000 AXNT20 KNHC 171756 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST TUE FEB 17 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 6N10W 2N20W 1N30W CROSSING THE EQUATOR AT 39W...AND INTO NE BRAZIL NEAR 3S47W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 140 NM N OF AXIS BETWEEN 28W-34W. SIMILAR CONVECTION IS FOUND WITHIN 70 NM EITHER SIDE OF AXIS BETWEEN 34W-45W...AND WITHIN 100NM NE OF LINE FROM 1S45W TO EQ51W. ...DISCUSSION... GULF OF MEXICO... A 1029 MB HIGH OVER THE CAROLINAS EXTENDS A RIDGE OVER THE SE CONUS AND THE ENTIRE GULF OF MEXICO PRODUCING MOSTLY FAIR WEATHER. SCATTERED COLD AIR STRATOCUMULUS CLOUDS ARE STILL NOTED PARTICULARLY OVER THE WESTERN HALF OF THE GULF WHERE A SE-S RETURN FLOW HAS ALREADY ESTABLISHED. THESE WINDS ARE EXPECTED TO INCREASE TO 20-25 KT THIS AFTERNOON. THE HIGH PRES WILL MOVE SE TOWARDS THE W ATLC IN ABOUT 24 HOURS ALLOWING THE NEXT COLD FRONT TO ENTER THE NW PORTION OF THE GULF WED AFTERNOON. THE FRONT IS FORECAST TO PUSH ACROSS THE ENTIRE GULF ON THU FOLLOWED BY MODERATE TO STRONG N-NE WINDS. IN THE UPPER LEVELS...A RIDGE ANCHORED ON A HIGH OVER EPAC REGION NEAR 6N93W COVERS MEXICO AND MOST OF THE GULF REGION PRODUCING STRONG NW FLOW...AND ALSO MODERATE TO STRONG SUBSIDENCE SOUTH OF 24N...INCLUDING SE MEXICO AND THE YUCATAN PENINSULA. CARIBBEAN SEA... AS OF 1500 UTC...THE TAIL END OF A COLD FRONT IS OVER THE WINDWARD PASSAGE/NW HAITI WITH BROKEN LOW CLOUDS AND ISOLATED SHOWERS. THIS FRONT WILL SWEEP SE AND GRADUALLY DISSIPATE AS IT CROSSES HISPANIOLA TONIGHT AND WED. LATEST VIS SATELLITE IMAGERY INDICATES THAT THE FRONTAL BOUNDARY IS ALREADY AFFECTING THE NW PORTION OF DOMINICAN REPUBLIC WITH NW WINDS AND SOME SHOWER ACTIVITY. HIGH PRES BEHIND THE COLD FRONT...CENTERED OVER THE CAROLINAS...COVERS CUBA AND THE NW CARIBBEAN. N-NE WINDS AROUND THE SOUTHERN PERIPHERY OF THIS HIGH ARE TRANSPORTING COLD AIR STRATOCUMULUS CLOUDS FROM THE W ATLC INTO CUBA AND THE NW CARIBBEAN. FURTHER E...A SURFACE TROUGH REMAINS OVER THE EASTERN CARIBBEAN WITH AXIS ALONG 67W/68W SOUTH OF 17S. THIS TROUGH IS GENERATING A LARGE ARE OF LOW/MID CLOUDS WITH SOME SHOWER ACTIVITY OVER THE ABC ISLANDS. LINES OF CLOUDS EMBEDDED IN THE NE TRADE WIND FLOW ARE NOTED AHEAD OF THIS SFC TROUGH OVER THE CENTRAL AND SW CARIBBEAN. THE TRADE WINDS WILL START TO INCREASE LATE TODAY ACROSS THE BASIN AS HIGH PRES OVER THE CAROLINAS MOVES SE ACROSS THE W ATLC TIGHTENING THE PRESSURE GRADIENT OVER THE CARIBBEAN. IN THE UPPER LEVELS...A RIDGE/TROUGH/RIDGE PATTERN COVERS THE ENTIRE BASIN AND CENTRAL AMERICA WITH STRONG SUBSIDENCE OVER THE W AND CENTRAL CARIBBEAN. ATLANTIC OCEAN... A VERY STRONG EXTRATROPICAL CYCLONE WITH HURRICANE FORCE WINDS ON THE WESTERN SEMICIRCLE IS SPINNING OVER THE W-CENTRAL ATLANTIC OCEAN NEAR 36N60W. THE ATTENDANT COLD FRONT ENTERS THE FORECAST AREA NEAR 32N56W THEN CONTINUES SW TO THE WINDWARD PASSAGE/NW HAITI. A WELL DEFINED BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS...CURRENTLY AFFECTING HISPANIOLA...IS RELATED TO THE FRONT. TIGHT PRES GRADIENT BETWEEN THIS STRONG SFC LOW AND THE HIGH PRES OVER THE CAROLINAS IS PRODUCING A WIDE SWATH OF STRONG NLY WINDS OF 30 TO 40 KT OVER THE DISCUSSION AREA... MAINLY N OF 27N AND WEST OF 65W. AS A RESULT...A GALE WARNING IS IN EFFECT FOR THAT AREA. THE REMAINDER OF THE ATLANTIC IS UNDER THE INFLUENCE OF A RIDGE ANCHORED ON A HIGH LOCATED WELL N OF REGION. THIS SYSTEM IS GENERATING MOSTLY FAIR WEATHER...AND MODERATE TO FRESH TRADE WINDS ACROSS THE TROPICS. ALOFT...AN AMPLIFIED TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE ATLANTIC OCEAN. A DEEP LAYERED TROUGH OVER THE W ATLC SUPPORTS THE ABOVE MENTIONED COLD FRONT. A RIDGE EXTENDS OVER THE CENTRAL ATLC TO BEYOND THE AZORES ISLANDS. E OF THE RIDGE...THERE IS ANOTHER DEEP LAYERED TROUGH STRETCHING FROM THE MADEIRA ISLANDS TO THE CAPE VERDE ISLANDS. W-NW UPPER-LEVEL FLOW COVERS THE DEEP TROPICS. $$ GR