000 AXNT20 KNHC 261823 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED SEP 26 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM KAREN AT 26/1500 UTC WAS NEAR 11.9N 42.9W OR 1065 NM/1970 KM EAST OF THE WINDWARD ISLANDS. THIS STORM IS IN THE CENTRAL TROPICAL ATLANTIC OCEAN. KAREN IS MOVING WEST-NORTHWEST 11 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 60 KT WITH GUSTS TO 70 KT. PLEASE READ THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS AND IT IS POSSIBLE FOR KAREN TO BECOME A HURRICANE TODAY. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 85 MILES/140 KM FROM THE CENTER. SCATTERED TO NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE FROM 11N TO 13N BETWEEN 42W AND 44W...AND IN TWO CELLS FROM 10.5N TO 11.5N BETWEEN 40W AND 41W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND OTHER SHOWERS AND THUNDERSTORMS OVERALL COVER THE ATLANTIC OCEAN FROM 10N TO 16N BETWEEN 38W AND 47W. KAREN CONTINUES TO SPIN UP AS A RAGGED EYE HAS BEEN SEEN INTERMITTENTLY. AN UPPER TROUGH NORTHWEST OF KAREN IS FORECAST BY ALL MODELS TO RETROGRADE SLOWLY AND PRODUCE ENOUGH OF A WEAKNESS IN THE RIDGE TO ALLOW THE CYCLONE TO TURN TO THE NORTHWEST. IT APPEARS THAT KAREN MAY REACH HURRICANE INTENSITY SOON GIVEN THAT THE CYCLONE IS INTENSIFYING. ENVIRONMENTAL CONDITIONS ARE MIXED. SEA SURFACE TEMPERATURES ARE A WARM 28C EVEN THOUGH THE SHEAR IS ANALYZED TO BE ABOUT 15 KT OUT OF THE WEST. THIS SHEAR DOES APPEAR TO BE RESTRICTING THE WESTERN OUTFLOW OF KAREN. THE SHEAR IS PREDICTED BY ALL MODELS TO BE MAINTAINED OR EVEN GET STRONGER FROM DAY 3 TO DAY 5 DUE TO THE INFLUENCE OF THE EARLIER MENTIONED UPPER LEVEL TROUGH. THE CENTER OF TROPICAL DEPRESSION THIRTEEN AT 26/1500 UTC WAS NEAR 20.9N 95.0W OR ABOUT 176 NM/335 KM EAST-SOUTHEAST OF TAMPICO MEXICO AND ABOUT 135 NM/250 KM EAST OF TUXPAN MEXICO. THIS IS IN THE SOUTHWESTERN GULF OF MEXICO. THE DEPRESSION WAS MOVING SOUTH 2 KT. THE MAXIMUM SUSTAINED WIND SPEEDS WERE 30 KT WITH GUSTS TO 40 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE WAS 1006 MB. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER THE AWIPS/WMO HEADERS MIATCMAT/WTNT23 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT3/ WTNT33 KNHC FOR MORE DETAILS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS....AND THE DEPRESSION COULD BECOME A TROPICAL STORM LATER TODAY. AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM THIS AFTERNOON. THERE HAS BEEN AN INCREASE IN DEEP CONVECTION AND ORGANIZATION OF THE DEPRESSION'S CLOUD PATTERN OVER THE PAST SEVERAL HOURS. WE WILL WAIT FOR THE NEXT AIR FORCE HURRICANE HUNTER FIX SCHEDULED FOR 26/1800 UTC TO SEE IF THE SYSTEM INDEED HAS STRENGTHENED INTO A TROPICAL STORM. AN UPPER-LEVEL CYCLONE NEAR TUXPAN MEXICO IS MOVING SOUTHWESTWARD...AND AWAY FROM THE TROPICAL CYCLONE...CREATING AN ENVIRONMENT THAT IS MORE FAVORABLE FOR STRENGTHENING. CIRRUS CLOUD MOTIONS SHOW THAT THE ANTICYCLONIC OUTFLOW IS BECOMING BETTER ESTABLISHED OVER THE SYSTEM. IT IS LIKELY THAT A TROPICAL STORM WATCH WILL BE REQUIRED FOR A SECTION OF THE GULF COAST OF MEXICO LATER TODAY. ...TROPICAL WAVES... AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 19W/20W SOUTH OF 15N MOVING WEST 10 TO 15 KT. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND SHOWERS FROM 8N TO 15N BETWEEN 17W AND 22W. SOME OF THE PRECIPITATION...ESPECIALLY AT THE SOUTHERN END OF THE WAVE... IS MORE ASSOCIATED WITH THE ITCZ. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 66W/67W SOUTH OF 23N MOVING WEST 10 TO 15 KT. A 1013 MB LOW PRESSURE CENTER IS ALONG THE WAVE NEAR 19N. STRONG SHOWERS AND THUNDERSTORMS ARE OVER THE OPEN WATERS OF THE CARIBBEAN SEA FROM 13N TO 15N BETWEEN 63W AND 65W. ISOLATED MODERATE SHOWERS ARE ELSEWHERE FROM 14N TO 20N BETWEEN 60W AND 70W. SOME PRECIPITATION CELLS IN THIS AREA FROM 14N TO 20N BETWEEN 60W AND 70W ARE ALTERNATELY DEVELOPING AND DISSIPATING WITH TIME. SOME CELLS ARE DEVELOPING WHILE OTHER THE CLOUD TOP TEMPERATURES IN OTHER AREAS ARE WARMING. THE CLOUDS AND PRECIPITATION WITH THIS WEATHER FEATURE ARE EXPECTED TO SPREAD WEST-NORTHWESTWARD PRODUCING LOCALLY HEAVY RAINFALL OVER SECTIONS OF HISPANIOLA LATER TODAY. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR DEVELOPMENT AT THIS TIME. ...THE ITCZ... 9N13W 10N18W 9N22W 9N37W 8N44W 5N50W 5N56W. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS/SOME THUNDERSTORMS WITHIN 150 NM ON EITHER SIDE OF 13N17W 9N23W 5N34W...MIXING IN SOME OF THE PRECIPITATION WITH THE 19W/20W TROPICAL WAVE. DISCUSSION... THE REST OF THE GULF OF MEXICO AWAY FROM T.D. THIRTEEN... A 1013 MB LOW PRESSURE CENTER HAS FORMED NEAR KEY WEST FLORIDA. THIS LOW CENTER IS ACCOMPANIED BY A LARGE AREA OF CLOUDINESS AND THUNDERSTORMS EXTENDING OVER SOUTH FLORIDA...THE FLORIDA STRAITS AND PARTS OF THE NORTHWESTERN BAHAMAS. THIS SYSTEM HAS THE POTENTIAL FOR SOME DEVELOPMENT DURING THE NEXT DAY OR TWO AS IT MOVES SLOWLY TOWARD THE NORTHEAST OVER SOUTH FLORIDA AND THE ADJACENT ATLANTIC OCEAN. A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS INLAND ON TOP OF MEXICO NEAR 21N99W... TO THE WEST OF T.D. THIRTEEN. UPPER LEVEL ANTICYCLONIC WIND FLOW MOVES ACROSS MEXICO NORTH OF 24N INTO TEXAS AND SOUTHWARD ACROSS THE GULF OF MEXICO WEST OF 86W...MOVING TOWARD T.D. THIRTEEN. THE CARIBBEAN SEA... UPPER LEVEL ANTICYCLONIC CIRCULATION CENTER COVERS THE NORTHWESTERN CORNER OF THE AREA...ANTICYCLONIC FLOW AROUND THE PERIPHERY OF T.D. THIRTEEN. A NARROW TROUGH CUTS INTO THE AREA FROM WESTERN CUBA TO AN AREA ABOUT 120 NM WEST OF JAMAICA... TO JUST OFFSHORE COSTA RICA. UPPER LEVEL ANTICYCLONIC FLOW COVERS THE REST OF THE CARIBBEAN SEA...AROUND AN UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 15N70W. THE ATLANTIC OCEAN... AN UPPER LEVEL RIDGE ON TOP OF A TROUGH IS THE PATTERN WEST OF 65W IN THE ATLANTIC OCEAN. THE TROUGH IS PART OF THE SYSTEM CONNECTED TO THE KEY WEST FLORIDA SURFACE LOW PRESSURE CENTER AND THE CLOUDS AND SHOWERS FROM THE FLORIDA KEYS TO THE BAHAMAS AND EVENTUALLY TO 32N76W. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS FROM 24N TO 32N BETWEEN 64W AND 67W IN AN AREA OF UPPER LEVEL DIFFLUENT FLOW. A COLD FRONT PASSES THROUGH 32N43W TO 29N52W TO 30N59W. SHOWERS FROM 26N TO 27N BETWEEN 49W AND 52W. A MIDDLE TO UPPER LEVEL TROUGH PASSES THROUGH 32N34W 29N37W 26N45W TO A SMALL CYCLONIC CIRCULATION CENTER NEAR 25N53W TO 24N55W. A SURFACE TROUGH CONTINUES THROUGH 32N36W TO 28N42W TO 25N50W. ISOLATED MODERATE SHOWERS ARE WITHIN 60 TO 90 NM ON EITHER SIDE OF 27N42W 29N35W 31N31W. A MIDDLE TO UPPER LEVEL TROUGH PASSES FROM A CYCLONIC CIRCULATION CENTER NEAR 31N16W... OVER THE CANARY ISLANDS TO 21N18W AND 17N25W NEAR THE CAPE VERDE ISLANDS. A RIDGE IS ALONG 26N36W BEYOND 32N27W. $$ MT