000 AXNT20 KNHC 041103 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED APR 4 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N7W 2N17W ALONG THE EQUATOR FROM 23W-44W AND INTO SOUTH AMERICA NEAR 2S46W. SCATTERED MODERATE/ ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF THE AXIS FROM 16W-20W. CLUSTERS OF SIMILAR CONVECTION ARE FROM 4N TO S OF THE EQUATOR E OF 20W ACROSS THE PRIME MERIDIAN...WITHIN 200 NM N OF THE AXIS 23W-31W...AND FROM 3N TO THE EQUATOR FROM 42W-47W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE EXTENDING FROM THE CARIBBEAN TO THE W ATLC COVERS THE GULF AND CONTINUES TO ADVECT UPPER LEVEL MOISTURE ACROSS MEXICO INTO THE GULF AND THE SE US. THE SHORT WAVE TROUGH OVER E TEXAS/MEXICO IS BEING ABSORBED BY A LONG WAVE TROUGH OVER THE CENTRAL PLAINS. THE UPPER TROUGH CONTINUES TO ENHANCE HEAVY SHOWERS/THUNDERSTORMS OVER E MEXICO AND TEXAS INTO THE W GULF W OF 92W. ASSOCIATED WITH THE UPPER TROUGH IS A FRONTAL BOUNDARY EXTENDING INLAND OVER TEXAS WITH A SQUALL LINE MOVING S WELL AHEAD OF THE FRONT. THE SQUALL LINE HAS HELD TOGETHER OVERNIGHT AND AS OF 0915Z THE SQUALL LINE STRETCHED FROM CENTRAL GEORGIA TO THE LOUISIANA/TEXAS BORDER NEAR 32N94W. THE SQUALL LINE IS APPROACHING THE GULF PUSHING ISOLATED SHOWERS/THUNDERSTORMS AHEAD OF THE MAIN LINE IN THE GULF WATERS. A WEAK SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS THE GULF ANCHORED BY A HIGH JUST NE OF THE BAHAMAS. THIS SURFACE RIDGE WILL GIVE WAY AS THE COLD FRONT IS EXPECTED TO ENTER THE NW GULF LATER TODAY AND PASS THROUGH THE AREA BY LATE THURSDAY WITH WINDS SHIFTING TO A NORTHERLY DIRECTION AND INCREASING BEHIND THE FRONTAL PASSAGE. CARIBBEAN SEA... A BROAD UPPER E/W RIDGE EXTENDS ACROSS THE N PORTION OF SOUTH AMERICA INTO THE W CARIBBEAN FROM COLOMBIA TO CUBA WITH SW WIND TRANSPORTING UPPER LEVEL MOISTURE FROM THE E PACIFIC ACROSS CENTRAL AMERICA INTO THE NW PORTION OF THE CARIBBEAN. LOWER PRESSURES IN THE TROPICS CONTINUE TO PRODUCE MODERATE/STRONG TRADE WINDS ACROSS THE BASIN EXCEPT IN THE NW WHERE LIGHTER WINDS PREVAIL. MODERATE/STRONG SUBSIDENCE AND DRY AIR COVER MUCH OF THE CARIBBEAN ESPECIALLY E OF 80W. ATLANTIC OCEAN... AN UPPER RIDGE/TROUGH/RIDGE PATTERN CONTINUES TO DOMINATE THE FORECAST AREA. A BROAD UPPER RIDGE EXTENDS FROM THE CARIBBEAN INTO THE W ATLC W OF 65W. A SURFACE RIDGE COVERS THE W ATLC INTO THE GULF OF MEXICO FROM 20N-30N W OF 65W ANCHORED BY A 1020 MB HIGH NE OF THE BAHAMAS NEAR 27N76W. A DEEP LAYERED TROUGH IS IN THE CENTRAL ATLC N OF 16N FROM 35W-65W WITH THE A SERIES OF UPPER LOWS N OF THE REGION. THE ASSOCIATED LEADING FRONTAL BOUNDARY HAS PULLED UP STATIONARY ENTERING THE E ATLC NEAR 32N23W EXTENDING SSW TO 22N34W CONTINUING SSW AS A SURFACE TROUGH TO 17N39W. A 1002 MB LOW CENTERED NEAR 33N52W CONTINUES TO DEEPEN WHILE EXTENDING A SECOND COLD FRONT SW INTO THE W/CENTRAL ATLC ALONG 32N51W ALONG 28N58W THEN NE TO 30N67W. THIS SYSTEM IS EXPECTED TO CONTINUE TO DEEPEN WHILE BEING ENTRAINED AROUND THE MAIN LOW INCREASING SHOWER ACTIVITY WITH ASSOCIATED STRONGER WINDS AND HIGH SEAS TO WELL WITHIN THE AREA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90/120 NM SE OF THE COLD FRONT. THE LEADING FRONT IS EMBEDDED WITHIN AN AREA OF MODERATE SUBSIDENCE AND DRY UPPER AIR LIMITING SHOWER ACTIVITY. BROAD E/W UPPER RIDGE COVERS THE TROPICAL ATLC EXTENDING FROM AFRICA ACROSS THE ATLC TO SOUTH AMERICA WITH THE AXIS ROUGHLY ALONG 7N/9N THUS SUPPRESSING THE ITCZ AXIS TO THE S. A SECOND UPPER RIDGE AXIS EXTENDS FROM THE E/W RIDGE N ALONG 20W. $$ WADDINGTON/WALLACE