000 AXNT20 KNHC 080000 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT MAY 07 2011 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... ITCZ AXIS IS ALONG 08N13W 03N24W 02N40W 03N51W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF A LINE FROM 05N13W TO 05N20W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE ITCZ AXIS BETWEEN 27W AND 30W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR SATELLITE IMAGERY INDICATES STRONG WESTERLY ZONAL FLOW ALOFT OVER THE GULF THIS EVENING WHICH IS PROMOTING MOSTLY FAIR WEATHER ACROSS THE BASIN. A DISSIPATING STATIONARY FRONT IS BECOMING MORE DIFFUSE. THIS FRONT REACHES FROM JUST S OF PALM BEACH FLORIDA TO JUST S OF FORT MYERS FLORIDA WESTWARD INTO THE E GULF NEAR 25N85W CONTINUING NW TO NEAR 27N90W. VISIBLE SATELLITE IMAGERY SHOWS THAT ISOLATED SHOWERS ARE POSSIBLE WITHIN 30 NM EITHER SIDE OF THE FRONTAL BOUNDARY. FLORIDA STATE WSR-88D RADAR MOSAIC INDICATES ISOLATED SHOWERS AND TSTMS JUST S OF THE FRONT OVER FLORIDA BEING ENHANCED BY CONVERGING SEA BREEZE BOUNDARIES. THIS ACTIVITY SHOULD WEAKEN WITH THE LOSS OF DAYTIME HEATING AFTER SUNSET. 1017 MB HIGH PRES IS IN THE PROCESS OF DEVELOPING IN THE NE GULF NEAR 28N86W WITH A FORMING RIDGE AXIS EXTENDING WESTWARD TO THE COAST OF TEXAS NEAR MATAGORDA BAY. E TO SE WINDS FLOW AROUND THE SURFACE RIDGE. THIS OVERALL PATTERN IS FORECAST TO PERSIST THROUGH THE REMAINDER OF THE WEEKEND AS WELL AS THROUGH MUCH OF NEXT WEEK AS THE SURFACE HIGH REMAINS NEARLY STATIONARY OVER THE NE GULF WATERS. SOUTHERLY RETURN FLOW WILL INCREASE TO UP TO 20 KT BEGINNING SUN OVER THE FAR WESTERN GULF WHERE THE PRESSURE GRADIENT WILL BE THE TIGHTEST. CARIBBEAN SEA... THE MAJORITY OF THE CARIBBEAN SEA BASIN IS UNDER THE INFLUENCE OF UPPER LEVEL RIDGING WHICH EXTENDS FROM NEAR TRINIDAD NW TO THE YUCATAN PENINSULA. WATER VAPOR SATELLITE IMAGERY INDICATES DRY AIR AND SUBSIDENCE N OF 16N ON THE NORTHERN PERIPHERY OF THE RIDGING ALOFT. THIS IS RESULTING IN MOSTLY CLEAR SKIES AND FAIR CONDITIONS ACROSS THAT AREA THIS EVENING ALTHOUGH A FEW LOW-TOPPED ISOLATED SHOWERS ARE OCCURRING FROM SOUTHWESTERN HISPANIOLA TO JAMAICA WITH ADDITIONAL ISOLATED ACTIVITY IN THE GULF OF HONDURAS. FARTHER EAST...TOTAL PRECIPITABLE WATER IMAGERY SHOWS INCREASING VALUES OF LOW-LEVEL MOISTURE BEING ADVECTED ACROSS THE LESSER ANTILLES THIS EVENING. THIS EAST-WEST BAND OF MOISTURE...MOST LIKELY REMNANT FRONTAL MOISTURE...IS GENERATING WIDELY SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF A LINE FROM 16N58W TO 15N69W. OTHERWISE...EASTERLY TRADES CONTINUE ACROSS THE BASIN IN THE RANGE OF 15-20 KT S OF 17N AND 10-15 KT N OF 17N. THESE CONDITIONS WILL NOT CHANGE MUCH THROUGH THE EARLY PART OF THE UPCOMING WEEK. ISOLATED TO SCATTERED SHOWERS AND TSTMS WILL CONTINUE TO MOVE ONSHORE ACROSS WESTERN PANAMA...COSTA RICA AND NICARAGUA THROUGH THE EVENING HOURS WITH THE HEAVIEST AND MOST CONCENTRATED ACTIVITY LOCATED OVER INLAND NICARAGUA. ATLANTIC OCEAN... AN UPPER LEVEL SHORTWAVE TROUGH IS LOCATED WITHIN 120-150 NM E OF THE OUTER BANKS OF NORTH CAROLINA SUPPORTING A SURFACE COLD FRONT INTO THE SW NORTH ATLC WATERS FROM 32N72W SW TO ACROSS GRAND BAHAMA ISLAND TO THE COAST OF FLORIDA JUST S OF WEST PALM BEACH. MAINLY ZONAL FLOW IS ALOFT S OF 30N. THE FRONT CONTINUES TO BECOME MORE DIFFUSE AS THE UPPER LEVEL ENERGY MOVES NE OF THE AREA. EARLIER SHOWER ACTIVITY THAT WAS LOCATED N OF 28N E OF THE FRONT HAS DIMINISHED AS THE FRONT CONTINUES TO WEAKEN. THE FRONT IS FORECAST TO MOVE NE-E DURING THE NEXT 24-48 HOURS AS HIGH PRESSURE BUILDS EASTWARD FROM THE NE GULF OF MEXICO. THE REMAINDER OF THE SW NORTH ATLC IS UNDER A VERY WEAK AND BROAD HIGH PRESSURE REGIME BETWEEN 57W AND SE OF THE AFOREMENTIONED COLD FRONT. A FEW ISOLATED SHOWERS CONTINUE TO ADVECT WESTWARD ACROSS THE TURKS AND CAICOS ISLANDS AND THE SE BAHAMAS THIS EVENING. ACROSS THE CENTRAL ATLC...A COMPLEX SYSTEM INCLUDING TWO SURFACE LOWS AND TROUGHS ARE MOVING NE-E. THE EASTERN AND STRONGER LOW 1005 MB IS JUST N OF THE AREA NEAR 33N43W WITH A TRAILING TROUGH ENTERING THE AREA NEAR 32N39W THROUGH 24N39W TO 17N50W. THE SECOND LOW 1010 MB IS POSITIONED NEAR 30N48W WITH A TROUGH EXTENDING FROM THE LOW THROUGH 28N48W TO 27N54W. THE MAJORITY OF THE ACTIVE WEATHER ASSOCIATED WITH THE STRONGER LOW AND EASTERN TROUGH REMAINS N OF 32N. SCATTERED SHOWERS REMAIN POSSIBLE WITHIN 120-150 NM EITHER SIDE OF THE EASTERN TROUGH AND WITHIN 90-120 NM AHEAD OF THE WESTERN TROUGH. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED NW OF THE CANARY ISLANDS NEAR 32N24W. THE SURFACE RIDGE AXIS EXTENDS SW FROM THE HIGH CENTER TO NEAR 16N37W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LEWITSKY