000 AXNT20 KNHC 131059 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED APR 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 05N09W 04N19W TO THE EQUATOR NEAR 28W...THEN INTO NE BRAZIL NEAR 04S38W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 02N-06N E OF 07W TO THE PRIME MERIDIAN. ISOLATED MODERATE CONVECTION IS FROM 05N-08N BETWEEN 11W-15W. ...DISCUSSION... GULF OF MEXICO... NW FLOW ALOFT IS ACROSS MUCH OF THE GULF THIS MORNING DUE TO AN EXPANSIVE UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER CENTRAL MEXICO NEAR 20N100W. WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL TROUGH CONTINUES TO ROTATE OVER THE MID-ATLC STATES THAT SUPPORTS A COLD FRONT THAT AT 13/0900 UTC EXTENDS ACROSS THE FLORIDA PENINSULA FROM STUART TO FORT MYERS BEACH AND INTO THE SE GULF NEAR 26N84W. THE FRONT CONTINUES STATIONARY WESTWARD TO 26N95W. WHILE MUCH OF THE UPPER LEVEL SUPPORT FOR THIS FRONT IS LOCATED IN THE W ATLC...THE FRONT GENERALLY REMAINS FAIRLY BENIGN WITH A NOTICEABLE CONTRAST IN DEWPOINTS ACROSS THE BOUNDARY. RECENT SHIP AND BUOY OBSERVATIONS INDICATE A MUCH DRIER AIRMASS IN PLACE N OF 26N AS A 1019 MB HIGH SETTLES IN ACROSS THE LOWER MISSISSIPPI RIVER VALLEY NEAR 34N91W. THE FRONT IS FORECAST TO GRADUALLY BECOME MORE DIFFUSE AND DISSIPATE THROUGH THE DAY ON WEDNESDAY AS THE HIGH SHIFTS SLOWLY EASTWARD PROVIDING LIGHT ANTICYCLONIC FLOW THROUGH LATE WEDNESDAY. S-SE RETURN FLOW IS EXPECTED TO RE-ESTABLISH ACROSS THE WESTERN GULF BY EARLY THURSDAY AS THE NEXT SURFACE LOW PRESSURE AREA ORGANIZES OVER THE U.S. CENTRAL PLAINS AND MOVES NE TOWARDS THE GREAT LAKES REGION. CARIBBEAN SEA... AN AMPLIFIED MIDDLE TO UPPER LEVEL TROUGH IS LOCATED OVER THE WESTERN CARIBBEAN WITH AXIS EXTENDING FROM THE SW NORTH ATLC NEAR 25N75W S-SW OVER EASTERN CUBA AND JAMAICA TO NORTHERN COSTA RICA NEAR 10N85W. STRONG SUBSIDENCE AND DRY AIR ACCOMPANY THIS UPPER LEVEL FEATURE AND THESE FACTORS CONTINUE TO PROVIDE OVERALL CLEAR SKIES AND FAIR CONDITIONS FOR THE WESTERN CARIBBEAN W OF 72W. EAST OF THE TROUGH AXIS HOWEVER...MOIST SOUTHWESTERLY FLOW IS ADVECTING A CONSIDERABLE AMOUNT OF MIDDLE TO UPPER LEVEL MOISTURE ACROSS THE EASTERN CARIBBEAN AND LESSER ANTILLES. A SURFACE TROUGH IS ANALYZED FROM EASTERN PUERTO RICO ALONG 15N70W TO LAKE MARACAIBO WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS E OF 70W. THE SURFACE TROUGH IS FORECAST TO DRIFT WESTWARD AND GRADUALLY WEAKEN THROUGH EARLY FRIDAY WITH EASTERLY TRADES REMAINING LIGHT DUE TO A RELAXED PRESSURE GRADIENT ACROSS THE ENTIRE BASIN. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH CONTINUES TO ROTATE OVER THE MID-ATLC STATES THIS MORNING THAT SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N75W EXTENDING SW TO THE FLORIDA PENINSULA NEAR STUART. A PRE-FRONTAL TROUGH ALSO EXTENDS FROM THE COLD FRONT NEAR 29N77W TO 24N80W. SATELLITE IMAGERY AND LIGHTNING DATA INDICATE SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 120 NM EAST OF THE FRONT N OF 26N. THE REMAINDER OF THE W ATLC WEST OF 50W IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED NE OF BERMUDA NEAR 34N59W. THE RIDGE AXIS EXTENDS FROM THE HIGH TO THE SE BAHAMAS. AN UPPER LEVEL LOW IS CENTERED NEAR 30N45W IN THE CENTRAL ATLC AND CONTINUES TO SUPPORT A WEAK 1015 MB LOW CENTERED VERY NEAR THE UPPER LEVEL LOW. A STATIONARY FRONT IS ANALYZED FROM 32N45W INTO THE LOW CENTER THEN A SURFACE TROUGH EXTENDS SOUTH FROM THE LOW ALONG 28N44W TO 24N50W. THIS AREA OF DEEP LAYER TROUGHING IS LARGELY EMBEDDED WITHIN THE SUBTROPICAL RIDGE PRODUCING AN AREA OF WIDELY SCATTERED SHOWERS FROM 25N-33N BETWEEN 38W-45W. THIS ACTIVITY IS LIKELY ENHANCED BY UPPER LEVEL DIFFLUENCE LOCATED E OF THE UPPER LEVEL LOW. STRONG HIGH PRESSURE IS EXPECTED TO BUILD IN OVER THE CENTRAL ATLC BY EARLY THURSDAY AND DISSIPATE ANY REMNANTS OF THE FRONT. NE WINDS ON THE SOUTHERN PERIPHERY OF A SURFACE RIDGE OVER THE EASTERN ATLC INFLUENCES THE OPEN WATERS E OF 35W UNDER MOSTLY FAIR AND STABLE CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN