000 AXNT20 KNHC 212342 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE NOV 21 2006 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 7N30W 6N40W 5N50W 5N55W. THE ITCZ IS PRETTY QUIET THIS EVENING. ISOLATED MODERATE CONVECTION IS FOUND WITHIN 120-150 NM ON EITHER SIDE OF THE AXIS WITH A SMALL CLUSTER OF MODERATE CONVECTION NEAR 7N16W. ...DISCUSSION... THE GULF OF MEXICO... AS WAS PREDICTED BY SEVERAL COMPUTER MODELS...A STRONG CUT-OFF LOW HAS DEVELOPED OVER THE SE U.S. WITH AN UPPER TROUGH THAT EXTENDS SW ACROSS THE FAR E GULF OF MEXICO AND THE NW CARIBBEAN. STRONG NLY FLOW AND MODERATE TO STRONG SUBSIDENCE ARE NOTED BEHIND THE TROUGH AXIS ACROSS NEARLY THE ENTIRE GULF. AS OF 2100 UTC...A STRONG SFC HIGH PRES COVERS THE ENTIRE AREA ANCHORED BY A 1029 MB HIGH NEAR 30N94W. STRATOCUMULUS CLOUDS COVER MUCH OF THE EASTERN GULF...THE BAY OF CAMPECHE AND THE NW CARIBBEAN DUE TO COLD AIR MOVING OVER THE WARM WATERS. THESE CLOUDS ARE THICKEST IN THE EXTREME ERN GULF WHERE DOPPLER RADAR DEPICTS SCATTERED TO NUMEROUS SHOWERS MOVING ACROSS THE LOWER FLORIDA KEYS AND THE STRAIT OF FLORIDA. THIS SHOWER ACTIVITY ALSO REACHES THE COAST OF WESTERN CUBA BETWEEN HAVANA AND VARADERO. THE COMBINATION OF DEEP LOW PRESSURE SYSTEM OFF THE GEORGIA/CAROLINAS COAST AND HIGH PRESSURE OVER THE GULF IS GENERATING STRONG NLY WINDS OVER THE EASTERN GULF AND THE NW CARIBBEAN...WHERE A GALE WARNING IS IN EFFECT. SEVERAL BUOYS ARE REPORTING WINDS BETWEEN 20-30 KT ACROSS THE GULF. UNSEASONABLY COLD AIR CONTINUES TO GRIP THE REGION...INCLUDING THE FLORIDA PENINSULA. WINDS AND SEAS WILL BEGIN TO SUBSIDE ACROSS THE GULF LATE WEDNESDAY. THE CARIBBEAN SEA... PATCHES OF MODERATE CONVECTION CONTINUE TO AFFECT THE CARIBBEAN SEA BETWEEN 70W-80W. THIS CONVECTIVE ACTIVITY IS ASSOCIATED WITH A STRONG COLD FRONT THAT EXTENDS FROM THE EASTERN BAHAMAS/CUBA TO WESTERN PANAMA AND A BROAD AREA OF LOW PRESSURE LOCATED SOUTH OF JAMAICA NEAR 15N78W. VIS SATELLITE IMAGERY SHOWS A SWIRL OF LOW/MID CLOUDS IN THIS AREA. BEHIND THE FRONT...COOLER AND NOTABLE DRIER AIR IS BEEN ADVECTED INTO THE REGION BY STRONG NLY WINDS. THESE WINDS HAVE REACHED GALE FORCE S OF 20N BETWEEN 80W AND 87W. A PRE-FRONTAL TROUGH IS OVER HAITI AND THE CARIBBEAN TO NEAR 15N75W. NUMEROUS MODERATE CONVECTION IS NEAR THE BASE OF THE FRONT S OF 14N BETWEEN 77W-80W. SIMILAR CONVECTION IS OVER NORTHERN COLOMBIA AND THE ADJACENT COASTAL WATERS. SOME OF THIS STRONGER ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER RIDGE THAT COVERS THE EAST-CENTRAL CARIBBEAN AND THE STRONG TROUGHING ACROSS THE E GULF AND NW CARIB. DRY AIR ALOFT DOMINATES THE EASTERN CARIBBEAN WITH SCATTERED SHOWERS EMBEDDED IN THE TRADE WINDS. ACCORDING TO THE GFS...THE DEEP TROPICAL MOISTURE WILL REMAIN IN PLACE AT LEAST DURING THE NEXT 24 HOURS...COVERING FROM EASTERN BAHAMAS/CUBA TO PANAMA. MODERATE ELY TRADES WILL CONTINUE OVER THE E CARIBBEAN. THE ATLANTIC OCEAN... A DEEP LOW PRESSURE SYSTEM IS OFF THE SE COAST. THE MID-UPPER LEVEL CENTER IS ALONG THE FL/GA COAST WHILE THE 1003 MB SFC LOW IS NEAR 32N77W. DOPPLER RADAR SHOWS BANDS OF NUMEROUS SHOWERS AND TSTMS AFFECTING MUCH OF THE CAROLINAS AND EASTERN GEORGIA. A COLD FRONT EXTENDS FROM THIS LOW ALONG 30N74W 22N74W ENTERING THE CARIBBEAN THROUGH E CUBA. A PRE-FRONTAL TROUGH IS WITHIN AROUND 150 NM AHEAD OF THE FRONT CROSSING THE E BAHAMAS AND HAITI. THESE FEATURES ALONG WITH A DIFFLUENT PATTERN ALOFT IS GENERATING A CONSIDERABLE AMOUNT OF MOISTURE WEST OF 67W. STRONG NLY WINDS BEHIND THE FRONT ARE ADVECTING MUCH COLDER AND DRIER AIR OVER THE STATE OF FLORIDA...THE NORTH-CENTRAL BAHAMAS AND WESTERN CUBA. A GALE WARNING IS IN PLACE FOR THE AREA N OF 28N W OF 78W. A STRONG TITLED MID-UPPER RIDGE LIES TO THE E OF THIS COMPLEX WEATHER PATTERN WITH THE AXIS EXTENDING FROM HISPANIOLA NORTHEASTWARD TO WELL BEYOND 32N57W. A NARROW TROUGH IS LOCATED TO THE E OF THE RIDGE WITH SEVERAL UPPER LEVEL LOWS AND EXTENDS INTO THE DEEP TROPICS TO NEAR 16N55W. DRY AIR ALOFT RESULTING IN MODERATE TO STRONG SUBSIDENCE LIES ACROSS MOST OF THE AREA BETWEEN 40W-67W. THE REMAINDER OF THE ATLC...E OF 35W...IS DOMINATED BY A LARGE CUT OFF LOW CENTERED NEAR 28N24W. AT THE SURFACE...A TROUGH...REFLECTION OF THIS UPPER LOW RUNS FROM 30N35W TO 23N24W. A SWIRL OF LOW CLOUDS IS NEAR 25N32W WHILE AN AREA OF SCATTERED SHOWERS IS MAINLY SOUTH OF THE UPPER LOW FROM 24N-28N BETWEEN 24W-28W. A 1032 MB SFC HIGH CENTERED OVER THE AZORES EXTENDS A RIDGE OVER THE CENTRAL AND ERN ATLC. $$ GR