000 AXNT20 KNHC 172342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN APR 17 2011 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION OF SOUTH AMERICA...AND 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. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED SOUTH OF THE EQUATOR. NUMEROUS STRONG CONVECTION IS FROM 4N TO INLAND OVER SW AFRICA E OF 5W TO JUST ACROSS THE PRIME MERIDIAN. CLUSTERS OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION ARE FROM 3N TO INLAND OVER SW AFRICA BETWEEN 6W-9W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER TROUGH CONTINUES TO MOVE INTO THE NW ATLC COVERING THE NE GULF N OF 27N E OF 90W SUPPORTING A DISSIPATING FRONTAL BOUNDARY THAT EXTENDS FROM THE W ATLC ACROSS S FLORIDA AT 17/2100 UTC BETWEEN FORT LAUDERDALE AND CAPE SABLE TO 24N87W. THE REMAINDER OF THE GULF IS DOMINATED BY A BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC REGION. WEAK SURFACE RIDGE REMAINS OVER THE NE GULF WITH A WEAK 1018 MB HIGH OFF THE FLORIDA COAST NEAR PENSACOLA. THE GULF REMAINS UNDER MOSTLY CLEAR SKIES THIS EVENING. THE EXCEPTION IS WITHIN 60 NM ALONG THE NW COAST OF CUBA WHERE AFTERNOON SHOWERS/THUNDERSTORMS THAT DEVELOPED INLAND ARE GIVING THE AREA ISOLATED SHOWERS THIS EVENING. HIGH PRESSURE WILL CONTINUE TO DOMINATE MUCH OF THE GULF THROUGH FRI. A TROUGH WILL DEVELOP OVER TEXAS AND NE MEXICO RESULTING IN FRESH SE FLOW OVER MOST OF THE MID AND W PORTIONS THROUGH FRI. CARIBBEAN SEA... A BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC REGION COVERS THE GULF OF MEXICO AND THE W CARIBBEAN N OF 16N W OF 70W. THE UPPER TROUGH OVER THE CENTRAL ATLC DIPS S OVER THE FAR NE CARIBBEAN FROM THE MONA PASSAGE TO THE LEEWARD ISLANDS N OF 16N. A SECOND UPPER RIDGE COVERS THE S CARIBBEAN S OF 15N E OF 80W. TROPICAL MOISTURE IS BEING DRAWN ACROSS THE S CARIBBEAN DUE TO THIS UPPER FLOW GENERATING ISOLATED SHOWERS WITHIN 90 NM OF LINE FROM 12N76W TO ACROSS THE WINDWARD ISLANDS NEAR SAINT VINCENT. LIGHT TO MODERATE TRADE WINDS PREVAIL ACROSS THE BASIN DUE TO THE BROAD PRESSURE GRADIENT. THESE TRADE WINDS ARE BANKING LOW LEVEL CLOUDS WITH SCATTERED SHOWERS OVER THE SE CARIBBEAN ALONG THE MOUNTAINS OF W PANAMA AND COSTA RICA AND WITHIN 75 NM ALONG THE COAST. THESE TRADE WINDS WILL CONTINUE OVER MOST OF THE CARIBBEAN THROUGH NEXT WEEK. ATLANTIC OCEAN... A BROAD UPPER TROUGH IS MOVING OFF THE E CONUS INTO THE NW ATLC SUPPORTING A COLD FRONT THAT ENTERS THE REGION AT 17/2100 UTC NEAR 32N73W EXTENDING TO W GRAND BAHAMA ISLAND WHERE IT BEGINS TO DISSIPATE ACROSS S FLORIDA INTO THE GULF OF MEXICO NEAR FORT LAUDERDALE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 30 NM OF THE FRONT MAINLY IN THE IMMEDIATE VICINITY OF S FLORIDA. A SURFACE TROUGH IS TO THE E OF THE FRONT EXTENDING FROM 27N77W ACROSS THE N BAHAMA ISLANDS INTO THE STRAITS OF FLORIDA TO 24N80W. AN UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC TO OVER THE FAR NE CARIBBEAN SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 24N55W ALONG 19N58W TO 16N58W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-26N BETWEEN 54W-58W. AN UPPER RIDGE AXIS IS OVER THE E/CENTRAL ATLC EXTENDING FROM 21N46W TO BEYOND 32N50W GENERATING BROKEN/ OVERCAST MULTILAYERED CLOUDS WITH ISOLATED SHOWERS COVERING AN AREA FROM 21N-32N BETWEEN 47W-55W. A DEEP LAYERED LOW IS OVER THE E ATLC WITH THE UPPER LOW CENTERED NEAR 31N20W AND A 997 MB SURFACE LOW NEAR 31N21W. A SURFACE TROUGH EXTENDS FROM THE SURFACE LOW OVER THE WESTERN MOST CANARY ISLANDS ALONG 23N22W TO 20N33W. ISOLATED SHOWERS ARE N OF 31N BETWEEN 13W-23W. W ATLC COLD FRONT WILL WEAKEN AS IT MOVES E AND DISSIPATE BY MON EVENING. HIGH PRESSURE WILL THEN BEGIN TO BUILD OVER THE W AND CENTRAL ATLC. THE SURFACE TROUGH CURRENTLY NE OF THE LEEWARD ISLANDS WILL DRIFT WESTWARD THROUGH LATE WED. A TIGHT PRESSURE GRADIENT INDUCED BETWEEN THIS TROUGH AND THE HIGH PRESSURE TO THE N WILL MAINTAIN FRESH NE WINDS OVER THE W AND CENTRAL ATLC THROUGH EARLY THU. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW