000 AXNT20 KNHC 200004 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAY 19 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 WAS RELOCATED ALONG 62W/63W S OF 13N TO INLAND OVER SOUTH AMERICA BASED ON SATELLITE IMAGERY...PRECIPITABLE WATER IMAGERY..AND HOVMOLLER PLOTS MOVING W 10-15 KT. WAVE REMAINS EMBEDDED WITHIN AN AREA OF DEEP LAYERED MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND OVER VENEZUELA. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 7N12W 5N15W 2N25W 1N37W TO INLAND OVER SOUTH AMERICA AT THE EQUATOR NEAR 49W. CLUSTERS OF SCATTERED/NUMEROUS STRONG CONVECTION ARE FROM 2N-5N BETWEEN 6W-14W. SMALL CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 75 NM EITHER SIDE OF THE ITCZ BETWEEN 16W-28W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER RIDGE COVERS MOST OF THE GULF WITH THE AXIS ALONG THE COAST OF MEXICO AND TEXAS TO INLAND OVER THE CENTRAL PLAIN STATES AND COUPLED WITH THE BROAD UPPER TROUGH OVER THE W ATLC IS GIVING THE GULF WATERS NW FLOW ALOFT. SOMEWHAT DRY STABLE AIR ALOFT COVERS MUCH OF THE GULF LIMITING SHOWER ACTIVITY. HOWEVER...LOW LEVEL MOISTURE REMAINS OVER THE NW GULF AND THE E TO SE SURFACE FLOW CONTINUES TO BANK LOW LEVEL CLOUDS OVER THE NW GULF N OF 27N W OF 92W. DENSE SMOKE IS OBSERVED ON VISIBLE SATELLITE IMAGERY W OF LINE FROM NE YUCATAN PENINSULA/YUCATAN CHANNEL TO E LOUISIANA NEAR GRAND ISLE FROM FIRES PREVIOUSLY REPORTED OVER MEXICO ON NOAA SSD FIRE PRODUCTS. A WEAK SURFACE RIDGE REMAINS OVER THE NE GULF WITH A 1018 MB HIGH OFF THE FLORIDA COAST NEAR 29N84W LEAVING THE REMAINDER OF THE GULF UNDER MOSTLY CLEAR SKIES THIS EVENING. SURFACE RIDGE OVER THE NE GULF WILL DRIFT E THROUGH FRI NIGHT THEN INTO THE W ATLC ON SAT. SE RETURN FLOW WILL CONTINUE OVER THE W GULF THROUGH TUE. CARIBBEAN SEA... A BROAD SHORTWAVE UPPER TROUGH EXTENDS FROM THE WINDWARD PASSAGE TO THE SW CARIBBEAN ALONG 12N78W TO THE COAST OF CENTRAL AMERICA NEAR THE PANAMA/COSTA RICA BORDER SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 19N75W TO 12N74W WITH ISOLATED SHOWERS WITHIN 75 NM EITHER SIDE OF THE TROUGH AXIS. A SECOND SURFACE TROUGH EXTENDS FROM THE SW ATLC THROUGH THE MONA PASSAGE TO 16N66W. A BROAD UPPER RIDGE COVERS THE E CARIBBEAN E OF 70W WITH THE AXIS E OF THE LESSER ANTILLES ALONG 57W/58W. DEEP LAYERED MOISTURE REMAINS OVER THE E CARIBBEAN AND COUPLED WITH THE DIFFLUENT FLOW ALOFT IS GENERATING SCATTERED SHOWERS OVER THE E CARIBBEAN E OF 72W ACROSS THE LESSER ANTILLES FROM SOUTH AMERICA ACROSS PUERTO RICO AND HISPANIOLA. DRY STABLE AIR ALOFT REMAINS OVER THE W CARIBBEAN LEAVING THE AREA W OF 77W UNDER MOSTLY CLEAR SKIES THIS EVENING. SMOKE IS OBSERVED ON THE LAST VISIBLE SATELLITE IMAGES W OF LINE FROM THE TIP OF HONDURAS/NICARAGUA TO THE NE YUCATAN PENINSULA/YUCATAN CHANNEL. SURFACE TROUGH FROM WINDWARD PASSAGE TO NORTHERN COLOMBIA WILL REMAIN NEARLY STATIONARY THROUGH SAT. THE TROPICAL WAVE WILL MOVE SLOWLY INTO THE CENTRAL CARIBBEAN THIS WEEKEND. ATLANTIC OCEAN... AN UPPER TROUGH COVERS THE W ATLC N OF 20N BETWEEN 67W-80W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N72W TO 30N74W WHERE IT DISSIPATES TO 29N75W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60 NM E OF THE FRONT. A CONVERGENCE LINE/SURFACE TROUGH THAT EXTENDS FROM 30N79W TO OVER ANDROS ISLAND NEAR 24N78W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM E OF THE SURFACE TROUGH. AFTERNOON THUNDERSTORMS HAVE DEVELOPED INLAND OVER S FLORIDA S OF LAKE OKEECHOBEE WITH DEBRIS CLOUDS SPREADING E OVER THE SE COAST OF FLORIDA. A SURFACE TROUGH IS TO THE SE OF THE BAHAMAS EXTENDING FROM 23N72W E OF THE TURKS AND CAICOS THROUGH THE MONA PASSAGE INTO THE NE CARIBBEAN. THIS TROUGH IS ALONG THE WESTERN EDGE OF AN UPPER RIDGE THAT EXTENDS FROM SOUTH AMERICA ALONG 57W/58W TO BEYOND 32N. ANOTHER SURFACE TROUGH IS TO THE NE EXTENDING ALONG 61W FROM 25N-32N. THE UPPER RIDGE IS SUPPLYING DIFFLUENT FLOW ALOFT ENHANCING CLUSTERS OF SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS OVER AN AREA FROM 28N TO THE THE GREATER ANTILLES BETWEEN 62W-72W AND SCATTERED SHOWERS WITHIN 150 NM OF LINE FROM THE LEEWARD ISLANDS NEAR 16N61W TO 32N57W. AN UPPER TROUGH IN THE CENTRAL ATLC IS N OF 25N BETWEEN 38W-46W SUPPORTING A WEAK 1021 MB LOW NEAR 31N48W AND A SURFACE TROUGH EXTENDING ALONG 30N47W TO 27N50W WITH POSSIBLE ISOLATED SHOWERS WITHIN 75 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. SURFACE RIDGE WILL GRADUALLY BUILD OVER THE W ATLC ALONG 30N THEN WILL WEAKEN SLIGHTLY AS IT MOVES TO 28N OVER THE WEEKEND. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW