000 AXNT20 KNHC 052344 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU MAR 05 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 6N10W 2N20W CROSSING THE EQUATOR NEAR 24W EXTENDING TO 3S35W INTO NE BRAZIL NEAR 5S43W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF AXIS BETWEEN 11W-19W. ...DISCUSSION... GULF OF MEXICO... A 1034 MB SFC HIGH LOCATED OFF THE CAROLINAS NEAR 36N74W EXTENDS A RIDGE SW ACROSS THE SE CONUS...THE ENTIRE GULF OF MEXICO AND E TEXAS PRODUCING GENERALLY FAIR WEATHER CONDITIONS AND MODERATE TO FRESH WINDS. THE STRONGEST WINDS OF 20-25 KT ARE FOUND IN THE STRAITS OF FLORIDA AND THE FAR SE PORTION OF THE GULF. 15-20 KT SOUTHEASTERLY RETURN FLOW HAS ESTABLISHED OVER THE WESTERN GULF WATERS AROUND THE PERIPHERY OF THIS HIGH. SCATTERED COLD AIR STRATOCUMULUS CLOUDS ARE STILL NOTED ACROSS THE CENTRAL AND WEST SECTIONS OF THE GULF MOVING NWD UNDER THE PREVAILING WIND FLOW. THE SFC HIGH IS FORECAST TO MOVE EAST THEN NE ACROSS THE W ATLANTIC OCEAN DURING THE NEXT 24 HOURS. ALOFT...A RIDGE WITH AXIS ALONG 90W DOMINATES MOST OF THE GULF WATERS RESULTING IN MODERATE TO STRONG SUBSIDENCE WITH THE ASSOCIATED DRY AIR MASS. STRONG NW WINDS ON THE EASTERN SIDE OF THE RIDGE ARE ADVECTING SOME MID/UPPER LEVEL MOISTURE ACROSS THE NE CORNER OF THE GULF AND N FLORIDA. THE OVERALL WEATHER PATTERN ACROSS THE GULF WILL CHANGE LITTLE THROUGH FRI NIGHT. CARIBBEAN SEA... A LONG-WAVE TROUGH PERSISTS OVER THE W ATLC. THE BASE OF THIS TROUGH REACHES HISPANIOLA AND PUERTO RICO. THIS UPPER-LEVEL FEATURE SUPPORTS A QUASI-STATIONARY FRONT EXTENDING ACROSS THE WEST-CENTRAL ATLC TO THE VIRGIN ISLANDS. THE FRONT HAS BECOME DIFFUSE OVER THE CARIBBEAN SEA. HOWEVER...THE TAIL END OF THIS FRONTAL SYSTEM IS STILL PRODUCING ABUNDANT LOW LEVEL CLOUDS WITH EMBEDDED SHOWERS OVER PUERTO RICO AND REGIONAL WATERS...AND OVER THE US/UK VIRGIN ISLANDS. NELY LOW LEVEL WINDS ASSOCIATED WITH THE SFC HIGH OFF THE CAROLINAS ARE ALSO TRANSPORTING PATCHES OF SHALLOW MOISTURE ACROSS CUBA AND HISPANIOLA. FRESH TO STRONG NE WINDS ARE BLOWING ACROSS THE MAJORITY OF THE BASIN ADVECTING POCKETS OF LOW LEVEL MOISTURE ACROSS THE CARIBBEAN WATERS INTO CENTRAL AMERICA. THE FRONT IS FORECAST TO DISSIPATE THROUGH FRI NIGHT WITH THE FRONTAL REMNANTS AFFECTING THE LEEWARD ISLANDS ON FRI. STRONG HIGH PRES BUILDING ACROSS THE WRN ATLC WILL COMBINE WITH A DEVELOPING LOW...LIKELY A GALE CENTER...OVER THE CENTRAL ATLC TO PRODUCE AN INCREASE IN WINDS AND SEAS ACROSS THE STRAITS OF FLORIDA AND THE CARIBBEAN PASSAGES AS WELL AS ACROSS MUCH OF THE CARIBBEAN SEA FRI THROUGH SUN. GALE FORCE WINDS ARE EXPECTED OFFSHORE THE COLOMBIAN COAST IN ABOUT 24 HOURS OR SO. 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 REMAINS OVER THE W ATLC AND THE NORTHERN CARIBBEAN. THE ATTENDANT FRONTAL SYSTEM ENTERS THE FORECAST AREA...AS A STATIONARY FRONT...NEAR 32N54W THEN CONTINUES SW TO NEAR THE VIRGIN ISLANDS. LOW LEVEL CONVERGENCE IS HELPING TO INDUCE SCATTERED SHOWERS WITHIN 140 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 1034 MB HIGH OFF THE CAROLINAS NEAR 36N74W. BROKEN COLD AIR STRATOCUMULUS CLOUDS ARE NOTED BEHIND THE FRONT MOVING ACROSS THE W ATLC INTO THE BAHAMAS AND CUBA UNDER A PREVAILING NE FLOW. A 1036 MB HIGH OVER THE AZORES IS IN CONTROL OF THE WEATHER PATTERN ACROSS THE REMAINDER OF THE ATLC DISCUSSION AREA. THIS SYSTEM IS PRODUCING MODERATE TO FRESH TRADE WINDS MAINLY EAST OF 40W...AND MOSTLY FAIR WEATHER CONDITIONS. THE GFS COMPUTER MODEL CONTINUES TO DEVELOP A STRONG SFC LOW ALONG THE FRONT NEAR 28N52W 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 55W-70W INCLUDING ALSO THE SE BAHAMAS AND THE CARIBBEAN PASSAGES FRI THROUGH SUN. GALE FORCE WINDS ARE EXPECTED WITHIN AROUND 300 NM NW QUADRANT OF THE LOW CENTER. SEE THE HIGH SEAS FORECAST FOR MORE DETAILS. ALOFT...A HIGH AMPLITUDE UPPER-LEVEL RIDGE IS OVER THE E-CENTRAL ATLC N OF 30N AND AN UPPER-LEVEL LOW IS SOUTH OF THE UPPER RIDGE NEAR 23N32W. LONG-WAVE TROUGHS AREA OVER THE W ATLC AND NW AFRICA. $$ GR