quickly warm into the 60s and 70s ahead of a surface cold front moving southward through the Plains on Monday. Additionally, a very dry airmass in place as a result of several days of northerly winds across the Plains and Gulf of Mexico scouring out most of what little moisture existed. The dry airmass is borne out in evening (00Z) soundings across the Plains where near-record low precipitable-water values for this time of year are observed. The result will be warm temperatures and relative-humidity values falling to near-critical to critical levels. These warm, dry conditions will combine with winds in the 10-20 mph range to result in elevated to locally critical fire-weather conditions across the region. Stronger winds may exist across northern portions of the highlighted area, but cold-air advection behind the front will allow for the relative humidity to increase, slightly offsetting the impacts of stronger winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

SPC Day 1 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 09:46
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0944 AM CST Mon Dec 11 2017 Valid 111700Z - 121200Z The ongoing forecast is on track with no changes needed. Gusty offshore winds will continue in southern California - especially in terrain-favored areas of Santa Barbara, Ventura, and Los Angeles counties where 30+ mph wind gusts are possible. Farther east, a broad area of elevated fire weather conditions will develop by mid-afternoon, with critical thresholds (25-35 mph and 12-15% RH) being exceeded briefly in northeastern Colorado and vicinity before sunset. See the previous discussion below for more information. ..Cook.. 12/11/2017 .PREV DISCUSSION... /ISSUED 0136 AM CST Mon Dec 11 2017/ ...Synopsis... Mid-level ridging will persist across the western United States, with a deep trough found across the East. A short-wave trough moving through the mid-level flow across the East will help drive a surface cold front south through the Plains. ...Southern California... Offshore winds will continue through Monday and Monday night, albeit not as strong as in previous days. Coincident with this, warm temperatures and a dry airmass will support minimum relative-humidity values falling into the single digits and teens across much of the area. Additionally, overnight recovery should remain poor, leaving little reprieve from the low relative humidity. The result will be elevated fire-weather conditions. ...Central United States... Temperatures will quickly warm into the 60s and 70s ahead of a surface cold front moving southward through the Plains on Monday. Additionally, a very dry airmass in place as a result of several days of northerly winds across the Plains and Gulf of Mexico scouring out most of what little moisture existed. The dry airmass is borne out in evening (00Z) soundings across the Plains where near-record low precipitable-water values for this time of year are observed. The result will be warm temperatures and relative-humidity values falling to near-critical to critical levels. These warm, dry conditions will combine with winds in the 10-20 mph range to result in elevated to locally critical fire-weather conditions across the region. Stronger winds may exist across northern portions of the highlighted area, but cold-air advection behind the front will allow for the relative humidity to increase, slightly offsetting the impacts of stronger winds. ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Mon, 12/11/2017 - 04:50

000
AXNT20 KNHC 111050
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
550 AM EST Mon Dec 11 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
0945 UTC.

...SPECIAL FEATURES...
A stationary front extends across the western Caribbean Sea
waters from the Windward Passage near 20N74W S-SW to 10N80W near
the western Panama coast. Strong high pressure remains to the W
of the front across Cuba...the NW Caribbean Sea...and much of
Central America this morning resulting in near gale to gale force
N winds generally S of 18N W of the front to 83W off the coast of
Nicaragua and Costa Rica. The front is forecast to remain nearly
stationary the next few days from the Windward Passage region to
the coast of Panama with fresh to strong N winds continuing to
diminish gradually through mid-week. See the latest NWS High Seas
Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more
details.

...ITCZ/MONSOON TROUGH...
The monsoon trough extends from the African coast near 06N11W to
06N19W. The Intertropical Convergence Zone axis extends from
06N19W to the Equator near 42W. Isolated moderate convection is
from 04N-06N between 22W-28W.

...DISCUSSION...

GULF OF MEXICO...
A surface ridge extends across the entire basin anchored by a
1030 mb high centered across southern Texas near 28N97W. Light to
gentle N winds are noted W of 90W...and gentle to moderate N
winds are noted E of 90W. The ridging will build in across the
northern Gulf through Monday night with generally gentle to
moderate anticyclonic winds expected across much of the basin. By
Tuesday...the next weak cold front will emerge off the SE CONUS
coast introducing a brief period of fresh W-NW winds to the
northern water Tuesday morning and eastern waters Tuesday
afternoon into the evening. The front will be quick to clear east
of the basin with moderate northerly winds prevailing Wednesday
into Thursday.

