000 AXNT20 KNHC 081748 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN MAR 08 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N8W CROSSING THE EQUATOR NEAR 20W EXTENDING TO 1S40W AND INTO NE BRAZIL NEAR 3S44W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 2N-6N BETWEEN 2W-10W. ISOLATED MODERATE CONVECTION IS S OF 1N BETWEEN 18W-23W AND BETWEEN 33W-39W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE DOMINATES MUCH OF THE GULF AND SE CONUS WITH MODERATE TO STRONG SUBSIDENCE IN PLACE OVER THE REGION SE OF A LINE FROM NEW ORLEANS LOUISIANA TO BROWNSVILLE TEXAS. SOUTHEASTERLY SURFACE RETURN FLOW OF UP TO 25 KT RESIDES ON THE WRN PERIPHERY OF A SURFACE RIDGE THAT EXTENDS FROM A 1027 MB HIGH IN THE W ATLC NEAR 29N71W. FRESH EASTERLIES CONTINUE TO FILTER THROUGH THE STRAITS OF FLORIDA AND INTO THE FAR SE GULF. THESE WINDS ARE TRANSPORTING PATCHES OF LOW-LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS ACROSS THE FLORIDA KEYS AND ADJACENT COASTAL WATERS. THE SURFACE HIGH IS FORECAST TO REMAIN NEARLY STATIONARY AND AS A RESULT...THE OVERALL WEATHER PATTERN ACROSS THE GULF WILL CHANGE LITTLE THROUGH LATE TUESDAY. LOOKING AHEAD...THE NEXT COLD FRONT IS POSITIONED TO IMPACT THE GULF LATE WEDNESDAY AND WILL LIE EAST-WEST ALONG THE NRN GULF COAST. CARIBBEAN SEA... FRESH TO STRONG WINDS ASSOCIATED WITH A 1027 MB SURFACE HIGH CENTERED IN THE W ATLC NEAR 29N71W ARE ADVECTING POCKETS OF SHALLOW MOISTURE WITH EMBEDDED ISOLATED LIGHT SHOWERS ACROSS THE GREATER ANTILLES ISLANDS AND MUCH OF THE CARIBBEAN SEA. AN EARLIER QUIKSCAT PASS SHOWED E-NE WINDS OF 20-30 KT OVER MUCH OF THE REGION. ALSO...A GALE WARNING REMAINS IN EFFECT FOR THE SW CARIBBEAN FROM 10N-13N BETWEEN 74W-77W OFF THE COLOMBIAN COAST. THE INCREASED SURFACE WINDS ARE THE RESULT OF A TIGHT SURFACE PRESSURE GRADIENT BETWEEN THE AFOREMENTIONED HIGH OVER THE W ATLC AND LOWER PRESSURE OVER NRN SOUTH AMERICA. ALOFT...STRONG SUBSIDENCE IS RESULTING FROM CONFLUENCE IN WESTERLY UPPER LEVEL FLOW...MAXIMIZED OVER THE ERN CARIBBEAN...AND IT IS THIS UPPER LEVEL REGIME THAT CONTINUES TO LIMIT ANY DEEP CONVECTION ACROSS THE BASIN. ATLANTIC OCEAN... A DEEP LAYERED TROUGH IS OVER THE CENTRAL ATLC WITH AN ELONGATED UPPER-LEVEL LOW CENTERED NEAR 28N49W. THIS TROUGH SUPPORTS A 1004 MB OCCLUDED SURFACE LOW CENTERED NEAR 27N51W. THE ATTENDANT COLD FRONT EXTENDS FROM 29N48W ALONG 24N45W 20N45W SW TO 10N53W. SCATTERED SHOWERS ARE WITHIN 90 NM OF THE COLD FRONT WHILE UPPER LEVEL DIFFLUENCE TO THE NE OF THE LOW IS AIDING IN GENERATING SCATTERED MODERATE CONVECTION E OF THE COLD FRONT FROM 22N-33N E OF 38W. ACROSS THE W ATLC...A RELATIVELY COOLER AND DRIER AIRMASS REMAINS IN PLACE WITH A 1027 MB SURFACE HIGH CENTERED NEAR 29N71W. BROKEN COLD AIR STRATOCUMULUS CLOUDS ARE NOTED ON SATELLITE IMAGERY ACROSS THE W ATLC INTO THE BAHAMAS AND CUBA UNDER PREVAILING E-NE FLOW. FARTHER TO THE EAST...AN UPPER-LEVEL LOW CONTINUES TO SPIN OVER THE E ATLC JUST NORTH OF THE CANARY ISLANDS. A WEAK 1013 MB SURFACE LOW IS CENTERED NEAR 29N16N WITH A SURFACE TROUGH ANALYZED FROM THE LOW ALONG 28N14W 25N14W TO 19N17W. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS TROUGH IS SUPPORTING AN AREA OF SCATTERED SHOWERS OVER SRN MOROCCO. ACROSS THE TROPICAL ATLC...A BROAD UPPER-LEVEL RIDGE CENTERED NEAR 6N17W IS HELPING TO INDUCE CONVECTION ALONG THE ITCZ. $$ HUFFMAN