000 AXNT20 KNHC 211759 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED NOV 21 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... TROPICAL WAVE IS ALONG 83W/84W S OF 19N MOVING W 10 KT. SOME SUBTLE CYCLONIC TURNING IS NOTED IN THE LOW CLOUD FIELD JUST N OF THE NE COAST OF HONDURAS. SCATTERED SHOWERS AND ISOLATED TSTMS ARE GENERALLY WITHIN 60 NM EITHER SIDE OF THE AXIS. TROPICAL WAVE WAS ALONG 97W S OF 19N MOVING W 10 KT. THIS WAVE WAS DROPPED FROM THE INTERMEDIATE 21/1500 UTC MAP DUE TO THE LACK OF SUPPORT IN SATELLITE AND SFC OBSERVATIONS. THE MIMIC TPW PRODUCT SHOWS A LOW AMPLITUDE MOISTURE SURGE...POSSIBLY ASSOCIATED WITH THE WAVE...ROUNDING THE RIDGING OVER THE GULF AND NOW MOVING N/NW ALONG THE COAST OF NE MEXICO. REGARDLESS...THE FEATURE IS INSIGNIFICANT AND DOES NOT APPEAR TO BE GENERATING SIGNIFICANT WEATHER. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N9W 5N35W 4N52W. ISOLATED CLUSTERS OF MODERATE CONVECTION ARE WITHIN 150 NM N AND 90 NM S OF THE AXIS BETWEEN 25W-45W. DISCUSSION... GULF OF MEXICO... A SFC RIDGE EXTENDS W/SW ACROSS THE GULF FROM A 1024 MB HIGH CENTERED JUST OFFSHORE NORTH FLORIDA IN THE WRN ATLC. THIS IS PRODUCING MOSTLY MODERATE SE/S RETURN FLOW ACROSS THE BASIN...WHICH IS EXPECTED TO PERSIST UNTIL TONIGHT. A COLD FRONT WILL ALLOW NLY WINDS TO INCREASE ESPECIALLY OVER THE NW PORTION ON THANKSGIVING. A SMALL AREA OF SCATTERED SHOWERS WITH POSSIBLE EMBEDDED ISOLATED TSTMS IS OVER THE MIDDLE GULF N OF 24N BETWEEN 85W-90W. THERE ALSO APPEARS TO BE SOME LOW LEVEL CYCLONIC TURNING IN THIS REGION...ESPECIALLY FROM 24N-27N BETWEEN 86W-89W. ALOFT...AN UPPER RIDGE DOMINATES...EXTENDING NW FROM THE NW CARIBBEAN TO THE NORTH CENTRAL GULF COAST. CARIBBEAN SEA... HIGH PRES JUST E OF NRN FLORIDA IS PRODUCING MODERATE TO FRESH ELY TRADES OVER MUCH OF THE CARIBBEAN TODAY. THE ONLY DEEP CONVECTION CURRENTLY OVER THE BASIN IS OVER THE WRN PORTION ALONG THE COAST OF CENTRAL AMERICA...PARTLY ASSOCIATED WITH THE TROPICAL WAVE ALONG 83W/84W AS DESCRIBED ABOVE. THIS ACTIVITY IS ALSO BEING SUPPORTED BY UPPER DIFFLUENCE AROUND AN UPPER RIDGE AXIS OVER THE AREA. A WEAKENING COLD FRONT IS AFFECTING THE LEEWARD ISLANDS EXTENDING W TO NEAR ERN HISPANIOLA....PRODUCING BROKEN UP PATCHES OF MOSTLY LOW TOPPED SHOWERS OVER THE AREA. VERY DRY MID TO UPPER AIR IS FILTERING INTO THE FAR NRN CARIBBEAN BEHIND THE ASSOCIATED UPPER TROUGH MOSTLY N OF THE AREA. MODERATE TO FRESH TRADES EXPECTED TO PERSIST OVER THE NEXT FEW DAYS. ATLANTIC OCEAN... A 1024 MB HIGH NEAR 29N76W...OR JUST OFFSHORE NRN FLORIDA...IS DOMINATING THE WRN ATLC. THIS IS PRODUCING FAIR WEATHER AND LIGHT WINDS JUST OFFSHORE NORTH AND CENTRAL FLORIDA AND N OF THE BAHAMAS. THE HIGH IS BUILDING SE BEHIND A COLD FRONT THAT ENTERS THE AREA NEAR 32N47W AND CONTINUES SW ALONG 23N52W TO THE N COAST OF DOMINICAN REPUBLIC. FRESH TO STRONG MOSTLY WLY WINDS ASSOCIATED WITH THE FRONT ARE GENERALLY N OF 26N BETWEEN 42W-66W. MODERATE N/NE WINDS ARE ELSEWHERE BEHIND THE FRONT TO THE COAST OF S FLORIDA. SCATTERED SHOWERS ARE GENERALLY WITHIN 120 NM AHEAD OF THE FRONT...THOUGH THE DEEPEST CONVECTION WITH ISOLATED TSTMS IS N OF 25N BETWEEN 39W-50W. THE FRONT IS ASSOCIATED WITH A WELL DEFINED DEEP LAYER LOW N OF THE AREA NEAR 36N54W. ANOTHER COLD FRONT IS JUST N OF THE NE PORTION OF THE AREA...BUT IS GENERATING ISOLATED SHOWERS WITH POSSIBLE EMBEDDED TSTMS OVER THE AREA N OF 27N BETWEEN 14W-21W...SOME OF WHICH ARE AFFECTING THE CANARY ISLANDS. THE REMAINDER OF THE E ATLC SFC PATTERN IS DOMINATED BY A 1021 MB HIGH NEAR 23N32W. A SFC TROUGH IS EMBEDDED IN THE SW PORTION OF THE ASSOCIATED RIDGE ALONG 44N FROM 7N-16N. THIS TROUGH HAS SHOWED UP WELL IN RECENT SCATTEROMETER PASSES...AND IS GENERATING ISOLATED SHOWER ACTIVITY WITHIN 120 NM OF THE AXIS. A WLY JET IS SPREADING TROPICAL MOISTURE EWD OVER THE AREA FROM 10N-20N E OF 37W...INCLUDING OVER THE CAPE VERDE ISLANDS. $$ WILLIS