000 AXNT20 KNHC 041800 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU OCT 04 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 1715 UTC. ...SPECIAL FEATURES... AS OF 1500 UTC...A 1007 MB LOW PRESSURE SYSTEM IS OVER THE NORTH-CENTRAL GULF OF MEXICO NEAR 27N91W MOVING W-NW NEAR 10 KT. SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS SYSTEM IS CURRENTLY LIMITED. A WELL DEFINED SWIRL OF LOW CLOUDS IS EVIDENT WITH THIS LOW...BUT SATELLITE AND LIGHTNING DATA ARE ONLY DEPICTING ISOLATED TSTM ACTIVITY WELL E OF THE CENTER FROM 26N-29N BETWEEN 87W-90W. NONETHELESS...THERE IS STILL SOME POTENTIAL FOR THIS SYSTEM TO BECOME A TROPICAL OR SUBTROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS IT APPROACHES THE TEXAS COAST. A BROAD 1011 MB LOW PRESSURE AREA IS JUST E OF THE BAHAMAS NEAR 26N73W...MOVING SLOWLY SW. THIS AFTERNOONS VISIBLE IMAGERY SHOWS MORE THAN ONE LOW LEVEL VORTICITY MAXIMUM IN THE VICINITY...SO HAVE OPTED WITH A MEAN CENTER FOR THE 12 AND 1500 UTC MAPS. SHOWER AND TSTM ACTIVITY IS MOSTLY S/SE OF THE LOW LEVEL CIRCULATIONS DUE TO UPPER NLY FLOW OVER THE AREA. THE DISORGANIZED SCATTERED SHOWER AND ISOLATED TSTMS ARE MOST CONCENTRATED FROM 20N-26N BETWEEN 64W-74W. ANY DEVELOPMENT OF THIS SYSTEM IS EXPECTED TO BE SLOW TO OCCUR ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 45W S OF 17N MOVING W 10-15 KT. A 1012 MB LOW IS ALONG THE WAVE AXIS NEAR 10N. DISORGANIZED SCATTERED SHOWERS AND TSTMS ARE WITHIN 150 NM EITHER SIDE OF THE AXIS MAINLY N OF 7N. UPPER LEVEL WINDS HAVE BECOME LESS FAVORABLE FOR THIS SYSTEM TO BECOME A TROPICAL CYCLONE...WITH W/SW FLOW ALOFT STRETCHING THE CLOUD TOPS OVER THE AREA TO THE E/NE. TROPICAL WAVE IS ALONG 55W SOUTH OF 15N MOVING WEST 10-15 KT. THIS REMAINS DIFFICULT TO LOCATE IN SATELLITE IMAGERY AND THE SURROUNDING BUOY/SHIP OBSERVATIONS...AND HAS BEEN THIS WAY FOR THE LAST COUPLE OF DAYS. THUS...THE WAVE MAY NEED TO BE DROPPED OR RELOCATED ON FUTURE MAPS. SHOWER ACTIVITY REMAINS MINIMAL IN THE AREA. ...THE ITCZ... AXIS CENTERED ALONG 10N13W 5N25W 10N43W 10N54W 9N62W. ISOLATED MODERATE CONVECTION IS WITHIN 150NM S OF THE AXIS BETWEEN 16W-23W. SCATTERED MODERATE IS WITHIN 180NM N/90NM S OF THE AXIS BETWEEN 23W-33W. DISCUSSION... THE GULF OF MEXICO... THE SPECIAL FEATURE OVER THE NORTH CENTRAL GULF IS THE DOMINANT WEATHER MAKER IN THE BASIN...THOUGH IS GENERATING MINIMAL SHOWER/TSTM ACTIVITY AT THE MOMENT. WINDS ASSOCIATED WITH THE LOW ARE MOSTLY 15 KT OR BELOW EXCEPT 15-20 KT NE OF THE CENTER WHERE THE LOW IS INTERACTING WITH HIGH PRESSURE RIDGING SW FROM THE MID ATLANTIC COAST. THE WELL DEFINED UPPER LOW THAT HAS BEEN AT LEAST PARTLY SUPPORTING THE SPECIAL FEATURE HAS FRAGMENTED...WITH ONE LARGE UPPER LOW NOW ALONG THE COAST OF MEXICO NEAR 19N96W...AND ANOTHER MID TO UPPER CYCLONIC CIRCULATION NOTED IN WV IMAGERY NEAR 27N89W. THE LATTER IS SUPPORTING ALMOST THE ONLY SHOWER/TSTM ACTIVITY OVER THE GULF AT THE MOMENT...AND AS NOTED ABOVE IS WELL E OF THE SFC LOW FROM 26N-29N BETWEEN 87W-90W. THE NEXT ITEM OF INTEREST WILL BE THE LOW PRES E OF THE BAHAMAS...WHICH IS EXPECTED TO MOVE SW ACROSS W CUBA BY SAT AND BE NEAR THE YUCATAN CHANNEL SUN AND MON. WINDS WILL INCREASE OVER THE NE GULF SAT THROUGH MON AS THE GRADIENT INCREASES BETWEEN THE LOW AND A RIDGE TO THE N. THE CARIBBEAN SEA... ACTIVE WEATHER PERSISTS BETWEEN THE COASTS OF COLOMBIA AND CUBA THIS AFTERNOON...WITH SCATTERED MODERATE CONVECTION NOTED N OF 11N BETWEEN 74W-81W. THIS ACTIVITY IS BEING SUPPORTED BY THE NEWLY FORMED SFC TROUGH THAT EXTENDS ALONG 82W FROM 12N-20W...IN ADDITION TO DIFFLUENT FLOW ALOFT AROUND THE PERIPHERY OF THE UPPER HIGH NEAR THE STRAITS OF FLORIDA. THE SFC TROUGH IS EXPECTED TO MOVE LITTLE OVER THE NEXT DAY OR SO...WHICH WILL KEEP SCATTERED SHOWER AND TSTM ACTIVITY IN THE VICINITY. SCATTERED SHOWERS/TSTMS ARE ALSO AFFECTING THE LEEWARD ISLANDS AND NE CARIBBEAN N OF 15N E OF 63W. A SFC TROUGH EXTENDS THROUGH THIS VICINITY AS WELL...FROM THE ATLC NEAR 21N62W TO THE NE CARIB NEAR 16N65W. THE LOW LEVEL CYCLONIC TURNING IN THIS VICINITY MAY BE ASSOCIATED WITH SOME OF THE ENERGY ASSOCIATED WITH THE REMNANTS OF KAREN. THE REMAINING NOTABLE CONVECTION IS OVER THE FAR SW PORTION S OF 10N...ASSOCIATED WITH THE ITCZ. ELSEWHERE CONDITIONS ARE FAIRLY QUIET. TRADE FLOW HAS BEEN DISRUPTED QUITE A BIT OVER MUCH OF THE BASIN DUE TO THE TROUGHING OVER THE NW AND NE PORTIONS. THE EXCEPTION IS MORE TYPICAL MODERATE ELY WINDS BETWEEN SOUTH AMERICA AND HISPANIOLA. THE ATLANTIC OCEAN... THE SPECIAL FEATURE E OF THE BAHAMAS DOMINATES THE PATTERN OVER THE WRN ATLC AS DESCRIBED ABOVE. THIS IN ADDITION TO VERY DIFFLUENT FLOW OVER THE AREA...BETWEEN THE UPPER HIGH NEAR 24N79W AND AN ELONGATED UPPER LOW NEAR 26N56W...IS SUPPORTING WIDESPREAD CLOUDINESS AND SHOWER ACTIVITY S OF 27N BETWEEN 60W-75W. ELY FLOW AND THE ASSOCIATED WIND WAVES/SWELL ARE EXPECTED TO INCREASE AGAIN OVER THE WRN ATLC INTO THE FIRST PART OF THE WEEKEND...AS HIGH PRES NEAR THE MID ATLC COAST BUILDS S AND INTERACTS WITH THE BROAD LOW NEAR THE BAHAMAS. THE REMNANTS OF MELISSA ARE NEAR 22N51W ANALYZED AS A 1015 MB LOW. THE EX-TROPICAL CYCLONE IS INTERACTING WITH AN APPROACHING FRONTAL SYSTEM TO PRODUCE SCATTERED MODERATE CONVECTION FROM 22N-26N BETWEEN 41W-52W. SIGNIFICANT REDEVELOPMENT IS NOT EXPECTED DUE TO STRONG UPPER-LEVEL W/SW WINDS AHEAD OF AN UPPER TROUGH. THE LINGERING COLD FRONT BOUNDARY ENTERS THE AREA NEAR 32N26W AND CONTINUES SW TO 25N43W THEN WNW TO 29N59W. SCATTERED SHOWERS/ISOLATED TSTMS ARE ELSEWHERE WITHIN 90 NM OF THE FRONT. THE REMAINDER OF THE E ATLC IS DOMINATED BY A PAIR OF 1020 MB HIGHS...ONE NEAR THE CANARY ISLANDS NEAR 29N13W AND THE OTHER NEAR 24N26W. THIS ALONG WITH STABLE AIR AND A SURGE OF AFRICAN DUST ARE PRODUCING FAIRLY QUIET CONDITIONS E OF 35W..EXCEPT FOR THAT AREA JUST AHEAD OF THE FRONT AS OUTLINED ABOVE. $$ WILLIS