[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230521
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN NOV 23 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 67W/68W S OF 18N MOVING W 10-15 KT. CIMSS
WAVETRAK PRODUCT INDICATES A MAXIMUM IN LOW LEVEL CYCLONIC
CIRCULATION IN THE VICINITY OF THIS WAVE. 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
13N.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 9N12W 8N24W 9N32W 9N44W 6N58W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-14N
BETWEEN 15W-29W. SCATTERED MODERATE CONVECTION IS FROM 5N-10N
BETWEEN 33W-39W.

...DISCUSSION...

GULF OF MEXICO...
STRONG WESTERLY UPPER LEVEL WINDS COVER THE GULF REGION. AT THE
SURFACE...A STATIONARY FRONT EXTENDS FROM W CUBA NEAR 22N84W TO
23N89W TO N OF THE YUCATAN PENINSULA NEAR 22N81W TO 22N94W...AND
A SURFACE TROUGH OVER THE W GULF EXTENDS FROM 27N97W TO 24N97W
TO 21N95W. LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED SHOWERS
WITHIN 60 NM OF THE SURFACE FRONT AND SURFACE TROUGH. OVER THE N
AND E GULF...A COOLER AND DRIER AIRMASS...CHARACTERIZED AS A
MODIFIED CONTINENTAL POLAR AIRMASS...IS IN PLACE. THIS AIRMASS
IS BEING SUPPORTED BY A 1035 MB SURFACE HIGH OVER SE NORTH
CAROLINA NEAR 35N79W...WITH AN ASSOCIATED SURFACE RIDGE
EXTENDING ACROSS THE NE GULF. 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 N OF 24N W OF 84W. 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 BLOWING THROUGH
THE ISTHMUS OF TEHUANTEPEC RESULTING IN GALE FORCE WINDS IN THE
E PACIFIC REGION. THESE WINDS ARE FORECAST TO DIMINISH BELOW
GALE FORCE AT 24/0000 UTC.

CARIBBEAN SEA...
IN THE SW CARIBBEAN...LOW LEVEL CONVERGENCE IN THE VICINITY OF A
1009 MB SURFACE LOW ALONG THE THE PANAMA-COSTA RICA BORDER IS
INTERACTING WITH DEEP LAYER MOISTURE OVER THE W CARIBBEAN TO
RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS OVER THE CARIBBEAN
S OF 13N W OF 76W...INCLUDING COASTAL AREAS OF PANAMA AND
COSTA RICA. 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 11N74W TO 17N82W TO THE NW CARIBBEAN NEAR
20N85W. ALSO...A SURFACE STATIONARY FRONT EXTENDS FROM W CUBA
NEAR 22N84W TO N OF THE YUCATAN PENINSULA NEAR 22N88W...WITH
SCATTERED SHOWERS WITHIN 60 NM OF THIS FRONT. OVER THE
E CARIBBEAN...UPPER LEVEL DIVERGENCE IS INTERACTING WITH DEEP
LAYER MOISTURE TO SUPPORT SCATTERED SHOWERS AND THUNDERSTORMS
S OF 16N BETWEEN 67W-72W. THIS ACTIVITY IS BEING ENHANCED BY LOW
LEVEL CONVERGENCE ASSOCIATED WITH THE TROPICAL WAVE ALONG
67W/68W DISCUSSED IN THE TROPICAL WAVES SECTION ABOVE.
ALSO...FOR LOCATIONS N OF 14N BETWEEN 69W-75W IN THE E
CARIBBEAN...NE TO E SURFACE WINDS OF 20 TO 30 KT ARE FORECAST TO
OCCUR THROUGH MONDAY NIGHT...WITH GUSTS TO GALE FORCE ACROSS THE
WINDWARD PASSAGE.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL TROUGH OVER THE W ATLC IS SUPPORTING A
SURFACE COLD FRONT THAT EXTENDS FROM W CUBA NEAR 22N84W TO
26N64W TO 32N58W TO NE 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 THE COAST OF THE SE CONUS. THIS RELATIVELY COOLER AND DRIER
AIRMASS IS BEING SUPPORTED BY A 1035 MB SURFACE HIGH OVER
SE NORTH CAROLINA NEAR 35N79W...WITH AN ASSOCIATED SURFACE RIDGE
EXTENDING ACROSS THE W ATLC. TO THE E...A SURFACE TROUGH EXTENDS
FROM 30N56W TO A 1018 MB SURFACE LOW NEAR 25N58W TO 22N57W...
WITH ANOTHER SURFACE TROUGH EXTENDING FROM 16N58W TO A 1012 MB
SURFACE LOW NEAR 15N53W TO 14N47W. ISOLATED SHOWERS ARE
OCCURRING WITHIN 60 NM EITHER SIDE OF THESE SURFACE LOWS AND
SURFACE TROUGHS. FARTHER TO THE E...AN UPPER TROUGH IS PRESENT
OVER THE E ATLC N OF 10N E OF 43W WITH AN UPPER LOW NEAR 30N36W.
AN ASSOCIATED SURFACE TROUGH EXTENDS FROM A 1014 MB SURFACE LOW
NEAR 23N34W TO 21N31W TO 16N34W. LOW LEVEL CONVERGENCE NEAR THE
SURFACE TROUGH AND SURFACE LOW IS SUPPORTING SCATTERED SHOWERS
FROM 20N-26N BETWEEN 24W-36W...WHICH IS BEING ENHANCED BY UPPER
LEVEL DIVERGENCE IN THE VICINITY OF A MID/UPPER-LEVEL WIND SPEED
MAXIMUM.

$$
COHEN




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