000 AXNT20 KNHC 161737 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN DEC 16 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 4N19W 2N35W 1N45W EQUATOR50W. SCATTERED MODERATE CONVECTION IS WITHIN 240 NM S OF THE AXIS BETWEEN 40W-46W. DISCUSSION... GULF OF MEXICO... STRONG FAST MOVING COLD FRONT HAS JUST ABOUT CLEARED MOST OF THE REGION. AS OF 15 UTC...THE BOUNDARY EXTENDED FROM NEAR NAPLES FLORIDA TO CANCUN MEXICO THEN ACROSS THE EXTREME SRN BAY OF CAMPECHE AND STATIONARY ALONG THE SLOPES OF THE SIERRA MADRE MOUNTAINS IN MEXICO S OF 23N. N TO NW WINDS ARE BLOWING STRONG BEHIND THE FRONT...TO GALE FORCE IN THE SW GULF AS NOTED IN A RECENT QSCAT PASS. WIDESPREAD BROKEN STRATOCUMULUS CLOUDS EXIST BEHIND THE FRONT...INDICATIVE OF THE COOL STABLE AIRMASS IN PLACE. CURRENT TEMPS ARE AS COLD AS THE LOW 40'S F ACROSS THE N GULF COAST AND AS WARM AS THE LOW 80'S F AHEAD OF THE FRONT IN SE FLORIDA. SHOWERS AND TSTMS ARE MOSTLY AHEAD OF THE FRONT OVER PORTIONS OF SE FLORIDA...THE STRAITS AND THE ADJACENT ATLC WATERS. WINDS ARE EXPECTED TO FALL BELOW GALE FORCE WITHIN THE NEXT 18 HOURS AS THE FRONT SLIDES FURTHER E ALLOWING THE PRES GRADIENT TO SLACKEN. COOL AND DRY WEATHER IS EXPECTED TO BE THE RULE FOR THE ENTIRE REGION THRU TOMORROW. CARIBBEAN SEA... LOW-LEVEL CONVERGENCE ALONG A PRE-FRONTAL TROUGH EXTENDING FROM WRN CUBA TO HONDURAS AND A FAST MOVING STRONG COLD FRONT IN THE YUCATAN CHANNEL IS GENERATING SCATTERED SHOWERS AND TSTMS WITHIN 30 NM OF THE TROUGH LINE AND ELSEWHERE N OF 19N BETWEEN 80W-85W. THE REMAINDER OF THE REGION IS EXPERIENCING FAIRLY TRANQUIL WEATHER WITH THE EXCEPTION OF QUICK MOVING SCATTERED SHOWERS DRIVEN BY STRONG ELY TRADES...ESPECIALLY E OF 75W. THE MID AND UPPER LEVEL PATTERN CONSISTS OF A RIDGE ABOVE THE WRN HALF SUPPORTED BY AN ANTICYCLONE NEAR 18N84W AND A TROUGH OVER THE ERN HALF. THIS PATTERN IS CREATING LITTLE SIGNIFICANT UPPER MOISTURE AND IS ACTUALLY LEADING TO STRONG SUBSIDENCE N OF 17N E OF 72W...WHICH IS LIKELY CAPPING THE LOW-LEVEL SHOWER ACTIVITY. ATLANTIC OCEAN... LINES OF SHOWERS AND TSTMS ARE SCATTERED ACROSS THE FAR WRN PORTION OF THE AREA...W OF 75W...ASSOCIATED WITH THE STRONG COLD FRONT PUSHING ACROSS THE STATE OF FLORIDA. S TO SW WINDS ARE BLOWING TO GALE FORCE AHEAD OF THE APPROACHING FRONT N OF 28N W OF 68W. LIGHTNING DATA REVEALS THE STRONGEST TSTMS IN THE FLA STRAITS AND N OF THE AREA OFF THE CAROLINA COASTLINE. VERTICALLY STACKED RIDGING DOMINATES THE AREA E OF THE FRONT TO ABOUT 50W. THE SFC CENTER...ANALYZED 1024 MB NEAR 29N55W...IS TIGHTENING THE PRES PATTERN ACROSS THE TROPICS GENERATING ELY TRADES IN THE 20-25 KT RANGE S OF 23N BETWEEN ABOUT 35W-70W. THESE STIFF WINDS ARE CARRYING PATCHES OF LOW TO MID LEVEL CLOUDINESS...BUT NONE OF THIS IS ACQUIRING MUCH VERTICAL DEPTH SUPPRESSED BY THE STABLE MID AND UPPER LEVEL ENVIRONMENT. LONGWAVE MID AND UPPER LEVEL TROUGHING DOMINATES THE FLOW ALOFT E OF ABOUT 50W. A SERIES OF SHORTWAVES ADD TO THE COMPLEXITY OF THE PATTERN AND ARE HELPING TO SUSTAIN THE LARGE SCALE TROUGH. THESE SHORTWAVES HAVE A FEW SFC CONNECTIONS...TWO OF WHICH ARE WEAK FRONTAL BOUNDARIES THAT CURRENTLY LIE JUST N OF THE AREA. THE OTHER IS A SFC TROUGH ANALYZED FROM 32N15W ACROSS THE WRN CANARY ISLANDS TO 22N22W. VIS IMAGES SHOW A SMALL SWIRL...WEAK LOW...ALONG THE TROUGH AXIS NEAR 25N21W. THIS FEATURE IS ONLY GENERATING CLOUDINESS AND POSSIBLE EMBEDDED ISOLATED SHOWERS WITHIN 90 NM OF THE CENTER. THE COMBINATION OF THE FRONTS AND SFC TROUGH HAS WEAKENED THE OVERALL PRES PATTERN WHICH HAS ALLOWED THE SFC WINDS TO BE LIGHT TO MODERATE E OF 30W. AN UPPER WLY JET...WITH CORE WINDS NEAR 90 KT OVER THE ATLC WATERS...LIES OVER THE TROPICS EXTENDING FROM 13N46W 18N23W 20N16W. DIFFLUENCE TO THE S/SE OF THE JET IS GENERATING ABUNDANT CLOUDINESS AND EMBEDDED SCATTERED SHOWERS WITHIN 300 NM. $$ CANGIALOSI