000 AXNT20 KNHC 111804 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED APR 11 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 4N20W 3N30W 1N40W EQ45W 1S51W. ISOLATED MODERATE CONVECTION IS WITHIN 150NM N AND 60NM S OF THE AXIS BETWEEN 21W-29W. SCATTERED MODERATE/ISOLATED STRONG IS WITHIN 240NM N OF THE AXIS BETWEEN 31W-40W...AND WITHIN 300NM N AND 180NM S OF THE AXIS W OF 40W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT IS APPROACHING THE TEXAS COAST. INTERESTING CLOUD SIGNATURE/GRAVITY WAVES ARE OUT AHEAD OF THE MAIN FRONT BETWEEN BROWNSVILLE AND SE LOUISIANA...THAT LED TO THE RECENT SW TO NW WIND SHIFT AT BUOY 42019. HAVE OPTED WITH A PREFRONTAL TROUGH WITH THIS ON THE 1500 UTC MAP PER COORDINATION WITH HPC. A WARM FRONT EXTENDS SE FROM THE FL/ALABAMA BORDER TO THE NE GULF NEAR 29N84W...WHICH APPEARS TO HAVE RECENTLY LIFTED N ALONG THE FL PANHANDLE WITH ISOLATED SHOWERS/TSTMS DEVELOPING JUST S OF THIS BOUNDARY NOTED FROM TALLAHASSEE RADAR IMAGERY. MORE NUMEROUS SHOWERS/TSTMS NOTED AROUND THE STRAITS OF FLORIDA...ASSOCIATED WITH DYNAMICS AHEAD OF A FLATTENING MID TO UPPER SHORTWAVE TROUGH...ALONG WITH LINGERING LOW LEVEL BOUNDARIES FROM ALL THE RECENT CONVECTION. THE COLD FRONT MOVING INTO THE NW PORTION WILL BECOME DIFFUSE DURING THU AS IT HEADS SE. ANOTHER COLD FRONT...THIS ONE EXPECTED TO BE MUCH STRONGER...IS FORECAST TO MOVE INTO THE NW GULF EARLY SAT INCREASING THE CHANCE OF RAIN AHEAD OF IT AND BRINGING ABOUT A MUCH COOLER AIRMASS THIS WEEKEND. WINDS/SEAS WILL ALSO BE STRONGER BOTH IN ADVANCE AND BEHIND THIS NEXT FRONT...SEE OFFSHORE WATERS FORECAST UNDER AWIPS HEADER MIAOFFNT4 FOR MORE DETAILS. THE CARIBBEAN SEA... A BROAD MID TO UPPER LEVEL RIDGE COVERS THE REGION ANCHORED BY AN UPPER HIGH CENTERED OVER THE S CENTRAL CARIB NEAR 12N76W. DIFFLUENCE ON THE W SIDE OF THIS UPPER ANTICYCLONE IS ENHANCING SCATTERED SHOWERS/ISOLD TSTMS NEAR THE EPAC COASTS OF PANAMA AND COSTA RICA. SIMILAR ACTIVITY NOTED IN THE SW CARIBBEAN BETWEEN THE COAST OF NICARAGUA AND COLOMBIA...WHICH SEEMS MOST ASSOCIATED WITH LOW LEVEL SPEED CONFLUENCE AS NOTED IN THIS MORNINGS QUIKSCAT PASS. ELSEWHERE AT THE SFC...HIGH PRES NE OF THE AREA IS PRODUCING MODERATE TO FRESH ELY TRADES ACROSS THE E AND CENTRAL CARIB VEERING TO THE SE IN THE NW CARIB AROUND THE SW PORTION OF THE RIDGE. LOW-LEVEL MOISTURE PATCHES REMAIN VERY THIN SO OUTSIDE OF THE AREAS OUTLINED FAIR SKIES ARE THE RULE. NO SIGNIFICANT CHANGES ARE EXPECTED OVER THE NEXT COUPLE OF DAYS AS MOST OF THE WX FEATURES REMAIN N OF THE REGION. ATLANTIC OCEAN... A 1009 MB SFC LOW IS OFF THE COAST OF NRN FLORIDA THAT HAS A STATIONARY FRONT EXTENDING E ALONG 30N80W 29N75W 31N68W. AS OF 11/1500 UTC...A SFC TROUGH EXTENDS THROUGH THE SW N ATLC THROUGH THE BAHAMAS AND INTO THE STRAITS OF FLORIDA ALONG 26N74W 24N80W. IN ADDITION TO THESE SFC FEATURES...UPPER DIFFLUENCE BETWEEN THE SHORTWAVE TROUGH EXTENDING S THROUGH FL/ERN GULF AND THE RIDGING EXTENDING N FROM THE CARIBBEAN IS SUPPORTING THE CONVECTION OVER THE WRN ATLC. ASIDE FROM THE ACTIVITY ALREADY MENTIONED IN THE STRAITS OF FLORIDA...THE MOST CONCENTRATED AREA OF SHOWS/TSTMS IS NOTED N OF 24N BETWEEN 68W-75W. MUCH OF THE REMAINDER OF THE E AND CENTRAL ATLC SFC PATTERN IS DOMINATED BY A 1025MB HIGH S OF THE AZORES NEAR 34N27W. THIS IS PRODUCING LIGHT TO MODERATE TRADES AND FAIR WEATHER OVER MUCH OF THE AREA E OF 45W. UPPER TROUGHING EXTENDING S ALONG 35W IS INTERACTING WITH RIDGING OVER AFRICA TO PRODUCE A SWLY JET SE OF THE CAPE VERDE ISLANDS. ASSOCIATED UPPER MOISTURE IS SPREADING NE INTO AFRICA...FROM 5N-18N E OF 28W. $$ WILLIS