000 AXNT20 KNHC 182334 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS INLAND ACROSS WEST AFRICA INTO THE E TROPICAL ATLC ACROSS THE COAST OF GUINEA NEAR 10N14W TO 7N14W TO 3N16W...WHERE THE ITCZ AXIS CONTINUES ALONG EQ24W 1N40W TO THE COAST OF BRAZIL NEAR EQ48W. CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE FROM 3S TO 4N BETWEEN 24W-35W. SIMILAR CONVECTION IS WITHIN 170 NM N OF THE ITCZ BETWEEN 16W-24W. ...DISCUSSION... GULF OF MEXICO... A STRONG UPPER LEVEL SHORTWAVE MOVES ACROSS THE NE BASIN ON WATER VAPOR IMAGERY. THIS FEATURE IS SUPPORTING A LOW PRESSURE SYSTEM OVER THE FLORIDA PANHANDLE AND ASSOCIATED COLD FRONT THAT EXTENDS S-SW ACROSS THE AREA FROM E OF PANAMA CITY NEAR 30N85W INTO THE YUCATAN PENINSULA ALONG 21N88W. DOPPLER RADAR AND INFRARED SATELLITE IMAGERY INDICATE SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS WITHIN 170 NM E OF THE BOUNDARY. THIS FRONT IS FORECAST TO MOVE INLAND TO CENTRAL FLORIDA OR LAKE OKEECHOBEE AREA ON THURSDAY...BEFORE LOOSING MOMENTUM AND REMAINING NEARLY STATIONARY THURSDAY NIGHT INTO FRIDAY. A SECOND STRONGER COLD FRONT WILL ENTER NW GULF FRIDAY NIGHT WITH NEAR GALE FORCE WINDS BEHIND IT. CARIBBEAN SEA... SCATTERED MODERATE TO HEAVY SHOWERS ARE BEGINNING TO AFFECT THE NW BASIN N OF 16N W OF 82W. THIS AREA OF CONVECTION IS ASSOCIATED TO THE SRN EXTENSION OF A COLD FRONT MOVING ACROSS THE YUCATAN PENINSULA. THIS FRONT IS FORECAST TO ENTER THE NW BASIN BY FRIDAY NIGH AND BECOME STATIONARY WITH LIMITED CONVECTION LASTING THROUGH THE WEEKEND. RELATIVELY DRY AIR AND SUBSIDENCE ALOFT COVERS A GREAT PORTION OF THE CARIBBEAN BASIN...ESPECIALLY OVER THE N-CENTRAL AND NE BASINS. CONVERGING TRADE WIND FLOW ALONG WITH REMNANT LOW LEVEL MOISTURE IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 90/120 NM ON EITHER SIDE OF A LINE FROM 14N62W TO 13N71W. THIS FLOW IS ALSO PUSHING LOW LOW LEVEL MOISTURE WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS INLAND AND WITHIN 120 NM ALONG THE COAST FROM ERN PANAMA TO NRN NICARAGUA. A SLOW MOVING SURFACE TROUGH IS E OF THE LESSER ANTILLES GENERATING SCATTERED HEAVY SHOWERS E OF THESE GROUP OF ISLANDS. SHORT RANGE COMPUTER MODELS SUGGEST THE CONVECTION WILL REMAIN E OF THESE ISLANDS DURING THE NEXT 24 HOURS. ATLANTIC OCEAN... AN AMPLIFIED UPPER RIDGE OVER THE WRN ATLC SUPPORTS A WEAK 1021 MB HIGH NEAR 30N75W MAINTAINING FAIR WEATHER CONDITIONS W OF 64W. A DEEP OCCLUDED 1006 MB LOW IS CENTERED NEAR 31N58W. THE LOW LEVEL CENTER CONTINUES TO BE EXPOSED ON SATELLITE IMAGERY ...WITH SOME SCATTERED WEAK CONVECTION WITHIN 65 NM ON THE ERN SEMICIRCLE OF THE LOW. THE ASSOCIATED COLD FRONT IS WELL DISPLACED TO THE EAST ENTERING THE REGION ALONG 32N51W TO 24N55W TO 23N63W. SCATTERED WEAK TO ISOLATED MODERATE CONVECTION IS WITHIN 50-100 NM ON EITHER SIDE OF THE FRONT. TO THE E OF THIS FRONT...A NEARLY STATIONARY SURFACE TROUGH EXTENDS S INTO THE AREA ALONG 31N46W TO 22N49W. SCATTERED WEAK TO ISOLATED MODERATE CONVECTION IS WITHIN 70-130 NM E OF THE TROUGH AXIS. THE STRONGEST CONVECTION WITHIN THESE TWO BOUNDARIES IS FOUND N OF 27N WHERE LOW LEVEL CONVERGENCE AND UPPER LEVEL DIFFLUENCE IS MAXIMIZED. THIS LOW PRESSURE SYSTEM IS EXPECTED TO SHIFT SSE TONIGHT. A BROAD SURFACE RIDGE ANCHORED BY A 1031 MB HIGH W OF THE AZORES OVERTAKES THE REMAINDER OF THE ATLC WITH FAIR WEATHER CONDITIONS E OF 42W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA