000 AXNT20 KNHC 182337 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAR 18 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC... ...SPECIAL FEATURE... A SURFACE TROUGH CONTINUES TO IMPACT THE CENTRAL CARIBBEAN ANALYZED ALONG 75W S OF 17N. SHOWERS/THUNDERSTORMS REMAIN MOSTLY E OF THE TROUGH AFFECTING CENTRAL COLOMBIA N OF 8N BETWEEN 71W-75W ACROSS HISPANIOLA...INCLUDING HAITI. A FEW ISOLATED SHOWERS MAY ALSO BE W OF THE TROUGH AXIS WITHIN 90 NM. TOTAL PRECIPITABLE WATER IMAGERY INDICATES SIGNIFICANT DEEP LAYER MOISTURE E OF THE TROUGH. THE TROUGH...ALONG WITH THE ASSOCIATED MOISTURE...IS FORECAST TO MOVE NORTHWARD AND MERGE WITH AN APPROACHING COLD FRONT CURRENTLY ACROSS THE WRN CARIBBEAN. THIS MERGE SHOULD OCCUR NEAR THE WINDWARD PASSAGE IN APPROXIMATELY 12 HRS. THIS FORECAST SETS UP THE POTENTIAL FOR HEAVY RAINFALL AND POSSIBLE FLOODING ACROSS HAITI AND THE DOMINICAN REPUBLIC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED FROM S LIBERIA NEAR 5N9W ALONG 6N15W 1N35W 2N44W TO THE NE BRAZIL COAST NEAR 1N53W. ISOLATED MODERATE CONVECTION IS FROM 2N-6N BETWEEN 13W-17W. SIMILAR ACTIVITY IS FROM 1N-3N BETWEEN 28W-36W. ...DISCUSSION... GULF OF MEXICO... SURFACE HIGH PRESSURE DOMINATES THE WRN GULF OF MEXICO ANCHORED BY A PAIR OF 1022 MB HIGHS CENTERED E OF TAMPICO MEXICO NEAR 22N96W...AND OVER E TEXAS NEAR 32N96W. THE SURFACE RIDGING ALONG WITH DRY AIR ALOFT IS PROVIDING GENERALLY FAIR WEATHER OVER THE BASIN W OF 87W. A DEEP LAYERED TROUGH COVERS THE ERN PORTION OF THE BASIN CENTERED AROUND AN UPPER LEVEL LOW OVER S CAROLINA NEAR 35N80W. THE UPPER LEVEL TROUGH IS SUPPORTING A SURFACE LOW PRESSURE SYSTEM AND A COLD FRONT OVER THE W ATLC. HOWEVER...A SECOND SURGE OF ENERGY ASSOCIATED WITH THIS UPPER LEVEL TROUGH IS SUPPORTING A SURFACE TROUGH EXTENDING FROM JUST W OF S FLORIDA NEAR 25N82W TO 23N88W. SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN 120 NM N OF THE AXIS E OF 86W...AND WITHIN 75 NM S OF THE AXIS E OF 87W. EXPECT THE SURFACE RIDGE TO SHIFT EWD AND REMAIN OVER THE ERN GULF OF MEXICO FOR THE NEXT COUPLE OF DAYS BEFORE A COLD FRONT MOVES OFF THE TEXAS COAST LATE SAT. THE CARIBBEAN SEA... A COLD FRONT EXTENDS FROM THE W ATLC ACROSS ERN CUBA NEAR 21N76W TO NW OF JAMAICA NEAR 18N79W CONTINUING SW TO THE HONDURAS/NICARAGUA BORDER NEAR 15N83W TO 15N88W. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF THE AXIS N OF 16N...AND WITHIN 75 NM OF THE AXIS WITH POSSIBLE THUNDERSTORMS S OF 16N. A DEEP LAYER TROUGH ANCHORED BY AN UPPER LEVEL LOW OVER S CAROLINA WITH AXIS DOWN THE W COAST OF FLORIDA INTO THE NW CARIBBEAN SUPPORTS THE FRONT. UPPER LEVEL SWLY FLOW BETWEEN THIS UPPER TROUGH AND AN UPPER LEVEL RIDGE TO THE E OF THE ANTILLES IS DRAWING MOISTURE ACROSS THE CENTRAL CARIBBEAN ENHANCING SHOWER ACTIVITY NEAR A SURFACE TROUGH ALONG 75W. SEE SPECIAL FEATURES ABOVE. FARTHER E...MODERATE TRADEWINDS PREVAIL ALONG WITH GENERALLY FAIR WEATHER. EXPECT MOISTURE ASSOCIATED WITH THE COLD FRONT AND THE TROUGH TO MERGE OVER THE NEXT 12 HOURS SETTING UP THE POTENTIAL FOR HEAVY RAINFALL OVER THE WINDWARD PASSAGE AND HISPANIOLA. THE ATLANTIC OCEAN... A DEEP LAYER TROUGH CENTERED OVER S CAROLINA DOMINATES THE W ATLC SUPPORTING AN OCCLUDED 1005 MB SURFACE LOW NEAR 32N75W. A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 31N72W ALONG 26N72W ACROSS THE SE BAHAMAS NEAR 22N74W TO ERN CUBA AND INTO THE CARIBBEAN. SCATTERED SHOWERS ARE E OF THE FRONT N OF 22N BETWEEN 61W-68W. ACROSS THE CENTRAL ATLC...A SURFACE RIDGE IS ANCHORED BY A 1019 MB HIGH NEAR 25N55W. THE HIGH IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 50W. HOWEVER...A FRONTAL BOUNDARY PROTRUDES INTO THE SURFACE RIDGE FROM THE E. THE COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N25W CONTINUING ALONG 25N34W 22N45W TO NEAR 20N53W WHERE IT BECOMES STATIONARY TO 20N61W. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE AXIS. THIS FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING FROM THE AZORES ISLANDS TO THE CANARY ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON