000 AXNT20 KNHC 182335 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE MAR 18 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 3N20W 1N27W CROSSING THE EQUATOR NEAR 31W TO NE BRAZIL NEAR 3S40W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 13W-17W. ISOLATED MODERATE IS WITHIN 240 NM EITHER SIDE OF THE AXIS BETWEEN 23W-34W. ...DISCUSSION... GULF OF MEXICO... A TIGHT PRESSURE GRADIENT BETWEEN A 996 MB LOW PRES TROUGH OVER S TEXAS AND MEXICO AND A 1033 MB HIGH OFFSHORE OF THE MID-ATLANTIC COAST IS PRODUCING SLY GALE FORCE WINDS OVER A GOOD PORTION OF THE WRN GULF. BUOYS AND SHIPS ARE REPORTING SEAS AS HIGH AS 16 FT IN THAT AREA. THESE SE TO S WINDS ARE AHEAD OF A STRONG COLD FRONT WHICH HAS JUST EMERGED OFF THE TEXAS COAST. DOPPLER RADAR AND LIGHTNING DATA DEPICT A NARROW SWATH OF SCATTERED TSTMS WITHIN 30 NM AHEAD OF THE FRONT. THIS BOUNDARY IS EXPECTED TO PUSH E ACROSS MOST OF THE REGION AS IT WEAKENS OVER THE NEXT COUPLE OF DAYS. IN THE MID AND UPPER LEVELS...STRONG SWLY FLOW LIES OVER THE WRN GULF BETWEEN A SHARP UPPER TROUGH (THE SUPPORT FOR THE FRONT) OVER SW TEXAS/N MEXICO AND BROAD RIDGING OVER THE E GULF. THIS FLOW IS ADVECTING A BROKEN SWATH OF MID-HIGH LEVEL CLOUDS W OF 94W. CARIBBEAN SEA... AN IMPRESSIVE COLD FRONT HAS SWEPT THROUGH THE NRN LEEWARD ISLANDS...PUERTO RICO AND HISPANIOLA. THIS BOUNDARY IS STILL WELL DEFINED FROM 18N63W TO 17N71W...NOTED AS A BROKEN ROPE CLOUD WHICH CONTAINS SCATTERED SHOWERS WITHIN 60 NM AHEAD OF IT. N TO NE WINDS ARE INCREASING BEHIND IT PULLING IN COOLER AIR. THE LONG N FETCH OVER THE ATLC IS CREATING VERY ROUGH MARINE CONDITIONS N OF THE ISLANDS. OTHERWISE...WIDESPREAD SUBSIDENCE ALOFT IS BEING ENHANCED BY CONFLUENCE ASSOCIATED WITH A RIDGE OVER THE W CARIB AND A HIGHLY ELONGATED TROUGH OVER THE EASTERN HALF. THIS STABLE PATTERN IS CAPPING THE TYPICAL LOW-LEVEL CLOUD STREAMERS STEERED BY STRONG TRADES. THE TRADES ARE EVEN TO GALE FORCE NEAR THE COAST OF COLOMBIA...EXPECTED TO PERSIST FOR ABOUT 24-36 HOURS. ATLANTIC OCEAN... A STRONG COLD FRONT CONTINUES TO PUSH E ACROSS THE CENTRAL ATLC ENTERING THE REGION NEAR 32N45W AND CONTINUING SW ACROSS THE NRN LEEWARD ISLANDS ALONG 25N49W 18N63W. LIGHTNING DATA SHOWS SCATTERED TSTM ACTIVITY WITHIN 120 NM E OF THE FRONT N OF 24N AND SCATTERED SHOWERS WITHIN 60 NM OF THE FRONT S OF 24N. SIMILAR SCATTERED SHOWER AND TSTM ACTIVITY IS OCCURRING N OF 28N BETWEEN 50W-60W. WIDESPREAD BROKEN STRATOCUMULUS DECK BEHIND THE FRONT CLEARLY INDICATES COOL STABLE AIR. A LONG N FETCH OF WINDS...TO GALE FORCE IN OUR REGION...IS PRODUCING VERY HIGH SEAS UP TO 27 FT. A 1033 MB HIGH PRES SYSTEM LOCATED OFF THE MID-ATLANTIC COAST NEAR 37N73W IS BUILDING SE IN THE WAKE OF THE FRONT. THE EASTERN ATLC REMAINS TRANQUIL THIS EVENING LYING ON THE S SIDE OF A 1026 MB HIGH OVER THE AZORES. A FAIRLY RELAXED GRADIENT ON ITS S SIDE IS PRODUCING LIGHT TO MODERATE TRADES...EXCEPT TO 20 KT NEAR THE COAST OF AFRICA WHERE THE PRES GRADIENT IS TIGHTENED DUE TO INVERTED TROUGHING OVER THE CONTINENT. ALOFT...THE FLOW IS MAINLY OUT OF THE W TO SW BETWEEN PRONOUNCED TROUGHING OVER THE NRN SUBTROPICS/MID-LATITUDES AND A FLAT UPPER RIDGE OVER AFRICA AND THE TROP E ATLC. DRY AIR IS ASSOCIATED WITH THIS MID-UPPER PATTERN LIMITING CONVECTION IN THE ITCZ. $$ CANGIALOSI