000 AXNT20 KNHC 231052 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURE... SUBTROPICAL DEPRESSION ELEVEN WAS UPGRADED AT 23/0900 UTC AND IS CENTERED NEAR 36.2N 46.1W OR ABOUT 920 NM W OF THE AZORES AT 23/0900 UTC AND IS NEAR STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 FOR MORE DETAILS. T.D. ELEVEN CURRENTLY DOES NOT SHOW ANY TROPICAL CHARACTERISTICS BUT WITH THE CONVECTION BEGINNING TO WRAP AROUND IT COULD BECOME TROPICAL CYCLONE LATER TODAY. T.D. ELEVEN HAS BEEN STATIONARY OVER THE PAST SEVERAL HOURS WHILE TRAPPED BENEATH AN UPPER LEVEL LOW BUT IS EXPECTED TO BEGIN TO MOVE N AND WILL BECOME ABSORBED WITHIN AN EXTRATROPICAL SYSTEM CURRENTLY OVER THE CANADIAN MARITIMES. CLUSTERS SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE REMOVED FROM THE CENTER AND COVERING AN AREA FROM 34N-40N BETWEEN 40W-51W. THE BROAD AREA OF LOW PRESSURE...ANALYZED AS A 1010 MB LOW IS ABOUT 600 NM SSW OF THE CAPE VERDE ISLANDS NEAR 6N27W. THIS SYSTEM CONTINUES TO BECOME BETTER ORGANIZED AND CONDITIONS APPEAR FAVORABLE FOR THIS SYSTEM TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES WESTWARD AT ABOUT 15 MPH. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION COVER A LARGE AREA FROM 2N-13N BETWEEN 22W-31W. A BROAD AREA OF LOWER PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS LOCATED ABOUT 500 NM EAST OF THE WINDWARD ISLANDS ALONG 52W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-13N BETWEEN 51W-54W WITH CLUSTERS OF SIMILAR CONVECTION S OF 10N TO THE COAST OF SOUTH AMERICA BETWEEN 52W-59W. THIS SYSTEM CONTINUES TO BECOME BETTER ORGANIZED AND A TROPICAL DEPRESSION COULD FORM DURING THE NEXT COUPLE OF DAYS AS IT APPROACHES THE WINDWARD ISLANDS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 35W S OF 17N MOVING W 10-15 KT. THIS WAVE HAS RAPIDLY BEGUN TO LOSE ITS IDENTITY OVERNIGHT AS THE TROPICAL LOW TO THE E...SEE SPECIAL FEATURES ABOVE...HAS BECOME BETTER ORGANIZED. NO ASSOCIATED SHOWER ACTIVITY/CONVECTION IS NOTED. TROPICAL WAVE IS IN THE CARIBBEAN ALONG 80W S OF 20N MOVING W 10-15 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 THUS MASKING ANY SATELLITE SIGNATURE. NO ASSOCIATED SHOWER ACTIVITY/CONVECTION. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N14W THROUGH THE 1010 MB LOW IN THE SPECIAL FEATURES THEN ALONG 5N31W 12N53W 9N62W. IN ADDITION TO ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES AND 1010 MB LOW IN THE E TROPICAL ATLC...CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 NM OF THE ITCZ AXIS FROM 44W-50W. DISCUSSION... GULF OF MEXICO... BROAD UPPER LOW COVERS THE W GULF CENTERED OVER NE MEXICO SW OF BROWNSVILLE TEXAS COVERING THE AREA W OF 93W. BROAD UPPER RIDGE EXTENDS FROM THE NE YUCATAN PENINSULA OVER THE E GULF TO THE FLORIDA PANHANDLE GENERATING DIFFLUENCE AND ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE TO PRODUCE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 85W-90W. THIS IS LEAVING THE THE W GULF CLEAR THIS MORNING WITH ISOLATED SHOWERS E OF 85W TO OVER THE FLORIDA PENINSULA. CARIBBEAN SEA... BROAD UPPER RIDGE COVERS THE W CARIBBEAN W OF 79W ANCHORED BY AN UPPER HIGH IN THE GULF OF HONDURAS AND EXTENDING A RIDGE AXIS N OVER THE E GULF OF MEXICO. A 1009 MB LOW IS OVER THE YUCATAN 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 80W WITH THE STRONGEST ACTIVITY OVER NE NICARAGUA. AN UPPER LOW IS OVER THE CENTRAL CARIBBEAN NEAR 14N74W COVERING THE AREA FROM 10N-18N BETWEEN 70W-77W...THUS PRODUCING STRONG NORTHERLY UPPER WINDS OVER THE TROPICAL WAVE ALONG 80W AND SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF LINE FROM COLOMBIA NEAR 10N75W TO 12N80W. UPPER RIDGE FROM THE TROPICAL ATLC COVERS THE E CARIBBEAN WITH DRY SOMEWHAT STABLE AIR...THUS CLEAR SKIES THIS MORNING. ATLANTIC OCEAN... BROAD UPPER RIDGE THAT EXTENDS FROM THE CARIBBEAN AND THE E GULF OF MEXICO COVERS THE W ATLC W OF 67W GENERATING DIFFLUENCE AND ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE BUT IS ONLY PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN A 75 NM RADIUS OF 28N74W AND ISOLATED SHOWERS W OF 68W. A LONG DRAWN OUT SURFACE TROUGH BISECTS THE CENTRAL ATLC EXTENDING FROM S OF T.D. ELEVEN NEAR 32N46W ALONG 25N53W TO JUST E OF THE LEEWARD ISLANDS NEAR 17N61W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE SURFACE TROUGH FROM 19N-22N AND WITHIN 120/150 NM OF A LINE FROM 24N53W TO BEYOND 32N39W. 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 15N50W. A SECOND UPPER TROUGH IS OVER THE E ATLC EXTENDING FROM AN UPPER LOW NEAR 32N21W W OF THE CAPE VERDE ISLANDS TO NEAR 14N28W BUT IS NOT PRODUCING ANY SIGNIFICANT ACTIVITY. WEAK SURFACE RIDGE COVERS THE W ATLC ANCHORED BY A 1020 MB HIGH N OF THE REGION NEAR 36N69W AND A SECOND SURFACE RIDGE COVERS THE E ATLC ANCHORED BY A 1025 MB HIGH E OF THE AZORES. $$ WALLACE