000 AXNT20 KNHC 170545 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE APR 17 2012 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 8N13W TO 2N21W WHERE THE ITCZ AXIS CONTINUES S OF THE EQUATOR NEAR 30W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 5N TO S OF THE EQUATOR E OF 20W TO ACROSS THE PRIME MERIDIAN AND FROM 4N TO THE EQUATOR BETWEEN 30W-44W. SCATTERED MODERATE CONVECTION IS FROM 6N-10N BETWEEN 46-50W. ...DISCUSSION... GULF OF MEXICO... A STRONG UPPER TROUGH DIPS S FROM THE CENTRAL PLAIN STATES TO OVER TEXES CLIPPING THE FAR NW GULF SUPPORTING A COLD FRONT AT 17/0300 UTC ALONG THE TEXAS COAST FROM THE LOUISIANA BORDER TO CORPUS CHRISTI WITH A SQUALL LINE EXTENDING INTO THE GULF WATERS FROM S MISSISSIPPI NEAR 31N89W ALONG 27N94W INTO NE MEXICO NEAR 25N98W GENERATING SCATTERED TO HEAVY SHOWERS WITH SCATTERED TO NUMEROUS THUNDERSTORMS WITHIN 45 NM E AND 90/120 NM W OF THE SQUALL LINE. AN UPPER RIDGE EXTENDS FROM THE E PACIFIC REGION ACROSS THE YUCATAN PENINSULA TO THE BIG BEND AREA OF FLORIDA. A SURFACE RIDGE ANCHORED IN THE W ATLC EXTENDS ALONG THE N GULF COAST TO THE ALABAMA/MISSISSIPPI BORDER GIVING THE NE GULF SW RETURN FLOW. STRONG SUBSIDENCE AND DRY STABLE AIR DOMINATES THE S AND NE GULF. HOWEVER A SURFACE TROUGH IS OVER THE S GULF EXTENDING FROM 25N88W TO OVER S MEXICO NEAR CIUDAD DEL CARMEN GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 27N TO INLAND OVER THE YUCATAN PENINSULA BETWEEN 85W-90W LEAVING THE REMAINDER OF THE GULF WITH CLEAR SKIES TONIGHT. THE COLD FRONT WILL EXTEND FROM THE MISSISSIPPI DELTA TO NE MEXICO ON TUE AND FROM THE FLORIDA PANHANDLE TO THE CENTRAL WATERS WED MOVING OUT OF GULF ON THU. REMNANTS OF THE FRONT WILL DISSIPATE OVER N FLORIDA THU NIGHT AND FRI AS AN E TO W RIDGE BUILDS ACROSS THE N GULF COAST. CARIBBEAN SEA... THE UPPER RIDGE OVER THE E GULF OF MEXICO COVERS THE W CARIBBEAN WITH A WEAK UPPER TROUGH OVER THE E CARIBBEAN WITH THE AXIS ALONG 71W. A RELATIVELY TIGHT PRESSURE GRADIENT COVERS THE CARIBBEAN AS THE SURFACE RIDGE OVER THE W ATLC EXTENDS S ACROSS THE GREATER ANTILLES TO OVER THE N CARIBBEAN N OF 18N AND IS GENERATING FRESH TO STRONG EASTERLY TRADE WINDS ACROSS THE BASIN. A SHEAR AXIS REMAINS OVER THE E CARIBBEAN EXTENDING FROM THE CENTRAL ATLC FRONT BETWEEN DOMINICA AND MARTINIQUE IN THE LESSER ANTILLES TO NEAR 15N72W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60/75 NM EITHER SIDE OF THE SHEAR AXIS. A BAND OF LOW LEVEL MOISTURE WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS IS WITHIN 60/75 NM OF A LINE FROM SW HAITI ALONG 18N80W TO THE YUCATAN PENINSULA NEAR 21N87W INCLUDING JAMAICA. A SECOND BAND OF LOW LEVEL MOISTURE WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS IS STREAMING W FROM THE SHEAR AXIS WITHIN 60/75 NM 14N72W TO 13N79W THEN SPREADING ACROSS THE SW CARIBBEAN S OF 13N BETWEEN 77W-84W. THE SHEAR AXIS WILL BECOME DIFFUSE ON TUE. OTHERWISE W ATLC SURFACE RIDGE WILL MAINTAIN TRADE WINDS THROUGH TUE THEN DIMINISHING FROM THE N WED THROUGH FRI. ATLANTIC OCEAN... A SURFACE RIDGE DOMINATES THE W ATLC N OF 18N W OF 60W AND ANCHORED BY A 1026 MB HIGH NEAR 30N72W. A BROAD UPPER TROUGH REMAINS OVER THE CENTRAL ATLC N OF 20N BETWEEN 40W-75W SUPPORTING A COLD FRONT THAT ENTERS THE AREA NEAR 32N45W ALONG 21N46W TO 17N54W WHERE IT BECOMES A SHEAR AXIS ENTERING THE CARIBBEAN BETWEEN DOMINICA AND MARTINIQUE. SCATTERED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 150 NM E OF THE FRONT N OF 27N WITH ISOLATED SHOWERS WITHIN 45 NM EITHER SIDE OF THE REMAINDER OF THE FRONT/SHEAR AXIS. A SMALL UPPER LOW IS OVER THE E ATLC NEAR 25N18W. A LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF 15N E OF 40W ANCHORED BY A 1036 MB HIGH OVER THE AZORES. THIS IS LEAVING THE REMAINDER OF THE ATLC WITH FAIR WEATHER TONIGHT. SURFACE RIDGE OVER THE W ATLC WILL WEAKEN ALLOWING A COLD FRONT TO PASS THROUGH THE AREA ON TUE. A SECOND COLD FRONT WILL STALL AND DISSIPATE OVER THE FAR NW WATERS THU. A SURFACE RIDGE WILL EXTEND FROM BERMUDA TO CENTRAL FLORIDA ON FRI AND SAT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW