000 AXNT20 KNHC 171738 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 4N20W CROSSING THE EQUATOR AT 36W INTO NE BRAZIL NEAR 3N44W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 70-100 NM N OF THE AXIS BETWEEN 16W AND 29W. ...DISCUSSION... GULF OF MEXICO... A MOSTLY DRY AND STABLE ATMOSPHERE DOMINATES THE GULF AND THE STATE OF FLORIDA THANKS TO A WEAK 1019 MB HIGH PRES LOCATED OVER THE SOUTHEASTERN US. THIS HIGH IS PRODUCING A NLY FLOW ACROSS THE FAR E GULF AND FLORIDA PENINSULA INTO CUBA AND THE WESTERN CARIBBEAN. BROKEN FAIR WEATHER STRATOCUMULUS CLOUDS ARE SEEN OVER THE SE PORTION OF THE GULF. ALOFT...A RIDGE DOMINATES THE ENTIRE GULF AND THE SE US ANCHORED ON A HIGH OVER THE NW CARIBBEAN...WHILE A SHARP SHORTWAVE TROUGH IS OVER THE NEW MEXICO AND CHIHUAHUA MEXICO. A PLUME OF UPPER LEVEL MOISTURE ASSOCIATED WITH THE EPAC JETSTREAM EXTENDS NEWD ACROSS N-CENTRAL MEXICO...SOUTH TEXAS AND THE NORTHERN GULF WATERS. THIS TROUGH WILL SUPPORT THE NEXT COLD FRONT THAT IS FORECAST TO MOVE OFF TEXAS COAST EARLY WED...REACHING THE STRAITS OF FLORIDA AND THE YUCATAN CHANNEL BY LATE THU. SLY RETURN FLOW OF 15 TO 20 KT HAS ALREADY ESTABLISHED OVER THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT. A 1008 MB LOW IS OVER NE MEXICO. THIS LOW IS FORECASTED TO MOVE TOWARD THE BAY OF CAMPECHE DURING THE NEXT 24 HOURS. CARIBBEAN SEA... THE STRONG COLD FRONT THAT HAS AFFECTED THE FORECAST AREA IS WEAKENING OVER THE CARIBBEAN SEA BUT IS GENERATING SOME CLOUDINESS WITH EMBEDDED SHOWERS OVER HISPANIOLA AND PARTS OF JAMAICA. PUERTO PLATA IN DOMINICAN REPUBLIC REPORTED NEAR 4 INCHES OF RAIN (106 MM) THIS MORNING WITH THE FRONTAL PASSAGE. MOISTURE ASSOCIATED WITH THE REMNANTS OF THE FRONT WILL ALSO AFFECT PUERTO RICO/VIRGIN ISLANDS LATE TODAY AND TOMORROW. NLY WINDS OF NEAR 15 KT ARE BEHIND THE FRONT OVER THE NW CARIBBEAN BUT WILL VEER TO THE E TONIGHT. VIS SAT IMAGERY ALSO SHOWS COLD AIR STRATOCUMULUS CLOUDS OVER THE YUCATAN CHANNEL AND THE NW CARIBBEAN. ALOFT...AN UPPER HIGH LOCATED OVER NE HONDURAS EXTENDS A RIDGE EWD TO THE LESSER ANTILLES...GIVING THE AREA DRY AIR AND MODERATE TO STRONG SUBSIDENCE. THE TRADES ARE LIGHT TO MODERATE ACROSS MUCH OF THE AREA DUE TO THE WEAK PRES GRADIENT. ATLANTIC OCEAN... THE AFOREMENTIONED COLD FRONT IS WELL DEFINED OVER THE ATLC ENTERING THE AREA NEAR 31N56W AND CONTINUING SW TO HISPANIOLA. EARLIER QUIKSCAT PASS CLEARLY SHOWED THE WIND SHIFTS ASSOCIATED WITH FRONT THAT IS STILL PRODUCING GALE FORCE WINDS AND HAZARDOUS MARINE CONDITIONS...PARTICULARLY N OF 27N. A DEEP LAYERED TROUGH OVER THE WEST ATLC IS SUPPORTING THIS FRONTAL BOUNDARY. A 100 NM WIDE BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS IS RELATED TO THE FRONT OVER THE 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 7N48W. STRONG SWLY WINDS AHEAD OF THE TROUGH ARE TRANSPORTING UPPER LEVEL MOISTURE/HIGH CLOUDS FROM N SOUTH AMERICA NEWD TO W AFRICA JUST N OF THE CAPE VERDE ISLANDS. AT THE SURFACE...A RIDGE DOMINATES MOST OF THE E-CENTRAL ATLC WITH THE SFC HIGH LOCATED WELL NORTH OF THE AREA. $$ GR