000 AXNT20 KNHC 251042 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT TUE SEP 25 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 FEATURES... TROPICAL DEPRESSION TWELVE HAS BEEN UPGRADED TO TROPICAL STORM KAREN IN THE EAST ATLANTIC...AND IS NO IMMEDIATE THREAT TO LAND AREAS. AT 25/0900 UTC T.S. KAREN WAS NEAR 10.4N 38.0W OR ABOUT 1360 NM E OF THE WINDWARD ISLANDS...MOVING W-NW AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WINDS ARE 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. KAREN IS A LARGE SYSTEM WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER MUCH OF THE AREA FROM 6N-15N BETWEEN 33W-43W. SOME ADDITIONAL STRENGTHENING IS FORECAST OVER THE NEXT DAY OR SO AS KAREN CONTINUES ON A WNW TRACK S OF A MID LEVEL RIDGE. A 1009 MB LOW IS OVER THE SW GULF OF MEXICO NEAR 22N94W. A SFC TROUGH EXTENDS THROUGH THE LOW FROM NEAR BROWNSVILLE TO THE YUCATAN ALONG 26N97W 22N94W 20N92W. DISORGANIZED SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM 21N-27N BETWEEN 90W-96W. UPPER LEVEL WINDS ARE BECOMING MORE FAVORABLE...AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS IT DRIFTS SLOWLY AND ERRATICALLY. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULE TO INVESTIGATE THE SYSTEM LATER TODAY...IF NECESSARY. A 1011 MB LOW PRESSURE AREA IS NEAR 15N62W ASSOCIATED WITH A TROPICAL WAVE MOVING THROUGH THE LESSER ANTILLES. SHOWER ACTIVITY ASSOCIATED WITH THIS SYSTEM HAS BECOME LESS ORGANIZED OVERNIGHT...AND UPPER-LEVEL WINDS ARE BECOMING LESS FAVORABLE FOR DEVELOPMENT OF A TROPICAL DEPRESSION. HOWEVER...THE SYSTEM IS EXPECTED TO MOVE NORTHWESTWARD AND BRING SQUALLY WEATHER TO PORTIONS OF THE LEEWARD ISLANDS TODAY...AND TO THE VIRGIN ISLANDS AND PUERTO RICO BY WEDNESDAY. SATELLITE IMAGERY AND METEO-FRANCE RADAR DATA FROM MARTINIQUE DEPICT ISOLATED SHOWERS AND TSTMS FROM 13N-21N BETWEEN 58W-65W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 62W AFFECTING THE LESSER ANTILLES. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A WEAK TROPICAL WAVE IS ALONG 90W S OF 18N MOVING W 10-15 KT. WAVE REMAINS DIFFICULT TO LOCATE WITH ITS POSITION BASED MAINLY ON CONTINUITY FROM PREVIOUS ANALYSES. SCATTERED MODERATE CONVECTION IS MOSTLY INLAND OVER CENTRAL AMERICA S OF 17N BETWEEN 88W-92W. FOR FUTURE INFO ON THIS WAVE PLEASE REFER TO PACIFIC DISCUSSION UNDER MIATWDEP. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 7N25W 12N35W 7N50W 13N59W. BESIDES THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES/TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS ALONG AND JUST OFF THE COAST OF AFRICA FROM 6N-13N BETWEEN 12W-18W. SCATTERED MODERATE/ISOLATED STRONG IS WITHIN 150NM EITHER SIDE OF THE AXIS BETWEEN 18W-27W. DISCUSSION... GULF OF MEXICO... THE MAIN WEATHER FEATURE ACROSS THE GULF IS THE AREA OF LOW PRES LOCATED OVER THE SW GULF WHICH COULD BECOME A TROPICAL CYCLONE OVER THE NEXT COUPLE OF DAYS. SEE SPECIAL FEATURES ABOVE. ABUNDANT DEEP LAYER MOISTURE IS OVER THE BASIN BETWEEN 87W-95W. THIS IS ASSOCIATED WITH THE SPECIAL FEATURE IN THE SW GULF IN ADDITION TO LIFT AHEAD OF AN UPPER TROUGH OVER THE FAR WRN GULF. AN UPPER RIDGE CONTINUES TO DOMINATE MUCH OF THE CENTRAL GULF...WITH THE AXIS NOW EXTENDING NE BETWEEN THE BAY OF CAMPECHE TO SE LOUISIANA. VERY DRY MID TO UPPER AIR IS BEING ADVECTED INTO THE NE GULF AROUND AN UPPER TROUGH EXTENDING INTO THE AREA FROM THE WRN ATLC...WHILE MOISTURE AND SCATTERED SHOWER ACTIVITY PERSISTS OVER THE SE GULF...FL KEYS...AND STRAITS OF FLORIDA. ELSEWHERE AT THE SFC...RIDGING EXTENDS INTO THE NE GULF AROUND HIGH PRES CENTERED NEAR MID ATLANTIC COAST. RIDGING WILL PERSIST OVER THE NRN GULF THROUGH WED WHILE LOW PRES MEANDERS IN THE SW PORTION. CARIBBEAN SEA... THE MAIN WEATHER FEATURE IN THE CARIBBEAN IS ASSOCIATED WITH THE TROPICAL WAVE AND ASSOCIATED LOW PRESSURE AREA MOVING THROUGH THE LESSER ANTILLES AS DESCRIBED ABOVE. OTHERWISE THE BASIN IS FAIRLY TRANQUIL. AN UPPER RIDGE/TROUGH/RIDGE PATTERN CONTINUES TO DOMINATE. DEEP MOISTURE AND A FEW ISOLATED TSTMS ARE AFFECTING THE FAR NW PORTION N OF 18N W OF 75W. THIS ACTIVITY SEEMS MOSTLY ASSOCIATED WITH DIFFLUENT FLOW ALOFT OVER THE AREA. UPPER SLY FLOW AHEAD OF AN UPPER TROUGH IS ADVECTING HIGH CLOUDS/MOISTURE NWD BETWEEN 66W-78W. ISOLATED SHOWER ACTIVITY ALSO ANTICIPATED IN THIS REGION...WITH LIGHTNING DATA SUPPORTING A FEW TSTMS CURRENTLY JUST S OF THE MONA PASSAGE...WHERE SHORTWAVE IR IMAGERY SHOWS A SMALL AREA OF LOW LEVEL CYCLONIC TURNING. TRADES REMAIN LIGHT TO MODERATE ACROSS THE BASIN...BUT WINDS/SEAS COULD BE HIGHER AT TIMES IN SQUALLS NEAR THE LOW/WAVE MOVING THROUGH THE LESSER ANTILLES. ATLANTIC OCEAN... MOST OF THE ACTIVE SFC FEATURES ARE DISCUSSED IN THE SPECIAL FEATURES SECTION ABOVE. ELSEWHERE AT THE SFC...WEAK HIGH PRES RIDGING AN ELY FLOW CONTROL THE W ATLC. A 1020 MB SFC HIGH NEAR 30N55W AND A PAIR OF WEAK TROUGHS DOMINATE THE CENTRAL ATLC AREA. THE FIRST OF THE TROUGHS IS ALONG 66W N OF 23N...WHICH IS GENERATING SCATTERED SHOWERS/TSTMS FROM 25N-29N BETWEEN 60W-67W. THE SECOND TROUGH ENTERS THE AREA NEAR 32N41W AND CONTINUES SW TO 26N56W. SCATTERED SHOWERS ARE GENERALLY WITHIN 90 NM EITHER SIDE OF THIS TROUGH. MODERATE RIDGING TAKES OVER IN THE E ATLC ANCHORED BY A 1031 MB HIGH LOCATED WELL NE OF THE AZORES. THIS PATTERN IS PRODUCING MODERATE TRADES IN THE E ATLC...EXCEPT STRONGER NEAR THE NW COAST OF AFRICA WHERE THE PRES GRADIENT TIGHTENS. THE WEAK LOW THAT WAS PREVIOUSLY NEAR 15N49W IS NOW ANALYZED AS A SMALL TROUGH ALONG 50W FROM 12N-19N...BASED ON RECENT ASCAT AND QUIKSCAT PASSES. IN THE MID AND UPPER LEVELS...A BROAD UPPER LOW NEAR 29N72W HAS TROUGHING OVER MUCH OF THE WRN ATLC. THE UPPER TROUGH IS SUPPORTING NUMEROUS SHOWERS AND TSTMS OVER THE STRAITS OF FLORIDA...WRN BAHAMAS...AND NEAR THE COAST OF SE FLORIDA S OF 27N W OF 76W. THERE ARE NO SIGNS OF ORGANIZATION OF THIS ACTIVITY...AND ANY DEVELOPMENT SHOULD BE SLOW TO OCCUR. VERY DRY AIR IS OVER THE REMAINDER OF THE WRN ATLC N OF 27N W OF 74W. WSW FLOW TO THE S OF AND AHEAD OF THE UPPER LOW DOMINATES THE CENTRAL ATLC N OF 20N. AN AMPLIFIED UPPER RIDGE IS SEEN E OF THE TROUGHING EXTENDING NE FROM AN UPPER HIGH SITUATED NEAR 15N60W TO BEYOND 32N34W. A LARGE UPPER LOW IS LOCATED E OF THE RIDGE W OF THE MADEIRA ISLANDS NEAR 31N21W. THIS APPEARS TO BE PRODUCING ISOLATED SHOWER ACTIVITY N OF 29N BETWEEN 19W-23W...BUT IS ONLY GENERATING PATCHES OF HIGH CLOUDINESS ELSEWHERE. $$ MW