[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192336
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT NOV 19 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
2315 UTC.

...SPECIAL FEATURES...

AN UPPER LEVEL LOW IS CENTERED NEAR 21N54W WITH AN UPPER LEVEL
TROUGH AXIS ORIENTED N-NW TO S-SE ALONG 27N58W TO 17N53W. THIS
UPPER LEVEL FEATURE SUPPORTS A COMPLEX AREA OF SURFACE TROUGHING
ACROSS THE CENTRAL ATLC WITH ONE SURFACE TROUGH ANALYZED FROM
12N55W TO 20N53W TO 31N52W...AND ANOTHER WEAKENING SURFACE
TROUGH FROM 20N57W TO 26N59W. THE DOMINANT EASTERLY SURFACE
TROUGH REMAINS THE FOCUS FOR POTENTIAL TROPICAL OR SUB-TROPICAL
CYCLONE GENESIS WITHIN THE NEXT 48 HOURS. THE UPPER LEVEL
TROUGHING WILL PERSIST ACROSS THE CENTRAL ATLC IN SUPPORT OF
SCATTERED MODERATE CONVECTION OCCURRING THIS EVENING EAST OF THE
SURFACE TROUGH FROM 16N-32N BETWEEN 45W-53W. STRONG UPPER LEVEL
DIFFLUENCE CONTINUES TO ENHANCE THIS CONVECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
10N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
08N21W TO 06N30W TO 06N50W. SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION IS FROM 03N-09N BETWEEN 21W-31W. SCATTERED
MODERATE CONVECTION IS FROM 04N-08N BETWEEN 16W-21W...AND FROM
03N-09N BETWEEN 31W-40W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES MOSTLY WEST-SOUTHWESTERLY UPPER
LEVEL FLOW IN DRY AIR ALOFT IS IN CONTROL ACROSS THE GULF BASIN
THIS EVENING. THIS UPPER LEVEL PATTERN IS RESULTING IN MUCH OF
THE GULF REMAINING UNDER THE INFLUENCE OF A SURFACE RIDGE WITH
AXIS EXTENDING SW FROM NORTHERN FLORIDA NEAR 30N82W TO
EAST-CENTRAL MEXICO NEAR 21N97W. FAIR WEATHER AND OVERALL STABLE
CONDITIONS ABOUND ACROSS THE BASIN WITH ONLY A SMALL AREA OF
ISOLATED SHOWERS OCCURRING FROM 27N-31N BETWEEN 84W-88W.
ELSEWHERE...E TO SE WINDS ARE IN THE RANGE OF 10-20 KT THIS
EVENING...WITH THOSE STRONGER 20 KT WINDS LOCATED WITHIN THE
FLORIDA STRAITS AND ADJACENT SE GULF WATERS...AND ALSO STRONGER
20 KT SOUTHERLY RETURN FLOW ACROSS PORTIONS OF THE NW GULF. THE
RIDGE IS FORECAST TO REMAIN NEARLY STATIONARY ACROSS THE GULF
WITH LITTLE CHANGE IN CONDITIONS THROUGH THE DURATION OF THE
WEEKEND INTO MONDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE AXIS EXTENDS FROM SOUTHERN MEXICO ALONG 19N
TO NEAR JAMAICA THAT CONTINUES FARTHER EASTWARD TO AN UPPER
LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 15N68W. SOUTH OF
THE RIDGE AXIS AND IN BETWEEN THE INFLUENCE OF THE TWO
ANTICYCLONES IS A WEAK UPPER LEVEL LOW CENTERED NEAR 13N80W AND
ASSOCIATED TROUGHING ACROSS THE SW CARIBBEAN. INCREASED LOW TO
MIDDLE LEVEL MOISTURE IS NOTED ON WATER VAPOR IMAGERY S OF 15N W
OF 75W WHICH IS SUPPORTIVE OF WIDELY SCATTERED SHOWER AND
ISOLATED TSTM ACTIVITY OVER THIS AREA...INCLUDING INLAND
PORTIONS OF PANAMA...COSTA RICA...NICARAGUA...AND EASTERN
HONDURAS. MUCH OF THE REMAINDER OF THE CARIBBEAN SEA BASIN IS
UNDER THE INFLUENCE OF NE TO E WINDS AT THE SURFACE WITH
ISOLATED SHOWERS OCCURRING W OF 75W AND MOVING GENERALLY
WESTWARD ON THE TRADE WINDS. AS NE WINDS CONTINUE OVER THE SW
NORTH ATLC ACROSS THE GREATER ANTILLES AND INTO NORTHERN
PORTIONS OF THE BASIN...STRONGER WINDS ARE ANTICIPATED THROUGH
LATE MONDAY IN THE VICINITY OF THE MONA AND WINDWARD PASSAGES.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM THE CENTRAL NORTH ATLC
WATERS NEAR 45N48W TO THE DISCUSSION BORDER NEAR 32N65W IN
SUPPORT OF A STATIONARY FRONT ANALYZED FROM 33N50W TO 30N70W
BECOMING A SHEAR LINE TO EAST OF THE CENTRAL BAHAMAS NEAR
26N74W. WITH A STRONG UPPER LEVEL SHORTWAVE TROUGH LOCATED
ACROSS THE CENTRAL ATLC SOUTH OF THE FRONTAL BOUNDARY AND
ASSOCIATED WITH THE SPECIAL FEATURE MENTIONED ABOVE...A LARGE
AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM
16N-32N BETWEEN 45W-53W. THIS AREA OF CONVECTION IS MORE LIKELY
ASSOCIATED WITH THE SPECIAL FEATURES TROUGHING...HOWEVER...THE
FRONT CONTINUES TO SLOWLY MERGE WITH THIS AREA N OF 30N. UPPER
LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL TROUGHING CONTINUES TO
ENHANCE THIS CONVECTION. TAILING SOUTHWESTWARD FROM THE
STATIONARY FRONT...A SHEAR LINE AXIS REMAINS EVIDENT ON EARLIER
MORNING ASCAT PASSES FROM 19/1318 UTC AND 19/1458 UTC. ISOLATED
SHOWERS ARE ALSO NOTED ON SATELLITE IMAGERY WITHIN 150 NM NORTH
OF THE SHEAR LINE. THE REMAINDER OF THE EASTERN ATLC IS UNDER
THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH
CENTERED NEAR 34N37W. NE TO E WINDS IN THE RANGE OF 15 TO 20 KT
CONTINUE ON THE SOUTHEASTERN PERIPHERY OF THE RIDGE S OF 32N E
OF 35W.

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

$$
HUFFMAN




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