000 AXNT20 KNHC 181047 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT APR 18 2015 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W SW TO 04N17W WHERE THE ITCZ BEGINS AND CONTINUES TO 01S30W TO THE NORTHERN COAST OF BRAZIL NEAR 01S50W. SCATTERED MODERATE CONVECTION IS FROM 04S TO 04N BETWEEN 18W AND 34W. ...DISCUSSION... GULF OF MEXICO... A 1014 MB LOW PREVAILS OVER SOUTH CAROLINA AND GEORGIA ADJACENT WATERS FROM WHICH A COLD FRONT EXTENDS SW TO CAPE CANAVERAL WHERE IT TRANSITIONS TO A STATIONARY FRONT NW TO THE FLORIDA PANHANDLE...ALONG THE NORTHERN GULF COASTLINE TO A 1008 MB LOW OVER NE MEXICO. A SURFACE TROUGH IS AHEAD OF THE FRONT ALONG 28N92W SW TO 25N95W. ABUNDANT MOISTURE OVER THE WESTERN AND NORTHERN GULF EXTENDING INLAND ALONG WITH DIFFLUENT FLOW ALOFT SUPPORT HEAVY SHOWERS AND TSTMS W OF A LINE FROM 30N87W TO 25N94W. FOG IS ALSO BEING REPORTED OVER THE NW GULF N OF 26N W OF 90W AND ALSO WITHIN THE VICINITY OF THE FRONT OVER NORTHERN FLORIDA AND ADJACENT WATERS. MOSTLY SE TO S WIND FLOW OF 15 KT S OF 25N WHILE LIGHTER VARIABLE WINDS DOMINATE ELSEWHERE. LOW PRESSURE WILL DOMINATE ACROSS THE GULF TODAY BUT SURFACE RIDGING REBUILDS SUNDAY MORNING. SHOWERS ACROSS THE NORTHERN GULF WILL CONTINUE THROUGH SUNDAY. CARIBBEAN SEA... A BROAD SURFACE RIDGE OVER THE ATLC OCEAN EXTENDS TO THE NORTHERN CARIBBEAN WHILE LOWER PRESSURE DOMINATES ELSEWHERE S OF 12N. A SLIGHTLY TIGHTER PRESSURE GRADIENT IS OVER THE CENTRAL CARIBBEAN ASSOCIATED WITH A 1009 MB LOW OVER N COLOMBIA...THUS RESULTING IN TRADES OF 20 TO 25 KT S OF 15N BETWEEN 71W AND 78W...BEING THE STRONGEST WINDS ALONG THE COAST OF COLOMBIA. ELSEWHERE TRADES OF 15 KT DOMINATE. MIDDLE TO UPPER LEVEL RIDGING IS OVER THE HALF WESTERN BASIN WHILE A TROUGH COVERS THE REMAINDER BASIN. DEEP LAYER MOISTURE OVER THE SE CARIBBEAN ALONG WITH A DIFFLUENT ENVIRONMENT SUPPORT SCATTERED SHOWERS OVER THE WINDWARD ISLANDS AND ADJACENT WATERS. SSMI TPW IMAGERY SHOW PATCHES OF SHALLOW MOISTURE MOVING ACROSS THE NW AND NE BASIN...THUS SUPPORTING CLOUDINESS AND POSSIBLE SCATTERED TO ISOLATED SHOWERS OVER THE VIRGIN ISLANDS...PUERTO RICO...WESTERN HISPANIOLA...JAMAICA AND THE WINDWARD PASSAGE. ISOLATED SHOWERS ARE ON PANAMA AND COSTA RICA COASTAL WATERS. FAIR WEATHER IS ELSEWHERE BEING SUPPORTED BY DRY AIR SUBSIDENCE FROM ALOFT. NOT SIGNIFICANT CHANGES ARE EXPECTED DURING THE NEXT TWO DAYS. ...HISPANIOLA... A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE SW N ATLC S ACROSS THE ISLAND TO NORTHERN VENEZUELA. SHALLOW MOISTURE ALONG WITH LIFTING PROVIDED BY THE UPPER TROUGH SUPPORT CLOUDINESS WITH POSSIBLE SCATTERED TO ISOLATED SHOWERS...MAINLY FOCUSED OVER HAITI AND THE WINDWARD PASSAGE. SHOWERS ARE EXPECTED TO CONTINUE THROUGH SATURDAY MORNING WHEN A DRY AIRMASS ENTERS THE ISLAND PROVIDING FAIR WEATHER CONDITIONS THROUGH SUNDAY EVENING. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH OVER THE NORTH-CENTRAL ATLC CONTINUE TO SUPPORT A SURFACE LOW PRESSURE SYSTEM FROM WHICH A COLD FRONT EXTENDS SW ENTERING THE AREA OF DISCUSSION FROM 30N32W SW TO 25N47W WHERE IT TRANSITIONS TO A STATIONARY FRONT ALONG 27N55W. FROM THAT POINT A WARM FRONT EXTENDS NW TO 28N60W TO 30N66W. ISOLATED SHOWERS ARE WITHIN 50 NM EITHER SIDE OF THE FRONTAL BOUNDARY. A 1014 MB LOW OVER GEORGIA ADJACENT WATERS EXTENDS A COLD FRONT SW TO CAPE CANAVERAL ENHANCING SCATTERED SHOWERS AND TSTMS MAINLY AHEAD OF THE FRONT N OF 26N W OF 72W. SURFACE RIDGING AND FAIR WEATHER DOMINATES ELSEWHERE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR