000 AXNT20 KNHC 172325 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE APR 17 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 2215 UTC. ...THE ITCZ... ITCZ AXIS EXTENDS FROM 7N12W 4N20W CROSSING THE EQUATOR AT 29W INTO NE BRAZIL NEAR 3N40W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN THE AFRICAN COAST AND 16W. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE AXIS BETWEEN 25W-28W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT EXTENDS FROM A 1006 MB LOW CENTERED OVER THE TEXAS/NEW MEXICO BORDER THROUGH CENTRAL TEXAS AND INTO N MEXICO NEAR 27N105W. A PRE-FRONTAL TROUGH EXTENDING FROM THE SFC LOW THROUGH CENTRAL MEXICO NEAR 18N99W IS ADVECTING LOW/MID LEVEL MOISTURE WITH POSSIBLE SHOWERS OVER THE W GULF FROM THE TEXAS/N MEXICO COASTLINES. THE FRONT IS EXPECTED TO ENTER THE GULF EARLY WED AND MOVE RAPIDLY THROUGH THE STRAITS OF FLORIDA AND THE YUCATAN CHANNEL BY LATE THURS. MODERATE TO STRONG SLY WINDS AHEAD OF THE TROUGH WILL WEAKEN AND BECOME WLY TO NLY FOLLOWING THE FRONTAL PASSAGE. ELSEWHERE...A WEAK 1018MB HIGH SOUTH OF LOUISIANA CONTINUES TO MAINTAIN A DRY AND STABLE AIRMASS OVER THE E/CENTRAL GULF. THIS HIGH IS PRODUCING NLY FLOW ACROSS THE FAR E GULF AND FLORIDA PENINSULA INTO CUBA AND THE WESTERN CARIBBEAN. BROKEN FAIR WEATHER STRATOCUMULUS CLOUDS COVER THE S-CENTRAL PORTION OF THE GULF. ALOFT...GENERALLY ZONAL FLOW DOMINATES THE ENTIRE GULF TRANSPORTING A PLUME OF UPPER LEVEL MOISTURE NEWD ACROSS N-CENTRAL MEXICO...SOUTH TEXAS AND THE NORTHERN GULF WATERS. CARIBBEAN SEA... THE STRONG COLD FRONT THAT HAS AFFECTED THE FORECAST AREA HAS WEAKENED OVER THE CARIBBEAN SEA BECOMING A TROUGH NEAR 19N74W AND EXTENDS SW INTO COSTA RICA. A NARROW BAND OF LOW/MID LEVEL CLOUDS WITH POSSIBLE SHOWERS IS CENTERED AROUND THE TROUGH. COLD AIR STRATOCUMULUS CLOUDS COVER THE YUCATAN CHANNEL AND THE NW CARIBBEAN. AN UPPER HIGH NEAR 16N84W EXTENDS A RIDGE EWD TO THE LESSER ANTILLES...GIVING THE AREA DRY AIR AND MODERATE TO STRONG SUBSIDENCE. THE TRADES REMAIN LIGHT TO MODERATE ACROSS MUCH OF THE AREA DUE TO THE WEAK PRES GRADIENT. ATLANTIC OCEAN... A STRONG COLD FRONT IS WELL DEFINED OVER THE ATLC ENTERING THE AREA NEAR 32N55W AND CONTINUING SW TO HISPANIOLA. THE COLD FRONT CONTINUES TO PRODUCE GALE FORCE WINDS AND HAZARDOUS MARINE CONDITIONS...PARTICULARLY N OF 25N WITHIN 240 NM AHEAD OF THE FRONT...AND N OF 27N BEHIND THE FRONT TO 77W. A BROAD BAND OF MOISTURE WITH EMBEDDED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS EXTENDS 100-200 NM AHEAD OF THE FRONT. A 15Z QUIKSCAT PASS SHOWS 25-35 KT ON EITHER SIDE OF THE FRONT HOWEVER...WINDS OVER THE W ATLC WILL DIMINISH TO 15 KT AS THE FRONT CONTINUES TO MOVE EWD. A TROUGH ENTERS THE REGION NEAR 31N28W EXTENDING FROM A COLD FRONT AND SFC LOW WELL NORTH OF THE AREA. THE TROUGH CONTINUES SW TO NEAR 24N39W WITH A BAND OF LOW/MID LEVEL MOISTURE EXTENDING 60-90 NM AHEAD OF THE TROUGH. A SFC HIGH REMAINS E OF THE TROUGH CENTERED NEAR 25N25W EXTENDING A RIDGE OVER THE E-CENTRAL ATLC. ALOFT...A DEEP LAYERED TROUGH IS SUPPORTING THE FRONTAL BOUNDARY OVER THE W ATLC. THE MID/UPPER LEVEL RIDGE OVER THE CARIBBEAN EXTENDS NE INTO THE CENTRAL ATLC THROUGH THE LEEWARD ISLANDS. FARTHER E...ANOTHER UPPER LEVEL TROUGH DOMINATES THE E ATLC WITH THE AXIS EXTENDING SW TO THE DEEP TROPICS NEAR 8N49W. STRONG SWLY WINDS AHEAD OF THE TROUGH ARE TRANSPORTING UPPER LEVEL MOISTURE FROM N SOUTH AMERICA NEWD TO W AFRICA JUST N OF THE CAPE VERDE ISLANDS. $$ RJW