000 AXNT20 KNHC 211054 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN SEP 21 2008 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... TROPICAL WAVE IS TILTED ACROSS PUERTO RICO NEAR 19N66W THROUGH A WEAK 1010 MB LOW NEAR 17N67W TO CURACAO AND THEN INTO NERN VENEZUELA NEAR 11N70W MOVING W NEAR 10 KT. THIS WAVE IS GENERATING A LARGE AREA OF CLOUDINESS WITH SCATTERED MODERATE/ STRONG CONVECTION FROM 14N-19N BETWEEN 62W-68W...INCLUDING THE NRN LEEWARD ISLANDS...THE US/UK VIRGIN ISLANDS AND PUERTO RICO. THIS SYSTEM IS SHOWING SIGNS OF ORGANIZATION AND UPPER LEVEL WINDS ARE EXPECTED TO BECOME MORE FAVORABLE OVER THE NEXT COUPLE DAYS FOR ADDITIONAL DEVELOPMENT. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 26W S OF 15N MOVING W NEAR 15-20 KT. A BROAD CYCLONIC CIRCULATION IS EVIDENT ON SATELLITE IMAGERY WITH A LOW TO MIDDLE LEVEL LOW ALONG THE WAVE NEAR 6N. BROAD AREA OF CLOUDINESS COVERS THE AREA WITHIN 300 NM ON EITHER SIDE OF THE WAVE AXIS AS THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ AND SCATTERED MODERATE CONVECTION IS OBSERVED FROM 7N-12N BETWEEN 25W-29W. TROPICAL WAVE IS ALONG 39W/40W FROM 11N-18N MOVING W 10-15 KT. LOW LEVEL CLOUDS INDICATE INVERTED-V CURVATURE BETWEEN 13N-18N. WAVE REMAINS EMBEDDED UNDER STRONG SUBSIDENCE AND A DRY...STABLE AIR MASS ALOFT...THUS NO ASSOCIATED CONVECTIVE ACTIVITY. TROPICAL WAVE IS ALONG 58W S OF 20N MOVING W NEAR 15 KT. WAVE IS BENEATH AN UPPER RIDGE PROVIDING UPPER LEVEL DIFFLUENCE WITH MIDDLE TO HIGH LEVEL CLOUDINESS OBSERVED ON THE NORTHERN HALF OF THE WAVE...MAKING IT DIFFICULT TO DISCERN ON SATELLITE IMAGERY. THIS AREA OF CLOUDINESS CONTINUES TO DISSIPATE AND CONTAINS POSSIBLE SCATTERED SHOWERS FROM 17N-21N BETWEEN 55W-61W. TROPICAL WAVE IS ALONG 86W S OF 20N MOVING W 15 KT. CYCLONIC CURVATURE IS NOTED OVER THE NW CARIBBEAN SEA WITH CLUSTERS OF SCATTERED MODERATE CONVECTION ACROSS ADJACENT CARIBBEAN COASTAL WATERS OF HONDURAS AND NICARAGUA W OF 82W. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 14N15W 9N24W 9N28W 7N40W 6N57W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 26W...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 12N-15N BETWEEN 19W-23W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 4N-8N BETWEEN 36W-41W. ...DISCUSSION... GULF OF MEXICO... A SURFACE TROUGH EXTENDS ACROSS THE WRN GULF OF MEXICO FROM 28N95W TO THE ERN BAY OF CAMPECHE NEAR 20N92W. A BROAD UPPER LEVEL RIDGE CENTERED OVER SRN MEXICO NEAR 20N97W DOMINATES THE GULF EXTENDING NE FROM VERACRUZ TO OVER THE CENTRAL FLORIDA PENINSULA. THIS COUPLED WITH THE SURFACE TROUGH IS PRODUCING WIDESPREAD CLOUDINESS IN AN AREA OF UPPER DIFFLUENCE ACROSS THE CENTRAL GULF WITH CLUSTERS OF SCATTERED SHOWERS N OF 23N BETWEEN 84W-93W AND SCATTERED SHOWERS AND TSTMS S OF 20N AND FROM 20N-24N W OF 95W...INCLUDING THE BAY OF CAMPECHE AND ACROSS INLAND SRN MEXICO. A SURFACE RIDGE COVERS THE SE US AND EXTENDS INTO THE FAR NRN GULF N OF 28N AND IS EXPECTED TO CONTINUE BUILDING IN SLOWLY ACROSS THE NRN GULF WATERS THROUGH MIDWEEK. CARIBBEAN SEA... AN ERN CARIBBEAN TROPICAL WAVE IS CONTINUING TO EXHIBIT SOME ORGANIZATION AND ADDITIONAL DEVELOPMENT IS POSSIBLE OVER THE NEXT FEW DAYS...SEE SPECIAL FEATURES ABOVE. THE WRN CARIBBEAN TROPICAL WAVE CONTINUES TO MOVE UNDER AN UPPER RIDGE ANCHORED OVER SRN MEXICO EXTENDING ACROSS THE NW CARIBBEAN W OF 82W AND IS PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED SHOWERS AND TSTMS ACROSS THE ADJACENT COASTAL WATERS OF ERN HONDURAS AND NICARAGUA. THE UPPER LEVELS ARE DOMINATED BY THE UPPER RIDGE OVER THE GULF OF MEXICO AND A SECOND UPPER RIDGE ANCHORED OVER THE ERN CARIBBEAN NEAR 15N63W EXTENDING W TO 82W AND E ACROSS THE LESSER ANTILLES INTO THE W TROPICAL ATLC. THESE UPPER LEVEL FEATURES ARE ENHANCING PATCHES OF MULTILAYERED CLOUDS ACROSS MUCH OF THE BASIN AND POSSIBLE SCATTERED SHOWER ACTIVITY S OF 14N BETWEEN 71W-84W. ATLANTIC OCEAN... A NARROW UPPER TROUGH IS OVER THE FAR W ATLC EXTENDING THROUGH 32N74W TO OVER THE CENTRAL BAHAMAS AND CUBA. A SURFACE TROUGH ENTERS THE W ATLC FROM A 1015 MB LOW N OF THE REGION THROUGH 32N73W TO NEAR CAPE CANAVERAL FLORIDA. SCATTERED SHOWERS/ ISOLATED TSTMS ARE NE OF THE BAHAMAS FROM 24N-32N BETWEEN 72W-76W AND SIMILAR ACTIVITY IS OFF THE NE COAST OF FLORIDA AND GEORGIA FROM 29N-32N BETWEEN 79W-82W. A PAIR OF UPPER LOWS ARE TO THE EAST ACROSS THE CENTRAL ATLC CENTERED NEAR 24N47W AND 25N64W. THE UPPER RIDGE OVER THE ERN CARIBBEAN EXTENDS ACROSS THE LEEWARD ISLANDS TO OVER THE W TROPICAL ATLC NEAR 17N50W. WEAK UPPER TROUGHING IS OVER THE NE ATLC EXTENDING FROM A DEEP LAYERED LOW N OF THE REGION TO 25N E OF 30W TO OVER THE CANARY ISLANDS. AN E/W UPPER RIDGE CONTROLS THE REMAINDER OF THE TROPICAL ATLC TO 40W S OF THE UPPER TROUGHING ACROSS THE NE ATLC. OTHERWISE THE ATLC IS DOMINATED BY A STATIONARY 1025 MB SURFACE HIGH CENTERED NORTH OF THE REGION NEAR 34N46W AND INFLUENCES THE ATLC N OF 24N FROM 20W-70W. $$ HUFFMAN