000 AXNT20 KNHC 250602 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE SEP 25 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0530 UTC. ...SPECIAL FEATURES... TROPICAL STORM JERRY HAS OPENED UP INTO A SHARP TROUGH AND IS NO LONGER A TROPICAL CYCLONE...AND THUS THE LAST ADVISORY HAS BEEN ISSUED BY THE NHC. AT 25/0300 UTC IT WAS CENTERED NEAR 44.5N 37.5W...OR ABOUT 610 NM...1135 KM...NORTHWEST OF THE AZORES...MOVING NE AT 20 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WINDS ARE 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 FOR MORE DETAILS. JERRY HAS DISSIPATED WITHIN A LARGE EXTRATROPICAL LOW...AND WILL BE REMOVED FROM THE SPECIAL FEATURE SECTION ON THE NEXT DISCUSSION. TROPICAL DEPRESSION TWELVE HAS FORMED IN THE EASTERN ATLANTIC. AT 25/0300 UTC T.D. 12 WAS NEAR 10.1N 36.2W OR ABOUT 1475 NM E OF THE SOUTHERN WINDWARD ISLANDS...MOVING W-NW AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT1/WTNT32 KNHC FOR MORE DETAILS. T.D. 12 IS LARGE SYSTEM WITH SCATTERED MODERATE CONVECTION OVER MUCH OF THE AREA FROM 5N-15N BETWEEN 31W-43W. SOME STRENGTHENING IS FORECAST AND THE DEPRESSION COULD BECOME A TROPICAL STORM LATER TODAY...AS IT CONTINUES ON A WNW TRACK S OF A MID LEVEL RIDGE. A 1011 MB LOW PRESSURE AREA IS NEAR 14N61W ASSOCIATED WITH A TROPICAL WAVE MOVING THROUGH THE LESSER ANTILLES. SHOWER ACTIVITY ASSOCIATED WITH THIS SYSTEM HAS DIMINISHED THIS EVENING. SATELLITE IMAGERY AND METEO-FRANCE RADAR DATA FROM MARTINIQUE DEPICT ISOLATED SHOWERS AND TSTMS FROM 13N-21N BETWEEN 57W-63W. THIS SYSTEM STILL HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR TWO AS IT MOVES NORTHWESTWARD THROUGH THE LEEWARD ISLANDS NEAR 10-15 KT. THE LOW IS EXPECTED TO BRING SQUALLY WEATHER TO PORTIONS OF THE LEEWARD ISLANDS THROUGH TUESDAY...AND INTO THE VIRGIN ISLANDS AND PUERTO RICO BY WEDNESDAY. AS OF 25/0300 UTC A 1010 MB LOW IS OVER THE SW GULF OF MEXICO NEAR 22N94W. A SFC TROUGH EXTENDS THROUGH THE LOW ALONG 26N95W 22N94W 19N91W. SHOWER ACTIVITY ASSOCIATED WITH THIS SMALL SYSTEM IS MINIMAL THIS EVENING. HOWEVER...UPPER LEVEL WINDS ARE EXPECTED TO BECOME MORE FAVORABLE FOR DEVELOPMENT...AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS IT DRIFTS SLOWLY AND ERRATICALLY. A SMALL CLUSTER OF MODERATE CONVECTION IS NOTED WITHIN 60NM NE QUADRANT ONLY. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 61W AFFECTING THE LESSER ANTILLES. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A WEAK TROPICAL WAVE IS ALONG 89W S OF 19N MOVING W 10-15 KT. WAVE REMAINS DIFFICULT TO LOCATE WITH ITS POSITION BASED MAINLY ON CONTINUITY FROM PREVIOUS ANALYSES. A CLUSTER OF MODERATE CONVECTION IS OVER THE NRN YUCATAN AND ADJACENT GULF WATERS FROM 19N-23N BETWEEN 88W-91W...BUT THIS MAY BE MORE ASSOCIATED WITH THE SFC TROUGHING EXTENDING SE FROM THE LOW IN THE SW GULF...AND DIFFLUENT FLOW ALOFT AROUND UPPER RIDGING. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N12W 6N20W 11N33W 6N47W 12N58W. BESIDES THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES/TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS E OF 25W. ANOTHER CLUSTER OF MODERATE CONVECTION IS FURTHER N...NEAR THE COAST OF AFRICA FROM 9N-12N BETWEEN 11W-18W. DISCUSSION... GULF OF MEXICO... MAIN WEATHER FEATURE ACROSS THE GULF IS THE SMALL AREA OF LOW PRES LOCATED OVER THE SW GULF WHICH COULD BECOME A TROPICAL CYCLONE OVER THE NEXT COUPLE OF DAYS. SEE SPECIAL FEATURES ABOVE. ABUNDANT DEEP LAYER MOISTURE IS OVER THE BASIN E OF 95W...EXCEPT FOR VERY DRY MID TO UPPER AIR NOTED OVER THE FAR NE PORTION. LIGHTNING DATA DEPICTS SCATTERED TSTMS OFFSHORE CENTRAL FLORIDA FROM 25N-29N BETWEEN 83W-87W...AND ALSO NW OF THE YUCATAN PENINSULA S OF 23N BETWEEN 88W-93W. THE DOMINANT UPPER FEATURE IS THE ANTICYCLONE CENTERED NEAR 25N90W...WITH TROUGHING AFFECTING THE FAR W AND E PORTIONS. ELSEWHERE AT THE SFC...RIDGING EXTENDS INTO THE NE GULF AROUND HIGH PRES CENTERED JUST OFF THE MID ATLANTIC COAST IN THE WRN ATLC. THIS PATTERN WILL PRODUCE MODERATE ELY FLOW OVER THE N GULF THROUGH WED AS IT INTERACTS WITH THE LOW IN THE SW PORTION. CARIBBEAN SEA... THE MAIN WEATHER FEATURE IN THE CARIBBEAN IS ASSOCIATED WITH THE TROPICAL WAVE AND ASSOCIATED LOW PRESSURE AREA MOVING THROUGH THE LESSER ANTILLES...SEE SPECIAL FEATURE SECTION ABOVE. OTHERWISE THE BASIN IS FAIRLY TRANQUIL. DEEP MOISTURE AND A FEW ISOLATED TSTMS ARE AFFECTING THE FAR NW PORTION W OF 86W...AND ALSO OFFSHORE CUBA N OF 19N. THIS ACTIVITY SEEMS MOSTLY ASSOCIATED WITH UPPER DIVERGENCE AROUND THE PERIPHERY OF THE UPPER HIGH OVER THE GULF. SIMILAR ACTIVITY IS OVER HAITI E OF AN UPPER TROUGH AXIS. UPPER SLY FLOW BETWEEN THIS TROUGH AND AN UPPER RIDGE OVER THE ERN CARIBBEAN IS ADVECTING HIGH CLOUDS N/NE E OF 76W. TRADES REMAIN LIGHT TO MODERATE ACROSS THE BASIN...BUT WINDS/SEAS COULD INCREASE A BIT OVER THE ERN PORTION OVER THE NEXT COUPLE OF DAYS...IN ASSOCIATION WITH THE WAVE/LOW CURRENTLY MOVING THROUGH THE LESSER ANTILLES. ATLANTIC OCEAN... MOST OF THE ACTIVE SFC FEATURES ARE DISCUSSED IN THE SPECIAL FEATURES SECTION ABOVE. ELSEWHERE AT THE SFC...WEAK HIGH PRES RIDGING AN ELY FLOW CONTROL THE W ATLC. ELONGATED TROUGHING DOMINATES MUCH OF THE CENTRAL ATLC AREA...ENTERING THE AREA NEAR 32N40W AND CONTINUING SW TO NEAR 24N61W. ISOLATED SHOWERS/TSTMS ARE GENERALLY WITHIN 150NM EITHER SIDE OF THIS TROUGH. MODERATE RIDGING TAKES OVER IN THE E ATLC ANCHORED BY A 1032 MB HIGH LOCATED WELL NE OF THE AZORES. THIS PATTERN IS PRODUCING MODERATE TRADES IN THE E ATLC...EXCEPT STRONGER NEAR THE NW COAST OF AFRICA WHERE THE PRES GRADIENT TIGHTENS. A WEAK 1012MB LOW IS OVER THE TROPICAL ATLC NEAR 14N49W WITH LIMITED SHOWER ACTIVITY. THIS LOW APPEARS TO HAVE OPENED UP INTO A TROUGH BASED ON A ASCAT PASS NEAR 0000 UTC...AND WILL BE ANALYZED ACCORDINGLY ON THE 0600 UTC MAP. IN THE MID AND UPPER LEVELS...AN UPPER LOW NEAR 29N71W HAS TROUGHING OVER MUCH OF THE WRN ATLC. UPPER DIFFLUENT BETWEEN THE TROUGHING AND THE UPPER HIGH OVER THE GULF IS SUPPORTING NUMEROUS SHOWERS AND TSTMS OVER THE STRAITS OF FLORIDA...WRN BAHAMAS...AND NEAR THE COAST OF SE FLORIDA S OF 27N W OF 75W. VERY DRY AIR IS OVER THE REMAINDER OF THE WRN ATLC N OF 27N W OF 70W. SW/WSW FLOW AHEAD OF THE UPPER LOW DOMINATES THE CENTRAL ATLC N OF 20N. AN AMPLIFIED UPPER RIDGE IS SEEN E OF THE TROUGHING EXTENDING NE FROM AN UPPER HIGH SITUATED NEAR 15N60W TO BEYOND 32N33W. A LARGE UPPER LOW IS LOCATED E OF THE RIDGE W OF THE MADEIRA ISLANDS NEAR 32N21W. THIS APPEARS TO BE PRODUCING ISOLATED SHOWER ACTIVITY N OF 30N BETWEEN 18W-22W...BUT IS ONLY GENERATING PATCHES OF HIGH CLOUDINESS ELSEWHERE. $$ MW