000 AXNT20 KNHC 220557 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON SEP 22 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE COVERS THE AREA WITH A 1008 MB LOW ANALYZED OVER THE MONA PASSAGE AS THE TROPICAL WAVE CONTINUES TO TRACK WESTWARD. THIS SYSTEM DOES NOT HAVE A WELL DEFINED CENTER WITH MULTIPLE ROTATIONS OBSERVED ON PUERTO RICO RADAR EMBEDDED WITHIN AN AREA OF HEAVY SHOWERS AND BANDS OF THUNDERSTORMS WITHIN 90 NM OF LINE FROM 16N68W TO 20N63W INCLUDING PUERTO RICO AND THE VIRGIN ISLANDS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 14N-21N BETWEEN 57W-64W ENHANCED BY UPPER LEVEL DIFFLUENCE AND INCLUDES THE LEEWARD ISLANDS. UPPER-LEVEL WINDS ARE GRADUALLY BECOMING MORE FAVORABLE FOR DEVELOPMENT AND THE SYSTEM COULD BECOME A TROPICAL DEPRESSION AT ANY TIME AS IT MOVES SLOWLY NORTH OR NORTH-NORTHWESTWARD DURING THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 26W/27W OF 18N MOVING W NEAR 10 KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE AS INDICATED BY MIMIC TPW ANIMATION BUT LACKS ANY WELL DEFINED ROTATION IN EITHER THE LOW OR MID LEVELS. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 11N-15N BETWEEN 24W-29W. TROPICAL WAVE IS ALONG 41W/42W FROM 10N-20N MOVING W NEAR 10 KT. THIS WAVE REMAINS WEAK AND ILL-DEFINED. WAVE IS EMBEDDED WITHIN DRY STABLE AIR...THUS NO ASSOCIATED SHOWERS/CONVECTION. TROPICAL WAVE IS ALONG 61W/62W S OF 21N MOVING W 10-15 KT. THIS WAVE IS MOVING INTO THE AREA OF THE BROAD LOW PRESSURE DESCRIBED IN THE SPECIAL FEATURES WITH ANY SHOWERS/THUNDERSTORMS ENHANCED BY THE UPPER LEVEL FEATURES. TROPICAL WAVE IS ALONG 70W S OF 18N MOVING NEAR 10 KT. THIS WAVE WAS PREVIOUSLY ASSOCIATED WITH THE LOW PRESSURE AREA DESCRIBED IN THE SPECIAL FEATURES. WAVE SIGNATURE IS MASKED ON SATELLITE IMAGERY DUE TO HIGH CLOUDS. TROPICAL WAVE IS ALONG 88W S OF 21N MOVING W NEAR 10 KT. THE TYPICAL INVERTED-V CURVATURE ASSOCIATED WITH THIS WAVE IS MAINLY IN THE E PACIFIC REGION WITH ANY SHOWER ACTIVITY INLAND OVER CENTRAL AMERICA AND IN THE E PACIFIC REGION. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 11N13W 11N22W 7N41W 7N53W 8N60W. SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF STRONG CONVECTION ARE FROM 2N-5N BETWEEN 38W-41W AND FROM 5N-9N BETWEEN 43W-48W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION FROM 2N-8N BETWEEN 31W-43W AND FROM 5N-9N BETWEEN 48W-51W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 9N-12N BETWEEN 35W-39W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH OVER THE E US EXTENDS INTO THE NW GULF ALONG THE MISSISSIPPI VALLEY ACROSS LOUISIANA TO THE TEXAS COAST BRINGING DRY STABLE AIR TO THE NW GULF ALONG THE LOUISIANA AND TEXAS COASTLINES. AN UPPER RIDGE ANCHORED OVER S/CENTRAL MEXICO EXTENDING ACROSS THE GULF NEAR BETWEEN TUXPAN AND VERACRUZ TO S FLORIDA BETWEEN NAPLES AND THE FLORIDA KEYS. A SURFACE TROUGH REMAINS OVER THE W GULF EXTENDING FROM 27N92W THROUGH THE BAY OF CAMPECHE TO S MEXICO NEAR 17N91W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 26N W OF 93W...S OF 22N W OF 87W...AND IN THE NE GULF N OF 25N E OF 86W TO OVER FLORIDA...ALL ENHANCED BY UPPER LEVEL DIFFLUENCE. CARIBBEAN SEA... THE MAIN CONCERN FOR THE NEXT FEW DAYS IS THE AREA OF LOW PRESSURE DESCRIBED IN THE SPECIAL FEATURES ABOVE. AN UPPER TROUGH EXTENDS FROM CENTRAL CUBA SW TO CENTRAL HONDURAS BOUNDED BY THE UPPER RIDGE OVER THE GULF OF MEXICO AND AN UPPER RIDGE ANCHORED IN THE CENTRAL CARIBBEAN NEAR 15N74W. AFTERNOON THUNDERSTORMS THAT DEVELOPED ACROSS CUBA ARE NOW WITHIN 60 NM ALONG THE S COAST BETWEEN 77W-84W. AN UPPER HIGH ASSOCIATED WITH THE AREA IN THE SPECIAL FEATURES IS LOCATED OVER THE VIRGIN ISLANDS AND IS ELONGATED FROM THE CENTRAL ATLC NEAR 24N58W SW TO 13N67W ENHANCING THE ACTIVITY IN THE SPECIAL FEATURES. OTHERWISE THE REMAINDER OF THE CARIBBEAN REMAINS RATHER CALM TONIGHT WITH THE EXCEPTION OF POSSIBLE ISOLATED SHOWERS FROM 12N-18N BETWEEN 80W-84W. ATLANTIC OCEAN... AN UPPER TROUGH EXTENDS ACROSS THE W ATLC FROM 28N74W INTO THE CARIBBEAN ACROSS CENTRAL CUBA BOUNDED TO THE W BY THE UPPER RIDGE THAT COVERS THE GULF OF MEXICO. A SURFACE TROUGH ENTERS THE W ATLC THROUGH 32N76W SW TO OVER FLORIDA FROM MELBOURNE TO TAMPA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NW OF THE TROUGH TO INLAND OVER THE SE US AND WITHIN 75 NM SE OF THE TROUGH N OF 30N. AN UPPER RIDGE IS IN THE CENTRAL ATLC ANCHORED N OF THE REGION COVERING THE AREA N OF 27N FROM 50W-65W PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 27N-31N BETWEEN 60W-65W. A RATHER BENIGN UPPER LOW IS ALSO IN THE CENTRAL ATLC NEAR 24N48W AND IS EMBEDDED IN DRY STABLE AIR. THE TYPICAL E/W UPPER RIDGE COVERS THE E ATLC ALONG 15W/16W EXTENDING FROM AFRICA TO NEAR 37W GIVING THE E SUBTROPICAL ATLC NEAR ZONAL WESTERLY FLOW. THE SURFACE OF THE ATLC IS DOMINATED BY A RIDGE E OF 70W ANCHORED BY A 1026 MB HIGH NEAR 33N52W. $$ WALLACE