000 AXNT20 KNHC 020008 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE APR 01 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. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 3N20W CROSSING THE EQUATOR NEAR 30W TO 1S45W. THE ITCZ IN THE ATLC REMAINS VERY ACTIVE THIS EVENING. SCATTERED TO NUMEROUS STRONG CONVECTION IN CLUSTERS ARE NOTED WITHIN 45-90 NM OF A LINE FROM THE EQUATOR AT 14W TO 2N22W. A LARGER AREA OF SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED WITHIN 150-180 NM EITHER SIDE OF THE AXIS BETWEEN 17W AND 30W...EXTENDING TO 4S BETWEEN 27W AND 30W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 180 NM N OF THE AXIS W OF 42W TO THE COAST OF SOUTH AMERICA. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER LEVEL ANTICYCLONE OVER THE E PACIFIC NEAR 14N103W STILL EXERTING AN INFLUENCE OVER OLD MEXICO AND THE GULF OF MEXICO. A SHEARING UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM THE MID-ATLC STATES SWWD TO THE LOWER MISSISSIPPI RIVER VALLEY/NW LOUISIANA. DIFLUENT FLOW BETWEEN THE UPPER HIGH AND THE SHEARED TROUGH WAS INDICATED ALONG THE GULF COAST AND NE GULF INTO FLORIDA. THIS AREA OF FLOW COUPLED WITH A 75-90 KT JET STREAK WAS AIDING IN MAINTAINING SCATTERED SHOWERS AND THUNDERSTORMS OVER PORTIONS OF LOUISIANA AND THE CENTRAL FLORIDA PENINSULA BETWEEN TAMPA BAY...ORLANDO AND LAKE OKEECHOBEE EXTENDING SWD TO THE NAPLES AND FT MYERS AREAS. THE STORMS OVER LOUISIANA WERE OCCURRING ALONG AND AHEAD OF A COLD FRONTAL BOUNDARY IN THE AREA WHILE THE STORMS OVER FLORIDA WERE BEING GENERATED BY SEABREEZE CONVERGENCE. A SURFACE RIDGE ANCHORED IN THE NW ATLC EXTENDS WWD ACROSS THE E GULF RESULTING IN SE SURFACE FLOW OVER MOST OF THE GULF BANKING SCATTERED TO BROKEN/OVERCAST LOW CLOUDS ALONG THE N GULF COAST. OTHERWISE THE REMAINDER OF THE GULF REMAINS CLEAR THIS EVENING WITH SOME ISOLATED SHOWERS MOVING OFF THE W COAST OF CUBA. CARIBBEAN SEA... THE FAR SWWD EXTENT OF AN UPPER TROUGH OVER THE ATLC EXTENDS SWD OVER THE CENTRAL CARIBBEAN TO A BASE NEAR 12N79W. A DEVELOPING CLOSED LOW/CYCLONIC CIRCULATION WAS JUST S OF HAITI NEAR 17N73W. THIS FEATURE WAS GENERATING A LARGE AREA OF MULTILAYERED CLOUDS WITH EMBEDDED SCATTERED SHOWERS ACROSS HISPANIOLA AND E CUBA EXTENDING NE OVER THE BAHAMAS. A NWLY JET STREAK WAS SWEEPING INTO THE BACK OF THE TROUGH ACROSS THE FLORIDA PENINSULA AND N CUBA. THE REMAINDER OF THE AREA IS DOMINATED BY LARGE UPPER LEVEL RIDGES OVER THE E PACIFIC AND THE TROPICAL ATLC WITH NWLY FLOW ALOFT OVER THE CARIBBEAN W OF 78W AND A BROAD AREA OF W TO SW UPPER FLOW E OF 70W. THE MOST SIGNIFICANT SURFACE FEATURE IS A SURFACE TROUGH...POSSIBLE PRE-SEASON TROPICAL WAVE EXTENDING FROM PUERTO RICO SWD TO NEAR 12N68W...MOVING WWD AT 20 KT. THIS FEATURE IS BECOMING INCREASINGLY INFLUENCED BY THE CYCLONIC CIRCULATION OVER HAITI WITH AN INCREASE IN SCATTERED SHOWER AND ISOLATED THUNDERSTORM ACTIVITY OVER THE E-CENTRAL CARIBBEAN N OF 15N BETWEEN 65W AND 71W. OVERALL SHOWER AND THUNDERSTORM ACTIVITY SHOULD BE ON THE INCREASE OVER HISPANIOLA AND E CUBA OVER THE NEXT 24 HOURS. ELSEWHERE OVER THE CARIBBEAN STRONG SUBSIDENCE AND DRY STABLE AIR WAS NOTED. ATLANTIC OCEAN... A STRONGLY POSITIVELY TILTED TROUGH EXTENDS ACROSS THE CENTRAL ATLC THROUGH 32N38W 28N53W AND CONNECTS TO THE DEVELOPING CYCLONIC CIRCULATION IN THE CARIBBEAN JUST S OF HAITI. MODERATE TO STRONG SUBSIDENCE WAS OCCURRING IN THE WAKE OF THE TROUGH OVER THE ATLC N OF 22N BETWEEN 40W AND 70W. ASSOCIATED SURFACE COLD FRONT ENTERING THE REGION NEAR 32N35W AND EXTENDED SW THROUGH 25N45W TO 23N56W. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE FRONT N OF 30N. STRONGLY DIFFLUENT FLOW WAS NOTED OVER THE FAR W ATLC W OF 73W EXTENDING WWD TO THE SE CONUS. THIS FLOW WAS AIDING IN MAINTAINING SCATTERED THUNDERSTORMS OVER THE FLORIDA PENINSULA AND FROM 30N TO 32N BETWEEN 78W AND 80W AS WELL AS ALONG THE GA AND SC COAST. BROAD UPPER RIDGE ANCHORED DEEP IN THE TROPICS COVERS THE TROPICAL ATLC S OF 20N E OF 60W AND WAS BEING SUPPRESSED ALONG THE NRN PERIPHERY BY THE TROUGH NOTED ABOVE. OTHER THAN THE COLD FRONT...THE ONLY OTHER MAJOR SURFACE FEATURE IN THE ATLC WAS A SPRAWLING 1036 MB HIGH NEAR 34N58W WHICH DOMINATED THE AREA NW OF THE COLD FRONT. BROAD SURFACE RIDGE COVERS THE E ATLC E OF THE FRONT ANCHORED BY A 1030 MB HIGH OFF THE NW COAST OF SPAIN. $$ COBB