000 AXNT20 KNHC 212351 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 52W/53W FROM 7N-20N ESTIMATED TO BE MOVING W 10-15 KT. THE LAST FEW VISIBLE PICTURES THIS EVENING CONTINUE TO SHOW CLEAR CYCLONIC TURNING ON THE LOWER CLOUD FIELD AROUND THE AXIS. SHOWER AND TSTM ACTIVITY REMAINS DISORGANIZED...AND MOSTLY DISPLACED TO THE E OF THE AXIS DUE TO WLY SHEAR OVER THE AREA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ESTIMATED TO BE OVER MUCH OF THE AREA FROM 8N-21N BETWEEN 45W-55W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 6N30W 12N50W 10N63W. BESIDES FOR THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE...ISOLATED SHOWERS AND TSTMS ARE WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 17W-37W. A CLUSTER OF MODERATE CONVECTION IS ALONG THE AXIS NEAR 8N43W. SCATTERED MODERATE CONVECTION IS ALSO NEAR THE NE COAST OF VENEZUELA...TRINIDAD...WINDWARD ISLANDS...AND ADJACENT WATERS FROM 6N-14N BETWEEN 57W-65W. DISCUSSION... GULF OF MEXICO... A WARM FRONT IS PUSHING N THROUGH THE NRN GULF TONIGHT...MOST DEFINED IN THE NE PORTION OFF THE FLORIDA PANHANDLE. THE FRONT IN ADDITION TO DIFFLUENT FLOW ALOFT ARE SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS OVER MUCH OF THE GULF WATERS E OF 92W. THE MOST PRONOUNCED TSTM ACTIVITY IS JUST OFFSHORE CAPE SAN BLAS FLORIDA. THIS ACTIVITY LOOKS POISED TO CONTINUE MOVING ONSHORE THE WRN FLORIDA PANHANDLE THROUGH SE LOUISIANA THROUGH THE NIGHT AND INTO MON. ISOLATED LOW TO MID LEVEL CLOUDS WITH A FEW EMBEDDED SHOWERS ARE OVER THE GULF W OF 92W...STREAMING N AROUND THE SLY FLOW SW OF A LOW/MID LEVEL HIGH JUST OFFSHORE SE VIRGINIA. A CLUSTER OF MODERATE TO STRONG CONVECTION IS PUSHING OFF THE NW COAST OF THE YUCATAN ASSOCIATED WITH WEAK SFC TROUGHING IN THE VICINITY ALONG WITH NORMAL DIURNAL EFFECTS. THE UPPER PATTERN IS DOMINATED BY AN UPPER HIGH OVER THE SW PORTION AND A SHORTWAVE TROUGH ROUGHLY ALONG 86W. THE WSW FLOW AROUND THE NW/N PERIPHERY OF THE UPPER HIGH IS ADVECTING TROPICAL DEBRIS MOISTURE FROM T.S. KIKO IN THE EPAC ACROSS MEXICO AND INTO THE NW GULF. THE SFC HIGH OFFSHORE VA WILL PUSH E THROUGH MON AS A COLD FRONT PUSHES OFFSHORE THE TEXAS COAST. MODERATE RETURN FLOW EXPECTED AHEAD OF THE FRONT...WITH NLY GALES DEVELOPING BEHIND THE FRONT. SEE HIGH SEAS FORECAST UNDER HEADER MIAHSFAT2 FOR MORE DETAILS. CARIBBEAN SEA... THE MESSY WEATHER THAT WAS PREVIOUSLY OVER THE NW CARIBBEAN HAS DIMINISHED...AND IN GENERAL VERY LITTLE DEEP CONVECTION IS AFFECTING THE BASIN TONIGHT. LIGHTNING DATA DEPICTS ISOLATED TSTMS IN THE SW CARIBBEAN S OF 15N BETWEEN 78W-83W. THIS SEEMS TO BE ASSOCIATED WITH A NARROW ZONE OF LOW LEVEL CONVERGENCE (MOSTLY SPEED)...WHERE THE FLOW GOES FROM MODERATE TRADES OVER THE CENTRAL CARIBBEAN TO LIGHT AND VARIABLE OFF THE COAST OF NICARAGUA AND COSTA RICA. THERE IS ALSO AN ELONGATED UPPER TROUGH IN THE VICINITY GIVING FURTHER SUPPORT...EXTENDING SW FROM WRN PUERTO RICO TO NEAR PANAMA. SW FLOW AHEAD OF THIS UPPER TROUGH IS ADVECTING ABUNDANT TROPICAL MOISTURE NE THROUGH THE ERN CARIBBEAN. THIS IS ALSO HELPING TO SUPPORT ISOLATED SHOWERS AND TSTMS BETWEEN 65W-75W. ELY TRADES ARE EXPECTED TO REMAIN MODERATE OVER THE CENTRAL AND ERN CARIBBEAN THROUGH MON...BENDING MORE SE IN THE NW PORTION ATLANTIC OCEAN... A LINGERING FRONTAL BOUNDARY CONTINUES TO AFFECT THE WRN ATLC...ENTERING THE AREA NEAR BERMUDA AND CONTINUING W-SW TO NEAR COCOA BEACH FLORIDA. MOST OF THE ACTIVE WEATHER ASSOCIATED WITH THE FRONT AT THE MOMENT IS JUST OFFSHORE AND OVER FLORIDA...WITH SCATTERED TSTMS FROM 27N-29N BETWEEN 78W-83W. THERE ARE NO N WINDS BEHIND THE FRONT ANY MORE...AT LEAST OVER THE TAFB AREA OF RESPONSIBILITY. INSTEAD...SFC WINDS HAVE VEERED MORE ELY IN THE 10-15 KT RANGE IN RESPONSE TO HIGH PRES PUSHING E FROM VIRGINIA BEACH. LIGHT TO MODERATE E TO SE FLOW EXPECTED INTO EARLY WEEK AS THE FRONT GRADUALLY BECOMES DIFFUSE. THE UPPER PATTERN OVER THE WRN ATLC IS DOMINATED BY A LARGE ANTICYCLONE CENTERED NEAR 28N75W...THAT HAS RIDGING EXTENDING INTO THE CENTRAL ATLC WELL NE OF THE AREA. A WELL DEFINED UPPER LOW IS NEAR 29N41W THAT HAS ELONGATED TROUGHING EXTENDING SW ACROSS MUCH OF THE CENTRAL ATLC TOWARDS PUERTO RICO. THIS IS SUPPORTING A SFC TROUGH ALONG 32N30W 24N42W 25N52W. SCATTERED SHOWERS/ISOLATED TSTMS ARE GENERALLY WITHIN 120 NM EITHER SIDE OF THE SFC TROUGH. HOWEVER...THE COMBINATION OF LIFT AHEAD OF THE UPPER LOW AND THE ASSOCIATED SFC TROUGH ARE GENERATING MORE WIDESPREAD MOISTURE AND SHOWER ACTIVITY N OF 24N BETWEEN 31W-43W. LOW LEVEL CONFLUENCE IS ALSO SUPPORTING THE SFC TROUGH...BETWEEN RIDGING AROUND A 1026 MB HIGH N OF THE AREA NEAR 38N40W AND RIDGING OVER THE FAR E ATLC FROM A 1024 MB HIGH JUST OFFSHORE PORTUGAL. $$ WILLIS