000 AXNT20 KNHC 202337 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT OCT 20 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 50W/51W S OF 18N MOVING W 10-15 KT. THIS WAVE CONTINUES TO SHOW UP WELL IN SATELLITE IMAGERY WITH CLEAR LOW TO MID LEVEL CYCLONIC TURNING AROUND THE AXIS. MOST OF THE ASSOCIATED...DISORGANIZED CONVECTION IS DISPLACED TO THE E OF THE AXIS DUE TO STRONG UPPER LEVEL SW WINDS OVER THE AREA. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM E OF THE AXIS MAINLY FROM 7N-13N. WEAK TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 78W S OF 15N MOVING W 10-15 KT. THERE ARE SCATTERED TSTMS OVER THE SW CARIBBEAN OFFSHORE PANAMA...S OF 14N BETWEEN 76W-82W. HOWEVER...IT IS UNCLEAR IF THIS ACTIVITY IS ACTUALLY FROM THE WAVE OR FROM DIVERGENCE ALOFT NEAR THE BASE OF AN UPPER TROUGH. A 48 HOUR LOOP OF THE UW-CIMSS TPW PRODUCT SHOWS THAT THE HIGHEST AREA OF MOISTURE CONTENT IN THE VICINITY IS ACTUALLY NOW IN THE NW CARIBBEAN...WHICH WAS BETWEEN HISPANIOLA AND VENEZUELA A COUPLE DAYS AGO. THE FEATURE NOW IN THE NW CARIBBEAN IS BEING ANALYZED AS A TROUGH JUST E OF THE YUCATAN PENINSULA. GIVEN THAT THE FLOW AROUND THE TROUGH IS DOMINATING THE AREA...THE WEAK WAVE AT 78W MAY BE DROPPED FROM THE NEXT MAP. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N12W 6N30W 10N48W 11N61W. BESIDES FOR THE ACTIVITY ASSOCIATED WITH THE TROPICAL SCATTERED ISOLATED TSTMS ARE WITHIN 90 NM EITHER SIDE OF AXIS BETWEEN 22W-35W. THE ITCZ MAY ALSO BE ENHANCING THE SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER THE TROPICAL ATLANTIC TO THE COAST OF SOUTH AMERICA...FROM 7N-12N BETWEEN 55W-62W. DISCUSSION... GULF OF MEXICO... AS OF 20/2100 UTC...A STATIONARY FRONT EXTENDS FROM SW FLORIDA NEAR 26N82W WSW THROUGH THE MIDDLE AND WESTERN GULF ALONG 24N88W 25N87W. AN UPPER HIGH IS NEAR THE ERN BAY OF CAMPECHE WHILE A SHORTWAVE UPPER TROUGH IS OVER THE ERN GULF GENERALLY ALONG 87W. THE COMBINATION OF THE SFC FRONT AND THE UPPER TROUGH IS SUPPORTING SCATTERED SHOWERS AND TSTMS AROUND THE FLORIDA KEYS AND JUST OFFSHORE SW FLORIDA...OVER THE SE GULF WATERS S OF 27N E OF 87W. A SECONDARY WEAK SFC TROUGH IS OVER THE BAY OF CAMPECHE ALONG 23N97W 19N92W. THIS ALONG WITH THE UPPER HIGH ARE SUPPORTING SCATTERED SHOWERS/ISOLATED TSTMS OFF THE COAST OF MEXICO S OF 23N W OF 93W. VERY DRY AIR AND MOSTLY CLEAR SKIES ARE OVER THE NRN GULF AND GULF COAST STATES...GENERALLY N OF 25N EXCEPT N OF 27N OVER THE ERN GULF. A WEAK SFC HIGH OVER ALABAMA IS ALSO SUPPORTING THE NICE WEATHER OVER THE NRN GULF. THIS HIGH IS EXPECTED TO MOVE E FAIRLY QUICKLY OVER THE NEXT COUPLE OF DAYS IN ADVANCE OF THE NEXT STRONGER COLD FRONT EXPECTED TO MOVE OFF THE TEXAS COAST DURING MONDAY. MODEL GUIDANCE SUGGESTS THE STATIONARY FRONT AND ASSOCIATED MOISTURE/SHOWERS CURRENTLY JUST OFF SW FLORIDA WILL SLIDE NW/N AS A WARM FRONT THROUGH EARLY WEEK...REACHING THE CENTRAL GULF COAST BY TOMORROW EVENING. CARIBBEAN SEA... SCATTERED SHOWERS AND ISOLATED TSTMS ARE OVER MUCH OF THE NW CARIBBEAN BETWEEN HONDURAS AND WRN CUBA...ASSOCIATED WITH A SFC TROUGH ANALYZED ALONG 23N84W 16N87W. UPPER DIFFLUENCE IS ALSO SUPPORTING THIS ACTIVITY...AROUND THE SW PERIPHERY OF AN UPPER HIGH NE OF THE BAHAMAS. THE SHOWER ACTIVITY OVER THE NW CARIBBEAN IS EXPECTED TO MOVE NW INTO THE GULF DURING SUNDAY. AN UPPER LOW IS JUST SW OF PUERTO RICO...THAT HAS TROUGHING EXTENDING SW TOWARDS PANAMA. LIFT AHEAD OF THIS FEATURE IS SUPPORTING DISORGANIZED SHOWERS AND TSTMS OVER THE FAR ERN CARIBBEAN...LESSER ANTILLES...AND TROPICAL NORTH ATLANTIC S OF 18N BETWEEN 56W-64W. MODEL GUIDANCE SUGGESTS THE UPPER TROUGHING WILL SLIDE WWD OVER THE NEXT COUPLE OF DAYS...AND THUS THE SHOWER ACTIVITY EXPECTED TO MOVE SLOWLY W THROUGH MON AFFECTING THE ERN CARIBBEAN. TRADES ARE MODERATE OVER THE CENTRAL AND ERN CARIBBEAN...AND BEND MORE SE IN THE WRN PORTION AHEAD OF THE TROUGH NEAR THE GULF OF HONDURAS. ATLANTIC OCEAN... A COLD FRONT IS OVER THE WRN ATLC...ENTERING THE AREA NEAR 32N76W AND CONTINUING SW TO NEAR PALM BEACH. SCATTERED SHOWERS AND TSTMS ARE ALONG AND WITHIN 120 NM OF THE FRONT. THE FRONT IS EXPECTED TO MOVE E AND WEAKEN TO A POSITION BETWEEN NEAR BERMUDA AND THE NW BAHAMAS THROUGH SUN EVENING...AS HIGH PRES BUILDS INTO THE WRN ATLC BEHIND THE FRONT. THE UPPER PATTERN OVER THE WRN ATLC IS DOMINATED BY A LARGE ANTICYCLONE CENTERED NEAR 27N75W. AN ELONGATED UPPER TROUGH EXTENDS SW ACROSS MUCH OF THE CENTRAL ATLC ALONG 32N45W 23N60W TO NEAR NE PUERTO RICO. THIS IS SUPPORTING A SFC TROUGH ALONG 32N34W 26N42W 25N55W...WHICH EXTENDS SW FROM A 1015 MB LOW NEAR 34N34W. SCATTERED SHOWERS ARE GENERALLY WITHIN 120 NM EITHER SIDE OF THE SFC TROUGH...WITH LIGHTNING DATA ALSO DEPICTING A FEW TSTMS NEAR THE WRN PORTION OF THE TROUGH AXIS FROM 24N-27N BETWEEN 50W-55W. LOW LEVEL CONFLUENCE IS ALSO SUPPORTING THE SFC TROUGH...BETWEEN RIDGING AROUND A 1028 MB HIGH N OF THE AREA NEAR 39N48W AND ANOTHER WEAK 1018 MB HIGH NEAR 26N31W. NWP GUIDANCE SUGGESTS WEAK TROUGHING AND SCATTERED SHOWER ACTIVITY WILL PERSIST OVER THIS PORTION OF THE ATLC THROUGH SUN. THE REMAINDER OF THE E ATLC JUST OFF THE AFRICAN COAST REMAINS TRANQUIL...UNDER THE INFLUENCE OF WEAK SFC RIDGING AND STABLE AIR. THIS IS EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS. $$ WILLIS