[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211127
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST FRI NOV 21 2008

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 53W/54W S OF 13N MOVING W NEAR 10 KT.
SATELLITE IMAGERY INDICATES THAT THIS WAVE COINCIDES WITH A
WELL-DEFINED INVERTED-V PATTERN IN CLOUD COVERAGE...WHERE CIMSS
WAVETRAK PRODUCT INDICATES A MAXIMUM IN LOW LEVEL CYCLONIC
CIRCULATION. ADDITIONALLY...A MAXIMUM IN DEEP LAYER MOISTURE
COINCIDES WITH THIS WAVE BASED ON TOTAL PRECIPITABLE WATER
PRODUCT FROM CIMSS. SCATTERED SHOWERS ARE OCCURRING WITHIN 120
NM EITHER SIDE OF THE WAVE AXIS N OF 9N. TRENDS IN SATELLITE
IMAGERY INDICATE THAT THIS TROPICAL WAVE IS NOW DETACHED FROM A
NEARLY STATIONARY AREA OF LOW LEVEL CYCLONIC CIRCULATION FARTHER
NORTH...WHICH IS BEING ANALYZED AS A SURFACE TROUGH EXTENDING
FROM 19N50W TO 16N51W TO 14N52W.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 11N14W 7N22W 5N32W 5N42W 3N52W.
SCATTERED MODERATE CONVECTION IS FROM 6N-8N BETWEEN 27W-30W.
SIMILAR CONVECTION IS WITHIN 150 NM N OF THE ITCZ AXIS BETWEEN
32W-39W.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS UPPER TROUGH OVER THE E CONUS IS SUPPORTING A SURFACE
COLD FRONT THAT IS MOVING SOUTHWARD ACROSS THE N GULF REGION.
THIS COLD FRONT EXTENDS FROM THE FLORIDA PANHANDLE NEAR 30N85W
TO 29N90W TO 29N94W TO S TEXAS NEAR 27N98W. A NEARLY SOLID LOW
LEVEL CLOUD BAND AROUND 15 NM WIDE ACCOMPANIES THIS FRONT.
NATIONAL WEATHER SERVICE DOPPLER RADARS NEAR THE GULF COAST ALSO
INDICATE SCATTERED SHOWERS WITHIN 30 NM N OF THE FRONT.
ADDITIONALLY...SATELLITE IMAGERY INDICATES THAT A WEAK WAVE IS
PRESENT ALONG THE FRONT BETWEEN 91W-95W...WHERE INCREASED LOW
LEVEL CONVERGENCE IS ENHANCING THE SHOWER ACTIVITY. IN THE WAKE
OF THIS COLD FRONT...AN EVEN COOLER AND DRIER AIRMASS...
CHARACTERIZED AS A MODIFIED CONTINENTAL POLAR AIRMASS...IS IN
PLACE. THIS AIRMASS IS BEING SUPPORTED BY A 1040 MB SURFACE HIGH
OVER THE CENTRAL PLAINS OF THE CONUS...WITH AN ASSOCIATED
SURFACE RIDGE EXTENDING INTO THE NW GULF. FREEZE WARNINGS ARE IN
EFFECT FOR TONIGHT THROUGH SATURDAY MORNING FOR N PORTIONS OF
FLORIDA. AS COOLER AIR IS BEING ADVECTED OVER THE RELATIVELY
WARMER GULF WATERS...WEAK LOW LEVEL INSTABILITY IS SUPPORTING
SCATTERED STRATOCUMULUS CLOUDS ACROSS THE GULF MAINLY S OF 26N.
HOWEVER...SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS HIGHER IN
THE ATMOSPHERE ARE INHIBITING DEEP CONVECTION ACROSS THE GULF
REGION. ADDITIONALLY...STRONG N TO NE SURFACE WINDS ARE FORECAST
TO BLOW THROUGH THE ISTHMUS OF TEHUANTEPEC RESULTING IN GALE
FORCE WINDS IN THE E PACIFIC REGION BEGINNING AT 21/1200 UTC.

CARIBBEAN SEA...
IN THE SW CARIBBEAN...A 1009 MB SURFACE LOW IS LOCATED N OF
PANAMA NEAR 10N80W. ADDITIONALLY...A SURFACE STATIONARY FRONT
EXTENDS FROM THIS SURFACE LOW TO 14N79W TO 16N75W...WITH A
SURFACE COLD FRONT EXTENDING FROM 16N75W TO E OF HISPANIOLA NEAR
18N68W. LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW AND SURFACE
FRONTS IS INTERACTING WITH DEEP LAYER MOISTURE OVER THE S
CARIBBEAN TO GENERATE SCATTERED SHOWERS AND THUNDERSTORMS OVER
THE S CARIBBEAN S OF 14N W OF 73W. THIS ACTIVITY IS BEING
ENHANCED BY UPPER LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER
RIDGE PRESENT OVER THE W CARIBBEAN...WITH THE AXIS OF THIS UPPER
RIDGE EXTENDING FROM N COLOMBIA NEAR 12N72W TO 16N80W TO THE NW
CARIBBEAN NEAR 20N85W. OVER THE E CARIBBEAN...UPPER LEVEL
DIVERGENCE IS INTERACTING WITH DEEP LAYER MOISTURE TO SUPPORT
SCATTERED SHOWERS AND THUNDERSTORMS S OF 16N E OF 70W.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH OVER THE W ATLC IS SUPPORTING A SURFACE
COLD FRONT THAT EXTENDS FROM E OF HISPANIOLA NEAR 18N68W TO
24N56W TO 32N49W TO N OF THE DISCUSSION AREA. ISOLATED SHOWERS
ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THIS COLD FRONT. TO
THE W OF THIS COLD FRONT...A MODIFIED CONTINENTAL POLAR AIRMASS
IS IN PLACE...WITH TEMPERATURES BELOW SEASONAL AVERAGES ACROSS
FLORIDA AND SCATTERED STRATOCUMULUS CLOUDS BETWEEN THIS FRONT
AND 79W. FARTHER TO THE E...A 1015 MB SURFACE LOW IS CENTERED
NEAR 27N44W...WITH SCATTERED SHOWERS FROM 26N-29N BETWEEN
40W-45W. ALSO...AN UPPER TROUGH IS PRESENT OVER THE E ATLC N OF
24N E OF 40W WITH AN ASSOCIATED SURFACE TROUGH EXTENDING FROM
28N36W TO 25N34W TO 21N34W. LOW LEVEL CONFLUENCE IN THE VICINITY
OF THIS SURFACE TROUGH IS SUPPORTING SCATTERED SHOWERS FROM
23N-29N BETWEEN 25W-36W...WHICH IS BEING ENHANCED BY UPPER LEVEL
DIVERGENCE ASSOCIATED WITH A MID/UPPER-LEVEL WIND SPEED MAXIMUM.
FARTHER TO THE S...A SURFACE TROUGH EXTENDS FROM 19N50W TO
16N51W TO 14N52W...WITH SCATTERED SHOWERS WITHIN 120 NM EITHER
SIDE OF THIS FEATURE. THIS SURFACE TROUGH IS NOW DETACHED FROM
THE TROPICAL WAVE CURRENTLY ALONG 53W/54W.

$$
COHEN


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