000 AXNT20 KNHC 300545 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... TROPICAL STORM MELISSA IS CENTERED NEAR 15.8N 30.2W OR ABOUT 410 NM WEST OF THE CAPE VERDE ISLANDS AT 30/0300 UTC MOVING WNW AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. CONVECTION IN THE PAST 3 HOURS DECREASED IN INTENSITY THOUGH MAINTAINED THE SAME SIZE OF COVERAGE. STRONG WESTERLY SHEAR PERSISTS OVER THE STORM. TROPICAL STORM STATUS IS FORECAST FOR A COUPLE OF DAYS FOLLOWED BY WEAKENING AS SHEAR INCREASES AND COOLER WATERS ARE ENCOUNTERED. PRESENTLY SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 14N-17N BETWEEN 28W-30W. ...TROPICAL WAVES... TROPICAL WAVE IS OFF THE COAST OF W AFRICA ALONG 20W S OF 14N MOVING W 10-15 KT. THIS WAVE IS LOWER AMPLITUDE THAT MANY OF PREVIOUS ONES THIS MONTH. THE MIMIC TPW ANIMATION SHOWS A MODEST BULGE OF MOISTENED AIR OFF THE AFRICAN COAST. SATELLITE IMAGERY AND DERIVED WINDS SHOW A BROAD AREA OF TURNING. SCATTERED MODERATE CONVECTION IS FROM 9N-11N BETWEEN 19W-22W... AND FROM 4N-6N BETWEEN 20W-25W. TROPICAL WAVE IS ALONG 39W S OF 16N MOVING W 15 KT OVER THE PAST 24 HOURS. NIGHT CHANNEL VIS IMAGES SHOWS AN AREA OF SLIGHT CYCLONIC TURNING IN THE SURROUNDING LOW CLOUDS. THERE IS ALSO A WEAK NWD PERTURBATION IN THE ITCZ...WHICH IS WELL REFLECTED IN THE MIMIC TPW ANIMATION. SHOWER ACTIVITY REMAINS VERY MINIMAL. TROPICAL WAVE IS OVER CENTRAL AMERICA AND THE NW CARIBBEAN ALONG 86W S OF 20N MOVING W 15 KT. LOW-LEVEL CONVERGENCE NEAR THE WAVE ALONG WITH DIFFLUENCE ALOFT IS GENERATING A GOOD AMOUNT OF CONVECTION W OF THE WAVE AXIS. SCATTERED MODERATE TO STRONG CONVECTION IS OVER EL SALVADOR AND HONDURAS FROM 12N-15N BETWEEN 86W-90W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N8W 7N20W 5N25W 8N38W 6N54W. OUTSIDE OF THE CONVECTION ASSOCIATED WITH THE E ATLC TROPICAL WAVE...SCATTERED MODERATE CONVECTION IS FROM 6N-8N BETWEEN 24W-26W... AND FROM 4N-6N BETWEEN 32W-36W. DISCUSSION... GULF OF MEXICO... A WEAK COLD FRONT HAS DIPPER S TO S FLORIDA. THE FRONT IS DELINEATED BY A WIND SHIFT AND SLIGHT THERMAL COOLING. THUNDERSTORMS ARE NOW OVER S FLORIDA S OF LAKE OKEECHOBEE. THE GULF OF MEXICO HAS NELY SURFACE FLOW AS HIGH PRESSURE RIDGING WITH MOSTLY FAIR WEATHER PREVAILS. WIND VELOCITIES ARE 20-25 KT OVER THE NE GULF AND 10-15 KT ELSEWHERE. IN THE UPPER LEVELS...AN UPPER HIGH WITH SIGNIFICANT UPPER LEVEL MOISTURE IS OVER THE W GULF NEAR 22N97W WITH A RIDGE AXIS EXTENDING N TO LOUISIANA. THE BASE OF A TROUGH WITH STRONG SUBSIDENCE IS OVER NE GULF AND FLORIDA N OF 24N AND E OF 90W. THIS UPPER LEVEL TROUGH IS HOSTING THE FRONTAL SYSTEM MENTIONED ABOVE. EXPECT THE COLD FRONT TO PUSH E INTO THE W ATLANTIC DURING THE NEXT 24 HOURS. EXPECT CONVECTION OVER THE BAHAMAS. ALSO EXPECT ONSHORE FLOW TO PRODUCE CONVECTION ALONG THE TEXAS AND MEXICO COASTS DURING THE NEXT 24 HOURS. CARIBBEAN SEA... A TROPICAL WAVE IS MOVING WWD ACROSS THE NW CARIBBEAN AND CENTRAL AMERICA WITH CONVECTION. SEE THE TROPICAL WAVE SECTION ABOVE. SCATTERED MODERATE CONVECTION IS ALONG THE COAST OF HONDURAS FROM 15N-17N BETWEEN 83W-86W. TRADEWINDS REMAIN LIGHT TO MODERATE ACROSS THE BASIN. SCATTERED MODERATE TO STRONG CONVECTION IS OVER HAITI FROM 18N-20N BETWEEN 72W-75W. IN THE UPPER LEVELS...AN UPPER LEVEL HIGH IS N OF COLOMBIA NEAR 13N76W. ANTICYCLONIC FLOW IS OVER THE CENTRAL AND EASTERN CARIBBEAN. SIGNIFICANT UPPER LEVEL MOISTURE AND BROKEN HIGH CLOUDS COVERS THIS AREA. EXPECT CONVECTION OVER MOST OF THE CARIBBEAN AND CENTRAL AMERICA W OF 65W DURING THE NEXT 24 HOURS. ATLANTIC OCEAN... A WEAK COLD FRONT IS OVER THE W ATLANTIC EXTENDING S TO S FLORIDA ALONG 32N67W 27N80W. CLUSTERS OF ISOLATED MODERATE CONVECTION ARE WITHIN 60 NM OF THE FRONT. A PREFRONTAL TROUGH EXTENDS FROM 30N68W TO E CUBA NEAR 20N75W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 21N-24N BETWEEN 71W-76W...AND FROM 23N-26N BETWEEN 68W-71W. A 1024 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 33N45W. ANOTHER 1022 MB HIGH IS OVER THE E ATLANTIC NEAR 27N22W. THE 1009 MB REMNANT LOW OF KAREN IS E OF THE LEEWARD ISLANDS NEAR 16N54W AND CONTINUES TO HAVE STRONG WESTERLY SHEAR OVER THE LOW CENTER. SCATTERED MODERATE TO STRONG CONVECTION IS E OF THE CENTER FROM 13N-19N BETWEEN 49W-53W. IN THE UPPER LEVELS...A TROUGH IS OVER THE W ATLANTIC N OF 25N W OF 75W. A RIDGE IS N OF 20N BETWEEN 70W-75W. A LARGE UPPER LEVEL LOW IS CENTERED OVER THE CENTRAL ATLANTIC NEAR 24N62W PRODUCING THE WESTERLY SHEAR OVER THE REMNANTS OF KAREN. WLY FLOW IS OVER THE E ATLANTIC N OF 20N E OF 40W. A LARGE UPPER LEVEL HIGH IS OVER THE TROPICS NEAR 13N33W. ANTICYCLONIC FLOW IS FROM EQ-20N BETWEEN 20W-50W. $$ FORMOSA