000 AXNT20 KNHC 171054 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU MAR 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0745 UTC. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED FROM 5N9W TO ACROSS THE EQUATOR NEAR 23N CONTINUING SW AND INLAND INTO NORTHERN BRAZIL. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE ITCZ BETWEEN 10W TO 14W AS WELL AS WITHIN 60 NM EITHER SIDE OF A LINE FROM 2N17W TO 3N26. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF LINE FROM 0N40W TO THE COAST OF NE BRAZIL NEAR 4N51W. ...DISCUSSION... GULF OF MEXICO... A LINGERING UPPER TROUGH FOUND FROM NEAR FORT MYERS FLORIDA TO FAR NE MEXICO IS BEGINNING TO BE OVERTAKEN BY A NEW TROUGH MOVING SOUTHEASTWARD INTO THE NE GULF. THIS NEW TROUGH IS ASSOCIATED WITH A DISSIPATING STATIONARY FRONT THAT LIES FROM CEDAR KEY FLORIDA TO 27N85W. A WEAK 1025 MB HIGH IS NW OF THE FRONT NEAR 29N87W. THE PRES GRADIENT BETWEEN THIS HIGH AND TROUGHING OVER THE U.S. SOUTHERN HIGH PLAINS AND CENTRAL MEXICO IS PRODUCING SE RETURN FLOW IN THE NW GULF. A SURFACE TROUGH IS IN THE E BAY OF CAMPECHE EXTENDING FROM 22N91W TO S MEXICO NEAR 16N93W. LOW TO MID LEVEL CLOUDS ARE PRIMARILY CONFINED TO AREAS W OF 90W...LEAVING THE REMAINDER OF THE GULF UNDER CLEAR SKIES THIS MORNING. THE FRONT IS EXPECTED TO DISSIPATE LATER THIS MORNING AS THE DEEP LAYER TROUGH SUPPORTING IT IS FORCED EASTWARD AWAY FROM THE GULF. CARIBBEAN SEA... AN UPPER RIDGE SPANS MUCH OF THE CARIBBEAN...EXTENDING FROM JUST S OF BARBADOS TO NEAR 16N80W. 40-60 KT SW WINDS ALOFT ON THE SOUTHERN EDGE OF AN UPPER JET ARE PASSING OVER THE NW CARIBBEAN AND TRANSPORTING MID TO UPPER LEVEL MOISTURE THAT IS MANIFESTING ITSELF AS ISOLATED CIRRUS CLOUDS. WATER VAPOR IMAGERY SHOWS RELATIVELY DRY CONDITIONS ALOFT OVER THE REMAINDER OF THE CARIBBEAN. THE SURFACE RIDGE OVER THE W ATLC CONTINUES TO MAINTAIN FRESH ENE TRADE WINDS ACROSS THE BASIN WITH STRONGER WINDS ALONG THE COAST OF COLOMBIA AND IN THE WINDWARD PASSAGE AS SEEN IN THE 0240 UTC ASCAT PASS. PRECIPITABLE WATER IMAGERY SHOWS A LOW LEVEL MOISTURE MAXIMA NEAR THE COAST OF VENEZUELA. SHOWERS LIE IN THIS AREA GENERALLY WITHIN 150 NM EITHER SIDE OF 65W S OF 16N. ISOLATED TO SCATTERED TRADE WIND SHOWERS CAN BE FOUND ELSEWHERE FROM 15N TO 20N AS WELL AS ALONG THE COAST OF NICARAGUA...COSTA RICA...AND WESTERN PANAMA. THE SURFACE RIDGE OVER THE W ATLC WILL MAINTAIN THE TRADE WINDS THROUGH FRI. ATLANTIC OCEAN... THE AFOREMENTIONED UPPER TROUGHS OVER THE GULF OF MEXICO ARE BEGINNING TO MERGE OVER THE SW N ATLC W OF 70W. THE COLD FRONT ASSOCIATED WITH THE UPPER TROUGH OVER NORTHERN FLORIDA LIES FROM 32N76W TO FLAGLER BEACH FLORIDA. CONVECTION HAS BECOME ENHANCED ALONG THE FRONT OVERNIGHT...WITH SCATTERED MODERATE CONVECTION NOTED WITHIN 45 NM SE OF THE FRONT N OF 30N. A DEEP LAYER TROUGH IS OVER THE CENTRAL ATLC N OF 25N BETWEEN 35W-40W AND IS SUPPORTING A WEAK COLD FRONT THAT ENTERS THE REGION NEAR 32N35W AND EXTENDS 27N45W AND BECOMES DISSIPATING TO 27N50W. A PRE-FRONTAL SURFACE TROUGH PARALLELS THE FRONT WITHIN 90 NM E OF IT FROM 30N TO 26N BEFORE THE TROUGH EXTENDS SOUTHEASTWARD TO 14N50W. SCATTERED MODERATE CONVECTION LIES WITHIN 90 NM E OF THE FRONT AND PRE-FRONTAL TROUGH N OF 28N AND SCATTERED SHOWERS ARE GENERALLY WITHIN 90 NM EITHER SIDE OF BOTH THE BOUNDARIES S OF 28N. ELSEWHERE...DRY UPPER LEVEL AIR ON WATER VAPOR IMAGERY DENOTES SUBSIDENCE OVER THE TROPICS FROM 10N-22N E OF BAHAMAS TO OVER AFRICA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ SCHAUER