000 AXNT20 KNHC 172357 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST MON DEC 17 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 2315 UTC ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 2N25W 1N35W 1N52W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 80-100 NM EITHER SIDE OF AXIS EAST OF 32W. SCATTERED MODERATE CONVECTION IS FROM 4N-11N BETWEEN 43W-55W...ENHANCED BY A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH AN ANTICYCLONE OVER NORTHERN SOUTH AMERICA. DISCUSSION... GULF OF MEXICO... A COOL AND DRY AIRMASS IS IN PLACE ACROSS THE REGION THIS EVENING UNDER THE INFLUENCE OF A 1029 MB HIGH LOCATED OVER THE LOWER MISSISSIPPI VALLEY. THE LEADING EDGE OF THIS AIRMASS IS A STRONG COLD FRONT THAT CURRENTLY EXTENDS OVER THE W ATLC AND THE NW CARIBBEAN. BRISK N TO NE WINDS ARE BLOWING ACROSS THE E GULF AND THE YUCATAN PENINSULA...WHERE THE PRES GRADIENT IS TIGHTEST BETWEEN THE ABOVE MENTIONED HIGH PRES AND THE FRONT. WINDS SHIFT TOWARD THE E IN THE W GULF MODIFYING THE TEMPS THERE. BROKEN TO OVERCAST COLD AIR STRATOCUMULUS CLOUDS COVER MOST OF THE GULF. A COOL TONGUE REGION IS SEEN ON SATELLITE IMAGERY ACROSS FLORIDA REACHING WESTERN CUBA. THIS WEATHER PATTERN COULD PRODUCE LOW TEMPERATURES NEAR 50 F...10 C IN PARTS OF THE PROVINCES OF HAVANA AND MATANZAS IN CUBA UNDER CLEAR SKIES. IN THE MID AND UPPER LEVELS...STRONG ZONAL FLOW DOMINATES THE AREA. A SUBTROPICAL JETSTREAM IS TRANSPORTING ABUNDANT UPPER-LEVEL MOISTURE FROM THE EPAC ACROSS NORTHERN MEXICO INTO TEXAS AND THE GULF. LOOKING AHEAD...SFC HIGH PRES WILL CONTINUE TO SHIFT E ALLOWING ELY FLOW TO DEVELOP AREA-WIDE TOMORROW WHICH WILL WARM TEMPS BACK TO CLIMO. THE NEXT COLD FRONT IS FORECAST TO MOVE IN LATE IN THE WEEK. CARIBBEAN SEA... A COLD FRONT TRAILS ACROSS THE BAHAMAS...EASTERN CUBA...THE CAYMAN ISLANDS AND NORTHERN HONDURAS. THE FRONT IS FORECAST TO STALL OVER THIS AREA TONIGHT AND DISSIPATE TOMORROW. A 120-140 NM WIDE BAND OF CLOUDS WITH EMBEDDED SHOWERS/RAIN IS ASSOCIATED WITH THE FRONT. COOL AIR HAS FILTERED WELL S INTO THE NW CARIB AND WESTERN CUBA WHERE SAT PICTURES SHOW OVERCAST COLD AIR STRATOCUMULUS CLOUDS. NLY WINDS OF 20-25 KT ARE BEHIND THE FRONT...PARTICULARLY OVER THE GULF OF HONDURAS. A PRE-FRONTAL TROUGH IS ANALYZED AROUND 80W/81W S OF 18N. LOW-LEVEL CLOUDINESS WITH ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. E OF THE FRONT...THE TRADE WINDS PREVAIL...CARRYING POCKETS OF LOW LEVEL MOISTURE WITH MAINLY LIGHT SHOWERS ACROSS THE EAST AND CENTRAL CARIBBEAN. ALOFT...A RIDGE/TROUGH PATTERN COVERS THE WHOLE AREA. AN UPPER-LEVEL HIGH IS NEAR CABO GRACIAS A DIOS IN NICARAGUA... WHILE AN UPPER TROUGH EXTENDS FROM THE LEEWARD ISLANDS TO NORTHERN COLOMBIA. STRONG SWLY WINDS AHEAD OF THIS TROUGH ARE HELPING TO INDUCE SOME CLOUDINESS WITH ISOLATED SHOWERS OVER THE SE CARIBBEAN. ATLANTIC OCEAN... A STRONG COLD FRONT CROSS JUST SE OF BERMUDA AND ENTERS THE AREA NEAR 31N65W...THEN CONTINUES SW ACROSS THE CENTRAL BAHAMAS AND EASTERN CUBA INTO THE CARIBBEAN SEA TO N HONDURAS. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 140 NM OF THE FRONT MAINLY N OF 25N. MUCH COOLER AND DRIER AIRMASS IS BEING ADVECTED IN BEHIND THE FRONT WITH BROKEN TO OVERCAST STRATOCUMULUS CLOUDS. ANOTHER COLD FRONT...A WEAK ONE...EXTENDS ACROSS THE EAST AND CENTRAL ATLC ALONG 31N22W 26N30W 25N40W TO 30N49W. A NARROW BAND OF MAINLY LOW CLOUDS AND POSSIBLE SHOWERS IS RELATED TO THIS SYSTEM. CONVECTIVE ACTIVITY IS MORE CONCENTRATE AHEAD OF THE FRONT N OF 27N AND BETWEEN THE CANARY/MADEIRA ISLANDS AND THE FRONT ITSELF. A 1027 MB HIGH LOCATED N OF AREA IS BETWEEN THE FRONTAL BOUNDARIES. A WEAK 1015 MB LOW IS NEAR 21N23W. A SWIRL OF LOW CLOUDS IS ASSOCIATED WITH THIS LOW. IN THE UPPER-LEVELS... A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE FORECAST AREA. AN UPPER TROUGH COVERS THE EASTERN U.S. MOVING INTO THE W ATLC. THIS TROUGH SUPPORTS THE STRONG COLD FRONT PREVIOUSLY MENTIONED. AN UPPER RIDGE ANCHORED IN THE CARIBBEAN EXTENDS NE ACROSS EASTERN CUBA AND HISPANIOLA ONTO THE CENTRAL ATLC TO BEYOND 31N43W. A HIGHLY ELONGATED MID TO UPPER TROUGH EXTENDS FROM THE FAR EAST ATLC ALONG 20N ENTERING THE E CARIBBEAN THROUGH THE LEEWARD ISLANDS. STRONG ZONAL FLOW ALOFT...OR JUST SOUTH OF WEST...LIES ABOVE MOST OF THE TROPICS. $$ GR