000 AXNT20 KNHC 180510 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU OCT 18 2012 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0445 UTC. ...TROPICAL WAVES... WEAK TROPICAL WAVE IS ANALYZED ALONG 39W/40W BETWEEN 10N-21N. THIS WAVE HAS BEEN DIFFICULT TO TRACK OVER THE PAST TWO DAYS. NO ASSOCIATED DEEP CONVECTION. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED ACROSS W AFRICA INTO THE E TROPICAL ATLC NEAR 11N16W ALONG 7N24W TO 9N35W. THE ITCZ IS ANALYZED STARTING NEAR 12N43W ALONG 10N51W TO 11N58W. A WEAK SURFACE TROUGH IS OVER THE W TROPICAL ATLC EXTENDING ALONG 60W FROM 10N-15N. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 150/180 NM N OF THE MONSOON TROUGH BETWEEN 18W-24W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 7N-13N BETWEEN 15W-18W...FROM 10N-19N BETWEEN 34W-38W...AND FROM 7N-15N BETWEEN 43W-54W. ...DISCUSSION... GULF OF MEXICO... A STRONG SHORTWAVE UPPER TROUGH EXTENDS FROM THE NORTH CAROLINA COAST TO ACROSS FLORIDA NEAR LAKE OKEECHOBEE THEN KEY WEST TO THE COAST OF CUBA NEAR 23N83W COVERING THE NE GULF. A SECOND UPPER TROUGH IS DIGGING S OVER THE MISSISSIPPI VALLEY TO LOUISIANA RE-ENFORCING THE SHORTWAVE AND SUPPORTING THE NEXT COLD FRONT EXPECTED TO ENTER THE GULF. A BROAD UPPER RIDGE DOMINATES THE REMAINDER OF THE GULF WATERS WITH THE AXIS EXTENDING FROM AN UPPER HIGH NEAR MEXICO CITY ACROSS THE BAY OF CAMPECHE AND THE YUCATAN PENINSULA INTO THE FAR NW CARIBBEAN. A SURFACE TROUGH EXTENDS FROM THE NW CARIBBEAN THROUGH THE YUCATAN CHANNEL NEAR THE W TIP OF CUBA ALONG 22N85W TO 26N84W WITH SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS S OF 26N E OF THE TROUGH THROUGH THE STRAITS OF FLORIDA. A COLD FRONT WILL MOVE OFF THE TEXAS COAST OVERNIGHT MOVING QUICKLY ACROSS THE GULF AND REACHING FROM NEAR TAMPA FLORIDA TO BROWNSVILLE TEXAS BY FRI MORNING. THE FRONT WILL DISSIPATE FROM NEAR FORT MYERS FLORIDA TO SE TEXAS ON SAT. WEAK HIGH PRESSURE WILL BUILD ACROSS THE AREA SAT AND SUN WITH INCREASING RETURN FLOW MON. CARIBBEAN SEA... A BROAD UPPER RIDGE EXTENDS AN AXIS FROM ACROSS THE YUCATAN PENINSULA NEAR 18N89W TO OVER THE NW CARIBBEAN TO NEAR 17N82W. A NARROW UPPER TROUGH EXTENDS FROM THE W ATLC INTO THE N/CENTRAL CARIBBEAN THROUGH THE WINDWARD PASSAGE TO 15N80W. A SURFACE TROUGH EXTENDS FROM 20N84W THROUGH THE YUCATAN CHANNEL NEAR THE W TIP OF CUBA INTO THE GULF OF MEXICO. A SECOND SURFACE TROUGH EXTENDS FROM 19N83W TO 15N83W. A SECOND BROAD UPPER RIDGE COVERS THE REMAINDER OF THE CARIBBEAN ANCHORED NEAR 16N67W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 12N E OF 70W TO ACROSS THE LESSER ANTILLES/PUERTO RICO AND S OF 13N BETWEEN 70W-75W. A WEAK 1008 MB LOW IS ANALYZED IN THE SW CARIBBEAN NEAR 11N81W WITH ISOLATED SHOWERS S OF 14N BETWEEN 77W-83W. LINGERING SWELLS THROUGH THE NE CARIBBEAN PASSAGES WILL DIMINISH TONIGHT. A SURFACE TROUGH E OF THE LESSER ANTILLES WILL MOVE W-NW ACROSS THE WINDWARD ISLANDS LATER TONIGHT AND INTO THE SE AND E CARIBBEAN THU. THE 1008 MB LOW IN SW CARIBBEAN WILL DRIFT N THROUGH MON. ATLANTIC OCEAN... A NARROW UPPER TROUGH EXTENDS FROM OFF THE CANADIAN MARITIMES INTO THE W ATLC OVER BERMUDA CONTINUING INTO THE N/CENTRAL CARIBBEAN THROUGH THE WINDWARD PASSAGE SUPPORTING A DISSIPATING STATIONARY FRONT THAT ENTERS THE REGION THROUGH 32N63W ALONG 29N71W TO 28N77W. A STRONG SHORTWAVE UPPER TROUGH EXTENDS FROM THE NORTH CAROLINA COAST TO ACROSS FLORIDA NEAR LAKE OKEECHOBEE INTO THE GULF OF MEXICO GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 23N-30N BETWEEN 72W-80W AND OVER S FLORIDA S OF LAKE OKEECHOBEE. AN UPPER RIDGE EXTENDS FROM THE E CARIBBEAN OVER THE LEEWARD/VIRGIN ISLANDS NEAR 17N62W ALONG 26N56W TO BEYOND 32N50W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 16N-21N BETWEEN 60W-66W AND SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM 22N59W TO BEYOND 32N53W. AN UPPER TROUGH EXTENDS ACROSS THE E ATLC FROM AFRICA JUST S OF THE CANARY ISLANDS ALONG 27N25W 28N38W TO AN UPPER LOW NEAR 18N49W INTO THE TROPICS TO THE BASE NEAR 12N50W. THIS UPPER TROUGH IS MASKING THE TROPICAL WAVE MAKING IT DIFFICULT TO LOCATE. THE CENTRAL AND E ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED WELL N OF THE DISCUSSION AREA. LINGERING SWELLS FROM POST-TROPICAL CYCLONE RAFAEL WILL CONTINUE TO SUBSIDE OVER THE CENTRAL ATLC TONIGHT. A COLD FRONT WILL MOVE INTO THE NW WATERS LATE FRI AND EXTEND FROM 32N72W TO WEST PALM BEACH BY LATE SAT THEN FROM 32N70W TO WEST PALM BEACH BY SUN AND FROM 32N58W TO SE FLORIDA BY LATE MON. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW