000 AXNT20 KNHC 041803 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT MAY 04 2013 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC BY COASTAL LIBERIA NEAR 5N9W THEN ALONG 3N11W 3N16W TO 2N21W. THE ITCZ BEGINS NEAR 2N21W AND CONTINUES ALONG 4N28W 1N35W TO EQ50W. SCATTERED MODERATE CONVECTION IS FROM 1S-3N BETWEEN 2W-10W. SIMILAR CONVECTION IS WITHIN 140 NM EITHER SIDE OF THE MONSOON TROUGH AND ITCZ AXES BETWEEN 10W AND 32W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LOW BETWEEN THE MIDDLE AND LOWER MISSISSIPPI VALLEYS EXTENDING A TROUGH AXIS SE ACROSS GEORGIA...ALONG THE COASTAL WATERS OF E FLORIDA TO S OF CUBA IN THE W CARIBBEAN IS SUPPORTING A FRONTAL SYSTEM OVER THE FLORIDA PENINSULA. THIS UPPER LEVEL TROUGHING IS ALSO SUPPORTING A STATIONARY FRONT THAT EXTENDS ALONG E ALABAMA AND ENTERS THE DISCUSSION AREA NEAR 31N85W TO A 1009 MB LOW NEAR 28N84W. A FORMING COLD FRONT EXTENDS FROM THE LOW ALONG 25N85W 23N89W TO 21N93W. ISOLATED SHOWERS ARE POSSIBLE IN THE VICINITY OF THE STATIONARY FRONT OVER THE NE GULF. A 1018 MB SURFACE HIGH IS OVER THE NW GULF NEAR 28N94W BEING SUPPORTED BY AN UPPER LEVEL RIDGE WITH AXIS ALONG THE CENTRAL AND SOUTHERN PLAINS. VERY DRY AIR IS OVER MOST OF THE BASIN WHICH IS MAINTAINING CLEAR SKIES N OF 21N AND W OF 86W. N-NE FLOW FROM THE SURFACE HIGH IS BANKING LOW LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS OVER THE SW GULF S OF 21N W OF 90W. OVER THE COURSE OF 24 HOURS...THE STATIONARY FRONT OVER THE NE GULF WILL TRANSITION TO A COLD FRONT FOR A SHORT PERIOD OF TIME TO MERGE WITH A STATIONARY FRONT OVER SE GEORGIA. THE COLD FRONT ACROSS THE GULF IS EXPECTED TO EXTEND ALONG THE W COAST OF FLORIDA...THE STRAITS OF FLORIDA AND ALONG THE E YUCATAN PENINSULA. A NEW COLD FRONT ENTERS THE N GULF EARLY ON SUNDAY WHILE THE HIGH PRESSURE OVER THE NW GULF DRIFTS SE TO THE CENTRAL GULF WHERE IT DISSIPATES. CARIBBEAN SEA... OVER THE W CARIBBEAN...NW WIND UP TO 20 KT IS BANKING LOW LEVEL CLOUDS AND CAUSING RAINSHOWERS AND THUNDERSTORMS ALONG THE COAST OF HONDURAS THAT MAY BE EXTENDING WITHIN 120 NM FROM THE COAST. THE REMAINDER OF THE W CARIBBEAN N OF 15N W OF 78W IS UNDER THE INFLUENCE OF DRY AIR WHICH IS KEEPING MOSTLY CLEAR SKIES. FURTHER EAST A SURFACE TROUGH EXTENDS FROM 19N75W TO 13N77W BEING SUPPORTED BY THE UPPER LEVEL TROUGHING DESCRIBED IN THE PRIOR SECTION. SCATTERED RAINSHOWERS ARE WITHIN 200 NM EAST OF THE TROUGH AXIS AND SPREAD ACROSS LA HISPANIOLA BEING SUPPORTED BY MOISTURE ADVECTION FROM THE PACIFIC MONSOON TROUGH. MOISTURE ADVECTION AROUND THE WEST PERIPHERY OF AN UPPER LEVEL RIDGE CENTERED N OF BRAZIL NEAR 8N44W IS ENHANCING RAINSHOWERS ALONG THE LESSER ANTILLES WITH POSSIBLE ISOLATED THUNDERSTORMS. MIXED LIGHT WINDS OF 5-10 KT SPREAD OVER THE CENTRAL...SOUTHERN AND E CARIBBEAN DUE TO A WEAK PRESSURE GRADIENT ACROSS THIS PART OF THE BASIN. RAINSHOWERS ARE WITHIN 120 NM OF THE COAST OF COSTA RICA DUE TO BANKING OF LOW LEVEL CLOUDS AS WELL AS THE INFLUENCE OF THE MONSOON TROUGH. TRADE WINDS ARE EXPECTED TO RETURN TO THE E CARIBBEAN TUE AND WED AS HIGH PRESSURE OVER THE CENTRAL ATLC BUILDS S AND SW. ATLANTIC OCEAN... AN UPPER LEVEL LOW BETWEEN THE MIDDLE AND LOWER MISSISSIPPI VALLEYS EXTENDING A TROUGH AXIS SE ACROSS GEORGIA...ALONG THE COASTAL WATERS OF E FLORIDA TO S OF CUBA IN THE W CARIBBEAN IS SUPPORTING A 1007 MB LOW OVER THE FLORIDA PENINSULA. FROM THIS LOW A STATIONARY FRONT EXTENDS OVER THE N ATLC SW WATERS ALONG 29N81W 27N77W TO 24N73W. FROM THIS LOW ALSO EXTENDS A SURFACE TROUGH ALONG 29N80W TO SW OF FREEPORT NEAR 26N78W. SCATTERED CLUSTERS OF MODERATE TO STRONG CONVECTION AND THUNDERSTORMS ASSOCIATED TO THIS FRONTAL SYSTEM ARE N OF 26N W OF 72W. A BROAD UPPER LEVEL TROUGH N OF 29N OVER THE CENTRAL N ATLC IS SUPPORTING AN ELONGATED SURFACE TROUGH ALONG 30N39W 25N50W 24N60W TO 24N71W. THIS SAME UPPER LEVEL TROUGH IS SUPPORTING ANOTHER SURFACE TROUGH ALONG 30N53W TO 28N61W. THESE SURFACE FEATURES ARE ENHANCING NUMEROUS MODERATE CONVECTION FROM 20N-30N BETWEEN 30W AND 67W. OVER THE E ATLC...UPPER LEVEL RIDGING IS SUPPORTING A 1023 MB SURFACE HIGH NEAR 36N15W THAT EXTENDS A RIDGE AXIS SW TO 17N41W. THIS IS PROVIDING FAIR WEATHER N OF 15N E OF 30W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE AT THE REQUEST OF METEO-FRANCE AND THE METEROLOGICAL SERVICES OF HAITI AND THE DOMINICAN REPUBLIC...THE TROPICAL ANALYSIS AND FORECAST BRANCH (TAFB) WILL BEGIN PROVIDING...ON A TEMPORARY BASIS...A SEPARATE DETAILED SECTION WITHIN THE ATLANTIC TROPICAL WEATHER DISCUSSION (TWDAT). IT WILL COVER BOTH HAITI AND THE DOMINICAN REPUBLIC DUE TO THE SHARED GEOGRAPHY OF BOTH COUNTRIES ON THE ISLAND OF HISPANIOLA. THE SECTION BEGINS ON MAY 15 2013 AT 1800 UTC...2 PM EDT. IT WILL PROVIDE GUIDANCE FOR SIGNIFICANT WEATHER EVENTS THAT ARE EXPECTED TO IMPACT THE REGION THROUGH 48 HOURS...WITH THE FOCUS ON ASSESSING THE POTENTIAL FOR HEAVY RAINFALL. $$ RAMOS