000 AXNT20 KNHC 250547 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI SEP 25 2009 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 29W/30W S OF 19N WITH A 1010 MB LOW ON THE WAVE NEAR 13N MOVING W 20-25 KT. WAVE IS ALONG THE LEADING EDGE OF A MOISTURE MAXIMUM AS INDICATED BY THE TOTAL PRECIPITABLE WATER IMAGERY WITH SAHARAN DUST TO THE N AND BEING DRAWN INTO THE SURFACE LOW. SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF ISOLATED STRONG CONVECTION ARE FROM 13N-17N BETWEEN 27W-30W AND FROM 12N-15N BETWEEN 30W-34W. TROPICAL WAVE IS ALONG 58W S OF 19N MOVING W 20-25 KT. WAVE IS ALONG W EDGE OF AN UPPER RIDGE DRAWING UPPER LEVEL MOISTURE N AWAY FROM THE WAVE. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 10N-14N BETWEEN 49W AND THE WAVE AXIS. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 11N15W 13N28W 9N40W 10N62W. LARGE AREA OF NUMEROUS STRONG CONVECTION IS JUST INLAND OVER W AFRICA WITH SCATTERED/NUMEROUS STRONG CONVECTION WITHIN 120 NM ALONG THE COAST OF SIERRA LEONE TO JUST S OF DAKAR SENEGAL AND SCATTERED STRONG CONVECTION FROM 5N-8N BETWEEN 15W-17W. SMALL CLUSTERS OF ISOLATED MODERATE CONVECTION DOT THE REMAINDER OF THE ITCZ FROM 5N-11N BETWEEN 24W-51W. ...DISCUSSION... GULF OF MEXICO... A STATIONARY FRONT ENTERS THE GULF OVER LOUISIANA NEAR VERMILION BAY CONTINUING S ALONG 27N95W INTO THE BAY OF CAMPECHE AND S MEXICO TO NEAR 18N96W. A WEAK SURFACE TROUGH IS IN THE E BAY OF CAMPECHE FROM 23N90W TO W GUATEMALA NEAR 15N92W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE W OF THE FRONT WITH CLUSTERS OF SIMILAR ACTIVITY OVER THE REMAINDER OF THE BAY OF CAMPECHE S OF 21N BETWEEN THE FRONT AND SURFACE TROUGH. BROAD UPPER RIDGE ANCHORED OVER THE NE GULF JUST OFF SHORE OF PENSACOLA FLORIDA EXTENDS AN AXIS SW TO TAMPICO MEXICO FORCING AFTERNOON THUNDERSTORMS THAT DEVELOPED OVER THE FLORIDA PENINSULA INTO THE GULF WATERS LEAVING ISOLATED SHOWERS/THUNDERSTORMS WITHIN 120 NM ALONG THE W COAST OF FLORIDA. SIMILAR SHOWERS/THUNDERSTORMS THAT DEVELOPED OVER W CUBA ARE WITHIN 60 NM OF OF THE NW COAST OF CUBA. OTHERWISE...THE REMAINDER OF THE GULF IS TRANQUIL TONIGHT. CARIBBEAN SEA... AN UPPER RIDGE IS OVER THE W CARIBBEAN EXTENDING THE AXIS FROM PANAMA TO THE NE YUCATAN PENINSULA PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/THUNDERSTORMS W OF A LINE FROM PANAMA NEAR 9N79W 15N80W TO 21N85W INCLUDING MOST OF CENTRAL AMERICA. BROAD UPPER TROUGH OVER THE W/CENTRAL ATLC EXTENDS OVER THE NE CARIBBEAN N OF 17N FROM THE VIRGIN ISLANDS TO CENTRAL CUBA PRODUCING ISOLATED SHOWERS OVER THE ISLANDS FROM PUERTO RICO TO THE WINDWARD PASSAGE. FRESH TO STRONG EASTERLY TRADE WINDS CONTINUE ACROSS THE AREA BUT THE E CARIBBEAN REMAINS RATHER CLEAR TONIGHT INCLUDING THE LESSER ANTILLES. ATLANTIC OCEAN... BROAD UPPER RIDGE ANCHORED IN THE NE GULF OF MEXICO COVERS THE W ATLC AND COMBINED WITH AN UPPER TROUGH OVER THE W/CENTRAL ATLC CENTERED NEAR 28N64W IS PRODUCING STRONG NE UPPER WINDS OVER THE W ATLC W OF 68W. THE UPPER TROUGH IS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 33N63W THROUGH A 1012 MB LOW NEAR 28N66W TO 24N67W. THE UPPER LOW IS ALSO PRODUCING CLUSTERS OF ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS FROM 19N-23N BETWEEN 61W-70W AND WITHIN 120/150 NM OF LINE FROM 26N55W 32N59W TO 32N64W. A PAIR OF WEAK SURFACE TROUGHS ARE ANALYZED FROM 32N44W TO 29N50W AND FROM 26N55W TO 22N57W WITH AN AREA OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS BETWEEN THEM FROM 22N-29N BETWEEN 49W-54W. THE REMAINDER OF THE ATLC IS DOMINATED BY A SURFACE RIDGE THAT COVERS THE AREA N OF 20N W OF 45W AND RESULTING IN FAIR WEATHER FOR THE E ATLC. THE LAST VISIBLE SATELLITE IMAGES SHOW A SWATH OF SAHARAN DUST WITHIN 200/225 NM OF LINE FROM WESTERN SAHARA NEAR SW TO THE W OF THE TROPICAL WAVE TO NEAR 40W AND BEING DRAWN BACK INTO THE LOW ASSOCIATED WITH THE TROPICAL WAVE. $$ WALLACE