000 AXNT20 KNHC 051803 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI OCT 05 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. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS TILTED ALONG 18N50W 4N48W...THAT HAS A WEAK 1011 MB LOW ALONG THE AXIS NEAR 12N49W...MOVING W 10-15 KT. DISORGANIZED SCATTERED SHOWER AND TSTM ACTIVITY IS FROM 9N-18N BETWEEN 43W-49W...WHICH IS MOSTLY E OF THE AXIS DUE TO APPROX 30 KT OF WLY SHEAR OVER THE AREA. THE SFC LOW ALONG THE WAVE MAY DISSIPATE OVER THE NEXT DAY OR SO DUE TO THE HOSTILE ENVIRONMENT. ...THE ITCZ... AXIS CENTERED ALONG 9N12W 5N26W 11N44W 9N53W 8N61W. ISOLATED CLUSTERS OF MODERATE CONVECTION ARE WITHIN 250NM EITHER SIDE OF THE AXIS E OF 17W. SIMILAR ACTIVITY IS N OF THE AXIS FROM 6N-9N BETWEEN 18N-26W. DISCUSSION... THE GULF OF MEXICO... A 1009 MB SFC LOW IS OVER THE NW GULF NEAR 28N93W JUST OFF THE COAST OF LOUISIANA AND THE UPPER TEXAS COAST. THERE IS A LITTLE MORE TSTM ACTIVITY ASSOCIATED WITH THIS LOW THIS AFTERNOON. SATELLITE...LIGHTNING...AND RADAR DATA DEPICT A SMALL CLUSTER OF MODERATE CONVECTION WITHIN 60 NM E SEMICIRCLE...WITH ISOLATED MOSTLY LOW TOPPED SHOWER ACTIVITY ELSEWHERE N OF 27N W OF 91W. THE LOW IS EXPECTED TO MOVE INLAND OVER SOUTHWESTERN LOUISIANA OR SOUTHEASTERN TEXAS TONIGHT. INTERESTS IN TEXAS AND LOUISIANA SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS SYSTEM UNTIL IT MOVES INLAND. THE ONLY OTHER TSTM ACTIVITY OVER THE GULF IS JUST S OF THE FL PANHANDLE THROUGH SE LOUISIANA...WITH ISOLATED CELLS NOTED N OF 27N BETWEEN 84W-90W. THIS ACTIVITY IS ASSOCIATED WITH LOW LEVEL CONVERGENCE BETWEEN THE SLY FLOW E OF THE LOW OFF WRN LOUISIANA...COLLIDING WITH MODERATE ELY WINDS OVER THE NE GULF AROUND RIDGING FROM NEW ENGLAND. AN UPPER COL REGION IS ALSO OVER THE N CENTRAL GULF...BETWEEN AN UPPER HIGH NEAR THE YUCATAN CHANNEL AND ANOTHER UPPER HIGH CENTERED ABOVE TEXARKANA. DRY AND MOSTLY STABLE CONDITIONS NOTED OVER MUCH OF THE GULF S OF 27N. ELY FLOW EXPECTED TO INCREASE OVER THE ERN GULF AS BROAD LOW PRESSURE FROM THE NW CARIBBEAN INTERACTS WITH PERSISTENT RIDGING FROM THE MID ATLC COAST. THE CARIBBEAN SEA... ACTIVE WEATHER PERSISTS BETWEEN COLOMBIA AND CUBA THIS AFTERNOON...WITH A SFC TROUGH EXTENDING OVER THE NW PORTION ALONG 21N82W 13N77W. VISIBLE IMAGERY ALSO DEPICTS A WEAK LOW MAY BE FORMING JUST WSW OF THE CAYMAN ISLANDS NEAR 19N82W. UPPER RIDGING DOMINATES MUCH OF THE BASIN THIS AFTERNOON FROM THE UPPER HIGH JUST NW OF THE YUCATAN CHANNEL IN THE SRN GOMEX. IN ADDITION TO THE MENTIONED SFC AND UPPER FEATURES...COLLIDING CONVECTIVE BOUNDARIES ARE ALSO HELPING TO SUPPORT WIDESPREAD CLOUDINESS AND SHOWER ACTIVITY WITH EMBEDDED TSTMS BETWEEN 71W-85W. THE MOST PRONOUNCED TSTM ACTIVITY IS BETWEEN THE COAST OF COLOMBIA AND SE JAMAICA BETWEEN 73W-78W. QUITE A BIT OF SHOWER ACTIVITY WITH EMBEDDED TSTMS ARE ALSO AFFECTING THE NORTH CENTRAL AND NORTHEAST CARIBBEAN. THIS ACTIVITY IS VERY EVIDENT FROM THE SAN JUAN RADAR...AND IS AFFECTING HISPANIOLA E THROUGH THE LEEWARD ISLANDS. THE DRIVING FORCE BEHIND THIS ACTIVITY IS PRIMARILY THE ELONGATED SFC TROUGH EXTENDING THROUGH THE BAHAMAS AND SW NORTH ATLC...THOUGH THE UPPER LOW N OF THE MONA PASSAGE IS ALSO PROVIDING ADDITIONAL FUEL. A WEAK 1011 MB LOW IS ALSO ANALYZED JUST N OF THE VIRGIN ISLANDS NEAR 19N65W AS DICTATED BY THE SAN JUAN RADAR AND THE SURROUNDING SFC OBSERVATIONS. THERE IS SOME DEBATE ON IF SOME OF THIS ENERGY COULD BE ASSOCIATED WITH THE EX-TROPICAL CYCLONE KAREN. COMPUTER MODEL GUIDANCE SUGGESTS THAT BROAD LOW PRES WILL SLOWLY CONSOLIDATE OVER THE NW CARIBBEAN OVER THE NEXT COUPLE OF DAYS WITH WEAK RIDGING OVER THE ERN CARIB. TRADE FLOW WILL THUS REMAIN DISRUPTED...WITH LIGHT TO MODERATE SE/S WINDS OVER THE CENTRAL AND ERN PORTIONS...AND WINDS OVER THE NW PORTION DEPENDENT ON THE DEVELOPMENT OF THE SFC LOW ANTICIPATED. THE ATLANTIC OCEAN... A VERY MESSY AND COMPLEX WEATHER PATTERN DOMINATES THE SW PORTION OF THE AREA. THE OVERALL SFC PATTERN CONSISTS OF AN ELONGATED AREA OF LOW PRESSURE WITH MULTIPLE VORTICITY MAXIMUMS. AT 1200 UTC A TROUGH WAS ANALYZED FROM FAR SE FLORIDA TO JUST N OF THE VIRGIN ISLANDS...WITH A MEAN 1010 MB LOW NEAR 23N74W AND ANOTHER 1011 MB CENTER JUST NE OF PUERTO RICO NEAR 19N65W. THE LATTER APPEARS TO BE THE DOMINANT FEATURE AND MORE SIGNIFICANT WEATHER PRODUCER...WITH WIDESPREAD SHOWER ACTIVITY WITH EMBEDDED TSTMS S OF 24N BETWEEN 60W-70W. MORE ON THIS SYSTEM FOUND IN CARIBBEAN SECTION. TROUGHING N OF THE BROAD LOW PRESSURE AREA IN ADDITION TO DIFFLUENT FLOW ALOFT IS SUPPORTING SCATTERED SHOWER/TSTM ACTIVITY OFF AND ALONG THE COAST OF FLORIDA W OF 77W. THE INTERACTION BETWEEN THE BROAD TROUGHING NEAR THE BAHAMAS AND HIGH PRES RIDGING S FROM THE MID ATLC COAST WILL PRODUCE MODERATE TO STRONG ELY WINDS AND STEEP WIND WAVES/SWELL OFFSHORE FLORIDA OVER THE NEXT COUPLE OF DAYS. THE CENTRAL ATLC SFC PATTERN DOES NOT GET MUCH MORE CLEAR CUT THAN THE MESS NEAR THE BAHAMAS. AN OLD FRONTAL ZONE ENTERS THE AREA NEAR 32N20W AND CONTINUES SW TO 25N32W THEN W TO 27N56W. MEANWHILE...THE REMNANTS OF MELISSA ARE NOW ANALYZED AS A TROUGH ALONG 25N52W 20N56W. THIS CIRCULATION APPEARS TO BE GETTING ABSORBED INTO THE BAROCLINIC ZONE FURTHER N THOUGH. FURTHERMORE...MOISTURE FROM THE TROPICAL WAVE NEAR 50W IS ALSO SPREADING INTO THIS OVERALL AREA. THE END RESULT IS WIDESPREAD DISORGANIZED CLOUDINESS AND SHOWERS N OF 18N BETWEEN 37W-55W...WITH THE MOST PRONOUNCED TSTM ACTIVITY NOTED FROM 20N-27N BETWEEN 40W-48W. THIS IS ALSO BEING SUPPORTED BY LIFT AHEAD OF THE MID TO UPPER TROUGHING IN THE VICINITY. THE REMAINDER OF THE E ATLC IS MUCH QUIETER...WITH STABLE CONDITIONS AND A PAIR OF 1020 MB SFC HIGHS OVER THE AREA NEAR 22N27W AND 30N12W. $$ WILLIS