000 AXNT20 KNHC 072355 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE MAY 07 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2245 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL NEAR 13N16W TO 6N20W. THE ITCZ BEGINS NEAR 6N20W AND CONTINUES ALONG 2N30W EQ37W 1N45W EQ49W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE AXIS BETWEEN 18W-26W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ALSO FROM EQ-5N BETWEEN 26W-41W. ...DISCUSSION... GULF OF MEXICO... SURFACE HIGH PRESSURE DOMINATES THE GULF OF MEXICO CENTERED AROUND A 1019 MB HIGH NEAR 26N91W...AS OF 2100 UTC. THE RIDGE IS PROVIDING MOSTLY FAIR CONDITIONS ACROSS THE BASIN WITH MOSTLY CLEAR SKIES AND LIGHT ANTI-CYCLONIC WINDS AROUND THE HIGH. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CURRENTLY TO THE WEST OVER TEXAS AND MEXICO. AN UPPER LEVEL TROUGH PRESENTLY RESIDES OVER THE GULF WITH AXIS EXTENDING FROM AN UPPER LOW OVER NORTH CAROLINA TO THE SW GULF. THE UPPER TROUGH SUPPORTS A SURFACE TROUGH ACROSS NORTHERN FLORIDA EXTENDING ALONG 31N80W 29N82W 28N86W. RADAR IMAGERY DOES NOT INDICATE ANY SHOWERS NEAR THE AXIS...BUT LOW CLOUDS ARE ALONG IT. THE RIDGE IS EXPECTED TO DOMINATE THE BASIN THROUGHOUT THE WEEK AS IT GRADUALLY SHIFTS EAST ALLOWING RETURN FLOW TO INCREASE ACROSS THE WESTERN GULF. CARIBBEAN SEA... DRY AIR AND SUBSIDENCE ALOFT COVER THE WESTERN CARIBBEAN BETWEEN AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO AND AN UPPER LEVEL RIDGE DOMINATING THE EASTERN CARIBBEAN. THE DRY AIR IS MAINTAINING FAIR CONDITIONS WEST OF 75W. MOIST SOUTHWESTERLY FLOW ALOFT COVERS THE EASTERN CARIBBEAN AS IT MOVES AROUND THE UPPER RIDGE. MOIST AIR ALOFT COMBINED WITH A BROAD SURFACE TROUGH EXTENDING FROM SOUTH OF HISPANIOLA NEAR 17N70W TO NORTHERN VENEZUELA NEAR 11N71W IS PROVIDING SHOWERS AND POSSIBLE THUNDERSTORMS ACROSS PORTIONS OF THE EASTERN CARIBBEAN. THE STRONGEST SHOWERS ARE MOVING ACROSS THE VIRGIN ISLANDS...PUERTO RICO...AND HISPANIOLA NORTH OF 17N BETWEEN 63W-73W. SCATTERED SHOWERS ARE ALSO WITHIN 200 NM TO EITHER SIDE OF THE SURFACE TROUGH. LIGHTER THAN NORMAL TRADEWIND FLOW OF MOSTLY 10 KT SPREADS ACROSS THE BASIN WITH BROAD TROUGHING NEAR THE TROUGH AXIS. THE TROUGH IS EXPECTED TO GRADUALLY SHIFT WEST AND DISSIPATE OVER THE NEXT SEVERAL DAYS AS THE TRADEWIND FLOW INCREASES. SHOWERS WILL CONTINUE NEAR THE TROUGH AXIS. ATLANTIC OCEAN... BROAD LOW PRESSURE COVERS THE FAR WEST ATLC ASSOCIATED WITH A DEEP LAYERED TROUGH CENTERED OVER NORTH CAROLINA. A COLD FRONT ENTERS THE AREA NEAR 32N73W AND CONTINUES TO 26N76W...AS OF 2100 UTC. A WARM FRONT EXTENDS TO THE EAST ALONG 32N71W 29N67W 25N61W. A LINE OF SHOWERS IS ALONG THE COLD FRONT WHILE SCATTERED SHOWERS ARE WITHIN 60 NM OF THE WARM FRONT. BROAD UPPER RIDGING COVERS THE REMAINDER OF THE WEST ATLC CENTERED NEAR 9N57W. THE UPPER RIDGE SUPPORTS SURFACE RIDGING ANCHORED BY A 1031 MB HIGH NORTH OF THE AREA NEAR 41N54W. UPPER TROUGHING COVERS MUCH OF THE EASTERN ATLC ALONG 36W SUPPORTING A COLD FRONT THAT SWEEPS ACROSS THE AREA FROM 32N24W TO 24N33W 20N42W WHERE IT BEGINS TO DISSIPATE TO 19N48W...AND BECOMES A SHEAR AXIS TO NEAR 19N64W. SCATTERED SHOWERS ARE WITHIN 150 NM OF THE FRONT WITH ISOLATED SHOWERS 90 NM OF THE SHEAR AXIS. A SURFACE TROUGH ENTERS THE AREA WEST OF THE FRONT ALONG 32N35W TO 27N42W CONNECTED TO A SURFACE LOW JUST NORTH OF THE DISCUSSION AREA. SCATTERED SHOWERS ARE ALONG THE AXIS NORTH OF 29N. WEAK SURFACE RIDGING COVERS THE FAR EASTERN ATLC AROUND A 1018 MB HIGH NEAR 27N21W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 9W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE AT THE REQUEST OF METEO-FRANCE AND THE METEOROLOGICAL 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. $$ WALTON