000 AXNT20 KNHC 202339 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST MON NOV 20 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 8N13W 5N30W 4N40W 2N51W. SCATTERED MODERATE CONVECTION IS WITHIN 150-180 NM EITHER SIDE OF THE AXIS EAST OF 32W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE. ...DISCUSSION... THE GULF OF MEXICO... A STRONG UPPER LEVEL TROUGH OVER THE EASTERN U.S. CONTINUES TO DIG SW INTO THE NW GULF AND NE MEXICO. SWLY FLOW AHEAD OF THIS TROUGH IS ADVECTING A PLUME OF UPPER LEVEL MOISTURE FROM A TROPICAL SYSTEM IN THE EPAC ACROSS THE BAY OF CAMPECHE AND THE YUCATAN PENINSULA INTO THE SE GULF AND SOUTH-CENTRAL FLORIDA. VERY DRY/STABLE AIR ALOFT IS BEHIND THE TROUGH. COLD AIR STRATOCUMULUS CLOUDS COVERS MUCH OF THE GULF...BUT PARTICULARLY THE EASTERN HALF. A STRONG 1032 MB SURFACE HIGH PRES LOCATED OVER NE TEXAS DOMINATES THE ENTIRE GULF. THE BIG STORY IS THE UNSEASONABLY COLD/DRY AIR AND INCREASING NLY WINDS DUE TO THE THE TIGHTENED PRES GRAD BETWEEN THIS STRONG HIGH PRESSURE AND A DEVELOPING STRONG LOW PRESSURE AREA OFF THE GEORGIA/CAROLINAS COASTS. 20-25 KT NLY WINDS ARE ALREADY BLOWING ACROSS THE GULF... ADVECTING COLD/DRY AIR INTO THE REGION. THIS COLD AIR ALOFT ALONG WITH NLY FLOW AT THE SFC WILL CONTINUE TO PRODUCE UNSEASONABLE COOL WEATHER ACROSS THE CENTRAL-EAST GULF AND THE FLORIDA PENINSULA OVER THE NEXT FEW DAYS. BREEZY AND CHILLY CONDITIONS ARE EXPECTED ACROSS THE SE U.S. WITH TEMPERATURES RUNNING 10-15 DEGREES BELOW SEASONAL NORMALS. THE CARIBBEAN SEA... A RIDGE DOMINATES MOST OF THE BASIN ANCHORED BY AN UPPER HIGH LOCATED OVER NORTHERN COLOMBIA. SWLY WINDS AHEAD OF THE STRONG UPPER TROUGH THAT LIES ACROSS THE GULF OF MEXICO ARE INVADING THE NW CORNER OF THE REGION. DRY AIR/MODERATE SUBSIDENCE DOMINATES THE E CARIBBEAN. A LARGE AREA OF MODERATE/ISOLATED STRONG CONVECTION EXISTS OVER THE CARIBBEAN SEA FROM 12N21N BETWEEN 73W-78W. THIS CONVECTIVE ACTIVITY IS ASSOCIATED WITH A 1010 MB SURFACE LOW LOCATED NEAR 16N80W AND A SFC TROUGH THAT EXTENDS NE FROM THE LOW ACROSS EASTERN CUBA/BAHAMAS INTO THE W ATLC. ANOTHER TROUGH EXTENDS SOUTH FROM THE SAME LOW TO WESTERN PANAMA WHERE CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE ALSO SEEN. THIS UNSETTLED WEATHER IS AFFECTING EASTERN CUBA AND PARTS OF HISPANIOLA AND JAMAICA. QUIKSCAT PASS INDICATED A PRONOUNCED WIND SHIFT WITH NLY 20-25 KT WINDS W OF THE TROUGH AXIS AND LIGHTER E TO NE WINDS E OF THE AXIS. MODERATE ELY TRADE WINDS ARE OFF THE VENEZUELAN COAST. A BAND OF DEEP TROPICAL MOISTURE WILL PERSIST FROM COSTA RICA AND PANAMA TO EASTERN CUBA/BAHAMAS DURING THE NEXT 24-48 HOURS. LATEST GFS MODEL RUN SUGGESTS THAT WINDS OVER THE WRN CARIBBEAN WILL SHARPLY INCREASE 25-30 KT LATE TONIGHT THROUGH LATE WED. THE ATLANTIC OCEAN... AN AMPLIFIED PATTERN LIES ACROSS THE ATLC OCEAN. A REINFORCING COLD FRONT...ASSOCIATED WITH THE STRONG UPPER TROUGH OVER THE EASTERN U.S AND THE GULF OF MEXICO ENTERS THE AREA NEAR 31N78W THEN CONTINUES SW ACROSS THE WESTERN BAHAMAS/CUBA. NWLY WINDS ARE INCREASING BEHIND THIS FRONTAL BOUNDARY. THIS WINDS ARE EXPECTED TO REACH GALE FORCE LATE TONIGHT OR TOMORROW. A LARGE TITLED RIDGE COVERS THE AREA BETWEEN 55W-75W. A SURFACE TROUGH EXTENDS FROM EASTERN CUBA TO 31N64W. CLOUDINESS WITH EMBEDDED SHOWERS AND TSTMS ARE BETWEEN THIS TROUGH AND THE COLD FRONT MENTIONED ABOVE...COVERING THE WESTERN ATLANTIC MAINLY W OF 70W. ANOTHER SFC TROUGH LIES ALONG 31N47W 22N54W. A WEAK LOW PRES SYSTEM REMAINS ALONG THIS TROUGH NEAR 26N52W WITH ONLY ISOLATED SHOWERS. THIS SFC FEATURE IS ASSOCIATED WITH A SMALL UPPER LOW NEAR 26N50W. A NARROW UPPER RIDGE EXTENDS NORTH FROM THE TROPICS ALONG 40W. THE REMAINDER OF THE ATLC...E OF 35W...IS DOMINATED BY A LARGE CUT OFF LOW CENTERED NEAR 26N22W. SCATTERED MODERATE CONVECTION IS MAINLY ON THE N SIDE OF THE LOW FROM 26N-30W BETWEEN 18W-24W. A SFC TROUGH...REFLECTION OF THIS UPPER LOW RUNS FROM 20N25W TO 31N20W. AT THE SFC...A 1033 MB HIGH CENTERED OVER THE AZORES EXTENDS A RIDGE ACROSS THE E-CENTRAL ATLC. $$ GR