CARIBBEAN SEA...
The primary feature across the basin is the stationary front
extending across the western waters generating the near gale to
gale force northerly winds. Scattered showers and tstms are
occurring generally S of 17N between 77W-84W...and within 60 nm
either side of the front N of 17N. Much of this convection is
supported aloft by a divergent upper level pattern on the western
periphery of an upper level anticyclone anchored over northern
Colombia near 10N75W. East of the anticyclonic circulation...dry
northerly flow prevails providing overall stability to the central
and eastern Caribbean this morning. A few isolated showers are
noted on satellite imagery E of 70W...but remain shallow...quick-
moving...and embedded within gentle to moderate trades. The front
is forecast to remain stationary across the western Caribbean and
begin to gradually weaken through mid-week.

...HISPANIOLA...
Fair weather conditions prevail across the island this morning
while a stationary front remains analyzed across the Windward
Passage region. Isolated showers and tstms are possible within 60
nm either side of the front which is expected remains stationary
during the next few days begin on a weakening trend through
Tuesday night.

ATLANTIC OCEAN...
Water vapor imagery indicates a middle to upper level trough over
the eastern CONUS and western North Atlc waters supporting the
Special Features cold front extending from 32N63W to 25N70W
becoming stationary to the Windward Passage and into the SW
Caribbean Sea. Isolated showers are occurring within 120 nm either
side of the front. Otherwise...the remainder of the SW North Atlc
waters are under the influence of a surface ridge anchored over
the Gulf of Mexico and portions of eastern Mexico. Elsewhere...
water vapor imagery indicates a cut-off middle to upper level low
centered near 24N49W that continues to slowly retrograde. A
surface trough extends from 16N54W to 29N48W providing focus for
scattered showers and tstms from 19N-30N between 40W-51W. The
trough is forecast to drift westward across the central Atlc
through Monday night.

For additional information please visit
http://www.hurricanes.gov/marine

$$
HUFFMAN

Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 01:39
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CST Mon Dec 11 2017 Valid 121200Z - 131200Z ...Synopsis... The persistent mid-level, west-to-east ridge-trough pattern across the United States will be reinforced on Tuesday as a short-wave trough crests the ridge and quickly digs toward the base of the eastern trough during the afternoon and nighttime hours. This pattern will maintain/reinforce the dry airmass across the central Plains and the offshore flow across Southern California. The aforementioned short-wave trough may aid the strengthening of the surface-pressure gradient across Southern California late on Tuesday, which would increase wind speeds to near or above critical fire-weather thresholds. Will hold off on adding a critical area at this time owing to uncertainty in just how strong the winds end up being. Farther east, in the Plains, despite the very dry airmass in place, cooler temperatures and weaker winds on Tuesday will act to limit the overall fire-weather threat. However, if temperatures end up being warmer than forecast or winds are a bit stronger, elevated highlights will become necessary. ..Marsh.. 12/11/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 01:39
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CST Mon Dec 11 2017 Valid 121200Z - 131200Z ...Synopsis... The persistent mid-level, west-to-east ridge-trough pattern across the United States will be reinforced on Tuesday as a short-wave trough crests the ridge and quickly digs toward the base of the eastern trough during the afternoon and nighttime hours. This pattern will maintain/reinforce the dry airmass across the central Plains and the offshore flow across Southern California. The aforementioned short-wave trough may aid the strengthening of the surface-pressure gradient across Southern California late on Tuesday, which would increase wind speeds to near or above critical fire-weather thresholds. Will hold off on adding a critical area at this time owing to uncertainty in just how strong the winds end up being. Farther east, in the Plains, despite the very dry airmass in place, cooler temperatures and weaker winds on Tuesday will act to limit the overall fire-weather threat. However, if temperatures end up being warmer than forecast or winds are a bit stronger, elevated highlights will become necessary. ..Marsh.. 12/11/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

SPC Day 1 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 01:38
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CST Mon Dec 11 2017 Valid 111200Z - 121200Z ...Synopsis... Mid-level ridging will persist across the western United States, with a deep trough found across the East. A short-wave trough moving through the mid-level flow across the East will help drive a surface cold front south through the Plains. ...Southern California... Offshore winds will continue through Monday and Monday night, albeit not as strong as in previous days. Coincident with this, warm temperatures and a dry airmass will support minimum relative-humidity values falling into the single digits and teens across much of the area. Additionally, overnight recovery should remain poor, leaving little reprieve from the low relative humidity. The result will be elevated fire-weather conditions. ...Central United States... Temperatures will quickly warm into the 60s and 70s ahead of a surface cold front moving southward through the Plains on Monday. Additionally, a very dry airmass in place as a result of several days of northerly winds across the Plains and Gulf of Mexico scouring out most of what little moisture existed. The dry airmass is borne out in evening (00Z) soundings across the Plains where near-record low precipitable-water values for this time of year are observed. The result will be warm temperatures and relative-humidity values falling to near-critical to critical levels. These warm, dry conditions will combine with winds in the 10-20 mph range to result in elevated to locally critical fire-weather conditions across the region. Stronger winds may exist across northern portions of the highlighted area, but cold-air advection behind the front will allow for the relative humidity to increase, slightly offsetting the impacts of stronger winds. ..Marsh.. 12/11/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

