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