[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 110000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT DEC 10 2011

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 2345 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH ENTERS THE ATLC WATERS ACROSS THE COAST OF
GUINEA-BISSAU NEAR 12N16W TO 6N20W. THE ITCZ CONTINUES FROM THIS
POINT WESTWARD ALONG 3N30W 4N40W TO 5N48W. SCATTERED MODERATE
CONVECTION IS WITHIN 90 NM ON EITHER SIDE OF THE ITCZ BETWEEN
20W-40W.

...DISCUSSION...

GULF OF MEXICO...
A STRONG 1037 MB HIGH IS MOVING ACROSS THE ERN CONUS THIS
EVENING. THE MOVEMENT OF THIS FEATURE IS CREATING A TIGHT
SURFACE PRESSURE GRADIENT OVER MOST OF THE NRN HALF OF THE
GULF...WITH MARINE OBSERVATIONS INDICATING GUSTY NE WINDS UP TO
25 KT N OF 24N. SPEED CONVERGENCE FLOW IS NOTICED NEAR THE TEXAS
AND MEXICO COAST N OF TAMPICO W OF 94W. DOPPLER RADAR IMAGERY
INDICATES SCATTERED WEAK SHOWERS IN THIS REGION. BROAD SURFACE
TROUGHINESS COVERS THE FLORIDA PENINSULA INCLUDING THE STRAITS
AND NW CUBA. SLOW MOVING SCATTERED HEAVY SHOWERS AND
THUNDERSTORMS ARE S OF 26N E OF 83W. OVERCAST LOW LEVEL
STRATOCUMULUS CLOUDS WITH A FEW POSSIBLE ISOLATES SHOWERS ARE
ELSEWHERE ACROSS THE DISCUSSION AREA. THE OVERALL ACTIVITY
ACROSS THE GULF IS EXPECTED TO REMAIN SIMILAR OVER THE NEXT 24
HOURS AS AN ELONGATED UPPER LEVEL SHORTWAVE MOVES ACROSS NRN
BASIN. WHILE SIMILARITIES REMAIN BETWEEN COMPUTER MODELS...THE
RAIN ACTIVITY IS LIKELY TO SPREAD TO THE CENTRAL BASIN DURING
THE FORECAST PERIOD.

CARIBBEAN SEA...
A SHEAR LINE IS ANALYZED OVER THE NW CARIBBEAN FROM 20N82W TO
CENTRAL HONDURAS NEAR 15N86W. MARINE OBSERVATIONS IN THIS REGION
SUGGESTED THE WIND SPEED GRADIENT ALONG THE LINE HAS DECREASED
DURING THE PAST 6 HOURS...YET THE SHOWER/THUNDERSTORM ACTIVITY
REMAINS WITHIN 170 NM W OF THE AXIS. A SIMILAR SHEAR LINE
EXTENDS INTO THE FAR NE CARIBBEAN ALONG BARBUDA TO NEAR 16N69W.
A RECENT SATELLITE SCATTEROMETER PASS OVER THIS AREA REVEALED
E-NE CONVERGING LOW LEVEL WINDS INCREASING FROM 5 KT T0 25 KT
FROM S TO N ALONG THE AXIS...GENERATING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS AFFECTING THE WATERS NEAR PUERTO RICO AND
THE LESSER ANTILLES N OF DOMINICA E OF 70W. THE CONVECTION IN
THIS REGION IS EXPECTED TO CONTINUE BUT DECREASE IN INTENSITY
OVER THE NEXT 24 HOURS. BROAD CYCLONIC TURNING IS OBSERVED IN
THE MULTI LAYER CLOUD FIELD OVER THE SW BASIN...IN RESPONSE OF
THE LOWER PRESSURE REGION ASSOCIATED TO THE MONSOON TROUGH
ANALYZED ACROSS COSTA RICA INTO NRN COLOMBIA. SCATTERED SHOWERS
AND THUNDERSTORMS ARE S OF 16N W OF 75W. THE REMAINDER OF THE
CARIBBEAN SEA IS UNDER FAIR WEATHER THIS EVENING.

ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE MOVES ACROSS THE SE CONUS SUPPORTING A
COLD FRONT EXTENDING ACROSS THE WRN N ATLC. AS THE FRONT ENTERS
OUR REGION IT BECOMES NEARLY STATIONARY/SURFACE TROUGH ALONG
3275 INTO THE FLORIDA PENINSULA S OF DAYTONA BEACH. AS THE UPPER
SHORTWAVE MOVES OFF THE SEABOARD...THE FRONTAL BOUNDARY IS
EXPECTED TO LIFT NE INTO THE N CENTRAL ATLC WITHIN THE NEXT 12
HOURS. A BROAD UPPER LEVEL LOW SPINS NEAR 22N57W SUPPORTING A
SURFACE TROUGH EXTENDING FROM 25N50W ALONG 18N50W TO 17N58W
WHERE IT BECOMES A SHEAR LINE EXTENDING W INTO THE CARIBBEAN
ALONG THE ISLAND OF DOMINICA. SCATTERED MODERATE SHOWERS AND
THUNDERSTORMS ARE WITHIN 200-250 NM E OF THE SURFACE TROUGH OF
15N. BROAD CYCLONIC TURNING 15-25 KT IS OVER A GREAT PORTION OF
THE CENTRAL ATLC SURROUNDING THE SURFACE TROUGH...WITH GALE
FORCE WINDS FROM 23N TO 29N BETWEEN 47W AND 54W...GENERATING
SEAS 12 TO 18 FT IN NE SWELL. WEATHER CONDITIONS ELSEWHERE
ACROSS THE BASIN REMAIN FAIR DUE TO A LARGE/STRONG 1033 MB HIGH
CENTERED NEAR 35N38W. THE CENTRAL ATLC SURFACE TROUGH WILL MOVE
WESTWARD DURING THE NEXT 24 HOURS. AT THE SAME TIME...A BROAD
SURFACE RIDGE CURRENTLY MOVING ACROSS THE ERN CONUS WILL
APPROACH THE FAR WRN ATLC. THIS WILL MAKE THE SURFACE PRESSURE
GRADIENT OVER THE WRN ATLC TO CONTRACT AND GENERATE GUSTY NE
WINDS UP TO 30 KT W OF 65W N OF 23N DURING THE TIME PERIOD.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA




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