SPC Day 1 Fire Weather Outlook

Weather - Fire Weather - Mon, 12/11/2017 - 01:38
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CST Mon Dec 11 2017 Valid 111200Z - 121200Z ...Synopsis... Mid-level ridging will persist across the western United States, with a deep trough found across the East. A short-wave trough moving through the mid-level flow across the East will help drive a surface cold front south through the Plains. ...Southern California... Offshore winds will continue through Monday and Monday night, albeit not as strong as in previous days. Coincident with this, warm temperatures and a dry airmass will support minimum relative-humidity values falling into the single digits and teens across much of the area. Additionally, overnight recovery should remain poor, leaving little reprieve from the low relative humidity. The result will be elevated fire-weather conditions. ...Central United States... Temperatures will quickly warm into the 60s and 70s ahead of a surface cold front moving southward through the Plains on Monday. Additionally, a very dry airmass in place as a result of several days of northerly winds across the Plains and Gulf of Mexico scouring out most of what little moisture existed. The dry airmass is borne out in evening (00Z) soundings across the Plains where near-record low precipitable-water values for this time of year are observed. The result will be warm temperatures and relative-humidity values falling to near-critical to critical levels. These warm, dry conditions will combine with winds in the 10-20 mph range to result in elevated to locally critical fire-weather conditions across the region. Stronger winds may exist across northern portions of the highlighted area, but cold-air advection behind the front will allow for the relative humidity to increase, slightly offsetting the impacts of stronger winds. ..Marsh.. 12/11/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Sun, 12/10/2017 - 23:03

000
AXNT20 KNHC 110503
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
1203 AM EST Mon Dec 11 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0000 UTC surface analysis and satellite imagery through
0415 UTC.

...SPECIAL FEATURES...
A cold front extends across the SW North Atlc waters from 32N64W
SW to the Windward Passage and then to the SW Caribbean Sea near
11N79W. Strong high pressure continues to build in W of the front
across Cuba...the NW Caribbean Sea...and much of Central America
this evening resulting in near gale to gale force N winds
generally S of 18N W of the front to 83W off the coast of
Nicaragua. As the front creeps eastward and eventually begins to
stall by Monday morning...the remaining boundary will extend from
the Windward Passage region to the coast of Costa Rica with fresh
to strong N winds continuing to diminish gradually through mid-
week. See the latest NWS High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH...
The monsoon trough extends from the African coast near 06N11W to
05N22W. The Intertropical Convergence Zone axis extends from
05N22W to 03N32W to 06N41W. No significant deep convection noted
on satellite imagery at this time.

...DISCUSSION...

GULF OF MEXICO...
A surface ridge extends across the entire basin anchored by a
1031 mb high centered across northern Mexico near 27N100W. Light
to gentle N winds are noted W of 90W...and gentle to moderate N
winds are noted E of 90W. The ridging will build in across the
northern Gulf through Monday night with generally gentle to
moderate anticyclonic winds expected across much of the basin. By
Tuesday...the next weak cold front will emerge off the SE CONUS
coast introducing a brief period of fresh W-NW winds to the
northern water Tuesday morning and eastern waters Tuesday
afternoon into the evening. The front will be quick to clear east
of the basin with moderate northerly winds prevailing Wednesday
into Thursday.

CARIBBEAN SEA...
The primary feature across the basin is the cold front extending
across the western waters generating the near gale to gale force
northerly winds. Scattered showers and tstms are occurring
generally S of 18N between 76W-84W...and within 60 nm either side
of the cold front N of 18N. Much of this convection is supported
aloft by a divergent upper level pattern on the western periphery
of an upper level anticyclone anchored over northern Colombia near
11N75W. East of the anticyclonic circulation...dry northerly flow
prevails providing overall stability to the central and eastern
Caribbean this evening. A few isolated showers are noted on
satellite imagery across the NE Caribbean...but remain quick-
moving and embedded within gentle to moderate trades. The front
is forecast to become stationary across the western Caribbean and
begin to gradually weaken through mid-week.

...HISPANIOLA...
Fair weather conditions prevail across the island this evening
while a cold front remains analyzed across the Windward Passage
region. Isolated showers and tstms are possible within 60 nm
either side of the front which is expected to stall overnight into
Monday and begin a weakening trend through Tuesday night.

ATLANTIC OCEAN...
Water vapor imagery indicates a middle to upper level trough over
the eastern CONUS and western North Atlc waters supporting the
Special Features cold front extending from 32N64W to the Windward
Passage and into the SW Caribbean Sea. Isolated showers are
occurring within 120 nm either side of the front. Otherwise...the
remainder of the SW North Atlc waters are under the influence of
a surface ridge anchored over the Gulf of Mexico and portions of
NE Mexico. Elsewhere...water vapor imagery indicates a cut-off
middle to upper level low centered near 24N48W that continues to
slowly retrograde. A surface trough extends from 20N47W to 29N44W
providing focus for scattered showers and tstms from 19N-28N
between 39W-49W. The trough is forecast to drift westward across
the central Atlc through Monday night.

For additional information please visit
http://www.hurricanes.gov/marine

$$
HUFFMAN

Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Sun, 12/10/2017 - 17:28

000
AXNT20 KNHC 102328
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
628 PM EST Sun Dec 10 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1800 UTC surface analysis and satellite imagery through
2315 UTC.

...SPECIAL FEATURES...

A cold front extends across the west Atlantic waters from 32N66W
to 22N73W, then becomes stationary from that point to 10N80W.
Strong high pressure continues to build west of the front across
the Gulf of Mexico and west Caribbean. With this, the pressure
gradient is strong enough to support gale force winds mainly
between the front and the coasts of Nicaragua, Costa Rica and
northern Panama. These conditions will continue through early
Tuesday. By that time, the front will weaken. See the latest NWS
High Seas Forecast under AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC
for more details.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 07N11W to
05N22W. The Intertropical Convergence Zone extends from 05N22W to
04N36W to 05N52W. No significant convection is observed within
these boundaries at this time.

...DISCUSSION...

GULF OF MEXICO...

Strong surface high pressure prevails across the entire basin
being anchored by a 1036 mb high over northeast Mexico. Deep
layer dry air continues to support fair weather. Scatterometer
data depicts gentle to moderate northerly winds across the basin.
The ridge will prevail across the Gulf through Monday ahead of
the next cold front that will enter the northern portion of the
basin by Tuesday morning. This new front will move across Florida
and the east Gulf through Wednesday supporting fresh northwest
winds mainly across the northeastern waters. Moderate northerly
winds will prevail across the basin through Thursday.

CARIBBEAN SEA...

The main feature in the basin is a stationary front extending from
the Windward Passage near 19N75W to northern Panama. Strong pressure
gradient building west of the front across the west Caribbean is
resulting in gale-force winds between the front and the coasts of
Nicaragua, Costa Rica and northern Panama. See the section above
for details. Scattered showers are within 105 nm on either side
of the front. Deep layer dry air supports fair weather elsewhere.
The front will begin drifting east again during the next 24 hours
reaching the central Caribbean while weakening.

...HISPANIOLA...

Isolated showers are in the Windward Passage due to the proximity
of a stationary front to the west. This activity is forecast to
continue through Tuesday as the front drifts east before dissipating
Wednesday.

ATLANTIC OCEAN...

Southwesterly flow aloft is noted on water vapor imagery over the
west Atlantic between a mid to upper-level trough over the
eastern CONUS and Florida peninsula and an upper-level ridge
anchored over adjacent waters between Panama and Colombia. The
troughing supports the Special Features' cold front, which
extends from 32N66W to the Windward Passage near 19N75W.
Scattered showers are occurring generally within 105 nm along and
east of the front. To the east, a surface trough extends from
30N43W to 22N46W with scattered showers between 38W-47W. The
remainder basin is under the influence of a surface ridge anchored
by a 1030 high centered southwest of the Azores. Expect for the
front to continue drifting east during the next 48 hours while
weakening. The trough over the central Atlantic is forecast to
drift westward through Monday with convection.

For additional information please visit
http://www.hurricanes.gov/marine

$$

ERA

Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Sun, 12/10/2017 - 13:45
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0143 PM CST Sun Dec 10 2017 Valid 111200Z - 121200Z Elevated to locally critical fire weather conditions remain likely across portions of southern California on Monday. Although lighter surface winds (10-20 mph) will be the key limiting factor for a higher fire weather threat, locally critical wind gusts will occur especially in terrain-favored areas due to the persistent offshore gradient. High-impact fire weather concerns remain likely, however, given ongoing large fires and very dry fuel states. Elsewhere, the elevated delineation across the central Plains has been extended eastward to include more of eastern Kansas. Here, gusty northwesterly winds will exceed 30 mph at times near the I-70 corridor (slightly weaker with southward extent) and RH values will fall into the 20-27% range. Fuels are also dry across the region and supportive of rapid fire spread. Spotty elevated fire weather conditions may also extend as far east as southern Missouri and northern Arkansas, although lighter surface flow and somewhat higher RH in those areas preclude any highlights for this outlook. See the previous discussion below for more information. ..Cook.. 12/10/2017 .PREV DISCUSSION... /ISSUED 0133 AM CST Sun Dec 10 2017/ ...Synopsis... Ridging is expected to remain in place over the western CONUS through Day 2/Monday, while a large-scale trough persists over the central/eastern CONUS. Meanwhile, an embedded shortwave trough (and associated mid-level speed maxima) is forecast to ride the western periphery of the larger-scale trough and shift from the northern/central Plains into the southeastern CONUS by the end of the period. At the surface, high pressure -- which has been entrenched over the Great Basin for several days -- will persist, although it will be weaker than previous days. ...Portions of Southern CA... Elevated to locally critical fire weather conditions are forecast Day 2/Monday, as modest weakening of the aforementioned surface high allows winds speeds to weaken a bit from previous days. Generally, sustained wind speeds of 10-20 mph (with higher gusts) are expected. However, there is some potential for stronger winds to occur early Day 2/Monday morning. Despite the somewhat weaker winds, critical RH values (and extremely dry fuels) are anticipated, as the stagnant dry low-level air mass remains in place. A Critical area could be need for portions of Southern CA if trends in guidance suggest stronger wind speeds than are currently anticipated. ...Portions of western NE, eastern CO, western KS, northeastern NM, TX/OK Panhandles, and western OK... Warming of a dry air mass is expected to yield minimum RH values around 15-25% (locally lower) during the afternoon amidst dry/dormant fuels. Additionally, the presence of the aforementioned mid-level speed maxima combined with efficient mixing during the afternoon will foster sustained winds speeds of 15-20 mph (with higher gusts). These conditions support Elevated to locally Critical fire weather conditions. If trends in guidance suggest stronger wind speeds and/or a greater degree of warming/drying, then a Critical area may be needed. ...Portions of Florida... A dry air mass is forecast to continue spreading over the area Day 2/Monday, with minimum RH values around 25-35% developing during the afternoon over the interior. Current expectation is that light winds (e.g., generally less than 10 mph) coupled with relatively unfavorable fuels -- owing to recent precipitation -- are expected to hinder a more robust fire weather threat. However, if trends in guidance suggest stronger winds over the area, then a fire weather area may be needed in future updates. ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Sun, 12/10/2017 - 12:05

000
AXNT20 KNHC 101805
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
105 PM EST Sun Dec 10 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 1200 UTC surface analysis and satellite imagery through
1745 UTC.

...SPECIAL FEATURES...

A cold front extends across the SW North Atlc waters from 30N68W
S-SW to the Windward Passage near 19N75W where it becomes
stationary continuing to western Jamaica and then to northern
Panama. Strong high pressure continues to build west of the
front across the NW and SW Caribbean Sea as well as Honduras and
Nicaragua. This is resulting in gale force winds between the front
and the coasts of Nicaragua, Costa Rica and northern Panama. The
front will remain stationary through Tuesday and will dissipate
Wednesday. Gale force winds are expected to diminish by early
morning Tuesday. See the latest NWS High Seas Forecast under
AWIPS/WMO headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH...

The monsoon trough extends from the African coast near 06N10W to
04N21W. The Intertropical Convergence Zone axis extends from
04N21W to 04N36W to 04N51W. Scattered showers are from 0N to 04N between
the Prime Meridian and 20W.

...DISCUSSION...

GULF OF MEXICO...

Strong surface high pressure prevails across the entire basin
being anchored by a 1035 mb high over NE Mexico and a pair of two
stronger high pressure centers over the NW CONUS. Deep layer dry
air, as shown by CIRA LPW and Water Vapor imagery, continue to
support clear skies. Otherwise, gentle to moderate N winds are
basin-wide. The ridge will prevail across the Gulf through Monday
ahead of the next cold front that will enter the northern basin
Tuesday morning. This new front will move across Florida and the E
Gulf through Wednesday supporting fresh NW winds in the NE basin. Moderate
northerly winds will be across the basin Wednesday into Thursday.

CARIBBEAN SEA...

The main feature in the basin is a stationary front extending from
the Windward Passage near 19N75W continuing to western Jamaica
and then to northern Panama. Strong high pressure building west
of the front across the NW and SW Caribbean Sea is resulting in
gale-force winds between the front and the coasts of Nicaragua,
Costa Rica and northern Panama. Besides the winds, scattered
showers are within 105 nm either side of the front. Isolated
showers are in the Windward Passage extending to Haiti and NW
Dominican Republic due to the proximity of the front. Deep layer
dry air support fair weather elsewhere. The front will remain
stationary through Tuesday and begin to gradually weaken through
mid-week. See special features section for further details.

...HISPANIOLA...

Isolated showers are in the Windward Passage extending to Haiti
and NW Dominican Republic due to the proximity of a stationary
front to the west. This shower activity is forecast to continue
through Tuesday as the front will continue to stall before
dissipating Wednesday.

ATLANTIC OCEAN...

Southwesterly flow aloft is noted on water vapor imagery over the
SW North Atlc between a middle to upper level trough over the
eastern CONUS and Florida peninsula and an upper level ridge
anchored over adjacent waters between Panama and Colombia. The
troughing supports the Special Features cold front which extends
from 30N68W S-SW to the Windward Passage near 19N75W where it
becomes stationary continuing to northern Panama. Scattered
showers and tstms are occurring generally within 190 nm E of the
front while isolated showers are within 120 nm W of it. The
remainder basin is under the influence of a surface ridge anchored
by a pair of 1030's highs SW of the Azores Islands. A weakness in
this ridge is analyzed as a surface trough that extends from
29N42W to 19N47W with scattered to isolated showers from 16N to
28N between 36W and 46W. The front will stall Tuesday morning
while the trough is forecast to drift westward across the
central Atlc through Monday.

For additional information please visit
http://www.hurricanes.gov/marine

$$
Ramos
Categories: Weather

SPC Day 1 Fire Weather Outlook

Weather - Fire Weather - Sun, 12/10/2017 - 09:52
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0951 AM CST Sun Dec 10 2017 Valid 101700Z - 111200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHERN CALIFORNIA... The elevated area across the central plains has been expanded eastward to include more of central South Dakota, central Nebraska, and central Kansas. Latest high-resolution guidance suggests that critical RH values will exist for at least an hour or two this afternoon amidst 10-20 mph northwesterly surface flow and full sunshine during the afternoon. Farther northwest into central Montana, conditions will also reach elevated criteria for a couple of hours, although concerns regarding fuel dryness preclude any highlights at this time. Gusty easterly/northeasterly surface winds will exceed critical criteria in many areas of southern California today as a long-duration Santa Ana event persists. A critical fire weather delineation remains in place for that region. See the previous outlook for more information. ..Cook.. 12/10/2017 .PREV DISCUSSION... /ISSUED 1153 PM CST Sat Dec 09 2017/ ...Synopsis... Overall synoptic pattern will change very little today, with ridging over the western CONUS and broad troughing over much of the central/eastern CONUS. A mid-level shortwave trough (with associated speed maxima) is forecast to dive southward over the northern High Plains late today. Meanwhile, the surface high over the Great Basin -- which has been ensconced over the area for several days -- will remain quasi-stationary while gradually weakening later tonight. ...Portions of Southern CA... The extended Santa Ana offshore wind event is expected to persist Sunday, as the aforementioned surface high over the Great Basin promotes gusty easterly/northeasterly winds. Sustained wind speeds are forecast to generally remain around 20-30 mph, however, stronger gusts around 40-55 mph are possible (especially along the higher terrain). The low-level air mass will change little from previous days, with very dry air (RH values of 5-15%) remaining entrenched over the area. When combined with very dry fuels, these meteorological conditions will promote Critical/Elevated fire weather conditions. While wind speeds are forecast to gradually weaken tonight -- owing to a weakening of the aforementioned surface high and associated pressure gradient -- they will remain breezy enough to keep Elevated to locally Critical conditions through the overnight. ...Portions of eastern WY, southwest SD, western NE, eastern CO, western KS, OK/TX Panhandle, northwest TX, and western OK... A very dry antecedent air mass is forecast to remain in place today, with RH values of 5-15% common over the area. While latest high resolution guidance continues to suggest sustained wind speeds will be only marginal for fire weather concerns (e.g., 10-15 mph), very dry fuels coupled with the dry air mass supports maintenance of the Elevated fire weather area. While greater sustained wind speeds may materialize over the northern High Plains -- due to the proximity of aforementioned mid-level speed maxima -- poor timing with the diurnal heating cycle and cooler temperatures over the area (and thus more marginal RH values) should keep fire weather concerns Elevated to locally Critical. ...Portions of central MT... While gusty westerly winds around 10-20 mph are expected this afternoon and RH values may flirt with Elevated criteria for a few hours, uncertainty regarding the degree of low-level warming/drying is currently too large to introduce a fire weather area. ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

NHC Atlantic Tropical Weather Discussion

NWS Weather - Sun, 12/10/2017 - 04:22

000
AXNT20 KNHC 101022
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
522 AM EST Sun Dec 10 2017

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
0945 UTC.

...SPECIAL FEATURES...
A cold front extends across the SW North Atlc waters from 32N70W
S-SW to eastern Cuba near 21N77W then to offshore of the coast of
Nicaragua near 12N82W. Strong high pressure continues to build in
N and W of the front across western Cuba...the NW Caribbean
Sea...and much of Central America this morning resulting in near
gale to gale force N winds generally S of 17N W of the front.
As the front creeps eastward and eventually begins to stall
through Monday...the near gale to gale force N winds are expected
to bleed southward along the NE Honduras coast and slip along the
Nicaragua coast. By Tuesday...the remaining boundary will extend
from the Windward Passage region to the coast of Costa Rica with
fresh to strong N winds continuing to diminish gradually through
mid-week. See the latest NWS High Seas Forecast under AWIPS/WMO
headers MIAHSFAT2/FZNT02 KNHC for more details.

...ITCZ/MONSOON TROUGH...
The monsoon trough extends from the African coast near 07N12W to
05N18W. The Intertropical Convergence Zone axis extends from
05N18W to 04N36W to the Equator near 46W. Widely scattered
moderate convection is from the Equator to 05N between the Prime
Meridian and 20W.

...DISCUSSION...

GULF OF MEXICO...
A surface ridge axis extends across northern Mexico and the
Yucatan peninsula anchored by a pair of 1033 mb highs centered
near 24N101W. The Special Features cold front has exited the
basin and remains across the SW North Atlc and western Caribbean
Sea waters this morning. Gentle to moderate N winds are noted W
of 90W...and moderate to fresh winds are noted E of 90W. The
ridging will build in across the northern Gulf through Monday with
generally gentle to moderate anticyclonic winds expected across
much of the basin. By Tuesday...the next weak cold front will
emerge off the SE CONUS coast introducing a brief period of fresh
W-NW winds to the north-central and eastern waters. The front
will be quick to clear east of the basin with moderate northerly
winds prevailing Wednesday into Thursday.

CARIBBEAN SEA...
The primary feature across the basin is the cold front extending
across the western waters generating the near gale to gale force
northerly winds. A pre-frontal surface trough extends from 11N79W
to 18N79W and along with the front supports scattered showers and
tstms occurring generally between 74W-84W...on either side of the
cold front. Much of this convection is supported aloft by a
divergent upper level pattern with south-southwesterly flow
occurring between a middle to upper level trough over the eastern
Gulf of Mexico supporting the cold front and an upper level
anticyclone anchored over the central Caribbean near 15N73W. East
of the anticyclonic circulation...dry northerly flow prevails
providing overall stability to the central and eastern Caribbean
this morning. A few isolated showers are noted on satellite
imagery across the NE Caribbean...but remain quick-moving and
embedded within moderate to occasional fresh trades. Other
isolated showers are occurring across the SE Caribbean stretching
from Trinidad to the ABC Islands. The front is forecast to stall
across the western Caribbean Sunday and begin to gradually weaken
through mid-week.

...HISPANIOLA...
Fair weather conditions prevail across the island this morning as
a surface high centered in the central Atlc extends ridging
across the area. Scattered showers and tstms are occurring across
eastern Cuba and the adjacent coastal waters as a cold front is
expected to stall from the Windward Passage region to the SW
Caribbean through Monday.

ATLANTIC OCEAN...
Southwesterly flow aloft is noted on water vapor imagery over the
SW North Atlc between a middle to upper level trough over the
eastern CONUS and Florida peninsula and an upper level ridge
anchored over the central Caribbean Sea. The troughing supports
the Special Features cold front which extends from 32N70W to
eastern Cuba near 21N77W. Scattered showers and tstms are
occurring generally from 20N-32N between 66W-77W. Otherwise...the
remainder of the SW North Atlc waters are under the influence of
a surface ridge axis extending from 32N55W to 22N72W and ridging
building in west of the cold front across the Florida peninsula
and far western waters off the coast of Georgia. Lastly...water
vapor imagery indicates a cut-off middle to upper level low
centered near 25N42W that continues to slowly retrograde. A
surface trough extends from 18N43W to 30N40W providing focus for
scattered showers and widely scattered tstms from 18N-30N between
31W-44W near and E of the trough axis. The trough is forecast to
drift westward across the central Atlc through Monday.

