000 AXNT20 KNHC 020001 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN MAY 01 2011 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION 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. ...ITCZ... ITCZ AXIS EXTENDS FROM THE LIBERIAN COAST NEAR 06N10W ALONG 01N20W 01N33W CROSSING THE EQUATOR NEAR 38W THEN ANALYZED INTO NE BRAZIL NEAR 02S44W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN 07W AND 20W... AND FROM THE EQUATOR TO 03N BETWEEN 20W AND 36W. ...DISCUSSION... GULF OF MEXICO... A NARROW UPPER LEVEL RIDGE AXIS EXTENDS OVER THE WEST-CENTRAL GULF FROM THE ISTHMUS OF TEHUANTEPEC TO 30N90W AND NORTHEASTWARD OVER THE DEEP SOUTH. DEEP LAYERED DRY AIR/SUBSIDENCE WAS INDICATED OVER THE EASTERN HALF OF THE RIDGE WITH SOME HIGH LEVEL MOISTURE APPROACHING THE WESTERN HALF OF THE RIDGE. AN UPPER LEVEL CYCLONIC CIRCULATION WAS ENTERING THE STRAITS OF FLORIDA ENHANCING THE SUBSIDENCE OVER THE FAR EASTERN GULF...BUT PROVIDING ENOUGH INSTABILITY TO TRIGGER SCATTERED STRONG THUNDERSTORMS OVER WESTERN CUBA. AT THE SURFACE...A RIDGE AXIS EXTENDS FROM THE SW NORTH ATLANTIC NEAR 32N79W TO THE W GULF NEAR 23N94W WITH E TO SE WINDS IN THE RANGE OF 15 TO 20 KT...EXCEPT TO 25 KT ALONG THE TEXAS COAST. VISIBLE SATELLITE IMAGERY STILL INDICATED AREAS OF SMOKE AND HAZE OVER THE GULF MAINLY W OF 90W WITH SURFACE AND SHIPS OBSERVATIONS INDICATING SMOKE/HAZE/FOG FROM THE MANY FIRES OVER MEXICO. SURFACE RIDGE IS EXPECTED TO REMAIN OVER THE NE GULF THROUGH MON. A STRONG LATE SEASON COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST LATE MON AND EXTEND FROM THE FLORIDA PANHANDLE TO THE BAY OF CAMPECHE BY LATE TUE. THIS FRONT IS EXPECTED TO USHER IN NORTHERLY WINDS OF 25-30 KT...POSSIBLY HIGHER BY TUE. CARIBBEAN SEA... UPPER LEVEL CYCLONIC CIRCULATION LOCATED OVER THE STRAITS OF FLORIDA AND NOW ENTERING THE GULF OF MEXICO IS PART OF A LARGER BROAD UPPER LEVEL TROUGH WITH AN AXIS ALONG 80W/81W. VERY STRONG SUBSIDENCE WAS NOTED OVER THE CARIBBEAN W OF THE TROUGH AXIS IN STRONG NW FLOW ALOFT. THE COMBINATION OF A BROAD AREA OF DIFFLUENT SOUTHWESTERLY FLOW ALOFT E OF THE UPPER LEVEL TROUGH AXIS AND THE PROXIMITY TO THE ENTRANCE REGION OF AN UPPER LEVEL 80-90 KT JET NE OF PUERTO RICO WAS PROVIDING ENHANCED LIFT IN THE AREA OF A SURFACE TROUGH EXTENDING FROM THE SW NORTH ATLANTIC ACROSS WESTERN PUERTO RICO TO 15N68W. OVERALL SURFACE PRESSURES ARE FAIRLY LOW FOR EARLY MAY. THE 1200 UTC UPPER AIR SOUNDING FROM SAN JUAN INDICATED MOISTURE UP TO 500 MB WITH PRECIPITABLE WATER VALUES OF 1.92 INCHES. ALTHOUGH THE WSR-88D FROM SAN JUAN INDICATED THAT THE AREAL COVERAGE OF SHOWERS AND THUNDERSTORM ACTIVITY HAS DECREASED...EXPECT ADDITIONAL ACTIVITY TO DEVELOP OVERNIGHT...MONDAY AND INTO TUESDAY AS THE TROUGH AXIS LINGERS IN THE AREA WITH ADDITIONAL SUPPORT FROM ANOTHER IMPULSE MOVING ACROSS THE NORTHERN LEEWARD ISLANDS. THUS THE POTENTIAL EXISTS FOR ADDITIONAL LOCALLY HEAVY RAINFALL AND FLOODING OVER THE ISLAND. ELSEWHERE ACROSS THE CARIBBEAN FRESH TO STRONG EASTERLY TRADEWIND FLOW CONTINUES AND IS EXPECTED TO PERSIST OVER THE NEXT FEW DAYS. THESE TRADES ARE BANKING MOISTURE AND ISOLATED SHOWERS WITHIN 120 NM OF THE COAST OF COSTA RICA AND S NICARAGUA WITH THE REMAINDER OF THE CARIBBEAN IS EXPERIENCING MOSTLY CLEAR SKIES. ATLANTIC OCEAN... A FRACTURING UPPER LEVEL TROUGH AXIS EXTENDS OVER THE W ATLC INTO THE DISCUSSION AREA THROUGH 32N62W SW ALONG 25N70W TO A CYCLONIC CIRCULATION ENTERING THE STRAITS OF FLORIDA. THIS TROUGH WAS SUPPORTING A COLD FRONT EXTENDING INTO THE AREA NEAR 32N61W WHICH BECOMES A DISSIPATING COLD FRONT NEAR 27N68W TO 27N71W. ISOLATED SHOWERS AND THUNDERSTORMS ARE OCCURRING WELL EAST OF THE FRONT..ABOUT 180 NM...N OF 30N. THE FRONT IS FORECAST TO CONTINUE EASTWARD AND WEAKEN AS THE UPPER LEVEL TROUGH SHEARS OUT. ELSEWHERE OVER THE ATLANTIC A RIDGE EXTENDED WESTWARD ALONG 7N/8N FROM AN ANTICYCLONE NEAR 7N35W DOMINATING THE DEEP TROPICS. BROAD ZONAL UPPER AIR FLOW DOMINATED THE REMAINDER OF THE SUBTROPICAL ATLANTIC. AT THE SURFACE A BROAD SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 37N44W. AN UPPER LEVEL LOW CONTINUES TO SPIN NE OF THE CANARY ISLANDS NEAR 33N10W THAT SUPPORTS A COLD FRONT OVER NW AFRICA. W-NW WINDS IN THE RANGE OF 15 TO 25 KT ARE OCCURRING BEHIND THE FRONT E OF 18W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ COBB