000 AXNT20 KNHC 112335 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N10W 4N25W 2N35W CROSSING THE EQUATOR AT 44W INTO NE BRAZIL. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 120NM N AND 80NM S OF THE AXIS BETWEEN 22W-32W. CLUSTERS OF MODERATE TO STRONG CONVECTION ARE OVER SW AFRICA BETWEEN 6N-12N JUST WEST OF THE PRIME MERIDIAN AND NEAR 8N10W. SIMILAR CONVECTION IS OVER NE BRAZIL. ...DISCUSSION... GULF OF MEXICO... AS OF 21Z...A COLD FRONT IS ENTERING THE NW CORNER OF THE GULF. THIS FEATURE WILL EXTEND FROM FLORIDA PANHANDLE TO S TEXAS LATE TONIGHT THEN STALL FROM TAMPA BAY TO S TEXAS THU AND DISSIPATE. A PREFRONTAL TROUGH LIES ALONG 29N86W 25N90W TO THE MEXICAN COAST JUST N OF TAMPICO. A NARROW LINE OF LOW CLOUDS AND A SW TO NW WIND SHIFT DEFINE THIS SFC TROUGH. AN AREA OF SHOWERS AND TSTMS IS DEVELOPING OVER THE NE CORNER OF THE GULF. MORE NUMEROUS SHOWERS/TSTMS ARE NOTED ACROSS THE STRAIT OF FLORIDA AND BETWEEN CENTRAL CUBA AND THE BAHAMAS...ASSOCIATED WITH DYNAMICS AHEAD OF A FLATTENING MID TO UPPER SHORTWAVE TROUGH LOCATED OVER THE FAR WEST ATLC. A DRIER AND MORE STABLE ATMOSPHERE IS GRIPPING THE FLORIDA PENINSULA BEHIND THE SHORT WAVE TROUGH WHILE A ZONAL FLOW DOMINATES THE GULF. 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. THE CARIBBEAN SEA... A BROAD MID TO UPPER LEVEL RIDGE COVERS THE REGION ANCHORED BY AN UPPER HIGH CENTERED OVER THE SW CARIB NEAR 12N75W. DIFFLUENCE ON THE W SIDE OF THIS UPPER ANTICYCLONE IS ENHANCING SCATTERED SHOWERS/TSTMS OVER PARTS OF NICARAGUA AND COSTA RICA WITH A CLUSTER A MODERATE CONVECTION OVER THE NW PORTION OF COSTA RICA. 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. VIS SAT IMAGERY SHOWS VERY WELL DEFINED LOW LEVELS CLOUDS LINES OVER THE NW CARIBBEAN MOVING INTO CUBA...UNDER THE SE WIND FLOW. AN AREA OF SHOWERS/TSTMS IS AFFECTING CENTRAL CUBA. THE KEY WEST DOPPLER RADAR IS SHOWING RAINFALL AMOUNTS BETWEEN 2-3 INCHES (50-75 MM) IN SOME SPOTS. AS MENTIONED BEFORE...A SHORT WAVE TROUGH IS SUPPORTING THIS CONVECTIVE ACTIVITY OVER CUBA. A SFC TROUGH IS ANALYZED JUST AHEAD OF THIS SHOWER/TSTMS ACTIVITY AND GOES FROM 26N72W TO CENTRAL CUBA NEAR 22N78W. THE ATLC RIDGE NE OF AREA WILL MAINTAIN THE TRADE WINDS THROUGH FRI. ATLANTIC OCEAN... AS WAS PREDICTED BY THE COMPUTER MODELS...A 1008 MB SFC LOW FORMED OFF THE COAST OF NRN FLORIDA THIS MORNING. AS OF 21Z...IT IS LOCATED 31N78W. A FRONTAL SYSTEM EXTENDS EWD FROM THE LOW ALONG 31N WEST OF 60W...THEN CONTINUES NE AS A COLD FRONT OVER THE ATLC OCEAN TO A 996 MB SFC LOW SITUATED WELL N OF THE FORECAST AREA. UPPER DIFFLUENCE BETWEEN THE SHORTWAVE TROUGH EXTENDING OVER THE FAR W ATLC AND THE RIDGING EXTENDING N FROM THE CARIBBEAN IS SUPPORTING A BROAD AREA OF CONVECTION OVER THE WRN ATLC...INCLUDING ALSO THE BAHAMAS AND CENTRAL CUBA. MUCH OF THE REMAINDER OF THE E AND CENTRAL ATLC SFC PATTERN IS DOMINATED BY A 1025MB HIGH S OF THE AZORES NEAR 35N26W. THIS IS PRODUCING LIGHT TO MODERATE TRADES AND FAIR WEATHER OVER MUCH OF THE AREA E OF 60W. UPPER TROUGHING EXTENDING SW FROM THE CANARY ISLANDS TO THE DEEP TROPICS NEAR 10N35W IS INTERACTING WITH RIDGING OVER AFRICA TO PRODUCE A SWLY JET SE OF THE CAPE VERDE ISLANDS. DRY AIR IS PRESENT ALONG THE TROUGH AXIS WITH A BROAD BAND OF UPPER LEVEL MOISTURE SPREADING NE FROM NE SOUTH AMERICA TO WESTERN AFRICA. $$ GR