000 AXNT20 KNHC 181050 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI MAR 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...ITCZ... ITCZ AXIS IS ALONG 07N11W 02N23W CROSSING THE EQUATOR NEAR 34W AND INTO NE BRAZIL NEAR 03S41W. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 07N BETWEEN 17W-25W. SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN 35W-44W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE IS OVER THE SE CONUS WITH AXIS FROM SE LOUISIANA NORTHEASTWARD TO THE MID-ATLC STATES. SOUTH OF THIS UPPER LEVEL RIDGE MOSTLY ZONAL WESTERLY FLOW ALOFT IS NOTED ON WATER VAPOR IMAGERY THIS MORNING. DRY AIR AND SUBSIDENCE ACCOMPANY THE RIDGE WHICH FILTERS DOWN TO THE LOW-LEVELS AS A FAIRLY STRONG 1026 MB HIGH CENTERED OVER THE NE GULF NEAR 29N85W. IT CONTINUES TO PROVIDE OVERALL FAIR WEATHER TO MUCH OF THE GULF THIS MORNING. LIGHT EAST TO SOUTHEAST WINDS ARE ACROSS THE GULF WITH VERY LITTLE SIGNIFICANT PRECIPITATION NOTED ON SATELLITE AND RADAR IMAGERY. HOWEVER...SHORTWAVE INFRARED SATELLITE IMAGERY AND A FEW COASTAL OBSERVATIONS ARE INDICATING LOW-LEVEL STRATUS AND LOWER VISIBILITIES IN FOG OVER THE NW GULF NORTHWEST OF A LINE FROM 23N97W TO 29N91W...IMPACTING MARINE AND AVIATION INTERESTS ALONG THE TEXAS AND LOUISIANA GULF COAST. THE SURFACE RIDGE IS FORECAST TO REMAIN NEARLY STATIONARY OVER THE NEXT SEVERAL DAYS AND CONTINUE TO PROVIDE OVERALL STABLE WEATHER CONDITIONS. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED EAST OF THE LESSER ANTILLES NEAR 07N44W AND CONTINUES TO PROVIDE SW WINDS ALOFT OVER MUCH OF THE CARIBBEAN SEA BASIN. MODERATE DRY AIR AND SUBSIDENCE IS ASSOCIATED WITH THE UPPER LEVEL RIDGING WHICH EXTENDS WESTWARD TO 85W. AT THE SURFACE...A STRONG SURFACE HIGH LOCATED OVER THE NE GULF AND PORTIONS OF THE SW NORTH ATLC CONTINUES TO PRODUCE A LARGE AREA OF FRESH TO STRONG E-NE TRADES OVER MUCH OF THE CARIBBEAN. THE STRONGEST WINDS ARE LOCATED IN THE VICINITY OF THE WINDWARD PASSAGE AND ALSO ALONG THE COAST OF COLOMBIA...MAINLY S OF 15N BETWEEN 72W-80W. THE HIGH OVER THE SW NORTH ATLC IS EXPECTED TO REMAIN NEARLY STATIONARY AND RELATIVELY STRONG OVER THE NEXT FEW DAYS...SO AS A RESULT...THE TRADES ARE FORECAST TO REMAIN QUITE BRISK THROUGH THE WEEKEND. ALTHOUGH NO SIGNIFICANT DEEP CONVECTION IS NOTED ON SATELLITE IMAGERY THIS MORNING...ISOLATED SHOWERS CONTINUE OVER MUCH OF THE EASTERN HALF OF THE BASIN...WHILE ISOLATED SHOWERS CONTINUE TO PUSH ONSHORE ALONG THE NICARAGUA...COSTA RICA...AND WESTERN PANAMA COASTS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS PROGRESSING ACROSS THE W ATLC WATERS WITH AXIS ALONG 33N64W TO 30N66W TO THE FLORIDA COAST NEAR 27N80W. THE UPPER LEVEL TROUGHING SUPPORTS A DISSIPATING COLD FRONT THAT ENTERS THE DISCUSSION AREA 32N66W AND EXTENDS SW TO 28N71W. A PRE-FRONTAL TROUGH IS ALSO ANALYZED FROM 31N64W TO 28N66W. VERTICAL DISTRIBUTION OF MOISTURE IS VERY LIMITED WITH THIS FRONT...HOWEVER...MARGINAL LOW-LEVEL CONVERGENCE IS GENERATING ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE FRONT AS IT CONTINUES TO BECOME MORE DIFFUSE. AN EARLIER ASCAT PASS FROM 18/0224 UTC INDICATES STRONGER NORTHERLY WINDS ARE LOCATED NW OF THE FRONT. THE FRONT IS FORECAST TO SHIFT NE OVER THE NEXT 24 HOURS AND LOCATE NORTH OF THE DISCUSSION AREA BY EARLY SATURDAY. SOUTHEAST OF THIS FRONT...ANOTHER SURFACE TROUGH IS ANALYZED FROM 27N64W TO 21N68W...PRIMARILY LOCATED WITHIN THE WEAKNESS OF THE SUBTROPICAL RIDGE BETWEEN 60W-70W. ISOLATED SHOWERS ARE OCCURRING FROM 24N-27N BETWEEN 61W-66W. FARTHER EAST...ANOTHER UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY ALONG 31W THAT SUPPORTS A COLD FRONT ANALYZED FROM 32N29W TO 28N30W THEN SW TO 22N40W. THE REMAINDER OF THE BOUNDARY STRETCHES WESTWARD TO 23N51W AS A DISSIPATING STATIONARY FRONT. SCATTERED SHOWERS ARE OCCURRING WITHIN 120 NM EAST OF THE FRONT N OF 26N WHILE ISOLATED SHOWERS LINGER WITHIN 60 NM EITHER SIDE OF THE FRONT W OF 32W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN