000 AXNT20 KNHC 242352 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON SEP 24 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION JERRY IS EXPECTED TO DISSIPATE LATER TONIGHT. AT 24/2100 UTC IT WAS CENTERED NEAR 41.8N 42.7W...OR ABOUT 775 NM...1400 KM...WEST-NORTHWEST OF THE AZORES...MOVING NE AT 20 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 FOR MORE DETAILS. SATELLITE IMAGES INDICATE THAT THE CENTER IS NOW NEAR THE SOUTHERN EDGE OF A SMALL MASS OF DEEP CONVECTION. HOWEVER A STRONG COLD FRONT IS NEARING THE AREA...AND THE ASSOCIATED VIGOROUS EXTRATROPICAL CYCLONE SHOULD ABSORB JERRY IN 12 HOURS OR SO. THERE ARE THREE AREAS OF LOW PRESSURE IN ATLANTIC BASIN THAT COULD BECOME TROPICAL DEPRESSIONS AT ANY TIME OVER THE NEXT DAY OR SO. FROM EAST TO WEST... AN AREA OF LOW PRESSURE...ANALYZED 1010 MB...ASSOCIATED WITH A TROPICAL WAVE IS LOCATED ABOUT 1475 NM EAST OF THE SOUTHERN WINDWARD ISLANDS. THIS LARGE SYSTEM IS WELL ORGANIZED...AND WILL LIKELY BECOME A TROPICAL DEPRESSION LATER TONIGHT AS IT MOVES WEST-NORTHWESTWARD AT ABOUT 15 MPH. LATEST SATELLITE IMAGERY SHOWS GOOD BANDING FEATURES. A CURVED BAND OF MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 220 NM OF THE LOW IN THE NW QUADRANT. ANOTHER BAND OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120-150 NM SOUTH OF THE LOW CENTER. AN AREA OF LOW PRESSURE...ANALYZED 1010 MB...ASSOCIATED WITH A TROPICAL WAVE ALONG 60W/61W HAS BECOME A LITTLE BETTER DEFINED THIS EVENING A SHORT DISTANCE EAST OF MARTINIQUE IN THE WINDWARD ISLANDS. ALTHOUGH SHOWERS AND THUNDERSTORMS WITH THIS SYSTEM ARE NOT WELL-ORGANIZED AT THIS TIME....THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES NORTHWESTWARD AT ABOUT 15 MPH. THE LOW IS EXPECTED TO BRING SQUALLY WEATHER TO PORTIONS OF THE WINDWARD AND LEEWARD ISLANDS THROUGH TUESDAY...AND INTO THE VIRGIN ISLANDS AND PUERTO RICO BY WEDNESDAY. INTERESTS IN THESE AREAS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. CLUSTERS OF MODERATE CONVECTION ARE MAINLY N OF LOW CENTER COVERING FROM 14N-16N BETWEEN 58W-61W. THE SMALL AREA OF LOW PRESSURE OVER THE SOUTHWESTERN GULF OF MEXICO HAS BECOME A LITTLE LESS ORGANIZED THIS EVENING DUE TO UNFAVORABLE UPPER-LEVEL WINDS. HOWEVER...THE UPPER FLOW IS EXPECTED TO BECOME MORE FAVORABLE FOR DEVELOPMENT OVER THE NEXT DAY OR SO...AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION TOMORROW AS IT DRIFTS SLOWLY AND ERRATICALLY. SCATTERED MODERATE CONVECTION IS MAINLY E OF THE LOW AFFECTING A GOOD PORTION OF THE GULF. DIFFLUENCE BETWEEN AN UPPER TROUGH EXTENDING THROUGH ERN TEXAS AND NE MEXICO...AND UPPER RIDGING OVER THE CENTRAL GULF IS ENHANCING THIS CONVECTIVE ACTIVITY. AT THE SAME TIME... STRONG UPPER LEVEL SLY WINDS AHEAD OF THIS UPPER TROUGH ARE KEEPING THE CONVECTION SHEARED FROM THE LOW LEVEL CENTER. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 41W S OF 18N MOVING W 10-15 KT. THIS WAVE HAS MAINTAINED GOOD WWD CONTINUITY IN BOTH SATELLITE HOVMOLLER DIAGRAMS AND THE MIMIC TPW ANIMATION SINCE EMERGING OFF THE COAST OF AFRICA A FEW DAYS AGO. HOWEVER...THE LARGE LOW PRESSURE SYSTEM E OF THE WAVE...ERN MOST SPECIAL FEATURE DISCUSSED ABOVE...CONTINUES TO OVERTAKE THIS WAVE. THE REMAINING SHOWER/TSTM ACTIVITY ASSOCIATED WITH THE WAVE IS LIMITED. THIS WAVE WILL BE DROPPED FROM THE 00Z SFC MAP. TROPICAL WAVE IS ALONG 60W/61W AFFECTING THE LESSER ANTILLES. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A WEAK TROPICAL WAVE IS ALONG 87W/88W S OF 20N MOVING W 10-15 KT. THE WAVE IS BENEATH STRONG UPPER NELY WINDS WHICH ARE HELPING TO INDUCE SCATTERED MODERATE CONVECTION OVER CENTRAL AMERICA AND THE YUCATAN PENINSULA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N12W 7N30W 6N42W 11N57W. BESIDES THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES/TROPICAL WAVES...SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS ALONG THE COAST OF AFRICA FROM 6N-12N BETWEEN 10W-16W. THIS ACTIVITY MAY BE ASSOCIATED WITH THE NEXT TROPICAL WAVE. SIMILAR CONVECTION IS WITHIN ABOUT 200 NM S OF AXIS BETWEEN 21W-25W. DISCUSSION... GULF OF MEXICO... MAIN WEATHER FEATURE ACROSS THE GULF IS THE SMALL AREA OF LOW PRES LOCATED OVER THE SW GULF...WITH POSSIBLE TROPICAL CYCLONE FORMATION. AS OF 2100 UTC...THE LOW WAS NEAR 22.5N93.5W WITH A TROUGH EXTENDING THROUGH THE LOW FROM 26N93W TO THE EASTERN PART OF THE BAY OF CAMPECHE NEAR 18N91W. SEE SPECIAL FEATURES ABOVE. A DIFFLUENT PATTERN ALOFT BETWEEN AN UPPER HIGH OVER THE CENTRAL GULF AND AN UPPER TROUGH OVER THE ATLC IS ENHANCING CONVECTION OVER THE SOUTH-CENTRAL FLORIDA PENINSULA...THE SE GULF AND MOST OF ISLE OF CUBA WHERE SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED TSTMS ARE SEEN. THE MOSAIC DOPPLER RADAR FROM THE SE US SHOWS SHOWERS AND ISOLATED TSTMS MOVING FROM EAST TO WEST ACROSS THE PENINSULA. THE MOST CONCENTRATED SHOWER/TSTM ACTIVITY IS OBSERVED OVER THE STRAITS OF FLORIDA. CARIBBEAN SEA... ATTENTION REMAINS FOCUSED ON THE AREA OF LOW PRES ASSOCIATED WITH A TROPICAL WAVE ALONG 60W/61W. REFER TO SPECIAL FEATURE FOR MORE DETAILS. COMPUTER MODELS HAVE MOISTURE FROM THIS SYSTEM AFFECTING THE LESSER ANTILLES TUE AND THE UK/US VIRGIN ISLANDS AND PUERTO RICO WED. PEOPLE LIVING IN OR NEARBY FLOODED AREAS... SMALL STREAMS AND EVEN LARGER RIVER AS WELL AS ALONG THE CORDILLERA CENTRAL IN PUERTO RICO SHOULD CLOSELY MONITOR THIS SYSTEM. SCATTRED MODERATE CONVECTION IS OVER PANAMA AND COSTA RICA DUE TO THE PRESENCE OF THE ITCZ. TRADES ARE MOSTLY LIGHT ACROSS THE BASIN...BUT ARE EXPECTED TO INCREASE AS THE CURRENTLY LOW/TROPICAL WAVE OVER THE LESSER ANTILLES MOVES WWD ACROSS THE AREA. ALOFT...A FAIRLY WELL DEFINED RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE AREA. ATLANTIC OCEAN... MOST OF THE ACTIVE SFC FEATURES ARE DISCUSSED IN THE SPECIAL FEATURES SECTION ABOVE. ELSEWHERE AT THE SFC...WEAK HIGH PRES RIDGING CONTROLS THE W ATLC AND THE SE U.S.. TROUGHING DOMINATES MUCH OF THE CENTRAL ATLC AREA. MODERATE RIDGING TAKES OVER IN THE E ATLC ANCHORED BY A 1031 MB HIGH LOCATED NORTH 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 NEAR 14N48W WITH LIMITED SHOWER ACTIVITY. IN THE MID AND UPPER LEVELS...A VERY BROAD TROUGH ENTERS THE FORECAST AREA NEAR 31N68W...THEN CONTINUES SW TO THE CENTRAL BAHAMAS. UPPER DIFFLUENT BETWEEN THIS TROUGH AND AN UPPER HIGH OVER THE GULF IS SUPPORTING THE CONVECTIVE ACTIVITY OVER THE BAHAMAS AND CUBA. UPPER DRY AIR IS N OF 26N WEST OF 70W. A SWLY UPPER LEVEL FLOW AHEAD OF THE TROUGH DOMINATES THE CENTRAL ATLC N OF 20N. AN AMPLIFIED UPPER RIDGE IS SEEN E OF THE TROUGH WITH THE AXIS EXTENDING NE FROM AN UPPER HIGH SITUATED NEAR 14N57W TO BEYOND 32N33W. A LARGE UPPER LOW IS LOCATED E OF THE RIDGE W OF THE MADEIRA ISLANDS NEAR 33N19W. $$ GR