000 AXNT20 KNHC 171756 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON OCT 17 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURE... A BROAD AREA OF LOW PRESSURE COVERS THE FAR NW CARIBBEAN AND THE SE GULF OF MEXICO CENTERED AROUND A 1004 MB LOW JUST N OF THE YUCATAN PENINSULA NEAR 22N89W. THE CIRCULATION AROUND THIS SYSTEM COVERS A GREAT PORTION OF THE BASIN...RAGING FROM 15 KT TO NEAR GALE FORCE CRITERIA S OF 28N E OF 91W. THIS SYSTEM IS INTERACTING WITH AN UPPER LEVEL SHORTWAVE/TROUGH THAT IS SHEARING THE CONVECTION TO THE EAST OF THE LOW LEVEL CIRCULATION E OF 89W FROM 20N-27N. SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE IN THIS REGION...WITH THE POSSIBILITY OF STRONG GUSTY OUT FLOW BOUNDARIES AND WATER SPOUTS. DUE TO THE COMPLEX SCENARIO INVOLVING THE ENVIRONMENT AROUND THE SYSTEM...IT IS IMPORTANT TO MENTION THAT THE SYSTEM HAS GENERATED MULTIPLE LOW LEVEL CENTERS SEEN ON VISIBLE SATELLITE IMAGERY OVER THE PAST 6 HOURS...AND CURRENT LOCATION OF THE MAIN CIRCULATION IS SOMEWHAT DIFFICULT TO PIN DOWN. CONDITIONS ARE EXPECTED TO BECOME LESS FAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT WITHIN THE NEXT DAY OR TWO... AND NOW THERE IS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES GENERALLY NORTHWARD AT 4-9 KT. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL AND GUSTY WINDS ARE EXPECTED OVER WESTERN CUBA...THE FLORIDA KEYS...AND SOUTH FLORIDA DURING THE NEXT DAY OR SO. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED FROM CAPE VERDE ISLANDS NEAR 16N23W TO 7N28W W AT 10-15 KT. WAVE IS WELL DEFINED IN THE LOW LEVEL CLOUD FIELD AND IS EMBEDDED WITHIN A DEEP SURGE OF MOISTURE DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE FROM 6N-15N BETWEEN 22W-30W. TROPICAL WAVE IS ANALYZED IN THE CENTRAL TROPICAL ATLC FROM 14N41W TO 6N45W MOVING W 10-15 KT. WAVE IS MOVING THROUGH A REGION OF UNFAVORABLE GROWTH AND HAS BECOME LEES DEFINED ON SATELLITE IMAGERY. NO SIGNIFICANT CONVECTION IS AROUND THIS SYSTEM. TROPICAL WAVE IS ANALYZED OVER THE ERN CARIBBEAN FROM 17N64W TO 10N66W MOVING 10-15 KT. WAVE IS BEING SUPPRESSED BY A DRY AND SUBSIDENT AIRMASS ALOFT INTRUDING ACROSS THE ERN AND N CENTRAL BASIN ON WATER VAPOR IMAGERY. WEAK CYCLONIC TURNING IS OBSERVED ON THE LOW LEVEL CLOUD FIELD ALONG THE WAVE AXIS. NO SIGNIFICANT CONVECTION IS AROUND THIS SYSTEM. ...THE ITCZ/THE MONSOON TROUGH... DUE TO THE LARGE CYCLONIC WIND FIELD ASSOCIATED TO THE TROPICAL WAVES...THE OCEANIC MONSOON TROUGH REMAINS INLAND OVER NRN AFRICA. CONSEQUENTLY...THE ITCZ IS DISRUPTED BY THE PRESENCE OF THESE TROPICAL WAVES. NEVERTHELESS...A WEAK 1011 MB LOW IS ANALYZED NEAR 10N40W. SCATTERED WEAK CONVECTION SURROUNDS THE LOW CENTER FROM 6N-14N BETWEEN 36W-42W. ...DISCUSSION... GULF OF MEXICO... THE MAIN AREA OF ACTIVE WEATHER CONTINUES TO FOCUS AROUND THE SPECIAL FEATURE LOW IMPACTING THE SE GULF. REFER TO THE SPECIAL FEATURE SECTION ABOVE FOR MORE DETAILS. FAIR WEATHER CONDITIONS ARE ELSEWHERE OUTSIDE THE CONVECTION ASSOCIATED TO THIS SYSTEM. THE FAIR WEATHER AND CLEARING SKIES TO THE NW OF THE SYSTEM ARE WELL ASSOCIATED TO STRONG SUBSIDENCE AND DRY AIR IN THE MID AND UPPER LEVELS OF THE ATMOSPHERE NOTICED ON WATER VAPOR IMAGERY... AS WELL AS WEAK SURFACE RIDGE OF HIGH PRESSURE ANCHORED OVER S CENTRAL GEORGIA. CARIBBEAN SEA... MOST OF THE CARIBBEAN BASIN IS EXPERIENCING FAIR WEATHER CONDITIONS THIS AFTERNOON...EXCEPT FOR THE FAR NW BASIN INCLUDING THE YUCATAN CHANNEL...AND THE FAR SW BASIN N OF PANAMA. THE BENIGN WEATHER IS OBSERVED AS A DRY AND SUBSIDENT AIRMASS ALOFT INTRUDES ACROSS THE ERN AND N CENTRAL BASIN ON WATER VAPOR IMAGERY. WHILE THE CONVECTION OVER THE FAR NW BASIN IS ATTACHED TO THE SPECIAL FEATURE LOW...THE CONVECTION OVER THE SW BASIN IS RELATED TO MONSOONAL FLOW ACROSS THIS AREA GENERATING SCATTERED HEAVY SHOWERS AND ISOLATED THUNDERSTORMS S OF 11N BETWEEN 75W-83W. OTHERWISE...LIGHT EASTERLY TRADE FLOW PREDOMINATES ACROSS THE AREA...BECOMING SSE IN RESPONSE OF THE LOWER PRESSURES RELATED TO THE SPECIAL FEATURE LOW. A TROPICAL WAVE MOVES ACROSS THE ERN BASIN WITHOUT ANY SIGNIFICANT CONVECTION...SEE ABOVE FOR MORE DETAILS. ATLANTIC OCEAN... A BROAD UPPER TROUGH COVERS THE NW ATLC N OF THE DISCUSSION AREA AND SUPPORTING A FRONTAL BOUNDARY THAT ENTERS THE REGION NEAR 32N64W AS A SURFACE TROUGH EXTENDING SW TO THE BAHAMA ISLANDS NEAR ELEUTHERA ISLAND. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 80 NM ON EITHER SIDE OF THE TROUGH AXIS. AN ELONGATED UPPER LEVEL CIRCULATION CENTERED NEAR 20N54W IS WRAPPED IN DRY AIR ALOFT. THE FLOW ASSOCIATED TO THIS CIRCULATION IS DRAWING THE UPPER DRY AIRMASS IN TO THE ERN AND N CENTRAL CARIBBEAN. TO THE E OF THIS CIRCULATION...A SUBTROPICAL JET STREAK IS DEPICTED ON MODEL DATA SUPPORTING AN UPPER LEVEL CIRCULATION AND ITS SURFACE REFLECTION CENTERED NEAR 32N34W. THE CONVECTION ASSOCIATED TO THIS SYSTEM IS WELL REMOVED TO THE E OF IT...N OF 27N BETWEEN 24W-40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA