000 AXNT20 KNHC 191740 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST THU FEB 19 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. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N9W 2N20W 1N30W EQ40W 1S50W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180 NM E OF THE AXIS E OF 14W AND WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 14W-20W. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM OF THE AXIS W OF 44W. ...DISCUSSION... GULF OF MEXICO... STRONG WESTERLY FLOW ALOFT COVERS THE GULF IN THE BASE OF A DEEP TROUGH OVER THE E CONUS. A COLD FRONT ASSOCIATED WITH THIS TROUGH EXTENDS FROM THE FLORIDA BIG BEND INTO THE NW GULF NEAR 25N96W TO THE COAST OF VERACRUZ NEAR 22N98W. THIS FRONT HAS SURGED SOUTHWARD OVER THE FAR WESTERN GULF...WHERE LOCAL TOPOGRAPHY CONTINUES TO FUNNEL THE COLDER AIRMASS NORTH OF THE REGION SOUTHWARD. THIS FUNNELING HAS RESULTED IN THE DEVELOPMENT OF A 1011 MB SURFACE LOW NEAR 20N96W. LOW LEVEL CONVERGENCE SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER SIDE OF THE FRONT...WITH EMBEDDED ISOLATED THUNDERSTORMS E OF 86W. SOUTH OF THE FRONT...SOUTHERLY AND EASTERLY DIFFLUENT FLOW AT THE SURFACE IS SUPPORTING FAIR WEATHER CONDITIONS...WHERE ATMOSPHERIC STABILITY IS IN PLACE. N OF THE FRONT...STRATOCUMULUS CLOUD DEVELOPMENT IS UNDERWAY IN RESPONSE TO COLD AIR ADVECTION OVER RELATIVELY WARMER GULF WATERS. THE 19/1200 UTC QUIKSCAT PASS DEPICTS N TO NE WINDS OF 20 TO 25 KT IN THE WAKE OF THE FRONT THAT CONTINUE TO USHER A COOLER AND DRIER AIRMASS INTO THE GULF REGION. THIS FRONT IS FORECAST TO CONTINUE MOVING SOUTHWARD DURING THE NEXT DAY WHILE WEAKENING...WITH SHOWER AND THUNDERSTORM ACTIVITY GRADUALLY DIMINISHING AS THE STRONGER UPPER LEVEL SUPPORT SHIFTS NORTH OF THE DISCUSSION AREA. CARIBBEAN SEA... FRESH TRADE WINDS CONTINUE ACROSS A LARGE PART OF THE CENTRAL AND E CARIBBEAN WITH A RIDGE PRESENT IN THE CENTRAL ATLC. THE STRONGEST WINDS...UP TO 30 KT...ARE FOUND ALONG THE COAST OF COLOMBIA. GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT ACROSS THE CARIBBEAN REGION WITH AN UPPER RIDGE DOMINATING THE REGIONAL WEATHER...THOUGH PATCHES OF LOW LEVEL MOISTURE CONTINUE TO BE ADVECTED EASTWARD ACROSS THE CARIBBEAN ON EASTERLY TRADE WINDS. ATLANTIC OCEAN... A DEEP TROUGH OVER THE E CONUS CONTINUES TO PROGRESS EASTWARD WITH AN ASSOCIATED COLD FRONT MOVING OFF THE SE GEORGIA COAST. THE STRONG PRESSURE GRADIENT ASSOCIATED WITH THIS FRONT IS SUPPORTING SOUTHWESTERLY GALES AHEAD OF THE FRONT BASED ON RECENT SHIP OBSERVATIONS. THIS FRONT WILL CONTINUE MOVING EASTWARD DURING THE NEXT DAY...THOUGH WILL WEAKEN AS THE ATTENDANT UPPER SUPPORT MOVES NORTH OF THE DISCUSSION AREA. SCATTERED SHOWERS AND THUNDERSTORMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE FRONT. FARTHER TO THE E...A 1025 MB SURFACE HIGH IS CENTERED NEAR 30N57W. SUBSIDENCE ASSOCIATED WITH THIS FEATURE IS RESULTING IN FAIR WEATHER CONDITIONS ACROSS A LARGE PART OF THE CENTRAL ATLC. FARTHER TO THE E...SURFACE COLD FRONT ENTERS THE DISCUSSION AREA NEAR 31N41W AND EXTENDS TO 23N49W BECOMING STATIONARY SOUTHWESTWARD TO 17N62W. SURFACE CONFLUENCE DEPICTED BY THE 19/1200 UTC ASCAT PASS NEAR THIS BOUNDARY IS SUPPORTING INCREASED CLOUDINESS AND ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THESE FRONTS. ACROSS THE E ATLC...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE AND A 1030 MB SURFACE HIGH NEAR 33N29W IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. ACROSS THE TROPICAL ATLC...DEEP LAYER DRY AIR EMBEDDED WITHIN AN UPPER TROUGH THAT EXTENDS SOUTHWARD FROM THE CENTRAL ATLC IS SUPPRESSING CONVECTION OVER THE WESTERN HALF OF THE ITCZ. UPPER LEVEL DIVERGENCE E OF THIS TROUGH IS ENHANCING THE CONVECTION OVER THE E HALF OF THE ITCZ. $$ COHEN