000 AXNT20 KNHC 011216 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED AUG 01 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURES... A 1010 MB LOW NEAR 12N55W IS ABOUT 325 NM E OF THE SOUTHERN WINDWARD ISLANDS. A BAND OF SCATTERED MODERATE ISOLATED STRONG CONVECTION HAS APPEARED INTERMITTENTLY WITHIN 90 NM OF THE LOW LEVEL CENTER OVER THE PAST SEVERAL HOURS AND THE OVERALL ORGANIZATION OF THE SYSTEM REMAINS INTACT. THE SYSTEM STILL HAS THE POTENTIAL FOR FURTHER DEVELOPMENT AND COULD BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO. EVEN IF DEVELOPMENT DOES NOT OCCUR...THE LOW WILL LIKELY BRING SQUALLS TO THE WINDWARD ISLANDS DURING THE NEXT DAY OR SO. ...TROPICAL WAVES... TROPICAL WAVE ALONG 21W/22W FROM 5N TO 20N CONTINUES TO PULL AWAY FROM THE AFRICAN COAST. A 1009 MB LOW WAS ALONG THE WAVE AXIS NEAR 13N AND WAS SOMEWHAT SUPPORTED BY A 0732 UTC QUIKSCAT PASS WHICH INDICATED BROAD TURNING IN THE WIND FIELD. SATELLITE WISE THE WAVE CONSISTS OF A WELL DEFINED LOW AND MID LEVEL CENTER WITH WIDELY SCATTERED SHOWERS AND A FEW THUNDERSTORMS IN THE W SEMICIRCLE AND JUST E OF THE CAPE VERDE ISLANDS. THE BULK OF THE DEEP CONVECTION IS ALONG THE INTERSECTION OF THE WAVE AND THE ITCZ FROM 8N TO 11N BETWEEN 18W AND 25W. TROPICAL WAVE IS ALONG 38W/39W S OF 20N MOVING W 12 KT. WAVE NOTED BY CYCLONIC TURNING IN STRATOCUMULUS FIELD. SCATTERED MODERATE CONVECTION NOTED AT THE INTERSECTION OF THE WAVE AXIS AND ITCZ BETWEEN 37W AND 43W. TROPICAL WAVE IS OVER THE E CARIBBEAN ALONG 65W MOVING W 15-20 KT. 0000 UTC SOUNDING FROM GUADELOUPE INDICATED THE WAVE HAD PASSED TO THE W OF THE SITE. WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WERE NOTED WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS WITH MOST OF THE SHOWER AND THUNDERSTORM PASSING OVER THE CARIBBEAN S OF PUERTO RICO AND EXTENDING SEWD TO THE SOUTHERN WINDWARD ISLANDS. TROPICAL WAVE IN THE CENTRAL CARIBBEAN AND SW ATLC IS BECOMING FRACTURED WITH A TROUGH FROM 25N71W TO 23N74W WHILE THE WAVE ITSELF EXTENDS FROM E CUBA ALONG 75W/76W TO THE COAST OF COLOMBIA AND IS CONTINUING W AT 15-20 KT IN MODERATE ELY FLOW OVER THE CARIBBEAN. THIS WAVE IS EMBEDDED WITHIN SOME RATHER DRY STABLE AIR ESPECIALLY OVER THE CARIBBEAN...THUS ONLY WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE BEING GENERATED AT THE NORTHERN PORTION OF THE WAVE AND THE SURFACE TROUGH OVER HAITI...E CUBA...THE WINDWARD PASSAGE AND THE EXTREME SE BAHAMAS. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 14N17W 10N30W 9N37W 13N50W 11N57W 9N61W. EXCEPT AS NOTED IN ASSOCIATION WITH THE TROPICAL WAVES ABOVE...ISOLATED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 120 NM OF THE AXIS W OF 58W TOWARD TRINIDAD AND TOBAGO. ...DISCUSSION... GULF OF MEXICO... ANOMALOUSLY DEEP LAYERED TROUGH FOR EARLY AUGUST ALONG THE US EASTERN SEABOARD IS BEGINNING TO EXERT MORE INFLUENCE ON THE NE GULF AS THE MID TO UPPER LEVEL ANTICYCLONE OVER THE BIG BEND AREA OF W TEXAS CONTINUES TO RETROGRADE AND THE ASSOCIATED RIDGE AXIS ALONG 27N90W TO SOUTH FLORIDA SAGS SLOWLY SWD WITH TIME. DESPITE THE PATTERN CHANGES ANTICYCLONIC FLOW STILL COVERS MOST OF THE GULF WITH THE EXCEPTION OF THE FAR NE PORTION. THE FLOW WAS BECOMING INCREASINGLY DIFLUENT OVER THE ERN THIRD OF THE GULF WITH WIDELY SCATTERED SHOWERS AND TSTMS N OF 26N AND E OF 90W. ADDITIONAL THUNDERSTORM ACTIVITY IS ALONG THE WEST COAST OF THE FLORIDA PENINSULA FROM EVERGLADES CITY NWD TO TARPON SPRINGS MOVING EWD AT 15-20 KT. THIS PATTERN IS EXPECTED TO REMAIN IN PLACE FOR THE NEXT FEW DAYS GENERATING ADDITIONAL TSTMS OVER THE E GULF STATES AND FLORIDA AS A WEAK STATIONARY FRONT CURRENTLY OVER THE FAR NE GULF REMAINS A FOCUS FOR THIS CONVECTIVE ACTIVITY AND THE WEAK SURFACE RIDGE EXTENDING ACROSS THE CENTRAL BAHAMAS...THE FLORIDA STRAITS TO THE CENTRAL GULF REMAINS IN PLACE. CARIBBEAN... CONDITIONS ACROSS THE MAJORITY OF THE CARIBBEAN SEA ARE TRANQUIL TONIGHT AS A RESULT OF A VAST AREA OF DRY STABLE AIR ALOFT. NW-SE ORIENTED UPPER LEVEL INVERTED TROUGH EXTENDS ACROSS THE CENTRAL CARIBBEAN FROM 19N85W SE TO THE N COAST OF COLOMBIA NEAR 10N72W RESULTING IN SE FLOW ALOFT OVER THE E CARIBBEAN AND N AND NWLY FLOW OVER THE W CARIBBEAN. WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ARE CONFINED TO THE E-CENTRAL CARIBBEAN E OF 70W IN ASSOCIATION WITH THE TROPICAL WAVE NOW ENTERING THE REGION ALONG 65W. THIS COULD BE THE BEGINNING OF SEVERAL DAYS OF UNSETTLED WEATHER OVER THE WINDWARD ISLANDS AND E CARIBBEAN AS THE AREA OF LOW PRESSURE E OF THE ISLANDS APPROACHES AND THE ASSOCIATED SHOWER AND THUNDERSTORM ACTIVITY SPREADS OVER THE REGION. ATLANTIC... SEE SPECIAL FEATURES FOR INFORMATION ON THE 1010 MB LOW IN THE W TROPICAL ATLC. ANOMALOUSLY DEEP LAYERED TROUGH ALONG THE US EASTERN SEABOARD EXTENDS INTO THE W ATLC N OF 29N W OF 70W TO OVER NE FLORIDA WITH AN ASSOCIATED WEAKENING COLD FRONT ENTERING THE REGION NEAR 32N72W TO NE FLORIDA IN THE VICINITY OF CAPE CANAVERAL. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 28N AND WITHIN 360 NM E OF THE COLD FRONT. A NARROW EXTENSION OF THE GULF RIDGE EXTENDS OVER SOUTH FLORIDA INTO THE W ATLC ALONG 27N70W TO BEYOND 32N63W. A SHARP NARROW SHEAR AXIS/TROUGH OVER THE CENTRAL ATLANTIC EXTENDS FROM A CYCLONIC CIRCULATION NEAR 31N51W SWD TO 22N54W. THE REMAINDER OF THE ATLC IS DOMINATED BY ANTICYCLONES NEAR 16N51W AND 26N30W WITH DEEP LAYERED EASTERLY FLOW NOTED. UW CIMSS SAL ANALYSIS INDICATES A VAST AREA OF AFRICAN DUST MAINLY N OF 15N AND E OF 45W WITH SOME OF DUST AND STABLE AIR BEING ENTRAINED INTO THE TROPICAL WAVES ALONG 38W/39W AND THE ONE EMERGING OFF THE W COAST OF AFRICA THEREBY LIMITING CONVECTION TO THE ITCZ. AT THE SURFACE...HIGH PRESSURE RIDGE CONTINUES TO DOMINATE THE ATLC ANCHORED BY A 1027 MB W OF THE AZORES NEAR 35N39W. $$ COBB