000 AXNT20 KNHC 190001 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED MAY 18 2011 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 57W/58W S OF 13N TO INLAND OVER SOUTH AMERICA DRIFTING W AT LESS THAN 10 KT. WAVE IS EMBEDDED IN A NARROW AREA OF MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS WITHIN 90/120 NM E OF THE WAVE AXIS S OF 9N. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 7N10W 4N14W 4N34W 1N50W. SCATTERED/ NUMEROUS STRONG CONVECTION IS WITHIN 150 NM S OF THE ITCZ BETWEEN 9W-11W AND WITHIN 120 NM N OF THE ITCZ BETWEEN 20W-23W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE ITCZ TO 8N BETWEEN 20W-24W AND FROM 3N-6N BETWEEN 32W-35W. SCATTERED MODERATE CONVECTION IS FROM 1N-4N BETWEEN 13W-16W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER TROUGH COVERS THE E GULF N OF 24N E OF 90W SUPPORTING A DISSIPATING COLD FRONT THAT EXTENDS FROM THE W ATLC AT 18/1800 UTC ACROSS CENTRAL FLORIDA BETWEEN VERO BEACH TO JUST N OF FORT MYERS INTO THE GULF OF MEXICO TO 27N88W. A PRE-FRONTAL SURFACE TROUGH EXTENDS AT 18-1800 UTC THROUGH THE STRAITS OF FLORIDA NEAR THE N TIP OF ANDROS ISLAND ALONG THE N COAST OF CUBA TO 23N84W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF THE SURFACE TROUGH TO INLAND OVER CUBA. BROAD LOW AMPLITUDE UPPER RIDGE COVERS THE REMAINDER OF THE GULF WITH DRY STABLE AIR ALOFT COVERING THE GULF S OF 27N LIMITING SHOWER ACTIVITY. LOW LEVEL MOISTURE REMAINS OVER THE FAR W GULF AND THE SE SURFACE FLOW IS BANKING LOW LEVEL CLOUDS MAINLY OVER THE NW GULF N OF 25N W OF 94W. SMOKE IS OBSERVED ON VISIBLE SATELLITE IMAGERY W OF LINE FROM NW YUCATAN PENINSULA TO CENTRAL LOUISIANA AND NOAA SSD FIRE PRODUCTS INDICATE NUMEROUS FIRES OVER S MEXICO. A SURFACE RIDGE IS BUILDING N OF THE FRONT ANCHORED BY A WEAK 1013 MB HIGH JUST OFF THE COAST OF PENSACOLA FLORIDA LEAVING THE NE GULF UNDER CLEAR SKIES THIS EVENING. HIGH PRESSURE OVER THE NE GULF WILL DRIFT E ON THU THROUGH FRI NIGHT THEN E OF THE AREA SAT. SE RETURN FLOW OVER THE W GULF WILL PREVAIL THROUGH MON. CARIBBEAN SEA... A SHORTWAVE UPPER TROUGH EXTENDS FROM THE DOMINICAN REPUBLIC NEAR 19N70W TO THE GULF OF VENEZUELA SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 17N70W 14N71W TO 12N70W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 12N-18N BETWEEN 66W-73W. A WEAKER SURFACE TROUGH IS OVER THE NE CARIBBEAN EXTENDING ALONG 64W FROM 15N THROUGH THE VIRGIN ISLANDS TO 19N WITH ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS. A BROAD LOW AMPLITUDE UPPER RIDGE COVERS THE W CARIBBEAN W OF 75W AND WITH DRY STABLE AIR ALOFT WHICH IS LEAVING THE CARIBBEAN W OF 75W UNDER MOSTLY CLEAR SKIES THIS EVENING. THE CENTRAL CARIBBEAN SURFACE TROUGH WILL REMAIN NEAR STATIONARY THROUGH THU THEN MOVE W AND DISSIPATES IN THE W CARIBBEAN THU NIGHT. TROPICAL WAVE E OF THE WINDWARD ISLANDS WILL MOVE INTO THE E CARIBBEAN ON THU AND A WEAK LOW PRESSURE WILL DEVELOP ALONG THE WAVE WHEN IT REACHES THE SW CARIBBEAN OVER THE WEEKEND. THE ATLANTIC OCEAN... AN UPPER TROUGH EXTENDS FROM THE GREAT LAKES REGION INTO THE W ATLC NEAR THE NORTH/SOUTH CAROLINA BORDER THEN S TO THE BAHAMA ISLANDS SUPPORTING A COLD FRONT THAT AT 18/1800 UTC ENTERS THE DISCUSSION AREA NEAR 32N76W ALONG 29N78W OVER CENTRAL FLORIDA INTO THE GULF OF MEXICO NEAR VERO BEACH THEN DISSIPATING INTO THE GULF OF MEXICO. A PRE-FRONTAL SURFACE TROUGH EXTENDS THROUGH 32N73W ALONG 28N75W ACROSS THE BAHAMAS AND INTO THE STRAITS OF FLORIDA NEAR THE N TIP OF ANDROS ISLAND. SCATTERED SHOWERS/ THUNDERSTORMS ARE WITHIN 150 NM E OF THE SURFACE TROUGH FROM 25N-29N AND WITHIN 120 NM SE OF THE TROUGH S OF 24N TO INLAND OVER CUBA. A WEAKENING SURFACE TROUGH IS JUST E OF THE TURKS AND CAICOS EXTENDING FROM 23N70W TO THE N COAST OF HISPANIOLA NEAR THE HAITI/DOMINICAN REPUBLIC BORDER. AN UPPER RIDGE IS OVER THE W/CENTRAL ATLC EXTENDING FROM THE W TROPICAL ATLC E OF THE LESSER ANTILLES ALONG 55W TO 20N THEN NNW TO BEYOND 32N60W PROVIDING DIFFLUENT FLOW ALOFT TO ENHANCE PATCHES OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 21N-30N BETWEEN 57W-69W. AN UPPER TROUGH IN THE CENTRAL ATLC EXTENDS THROUGH 32N45W TO 20N40W SUPPORTING A REMNANT SURFACE TROUGH THAT EXTENDS THROUGH 32N46W TO 26N50W WITH ISOLATED SHOWERS WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH. THIS SURFACE TROUGH SPLITS A BROAD SURFACE RIDGE THAT COVERS THE ATLC N OF 20N BETWEEN SW AFRICA AND 70W. W ATLC FRONT WILL MOVE E TONIGHT AND DISSIPATE ON THU. SURFACE RIDGE WILL GRADUALLY BUILD E ALONG 30N ON THU AND WEAKENS AS IT DRIFTS S OVER THE WEEKEND. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW