000 AXNT20 KNHC 302325 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN SEP 30 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 FEATURE... STRONG SHEAR HAS TAKEN ITS TOLL ON TROPICAL DEPRESSION MELISSA AND THE FINAL ADVISORY HAS BEEN ISSUED. ONLY VERY SMALL SHORT LIVED BURSTS OF CONVECTION ARE ASSOCIATED WITH THE SYSTEM. CURRENTLY...SCATTERED MODERATE IS FROM 16N-17N BETWEEN 33W-35W. AS OF 30/21Z...THE WEAKENING SYSTEM WAS CENTERED NEAR 16.3N 34.0W OR ABOUT 575 NM WEST OF THE CAPE VERDE ISLANDS...MOVING WNW AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE LIES ACROSS THE SRN CAPE VERDE ISLANDS ALONG 24W S OF 15N MOVING W 15 KT OVER THE PAST 24 HOURS. THIS LOW AMPLITUDE WAVE HAS BECOME A LITTLE LESS DEFINED SINCE MOVING OFF THE AFRICAN COAST A DAY OR SO AGO. NIGHT CHANNEL VIS IMAGERY AND DERIVED WINDS SHOW A RATHER NARROW NW-SE TITLED AREA OF LOW TO MID LEVEL TURNING IN THE ASSOCIATED CLOUDINESS. CONVECTIVE ACTIVITY IS MINIMAL...ONLY ISOLATED SHOWERS AND TSTMS ARE WITHIN 180 NM OF THE AXIS. TROPICAL WAVE IS ALONG 41W S OF 14N MOVING W 10 KT. THIS WEAK WAVE IS BARELY IDENTIFIABLE ON SATELLITE IMAGERY DUE TO THE LACK OF ANY ORGANIZED CLOUDINESS. THE MIMIC TPW ANIMATION DOES REVEAL A SLIGHT MOISTURE BULGE MOVING W...LIKELY ASSOCIATED WITH THIS WEAK WAVE. THE NRN PORTION OF A TROPICAL WAVE ALONG 89W EXTENDS ACROSS CENTRAL AMERICA. THERE IS A CONSIDERABLE AREA OF DISORGANIZED CLOUDINESS...SHOWERS AND TSTMS ENHANCED BY THIS LOW-LEVEL FEATURE. HOWEVER...BASED ON THE STRUCTURE AND OVERALL LITTLE MOVEMENT SINCE YESTERDAY DIFFLUENCE ALOFT IS LIKELY THE PRIMARY CULPRIT. MORE ON THIS ACTIVITY IN THE CARIBBEAN DISCUSSION BELOW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N11W 5N26W 8N39W 9N60W. BESIDES FOR THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED SHOWERS AND TSTMS ARE WITHIN 360 NM S OF THE AXIS BETWEEN 20W-40W. A CLUSTER OF MODERATE CONVECTION IS ALONG AND JUST OFF THE AFRICAN COAST FROM 10N-12N E OF 17W. DISCUSSION... GULF OF MEXICO... RATHER STRONG NELY WINDS...15-25 KT...IS OBSERVED ACROSS THE E GULF. THIS STRONG FLOW IS ASSOCIATED WITH A TIGHT PRES PATTERN SET UP BETWEEN A VERY HEALTHY 1035 MB HIGH OFF THE NRN NEW ENGLAND COAST AND A STALLED FRONT WHICH EXTENDS FAR TO THE S OVER NW CUBA. BUOY DATA IN THE REGION SHOWS AN INCREASE IN SEA HEIGHTS WITH A FEW REPORTING 8 FT. BESIDES FOR THE STRONG WINDS...THE WEATHER IS RATHER TRANQUIL WITH ONLY SCATTERED LOW TO MID LEVEL CLOUDS ACROSS THE REGION. THIS FAIR WEATHER IS BEING PRODUCED BY LARGE SCALE STRONG SUBSIDENCE E OF 95W ON THE BACK SIDE OF AN UPPER LOW CENTERED JUST W OF FT MYERS FLORIDA. ONE EXCEPTION IN THE WIDESPREAD FAIR WEATHER IS OVER THE EXTREME SE PORTION WHERE MOSAIC DOPPLER RADAR SHOWS SCATTERED SHOWERS AND TSTMS PRESSING SW ACROSS SE FLORIDA...THE KEYS AND INTO THE STRAITS. FOR DETAILS ON THIS ACTIVITY REFER TO THE ATLANTIC DISCUSSION BELOW. FARTHER W...AN UPPER RIDGE IS CENTERED OVER CENTRAL MEXICO PRODUCING SOME HIGH CLOUDINESS ACROSS THE REGION W OF 95W. CARIBBEAN SEA... SHOWERS AND TSTMS ARE AFFECTING A GOOD PORTION OF THE CARIBBEAN SEA THIS EVENING. STARTING IN THE W CARIB...THE MAIN TRIGGERS ARE A TROPICAL WAVE LOCATED OVER CENTRAL AMERICA AND A DIFFLUENT PATTERN BETWEEN WLY FLOW ON THE S SIDE OF AN UPPER LOW AND ELY FLOW ON THE SW PERIPHERY OF A RIDGE OVER MEXICO. THIS INSTABILITY AND LIFT IS PRODUCING DISORGANIZED SCATTERED SHOWERS AND TSTMS S OF 18N W OF 78W. A SEPARATE AREA OF SIMILAR ACTIVITY LIES OVER THE CENTRAL CARIB N OF 16N BETWEEN 70W-77W. THE FORCING HERE IS CONVERGENCE NEAR THE BASE OF A SW ATLC LOW-LEVEL TROUGH AND AGAIN DIFFLUENCE ALOFT BETWEEN THE UPPER LOW IN THE SE GULF AND A TITLED UPPER RIDGE WHICH RUNS FROM COLOMBIA ACROSS HISPANIOLA. SHOWERS AND TSTMS ARE MORE ISOLATED IN COVERAGE ACROSS THE E CARIB ROUGHLY E OF 66W. THIS LESS ORGANIZED ACTIVITY IS ASSOCIATED WITH DEBRIS CLOUDINESS SPREAD OVER FROM THE CENTRAL CARIB AND THEN LIFTED BY THE DEEP LAYERED LOW PRES SYSTEM...REMNANTS OF KAREN...JUST E OF THE AREA. MORE ON THIS SYSTEM IN THE ATLANTIC DISCUSSION BELOW. CLUSTERS OF MODERATE TO STRONG ITCZ RELATED CONVECTION HAVE FORMED THIS AFTERNOON OVER PORTIONS OF NRN VENEZUELA AND COLOMBIA. ATLANTIC OCEAN... THERE ARE A FEW AREAS THAT WE ARE MONITORING IN THE ATLANTIC DISCUSSION AREA...BUT OVERALL IT HAS QUIETED DOWN SOME AS KAREN AND NOW MELISSA ARE NO LONGER TROPICAL CYCLONES. IN THE SW ATLC...THERE IS A MESSY SFC PATTERN. THE FOCUS IS A WEAK AREA OF LOW PRES...ANALYZED 1010 MB BASED ON OBS IN THE BAHAMAS ...CENTERED NEAR 26N74W. A TROUGH HANGS SSW FROM THE LOW ACROSS THE CENTRAL BAHAMAS AND ERN CUBA. A STALLED SLOWLY WEAKENING FRONTAL BOUNDARY LIES JUST TO THE W OF THE LOW ALONG 32N65W 25N77W TO THE WRN TIP OF CUBA. CONVERGENCE ALONG THESE BOUNDARIES COUPLED WITH DIFFLUENCE ALOFT BETWEEN AN UPPER LOW OVER THE SE GULF AND AN UPPER RIDGE ALONG 67W/68W IS PRODUCING SCATTERED SHOWERS AND TSTMS BETWEEN 67W-75W. IR IMAGERY SHOWS A MID-LEVEL LOW BEGINNING TO TAKE SHAPE TO THE W OF THE FRONTAL ZONE NEAR 26N78W. DOPPLER RADAR FROM MIAMI SHOWS SWATHS OF SHOWERS AND TSTMS PRESSING SW ON THE BACK SIDE OF THAT ENERGY. IN ADDITION TO THE HEAVY RAIN THREAT...STRONG NELY WINDS ARE PROBABLY THE BIGGEST CONCERN WITH SFC DATA AND QSCAT SUGGESTING WINDS TO 30 KT. THESE LOCAL WINDS ALONG WITH A LARGE NELY FETCH IS PRODUCING DANGEROUS MARINE CONDITIONS WITH SEAS IN THE 10-15 FT RANGE. IN THE TROPICAL CENTRAL ATLC...A LARGE AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS ARE ASSOCIATED WITH THE REMNANTS OF KAREN WHICH IS CENTERED NEAR 16N58W...ESTIMATED TO BE 1011 MB. THE ILL-DEFINED LOW LEVEL CIRCULATION IS LOCATED TO THE SE OF AN UPPER LOW WHICH IS PROVIDING STRONG W TO SWLY SHEAR OVER THE REMNANT TC. MOST OF THE SHOWER ACTIVITY IS DOWNSHEAR AND IN A DIFFLUENT ZONE TO THE E OF THE REMNANTS FROM 13N-19N BETWEEN 52W-60W. SHALLOWER ACTIVITY HAS SPREAD W OF THE LOW OVER THE LEEWARD ISLANDS...STEERED BY THE LOW-LEVEL FLOW. THE E ATLC IS RELATIVELY QUIET BESIDES FOR THE SMALL BURSTS OF CONVECTION NEAR WHATS LEFT OF MELISSA. FOR DETAILS ON THIS WEAKENING SYSTEM REFER TO THE SPECIAL FEATURES SECTION ABOVE. THE PATTERN ACROSS THE E ATLC CONSISTS OF LARGE SCALE TROUGHING IN THE SUBTROPICS AND RIDGING IN THE TROPICS. THE TROUGHING IS ASSOCIATED WITH A VERY LARGE NEARLY STATIONARY OCCLUDED LOW CENTERED W OF THE IBERIAN PENINSULA. ITS ASSOCIATED COLD FRONT ACTUALLY EXTENDS INTO OUR AREA ACROSS THE AZORES ALONG 32N16W 30N27W 31N38W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 60 NM AHEAD OF THE FRONT. $$ CANGIALOSI