000 AXNT20 KNHC 042340 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED MAR 04 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 1800 UTC SURFACE ANALYSIS...SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N9W 1N20W CROSSING THE EQUATOR NEAR 23W EXTENDING TO 2S30W INTO NE BRAZIL NEAR 3S42W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM SOUTH OF AXIS BETWEEN 18W-22W. SCATTERED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF AXIS WEST OF 30W. ...DISCUSSION... GULF OF MEXICO... A 1033 MB SFC HIGH LOCATED OVER THE CAROLINAS EXTENDS A RIDGE SW ACROSS THE SE CONUS AND THE ENTIRE GULF OF MEXICO PRODUCING MOSTLY FAIR WEATHER AND LIGHT TO MODERATE WINDS OF 10-15 KT. COLD AIR ADVECTION OVER THE RELATIVELY WARMER GULF WATERS IS STILL RESULTING IN SCATTERED STRATOCUMULUS CLOUDS ACROSS MUCH OF THE AREA. THE SFC HIGH IS FORECAST TO MOVE EAST INTO THE W ATLC DURING THE NEXT 24 HOURS INCREASING SLY WINDS OVER THE W GULF TONIGHT THROUGH FRIDAY. ALOFT...A RIDGE ANCHORED ON AN UPPER- LEVEL HIGH OVER THE BAY OF CAMPECHE DOMINATES MOST OF THE GULF WATERS RESULTING IN MODERATE TO STRONG SUBSIDENCE WITH THE ASSOCIATED DRY AIR MASS...PARTICULARLY ACROSS THE WESTERN GULF. STRONG NW WINDS ON THE EASTERN SIDE OF THE RIDGE ARE ADVECTING SOME MID/UPPER LEVEL MOISTURE ACROSS THE NE CORNER OF THE GULF. CARIBBEAN SEA... A LONG-WAVE TROUGH OVER THE W ATLC AND THE NORTH-CENTRAL CARIBBEAN SUPPORTS A COLD FRONT THAT ENTERS THE REGION THROUGH PUERTO RICO THEN CONTINUES SW ACROSS THE CENTRAL CARIBBEAN TO 14N74W. AT THIS POINT...IT BECOMES STATIONARY EXTENDING ALONG 12N78W INTO WESTERN PANAMA. MODERATE TO FRESH NLY WINDS BEHIND THE FRONTAL BOUNDARY ARE ADVECTING LOW LEVEL MOISTURE WITH EMBEDDED LIGHT SHOWERS OVER THE CARIBBEAN SIDE OF COSTA RICA AND WESTERN PANAMA. THE FRONTAL ZONE IS ALSO GENERATING SCATTERED TO NUMEROUS SHOWERS AND ISOLATED TSTMS OVER PUERTO RICO...VIEQUES AND CULEBRA PER THE SAN JUAN DOPPLER RADAR. THE FRONT IS FORECAST TO SLOWLY MOVE ACROSS PUERTO RICO TONIGHT AND THURSDAY KEEPING THE CHANCE OF RAIN OVER THOSE ISLANDS. STRONG HIGH PRES BUILDING ACROSS THE WRN ATLC WILL PUSH THIS FRONT SOUTHEAST OF THE AREA BY FRI. AT THE SAME TIME...THIS SFC HIGH WILL FAVOR AN INCREASE IN WINDS AND SEAS ACROSS THE STRAITS OF FLORIDA AND THE CARIBBEAN PASSAGES AS WELL AS ACROSS MUCH OF THE BASIN THU THROUGH SUN. ACROSS THE E CARIBBEAN...MID/UPPER LEVEL MOISTURE CONTINUES TO BE DRAWN NORTHWARD BETWEEN A RIDGE OVER THE TROPICAL ATLC AND THE AFOREMENTIONED DEEP LAYERED TROUGH. ATLANTIC OCEAN... AS PREVIOUSLY MENTIONED...A LONG-WAVE TROUGH IS OVER THE W ATLC AND THE N-CENTRAL CARIBBEAN. THE ATTENDANT COLD FRONT ENTERS THE FORECAST AREA NEAR 32N57W THEN CONTINUES SW TO NEAR 23N62W ENTERING THE CARIBBEAN SEA THROUGH PUERTO RICO. LOW LEVEL CONVERGENCE IS HELPING TO INDUCE SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF THIS FRONT. THIS ACTIVITY IS BEING SUPPORTED BY STRONG UPPER LEVEL DIVERGENCE ASSOCIATED WITH AN UPPER LEVEL JET MAXIMUM TO THE W OF THE FRONT. IN THE WAKE OF THE FRONT...A RELATIVELY COOLER AND DRIER AIRMASS IS PRESENT ASSOCIATED WITH THE 1033 MB HIGH OVER THE CAROLINAS. THE REMAINDER OF THE ATLC DISCUSSION AREA IS UNDER THE INFLUENCE OF A STRONG 1041 SFC HIGH LOCATED JUST WEST OF THE AZORES. THIS SYSTEM IS PRODUCING A LARGE AREA OF MODERATE TO FRESH TRADE WINDS MAINLY EAST OF 45W...AND MOSTLY FAIR WEATHER CONDITIONS. LOOKING AHEAD...THE GFS COMPUTER MODEL ANTICIPATES THE DEVELOPMENT OF A SFC LOW ALONG THE FRONT NEAR 26N56W ON FRI. A DIFFERENCE IN PRES BETWEEN THIS LOW AND THE STRONG HIGH PRES OVER THE W ATLC WILL RAISE WINDS ACROSS THE W-CENTRAL ATLC MAINLY BETWEEN 56W-70W INCLUDING ALSO THE SE BAHAMAS AND THE CARIBBEAN PASSAGES. GALE FORCE WINDS ARE EXPECTED WITHIN AROUND 180 NM NW QUADRANT OF THE LOW CENTER. SEE THE HIGH SEAS FORECAST FOR MORE DETAILS. AN UPPER- LEVEL HIGH CENTERED NEAR 3N47W DOMINATES MUCH OF THE DEEP TROPICS. THIS FEATURE IS ENHANCING CONVECTION ALONG THE ITCZ WEST OF 30W...AND OVER N SOUTH AMERICA. $$ GR