[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202352
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE NOV 20 2012

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.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO
07N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
07N17W TO 06N20W TO 08N28W TO 07N33W TO 08N41W TO 06N48W TO
08N57W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 03N-11N
BETWEEN 26W-40W. MUCH OF THIS CONVECTION IS ENHANCED BY A MIDDLE
TO UPPER LEVEL LOW CENTERED NEAR 17N41W PROVIDING MAXIMUM
DIFFLUENCE EAST OF THE UPPER LEVEL TROUGH AXIS.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES FAIRLY ZONAL WESTERLY FLOW OVER
MUCH OF THE GULF THIS EVENING...HOWEVER A MID-LEVEL SHORTWAVE
TROUGH IS PROGRESSING OVER THE LOWER MISSISSIPPI RIVER VALLEY
CURRENTLY AND PROVIDING FOR SOME ISOLATED SHOWERS OVER INLAND
PORTIONS OF THE FLORIDA PANHANDLE...SOUTHERN ALABAMA...AND
GEORGIA. ELSEWHERE OVER THE GULF...SURFACE RIDGING ANCHORED OVER
THE NW GULF WATERS IS PROVIDING NORTH-NORTHEASTERLY WINDS IN THE
RANGE OF 10 TO 20 KT WITH THE SURFACE RIDGE AXIS EXTENDING
SOUTHWARD ALONG THE EASTERN MEXICO COAST. DUE TO LOW-LEVEL
CONVERGENCE...A SURFACE TROUGH IS ANALYZED FROM 18N92W TO 23N93W
AND IS PROVIDING FOCUS FOR MOISTURE CONVERGENCE AND ISOLATED
SHOWERS S OF 24N BETWEEN 88W-97W. THE RIDGING IS FORECAST TO
REMAIN ANCHORED OVER THE SE CONUS WITH N-NE WINDS PERSISTING
THROUGH EARLY THURSDAY.

CARIBBEAN SEA...
SOUTHWESTERLY TO WESTERLY UPPER LEVEL FLOW DOMINATES OVER THE
CARIBBEAN THIS EVENING AND IS PROVIDING FOR MAXIMUM UPPER LEVEL
DIFFLUENCE EAST OF AN UPPER LEVEL TROUGH AXIS FROM 20N87W TO
10N92W. LOW-LEVEL CONVERGENCE IS ALSO MAXIMIZED OVER THE SW
CARIBBEAN EAST OF THE UPPER LEVEL TROUGH AND IS GENERATING
SCATTERED SHOWERS AND TSTMS FROM 08N-16N BETWEEN 76W-83W.
LOW-LEVEL MOISTURE AND THE CONVECTIVE DEBRIS CLOUDINESS STREAMS
NORTHEASTWARD ACROSS PORTIONS OF HISPANIOLA AND PUERTO RICO THIS
EVENING INTO AN UPPER LEVEL TROUGH OVER THE SW NORTH ATLC WITH
AXIS ALONG 67W. A FEW  ALTHOUGH THE REGION LACKS A SURFACE
BOUNDARY...ENOUGH MIDDLE TO UPPER LEVEL DYNAMICS ARE IN PLACE TO
GENERATE ISOLATED SHOWERS AND TSTMS WITHIN 120 NM EITHER SIDE OF
A LINE FROM 20N65W TO 15N76W. OTHERWISE...THE OVERALL SYNOPTIC
PATTERN IS LIKELY TO CHANGE LITTLE OVER THE NEXT FEW DAYS AS A
LOW PRESSURE AREA REMAINS OVER THE SW NORTH ATLC WITH TROUGHING
DIPPING SOUTHWARD ACROSS THE EASTERN CARIBBEAN AND RIDGING
HOLDING IN PLACE OVER THE NW CARIBBEAN.

ATLANTIC OCEAN...
A COMPLEX AREA OF SURFACE LOW PRESSURE IS LOCATED OVER THE SW
NORTH ATLC IS CONTINUES TO BE SUPPORTED WITH A MIDDLE TO UPPER
LEVEL LOW CENTERED NEAR 35N64W. THE MAIN 997 MB OCCLUDED LOW IS
CENTERED NEAR 35N65W AND EXTENDS A COLD FRONT INTO THE
DISCUSSION AREA NEAR 32N60W THEN SW TO 24N67W. LOCATED IN AN
AREA OF MAXIMUM UPPER LEVEL DIFFLUENCE...SCATTERED SHOWERS AND
TSTMS ARE OCCURRING WITHIN 420 NM EAST OF THE COLD FRONT.
ISOLATED SHOWERS ARE ELSEWHERE SE OF THE COLD FRONT FROM 18N-24N
BETWEEN 52W-67W. SECONDARY AND TERTIARY WAVES OF ENERGY FOLLOW
IN WAKE OF THE PRIMARY COLD FRONT AS TWO WEAK LOWS ARE EASTWARD
MOVING ALONG 29N BETWEEN 68W AND 76W. FARTHER EAST...THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE
OF SURFACE RIDGING ANCHORED BY A 1025 MB HIGH CENTERED NEAR
36N35W. HOWEVER...WATER VAPOR IMAGERY INDICATES A MIDDLE TO
UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM 32N23W TO 24N29W AND
SUPPORTS A COLD FRONT ANALYZED FROM 32N17W TO 29N31W THAT
BECOMES STATIONARY TO 30N44W TO 32N50W...BRIDGING THE PREVIOUSLY
MENTIONED SURFACE RIDGE. ISOLATED SHOWERS ARE OCCURRING WITHIN
60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. FINALLY...A MIDDLE TO
UPPER LEVEL LOW IS CENTERED NEAR 17N41W AND CONTINUES TO
PROVIDING MAXIMUM UPPER LEVEL DIFFLUENCE E OF 40W. WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 11N-22N
BETWEEN 27W-42W.

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

$$
HUFFMAN




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