000 AXNT20 KNHC 270605 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU SEP 27 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 0515 UTC. ...SPECIAL FEATURES... KAREN REMAINS JUST BELOW HURRICANE STRENGTH OVER THE CENTRAL TROPICAL ATLANTIC. AT 27/0300 UTC KAREN WAS NEAR 13.0N 45.1W OR ABOUT 930 NM EAST OF THE WINDWARD ISLANDS...MOVING W-NW NEAR 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 996 MB. MAXIMUM SUSTAINED WINDS ARE 60 KT WITH GUSTS TO 75 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. MODERATE TO STRONG SOUTHWESTERLY SHEAR AHEAD OF A MID-OCEANIC TROUGH IS AFFECTING KAREN AND THIS SHEAR IS FORECAST TO PERSIST OR EVEN INTENSIFY OVER THE NEXT SEVERAL DAYS. WHILE LITTLE CHANGE IN STRENGTH IS EXPECTED OVER THE NEXT DAY OR SO...THE SHEAR IS EXPECTED TO RESULT IN SOME WEAKENING THEREAFTER. MODERATE TO STRONG CONVECTION IS MOSTLY LIMITED TO THE NE SEMICIRCLE WITHIN 210 NM OF THE CENTER. KAREN IS VERY CLOSE TO NOAA BUOY 41041...WHICH RECENTLY REPORTED A GUST FROM THE ENE AT 42 KT. SEAS AT THIS BUOY HAVE ALSO BUILT RAPIDLY OVER THE LAST FEW HOURS TO 22 FT...AND ARE LIKELY A FEW FEET HIGHER A LITTLE FURTHER S CLOSER TO THE CORE. A MODERATE TO STRONG LONGER PERIOD E SWELL WILL RACE AHEAD OF KAREN AND AFFECT EAST EXPOSED BEACHES OF THE LESSER ANTILLES LATE FRIDAY THROUGH THE WEEKEND. TROPICAL DEPRESSION THIRTEEN AT 27/0600 UTC WAS OVER THE SW GULF OF MEXICO NEAR 20.8N 94.7W OR ABOUT 200 NM EAST-SOUTHEAST OF TAMPICO MEXICO AND ABOUT 150 NM EAST OF TUXPAN MEXICO. THE DEPRESSION IS NEARLY STATIONARY. A SLOW MOTION TO THE WEST OR WEST-SOUTHWEST IS EXPECTED OVER THE NEXT 24 HOURS. ESTIMATED MINIMUM CENTRAL PRESSURE JUST REPORTED BY THE HURRICANE HUNTER IS 1009 MB. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. THE DEPRESSION IS FORECAST TO BECOME A TROPICAL STORM LATER TODAY. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS...INCLUDING THE LATEST WATCH AND WARNING INFORMATION. DEEP CONVECTION IS CURRENTLY LIMITED WITH THE DEPRESSION...WITH BANDING SCATTERED SHOWER/TSTM ACTIVITY GENERALLY OVER THE SW GULF S OF 23N W OF 94W. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE E ATLC AND CAPE VERDE ISLANDS ALONG 23W SOUTH OF 17W MOVING W 10-15 KT. THE WAVE SHOWS UP WELL IN LOW LEVEL SATELLITE DERIVED WINDS AND VORTICITY...AND THE UW CIMSS TPW PRODUCTS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF AXIS...MAINLY S OF 14N. SOME DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT COUPLE OF DAYS. A TROPICAL WAVE IS OVER THE CARIBBEAN ALONG 70W S OF 21N MOVING W 10-15 KT. THIS WAVE IS PRODUCING LOCALLY HEAVY RAINS OVER PORTIONS OF HISPANIOLA. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR DEVELOPMENT OF THIS SYSTEM. SCATTERED SHOWER AND ISOLATED TSTMS ARE LIMITED TO THE N PORTION OF THE WAVE N OF 16N WITHIN 250 NM EITHER SIDE OF THE AXIS. THIS MOISTURE IS EXPECTED SPREAD INTO ERN CUBA AND JAMAICA THROUGH FRIDAY. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N14W 11N22W 7N32W 13N41W 4N55W. BESIDES FOR THE ACTIVITY ASSOCIATED WITH T.S. KAREN AND THE TROPICAL WAVE OVER THE E ATLC...SCATTERED MODERATE CONVECTION IS NEAR THE COAST OF AFRICA WITHIN 90 NM EITHER SIDE OF THE AXIS E OF 17W...AND BETWEEN 31W-36W. DISCUSSION... GULF OF MEXICO... THE MAIN WEATHER FEATURE ACROSS THE GULF OF MEXICO IS TROPICAL DEPRESSION THIRTEEN LOCATED IN THE SW PORTION. A TROPICAL STORM WATCH HAS BEEN POSTED FOR THE COAST OF MEXICO FROM PALMA SOLA TO LA CRUZ. SEE SPECIAL FEATURES ABOVE FOR DETAILS. A WEAK 1013 MB LOW IS JUST S OF THE FLORIDA KEYS NEAR 24N82W THAT HAS TROUGHING EXTENDING FROM THE WRN ATLC TO NEAR THE YUCATAN CHANNEL. THE LOW IS NOT IMPRESSIVE LOOKING ON THIS EVENINGS SHORTWAVE IR IMAGERY WHICH SHOWS A NAKED SWIRL OF LOW CLOUDS BETWEEN KEY WEST AND WRN CUBA. MOST OF THE WEATHER ASSOCIATED WITH THIS TROUGHING IS NOW OVER THE WRN ATLC...AND IS EXPECTED TO CONTINUE LIFTING NE FROM THE GULF THROUGH THE DAY WITH DRIER AIR FILLING IN ITS WAKE. A CLUSTER OF MODERATE CONVECTION IS AFFECTING THE ERN BAY OF CAMPECHE AND WRN YUCATAN PENINSULA. THE REMAINDER OF THE GULF IS TRANQUIL...WITH ABUNDANT NLY FLOW ALOFT BETWEEN AN UPPER HIGH OVER NE MEXICO AND TROUGHING OVER THE ERN GULF. WEAK SFC RIDGING IS OVER THE NRN GULF KEEPING WINDS MOSTLY LIGHT N OF 24N. CARIBBEAN SEA... A TROPICAL WAVE IS MOVING WWD ACROSS THE EASTERN CARIBBEAN. THE WAVE...COUPLED WITH A DIFFLUENT PATTERN ALOFT IS GENERATING A CLUSTER OF MODERATE TO STRONG CONVECTION OVER HISPANIOLA AND ANOTHER JUST S OF PUERTO RICO. SEE TROPICAL WAVE SECTION. OTHERWISE THE BASIN IS FAIRLY TRANQUIL. A DEEP LAYERED TROUGH OVER FLORIDA AND CENTRAL CUBA IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS BETWEEN JAMAICA AND THE WRN BAHAMAS. TRADES REMAIN LIGHT TO MODERATE ACROSS THE BASIN...BUT WINDS/SEAS COULD BE HIGHER AT TIMES NEAR SQUALLS ASSOCIATED WITH THE TROPICAL WAVE. ALOFT...A RIDGE/TROUGH/RIDGE PATTERN REMAINS IN PLACE THOUGH THE DOMINANT FEATURE IS THE LARGE UPPER HIGH JUST S OF HISPANIOLA. ATLANTIC OCEAN... A SFC TROUGH IS OVER THE WRN ATLC...AND AS OF 0900 UTC EXTENDS FROM JUST OFFSHORE GEORGIA NEAR 31N79W AND THROUGH THE COAST OF SE FLORIDA. THIS IS GENERATING A LARGE AREA OF CLOUDINESS AND SHOWERS OVER THE WRN ATLC MAINLY W OF 75W. THERE IS SOME POTENTIAL FOR A NEW AREA OF LOW PRESSURE TO DEVELOP OFF THE FLORIDA EAST COAST TODAY...AND MOVE NORTHEASTWARD. UPPER FLOW REMAINS VERY DIFLUENT OVER THIS AREA BETWEEN TROUGHING THROUGH FLORIDA AND RIDGING EXTENDING N FROM THE CARIBBEAN ALONG 69W. ANOTHER SFC TROUGH IS ANALYZED ALONG 68W FROM 21N-28W...WHICH IS ASSOCIATED WITH THE N PORTION OF THE TROPICAL WAVE THAT APPEARS TO BE SPLITTING. THIS IS PRODUCING SCATTERED SHOWERS/ISOLATED TSTMS WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS. THE REMAINDER OF THE CENTRAL ATLC IS DOMINATED BY A SFC TROUGH ENTERING THE AREA NEAR 32N35W AND CONTINUING SW TO 23N60W. SCATTERED SHOWER ACTIVITY NOTED WITHIN 120 NM EITHER SIDE OF THE TROUGH AXIS. THE TROUGH IS AHEAD OF A COLD FRONT CLIPPING THE AREA ALONG 32N41W 27N54W 30N62W. SHOWER ACTIVITY IS LIMITED AND SHALLOW NEAR THE COLD FRONT ITSELF. MODERATE SFC RIDGING REMAINS ANCHORED OVER THE E ATLC...PRODUCING LIGHT TO MODERATE NE TRADES E OF 35W. THE UPPER LOW THAT HAS BEEN AFFECTING THE FAR NE PORTION OF THE DISCUSSION AREA THE LAST FEW DAYS IS NOW E OF THE MADEIRA ISLANDS NEAR 32N15W. SHOWER ACTIVITY HAS DIMINISHED WITH THIS UPPER LOW...WHICH IS EXPECTED TO MOVE NE OF THE AREA WHILE OPENING INTO A TROUGH THROUGH FRI. $$ WILLIS