000 AXNT20 KNHC 131746 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI MAR 13 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 6N8W CROSSING THE EQUATOR NEAR 20W EXTENDING TO 4S30W INTO NE BRAZIL NEAR 6S36W. SCATTERED MODERATE CONVECTION IS S OF 4N BETWEEN 1W-10W AND BETWEEN 12W-23W. ...DISCUSSION... GULF OF MEXICO... INCREASING SOUTHWESTERLY FLOW ALOFT IS PRESENT ACROSS THE WRN GULF REGION. DEEP LAYER ATMOSPHERIC LIFT IN THIS FLOW IS SUPPORTING A SURFACE STATIONARY FRONT THAT EXTENDS ACROSS THE FLORIDA PANHANDLE AND INTO THE GULF NEAR VERMILION BAY. THE FRONT CONTINUES SW INTO A 1014 MB LOW CENTERED NEAR 26N95W THEN S ALONG 22N96W TO THE COAST OF MEXICO NEAR 20N97W. LOW LEVEL CONVERGENCE ALONG THE FRONTAL BOUNDARY IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 26N W OF 88W. TO THE NW OF THE FRONT...NLY SURFACE WINDS OF 15 TO 20 KT ARE OBSERVED OVER THE FAR NW GULF. TO THE SE OF THE FRONT ACROSS MUCH OF THE REMAINDER OF THE GULF...DEEP LAYER DRY AIR IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS THIS AFTERNOON. THE LOW IS FORECAST TO MOVE NE AND LOCATE OVER NW ALABAMA BY SATURDAY WITH THE ATTENDANT COLD FRONT EXTENDING FROM THE N/CENTRAL GULF TO THE WRN BAY OF CAMPECHE. CARIBBEAN SEA... A STRONG SURFACE RIDGE OF HIGH PRESSURE LOCATED OVER THE W ATLC IS MAINTAINING MODERATE TO STRONG TRADES OVER MUCH OF THE CARIBBEAN SEA. GENERALLY FAIR WEATHER CONDITIONS ARE OBSERVED ACROSS MUCH OF THE CARIBBEAN REGION...WHERE DEEP LAYER DRY AIR IS IN PLACE. HOWEVER...THE TRADE WINDS ARE ADVECTING PATCHES OF LOW LEVEL MOISTURE WWD ACROSS THE CARIBBEAN...WITH ISOLATED SHOWERS EMBEDDED WITHIN THESE PATCHES OF LOW LEVEL MOISTURE. THE GREATEST CONCENTRATION OF THESE SHOWERS ARE ACROSS ERN HISPANIOLA...PUERTO RICO...AND THE LEEWARD ISLANDS. ALSO... INCREASED UPPER LEVEL MOISTURE IS STREAMING NE ACROSS PORTIONS OF THE FAR SE CARIBBEAN. ATLANTIC OCEAN... SOUTHWESTERLY FLOW ALOFT IS PRESENT ACROSS THE SE CONUS AND FAR W ATLC AS DEEP LAYER ATMOSPHERIC LIFT IN THIS FLOW IS SUPPORTING A SURFACE STATIONARY FRONT EXTENDING FROM A 1018 MB LOW CENTERED NEAR 32N77W. THE STATIONARY FRONT EXTENDS WSW TO NEAR JACKSONVILLE FLORIDA AND ALONG THE NE GULF COAST. LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS FRONT. TO THE SE OF THIS FRONT...AN UPPER LEVEL RIDGE IS IN PLACE WITH AXIS ALONG 64W...WITH A 1026 MB SURFACE HIGH NEAR 31N67W. DEEP LAYER DRY AIR AND ATMOSPHERIC STABILITY IN THE VICINITY OF THE SURFACE HIGH AND UPPER LEVEL RIDGE ARE RESULTING IN GENERALLY FAIR WEATHER CONDITIONS TO THE SE OF THE FRONT. FURTHER TO THE E...AN UPPER LEVEL TROUGH IS N OF 20N BETWEEN 30W-45W...WITH AN UPPER LEVEL LOW NEAR 29N38W. THESE FEATURES SUPPORT A 1001 MB SURFACE LOW NEAR 28N39W...WITH A DISSIPATING SURFACE COLD FRONT EXTENDING FROM 13N44W TO 20N36W TO 32N35W TO N OF THE DISCUSSION AREA. A DISSIPATING SURFACE OCCLUDED FRONT ALSO ACCOMPANIES THIS LOW EXTENDING FROM 27N41W TO 30N43W TO N OF THE DISCUSSION AREA. ATMOSPHERIC INSTABILITY AND LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW AND SURFACE FRONTS ARE SUPPORTING SCATTERED SHOWERS AND TSTMS N OF 25N BETWEEN 31W-37W. ACROSS THE E ATLC...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE IS RESULTING IN FAIR WEATHER CONDITIONS. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 20N E OF 55W WITH AN UPPER LEVEL HIGH CENTERED NEAR 10N24W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL HIGH AND UPPER LEVEL RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ. $$ HUFFMAN