000 AXNT20 KNHC 292327 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE APR 29 2014 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. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO 01N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 01N20W TO THE EQUATOR NEAR 22W. SCATTERED MODERATE CONVECTION IS WITHIN 60-90 NM EITHER SIDE OF THE MONSOON TROUGH BETWEEN 14W AND 20W...AND WITHIN 30 NM EITHER SIDE OF THE ITCZ BETWEEN 28W AND 31W. ...DISCUSSION... GULF OF MEXICO... A VERY BROAD AND VIGOROUS MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE MID-MISSISSIPPI RIVER VALLEY THIS EVENING SUPPORTING A 996 MB SURFACE LOW CENTERED OVER CENTRAL IOWA. THIS LOW EXTENDS AN OCCLUDED FRONT TO A 998 MB LOW CENTERED NEAR CHICAGO ILLINOIS WHICH EXTENDS A COLD FRONT ACROSS THE OHIO RIVER VALLEY TO THE LOWER MISSISSIPPI VALLEY...TO OFF THE COAST OF SW LOUISIANA TO NE MEXICO JUST S OF BROWNSVILLE TEXAS. CURRENTLY THE FRONT REMAINS RELATIVELY VOID OF DEEP CONVECTION IN THE NW GULF...WITH IMPRESSIVE CONVECTION AHEAD OF THE FRONT IN THE NE GULF COASTAL WATERS EXTENDING INLAND THROUGH THE SE UNITED STATES. AN OUTFLOW BOUNDARY...REMNANTS OF AN EARLIER SQUALL LINE WHICH HAS FALLEN APART...EXTENDS FROM NE FLORIDA NEAR JACKSONVILLE SW INTO THE NE GULF NEAR 28.5N86.5W. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER MOSTLY CLEAR TO PARTLY CLOUDY SKIES S OF 27N AS SOUTH-SOUTHEAST FLOW PERSISTS IN THE RANGE OF 10 TO 20 KT WITH WINDS VEERING SLIGHTLY SOUTH- SOUTHWESTERLY ACROSS THE NW GULF WATERS AHEAD OF THE COLD FRONT. NORTH-NORTHEASTERLY WINDS ARE FOLLOWING THE COLD FRONT IN THE TEXAS AND WESTERN LOUISIANA COASTAL WATERS AND THE FRONT WILL EXTEND FROM SOUTHERN ALABAMA TO MEXICO NEAR 21N97W WEDNESDAY MORNING...THEN IS EXPECTED TO BECOME STATIONARY FROM THE FLORIDA BIG BEND REGION SW TO THE BAY OF CAMPECHE THURSDAY MORNING THROUGH THURSDAY EVENING. CARIBBEAN SEA... WESTERLY FLOW ALOFT PREVAILS OVER THE CARIBBEAN WITH WATER VAPOR IMAGERY INDICATING RELATIVELY DRY AND STABLE CONDITIONS IN THE MIDDLE TO UPPER LEVELS THIS EVENING. THIS IS RESULTING IN RELATIVELY FAIR SKIES...HOWEVER WITH A STRONG PRESSURE IN PLACE DUE TO A RIDGE ACROSS THE SW NORTH ATLC REGION...TRADES PERSIST IN THE RANGE OF 15 TO 25 KT...STRONGEST BETWEEN 69W-75W AND IN THE GULF OF HONDURAS. ELSEWHERE...LOW-LEVEL MOISTURE CONVERGENCE INCREASES ACROSS THE SW CARIBBEAN AND CENTRAL AMERICA S OF 12- 13N AS SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS PANAMA AND COSTA RICA...INCLUDING THE ADJACENT COASTAL WATERS ON BOTH CARIBBEAN WATERS AND EASTERN PACIFIC WATERS. THIS ACTIVITY IS LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS EXTENDING ALONG 09N. ADDITIONAL CONVECTION HAS BEEN FIRING OVER THE REMAINDER OF CENTRAL AMERICA DUE TO DAYTIME HEATING ALTHOUGH THIS CONVECTION SHOULD DIMINISH A FEW HOURS AFTER SUNSET. ...HISPANIOLA... WITH PEAK AFTERNOON HEATING AND INSTABILITY...A FEW ISOLATED SHOWERS AND TSTMS HAVE DEVELOPED LATE THIS AFTERNOON INTO THE EARLY EVENING HOURS...HOWEVER ANY ONGOING CONVECTION WILL LIKELY GRADUALLY DIMINISH LATE THIS EVENING INTO THE OVERNIGHT HOURS. OTHERWISE MAINLY DRY AND STABLE WESTERLY FLOW ALOFT WILL PROVIDE FAIR CONDITIONS ACROSS THE ISLAND THROUGH THURSDAY. ATLANTIC OCEAN... OVERALL RIDGING ALOFT IS NOTED ON WATER VAPOR IMAGERY OVER THE SW NORTH ATLC THAT SUPPORTS A 1021 MB HIGH CENTERED SW OF BERMUDA NEAR 30N69W. HOWEVER...WATER VAPOR IMAGERY ALSO INDICATES A WEAK MID-LEVEL SHORTWAVE TROUGH AND ASSOCIATED ENERGY OVER THE BAHAMAS NEAR 24N76W. WHILE NO SURFACE-BASED BOUNDARY OR FRONT IS IN THE VICINITY...THE MID-LEVEL ENERGY WAS MANAGING TO GENERATE AN AREA OF SCATTERED SHOWERS AND TSTMS S OF 24N BETWEEN 73W-77W...HOWEVER THE TSTMS HAVE DISSIPATED WITH THE ARRIVAL OF SUNSET AND MORE STABLE CONDITIONS THIS EVENING. FARTHER EAST...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 37N53W WHICH REFLECTS AT THE SURFACE AS A 1003 MB LOW CENTERED NEAR 35N56W THAT CONTINUES TO DRIFT EAST-NORTHEAST. THE ASSOCIATED COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N48W EXTENDING SW TO 26N61W. A PRE-FRONTAL TROUGH HAS BECOME LESS EVIDENT AT THE SURFACE WHILE A MID-UPPER LEVEL SHORTWAVE CONTINUES TO SUPPORT CONVECTION APPROXIMATELY 180 NM SE OF THE SURFACE COLD FRONT. OTHERWISE...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED NEAR 33N29W AND A 1024 MB HIGH CENTERED NEAR 37N19W. THE SURFACE RIDGE AXIS EXTENDS FROM THE 1023 MB HIGH SW TO 22N50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY