000 AXNT20 KNHC 180550 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED APR 18 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 3N18W WHERE THE ITCZ AXIS CONTINUES S OF THE EQUATOR NEAR 24W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 7N TO JUST S OF THE EQUATOR E OF 11W TO ACROSS THE PRIME MERIDIAN AND FROM 2N TO S OF THE EQUATOR BETWEEN 27W-33W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM N OF THE ITCZ/MONSOON TROF BETWEEN 14W-24W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH DIPS S OVER THE MISSISSIPPI VALLEY INTO THE N GULF N OF 28N SUPPORTING A COLD FRONT AT 18/0300 UTC EXTENDS INTO THE GULF ALONG THE FLORIDA/ALABAMA BORDER 28N89W 23N93W TO THE COAST OF S MEXICO NEAR 18N93W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 200 NM E OF THE FRONT N OF 25N WITH ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 200 NM E OF THE REMAINDER OF THE FRONT. A BROAD UPPER RIDGE EXTENDS FROM OVER CENTRAL AMERICA THROUGH THE YUCATAN CHANNEL ACROSS NE FLORIDA INTO THE FAR W ATLC. A SURFACE RIDGE REMAINS ANCHORED IN THE W ATLC EXTENDING INTO THE E GULF TO THE FRONT. STRONG SUBSIDENCE AND DRY STABLE AIR ARE DOMINATING THE GULF W OF THE FRONT AS A SURFACE RIDGE BUILD S OVER THE W GULF GIVING THE AREA W OF THE FRONT MOSTLY CLEAR SKIS TONIGHT. A SURFACE TROUGH IS OVER THE THE YUCATAN PENINSULA EXTENDING FROM 22N89W OVER S MEXICO TO NEAR 16N91W. SCATTERED SHOWERS/THUNDERSTORMS ARE INLAND OVER THE YUCATAN PENINSULA. COLD FRONT WILL SLOWLY WEAKEN AND BECOME STATIONARY AS IT REACHES FROM THE W FLORIDA PANHANDLE TO THE E BAY OF CAMPECHE WED. A WEAK LOW PRESSURE WILL FORM ALONG THE FRONT AND TRACK NE THROUGH WED NIGHT PULLING THE WEAKENING FRONTAL TROUGH TO THE E BEFORE DISSIPATING OVER NE GULF THU. W ATLC SURFACE RIDGE WILL AGAIN EXTEND W INTO GULF LATE THU THROUGH LATE FRI. A STRONG COLD FRONT IS FORECAST TO ENTER THE NW GULF SAT FOLLOWED BY STRONG OFFSHORE FLOW. CARIBBEAN SEA... THE UPPER RIDGE OVER THE E GULF OF MEXICO IS ANCHORED OVER COSTA RICA COVERING THE W CARIBBEAN WITH A WEAK UPPER TROUGH OVER THE E CARIBBEAN WITH THE AXIS ALONG 67W. A RELATIVELY TIGHT PRESSURE GRADIENT IS BEGINNING TO RELAX AS THE W ATLC SURFACE RIDGE WEAKENS TO JUST OVER THE GREATER ANTILLES THUS WEAKENING THE TRADE WINDS SOMEWHAT. REMNANT LOW LEVEL MOISTURE WITH SCATTERED SHOWERS ARE WITHIN 120 NM OF A LINE FROM 17N60W ACROSS THE LEEWARD ISLANDS TO 11N81W. THE TRADE WINDS CONTINUE TO BANK LOW CLOUDS WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS INLAND AND WITHIN 120 NM ALONG THE COAST OF COSTA RICA AND NICARAGUA. A SURFACE TROUGH OVER THE W YUCATAN PENINSULA IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE PENINSULA AND INTO THE FAR NW CARIBBEAN WITHIN 60 NM ALONG THE COAST N OF 17N. SURFACE RIDGE OVER W ATLC WILL CONTINUE TO WEAKEN THROUGH THU DIMINISHING THE TRADE WINDS. ATLANTIC OCEAN... THE UPPER RIDGE OVER THE E GULF OF MEXICO AND THE W CARIBBEAN COVERS THE W ATLC W OF 70W. A SURFACE RIDGE DOMINATES THE W ATLC W OF 70W AND ANCHORED BY A 1023 MB HIGH NEAR 30N75W. A BROAD UPPER TROUGH REMAINS OVER THE CENTRAL ATLC N OF 20N BETWEEN 45W-70W SUPPORTING A NEWLY DEVELOPED COLD FRONT THAT ENTERS THE AREA NEAR 32N54W ALONG 27N57W 26N63W TO 29N66W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE N OF 27N BETWEEN 51W-59W. THE PRECEDING FRONT IS NOW STATIONARY ENTERING THE REGION NEAR 32N44W ALONG 24N46W TO 22N48W WHERE IT BECOMES A SURFACE TROUGH ALONG 19N52W TO 15N56W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 90 NM EITHER SIDE OF THE STATIONARY FRONT/SURFACE TROUGH. A SMALL UPPER LOW IS OVER THE FAR E ATLC ALONG THE COAST OF WESTERN SAHARA NEAR 25N15W WITH A BROAD E/W UPPER RIDGE DOMINATING THE TROPICAL ATLC. A LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF 10N E OF 40W ANCHORED BY A 1035 MB HIGH OVER THE AZORES. THIS IS LEAVING THE REMAINDER OF THE ATLC WITH FAIR WEATHER TONIGHT. W ATLC SURFACE RIDGE WILL REMAIN NEARLY STATIONARY AND WEAKEN THROUGH THU AS A WEAK FRONT MOVES INTO THE FAR NW PORTION. THE FRONT WILL THEN LIFT BACK N AS A WARM FRONT LATE THU INTO LATE FRI AS STRONGER RIDGE BUILDS FROM NEAR BERMUDA TO CENTRAL FLORIDA FRI AND SAT. THE CENTRAL ATLC COLD FRONT WILL MOVE SLOWLY E AS THE SURFACE LOW MOVES S INTO THE DISCUSSION AREA WED. THE FRONT WILL THEN DISSIPATE WED NIGHT THROUGH FRI BEFORE THE LOW MOVES NE OUT OF THE AREA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW