000 AXNT20 KNHC 230458 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN SEP 23 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 0315 UTC. ...SPECIAL FEATURE... A 1009 MB LOW LOCATED 840 NM WSW OF THE AZORES NEAR 36N45W IS ON THE VERGE OF BECOMING A SUBTROPICAL OR TROPICAL CYCLONE. CONVECTION IS LOCATED IN A SPIRAL BAND AROUND THE LOW CENTER. SCATTERED MODERATE CONVECTION IS WITHIN 160 NM OF THE CENTERED IN THE W SEMICIRCLE AND N QUADRANT. THIS SYSTEM IS EXPECTED TO MOVE LITTLE OVER THE NEXT 12 TO 24 HOURS THEN MOVE TO THE NE OVER THE OPEN ATLC. THE BROAD AREA OF LOW PRESSURE...ANALYZED AS A 1010 MB LOW IS ABOUT 500 NM S OF THE CAPE VERDE ISLANDS NEAR 8N24W MOVING WNW AT 15-20 KT. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 3N-13N BETWEEN 22W-30W. THIS SYSTEM REMAINS WELL-ORGANIZED AND HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT FEW DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 34W S OF 17N MOVING W 15 KT. NARROW LOW LEVEL INVERTED-V CURVATURE WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS EMBEDDED WITHIN THE ITCZ WITHIN 120 NM OF LINE FROM 5N32W TO 8N38W. TROPICAL WAVE IS ALONG 49W S OF 17N MOVING W 15-20 KT. BROAD WAVE WITH A FAINT INVERTED-V CURVATURE. SCATTERED MODERATE/ STRONG CONVECTION IS W OF THE WAVE AXIS WITHIN 120 NM OF LINE FROM 14N52W TO 9N56W. TROPICAL WAVE IS IN THE CARIBBEAN ALONG 79W S OF 20N MOVING W 15 KT. WAVE IS BENEATH AN AREA OF STRONG UPPER NORTHERLY WINDS BETWEEN AN UPPER RIDGE TO THE W AND AN UPPER LOW TO THE E. THIS COUPLED WITH DRY STABLE AIR AT THE SURFACE IS LIMITING ANY SHOWER ACTIVITY OR CONVECTION. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N16W THROUGH THE 1010 MB LOW IN THE SPECIAL FEATURES THEN ALONG 7N28W 11N47W 8N62W. IN ADDITION TO ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES AND 1010 MB LOW IN THE E TROPICAL ATLC...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MOVING OFF THE COAST OF W AFRICA FROM 11N-15N E OF 19W. DISCUSSION... GULF OF MEXICO... BROAD UPPER LOW COVER THE W GULF CENTERED ALONG THE NE MEXICAN COAST JUST S OF BROWNSVILLE TEXAS COVERING THE AREA W OF 90W. BROAD UPPER RIDGE EXTENDS FROM THE YUCATAN CHANNEL/YUCATAN PENINSULA OVER THE E GULF TO NE FLORIDA GENERATING DIFFLUENCE AND ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE TO PRODUCE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF A LINE FROM THE MISSISSIPPI COAST TO THE YUCATAN NEAR MERIDA. THIS IS LEAVING THE REMAINDER OF THE GULF CLEAR TONIGHT. CARIBBEAN SEA... BROAD UPPER RIDGE COVERS THE W CARIBBEAN W OF 78W ANCHORED BY AN UPPER HIGH IN THE GULF OF HONDURAS AND EXTENDING A RIDGE AXIS N OVER THE E GULF OF MEXICO. A 1008 MB LOW IS OVER THE YUCATAN NEAR N BELIZE WITH A WEAK SURFACE TROUGH EXTENDING JUST INTO THE S GULF OF MEXICO. THIS LOW HAS THE POTENTIAL FOR SOME DEVELOPMENT AFTER IT MOVES OVER OPEN WATER. THIS UPPER RIDGE IS ALSO GENERATING DIFFLUENCE AND ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE TO PRODUCE CLUSTERS OF SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS W OF 79W. AN UPPER LOW IS OVER THE CENTRAL CARIBBEAN NEAR 14N73W COVERING THE AREA FROM 12N-18N BETWEEN 67W-75W...THUS PRODUCING STRONG NORTHERLY UPPER WINDS OVER THE TROPICAL WAVE ALONG 79W. UPPER RIDGE FROM THE TROPICAL ATLC COVERS THE REMAINDER OF THE CARIBBEAN. ATLANTIC OCEAN... BROAD UPPER RIDGE THAT EXTENDS FROM THE CARIBBEAN AND THE E GULF OF MEXICO COVERS THE W ATLC W OF 70W GENERATING DIFFLUENCE AND ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE TO PRODUCE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF A LINE FROM 31N74W TO CENTRAL CUBA NEAR 22N79W. A LONG DRAWN OUT SURFACE TROUGH BISECTS THE CENTRAL ATLC EXTENDING FROM 31N47W ALONG 24N54W TO 16N59W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM OF A LINE FROM 20N58W 26N49W TO BEYOND 32N40W. THIS SURFACE TROUGH LIES ON THE BOUNDARY BETWEEN AN UPPER TROUGH TO THE W AND A BROAD UPPER RIDGE COVERING THE TROPICAL ATLC CENTERED NEAR 16N47W. A SECOND UPPER TROUGH IS OVER THE E ATLC EXTENDING FROM AN UPPER LOW NEAR 32N22W W OF THE CAPE VERDE ISLANDS TO NEAR 13N31W BUT IS NOT PRODUCING ANY SIGNIFICANT ACTIVITY. A SURFACE RIDGE COVERS THE W ATLC ANCHORED BY A 1021 MB HIGH N OF THE REGION NEAR 36N68W AND A SECOND SURFACE RIDGE COVERS THE E ATLC ANCHORED BY A 1027 MB HIGH E OF THE AZORES. $$ WALLACE