000 AXNT20 KNHC 261030 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... TROPICAL STORM KAREN IS STRENGTHENING OVER THE CENTRAL TROPICAL ATLANTIC. AT 26/0900 UTC KAREN WAS NEAR 11.2N 42.1W OR ABOUT 1115 NM EAST OF THE WINDWARD ISLANDS...MOVING W NEAR 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. MAXIMUM SUSTAINED WINDS ARE 45 KT WITH GUSTS TO 55 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. THE CONVECTIVE PATTERN ASSOCIATED WITH KAREN CONTINUES TO IMPROVE WITH NUMEROUS MODERATE TO STRONG CONVECTION WITHIN 60 NM OF W AND 120 NM E SEMICIRCLES. BANDS OF SCATTERED MODERATE ARE ELSEWHERE FROM 8N-17N BETWEEN 38W-45W. KAREN IS EXPECTED TO MOVE W-NW OVER THE NEXT 24 HOURS WITH SOME ADDITIONAL STRENGTHENING EXPECTED. TROPICAL DEPRESSION THIRTEEN AT 26/0900 UTC WAS OVER THE SW GULF OF MEXICO NEAR 21.0N 95.0W OR ABOUT 175 NM E-SE OF TAMPICO AND ABOUT 135 NM E OF TUXPAN MEXICO...MOVING SLOWLY S NEAR 3 KT. A SLOW AND ERRATIC MOTION IS EXPECTED OVER THE NEXT DAY OR SO. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WINDS...AS INDICATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT...ARE 25 KT WITH GUSTS TO 35 KT. SLOW STRENGTHENING IS POSSIBLE DURING THE NEXT 24 HOURS. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. SATELLITE IMAGERY SHOWS AN INCREASE IN CONVECTION MOSTLY EAST OF THE CENTER OVER THE PAST FEW HOURS...WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 19N-24N BETWEEN 92W-97W. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE E ATLC ALONG 20W/21W S OF 16W...ESTIMATED TO BE MOVING W 10-15 KT. THE WAVE SHOWS UP WELL IN LOW LEVEL SATELLITE DERIVED WINDS AND VORTICITY...AND THE UW CIMSS TPW PRODUCTS. A CLUSTER OF MODERATE TO STRONG CONVECTION IS JUST E OF THE AXIS FROM 8N-12N BETWEEN 17W-21W. ISOLATED TSTMS ARE ELSEWHERE WITHIN 150 NM EITHER SIDE OF THE AXIS. A MORE CONCENTRATED AREA OF MODERATE TO STRONG CONVECTION IS EMBEDDED IN THE ITCZ JUST TO THE E OF THE WAVE...WITHIN 180 NM OF 6N27W. A 1012 MB LOW PRESSURE AREA IS OVER THE NE CARIBBEAN NEAR 17N65W...ASSOCIATED WITH A TROPICAL WAVE ALONG 65W SOUTH OF 24N. THIS SYSTEM IS POORLY ORGANIZED...AND UPPER-LEVEL WINDS ARE EXPECTED TO BE UNFAVORABLE FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS. HOWEVER...THIS SYSTEM COULD PRODUCE LOCALLY HEAVY RAINFALL OVER PORTIONS OF PUERTO RICO AND HISPANIOLA TODAY. SATELLITE...SAN JUAN RADAR...AND LIGHTNING DATA DEPICT SCATTERED SHOWER AND TSTM ACTIVITY FROM 16N-20N BETWEEN 64W-68W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 11N19W 6N31W 10N38W 5N53W. BESIDES FOR THE ACTIVITY ASSOCIATED WITH T.S. KAREN AND THE TROPICAL WAVE OVER THE E ATLC...NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 23W-33W. DISCUSSION... GULF OF MEXICO... THE MAIN WEATHER FEATURE ACROSS THE GULF OF MEXICO IS TROPICAL DEPRESSION THIRTEEN LOCATED IN THE SW PORTION. SEE SPECIAL FEATURES ABOVE. CONVECTION HAS FLARED UP A BIT OVERNIGHT IN ASSOCIATION WITH T.D. 13...WHICH IS ALSO BEING ENHANCED BY UPPER DIFFLUENCE E OF AN UPPER LOW NEAR TUXPAN MEXICO. THE UPPER LOW IS EXPECTED TO MOVE S OR SW AWAY FROM THE DEPRESSION...ALLOWING AN UPPER HIGH TO BUILD OVER THE SYSTEM WHICH WOULD PROMOTE STRENGTHENING. THE OTHER FEATURE BEING MONITORED IS THE DISTURBED WEATHER OVER THE STRAITS OF FLORIDA. THIS ACTIVITY IS ASSOCIATED WITH A MID TO UPPER LEVEL TROUGH AND ITS ASSOCIATED SURFACE TROUGH...WHICH EXTENDS FROM SE FLORIDA TO WRN CUBA. SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT DAY OR TWO AS IT LIFTS NORTHEASTWARD...AND LOCALLY HEAVY RAINS COULD OCCUR OVER SOUTH FLORIDA AND THE BAHAMAS DURING THIS TIME. ELSEWHERE AT THE SFC...RIDGING DOMINATES THE NRN GULF FROM MODEST HIGH PRES OVER THE CAROLINAS. CARIBBEAN SEA... THE MAIN WEATHER FEATURE IN THE CARIBBEAN IS ASSOCIATED WITH THE TROPICAL WAVE AND ASSOCIATED LOW PRESSURE AREA AFFECTING THE NE PORTION. SEE TROPICAL WAVE SECTION. OTHERWISE THE BASIN IS FAIRLY TRANQUIL. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OVER JUST S OF WRN CUBA NW N OF 19N BETWEEN 78W-85W...ASSOCIATED WITH DEEP LAYER TROUGHING EXTENDING INTO THE REGION FROM FLORIDA AND THE ERN GULF. A CLUSTER OF MODERATE CONVECTION IS IN THE SW CARIBBEAN FROM 10N-13N BETWEEN 76W-79W...ASSOCIATED WITH THE ITCZ AND DIFFLUENCE ALOFT AROUND THE PERIPHERY OF AN UPPER RIDGE SPRAWLING W FROM THE UPPER HIGH OVER THE ERN CARIBBEAN. 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 EASTERN CARIBBEAN. ATLANTIC OCEAN... AS NOTED IN THE GULF SECTION DISTURBED WEATHER NEAR THE STRAITS OF FLORIDA IS BEING MONITORED FOR SIGNS OF SLOW DEVELOPMENT. SCATTERED SHOWER AND TSTM ACTIVITY IS OVER MUCH THE WRN ATLC AND BAHAMAS W OF 73W. UPPER FLOW IS VERY DIFFLUENT OVER THIS AREA BETWEEN THE TROUGH EXTENDING S THROUGH THE WRN FLORIDA PENINSULA AND AN UPPER RIDGE OVER THE WRN ATLC. SOME OF THE ENERGY ASSOCIATED WITH THE NRN PORTION OF THE TROPICAL WAVE OVER THE ERN CARIBBEAN APPEARS TO BE ENHANCING SCATTERED SHOWERS/ISOLATED TSTMS BETWEEN 62W-69W. THIS ACTIVITY IS MOVING W/NW S OF DEEP LAYERED RIDGING OFF THE MID ATLC COAST. THE REMAINDER OF THE CENTRAL ATLC IS DOMINATED BY A SFC TROUGH ENTERING THE AREA NEAR 32N37W AND CONTINUING SW TO 25N51W. SHOWER ACTIVITY IS GENERALLY ISOLATED WITHIN 90 NM OF THIS BOUNDARY. THE TROUGH IS AHEAD OF A COLD FRONT CLIPPING THE AREA ALONG 32N44W 30N53W. MODERATE SFC RIDGING REMAINS ANCHORED OVER THE E ATLC...PRODUCING LIGHT TO LIGHT TO MODERATE NE TRADES E OF 35W. A WELL DEFINED UPPER LOW IS JUST N OF THE CANARY ISLANDS NEAR 31N17W. THIS APPEARS TO BE GENERATING SCATTERED SHOWERS AND POSSIBLY ISOLATED TSTMS FROM 29N-32N BETWEEN 16W-21W. $$ WILLIS