For additional information please visit
http://www.hurricanes.gov/marine

$$
HUFFMAN

Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Sun, 12/10/2017 - 01:34
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0133 AM CST Sun Dec 10 2017 Valid 111200Z - 121200Z ...NO CRITICAL AREAS... ...Synopsis... Ridging is expected to remain in place over the western CONUS through Day 2/Monday, while a large-scale trough persists over the central/eastern CONUS. Meanwhile, an embedded shortwave trough (and associated mid-level speed maxima) is forecast to ride the western periphery of the larger-scale trough and shift from the northern/central Plains into the southeastern CONUS by the end of the period. At the surface, high pressure -- which has been entrenched over the Great Basin for several days -- will persist, although it will be weaker than previous days. ...Portions of Southern CA... Elevated to locally critical fire weather conditions are forecast Day 2/Monday, as modest weakening of the aforementioned surface high allows winds speeds to weaken a bit from previous days. Generally, sustained wind speeds of 10-20 mph (with higher gusts) are expected. However, there is some potential for stronger winds to occur early Day 2/Monday morning. Despite the somewhat weaker winds, critical RH values (and extremely dry fuels) are anticipated, as the stagnant dry low-level air mass remains in place. A Critical area could be need for portions of Southern CA if trends in guidance suggest stronger wind speeds than are currently anticipated. ...Portions of western NE, eastern CO, western KS, northeastern NM, TX/OK Panhandles, and western OK... Warming of a dry air mass is expected to yield minimum RH values around 15-25% (locally lower) during the afternoon amidst dry/dormant fuels. Additionally, the presence of the aforementioned mid-level speed maxima combined with efficient mixing during the afternoon will foster sustained winds speeds of 15-20 mph (with higher gusts). These conditions support Elevated to locally Critical fire weather conditions. If trends in guidance suggest stronger wind speeds and/or a greater degree of warming/drying, then a Critical area may be needed. ...Portions of Florida... A dry air mass is forecast to continue spreading over the area Day 2/Monday, with minimum RH values around 25-35% developing during the afternoon over the interior. Current expectation is that light winds (e.g., generally less than 10 mph) coupled with relatively unfavorable fuels -- owing to recent precipitation -- are expected to hinder a more robust fire weather threat. However, if trends in guidance suggest stronger winds over the area, then a fire weather area may be needed in future updates. ..Elliott.. 12/10/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

SPC Day 2 Fire Weather Outlook

Weather - Fire Weather - Sun, 12/10/2017 - 01:34
SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0133 AM CST Sun Dec 10 2017 Valid 111200Z - 121200Z ...NO CRITICAL AREAS... ...Synopsis... Ridging is expected to remain in place over the western CONUS through Day 2/Monday, while a large-scale trough persists over the central/eastern CONUS. Meanwhile, an embedded shortwave trough (and associated mid-level speed maxima) is forecast to ride the western periphery of the larger-scale trough and shift from the northern/central Plains into the southeastern CONUS by the end of the period. At the surface, high pressure -- which has been entrenched over the Great Basin for several days -- will persist, although it will be weaker than previous days. ...Portions of Southern CA... Elevated to locally critical fire weather conditions are forecast Day 2/Monday, as modest weakening of the aforementioned surface high allows winds speeds to weaken a bit from previous days. Generally, sustained wind speeds of 10-20 mph (with higher gusts) are expected. However, there is some potential for stronger winds to occur early Day 2/Monday morning. Despite the somewhat weaker winds, critical RH values (and extremely dry fuels) are anticipated, as the stagnant dry low-level air mass remains in place. A Critical area could be need for portions of Southern CA if trends in guidance suggest stronger wind speeds than are currently anticipated. ...Portions of western NE, eastern CO, western KS, northeastern NM, TX/OK Panhandles, and western OK... Warming of a dry air mass is expected to yield minimum RH values around 15-25% (locally lower) during the afternoon amidst dry/dormant fuels. Additionally, the presence of the aforementioned mid-level speed maxima combined with efficient mixing during the afternoon will foster sustained winds speeds of 15-20 mph (with higher gusts). These conditions support Elevated to locally Critical fire weather conditions. If trends in guidance suggest stronger wind speeds and/or a greater degree of warming/drying, then a Critical area may be needed. ...Portions of Florida... A dry air mass is forecast to continue spreading over the area Day 2/Monday, with minimum RH values around 25-35% developing during the afternoon over the interior. Current expectation is that light winds (e.g., generally less than 10 mph) coupled with relatively unfavorable fuels -- owing to recent precipitation -- are expected to hinder a more robust fire weather threat. However, if trends in guidance suggest stronger winds over the area, then a fire weather area may be needed in future updates. ..Elliott.. 12/10/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more
Categories: Weather

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