000 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