000 AXNT20 KNHC 170038 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC ...ITCZ... ITCZ AXIS ALONG 7N11W 4N19W 2N35W 1N45W EQUATOR50W. SCATTERED MODERATE CONVECTION WITHIN 240 NM S OF AXIS FROM 40W-46W. DISCUSSION... GULF OF MEXICO... LONGWAVE UPPER LEVEL TROUGH ACROSS BASIN SUPPORTS STRONG FAST MOVING COLD FRONT THAT HAS JUST EXITED EASTERN BORDER OF GULF. STRONG N TO NW WINDS BEHIND FRONT...TO GALE FORCE IN SW GULF S OF 20N W OF 92W. WIDESPREAD BROKEN TO OVERCAST STRATOCUMULUS CLOUDS ENGULF ENTIRE BASIN...INDICATIVE OF COOL STABLE AIRMASS BUT ALL CONVECTION NOW E OF BASIN. WINDS EXPECTED BELOW GALE FORCE WITHIN NEXT 12 HOURS AS FRONT MOVES FURTHER E ALLOWING HIGH PRES TO SLACKEN GRADIENT WITH DRY WEATHER ACROSS ENTIRE REGION THRU MON. CARIBBEAN SEA... COLD FRONT FROM WESTERN CUBA TO BAY ISLANDS IN HONDURAS CARRIES ONLY SIGNIFICANT CONVECTION IN WESTERN CARIBBEAN AS DRY SUBSIDING AIR MASS UNDER MID TO UPPER LEVEL RIDGE HAS BEEN IN PLACE SINCE...WHAT ONCE WAS TROPICAL STORM...OLGA WENT THROUGH. NOT EVEN LOW-LEVEL CONVERGENCE ALONG PRE-FRONTAL TROUGH EXTEND FROM WESTERN CUBA TO NICARAGUA-HONDURAS BORDER IS ABLE TO GENERATE ANY SIGNIFICANT CONVECTION. REMAINDER OF BASIN REMAIN QUIET WITH ONLY ISOLATED SHOWERS EMBEDDED IN EASTERLY TRADES. UPPER LEVEL TROUGH CROSSES EASTERN CARIBBEAN FROM LEEWARD ISLANDS IN THE NORTHEAST TO WESTERN VENEZUELA. ONLY NOTED MOISTURE IN BASIN RIDES SW WINDS ALOFT S OF 14N E OF 68W. LITTLE SIGNIFICANT MOISTURE AVAILABLE ELSEWHERE DUE TO STRONG SUBSIDENCE N OF 17N E OF 72W. ATLANTIC OCEAN... SCATTERED CONVECTION WITHIN 90 NM E OF COLD FRONT ACROSS SOUTHWEST NORTH ATLANTIC FROM 31N78W TO EXTREME SOUTHEAST FLORIDA TO NORTHWEST CUBA TO NORTHEAST YUCATAN PENINSULA. GALE FORCE SW WINDS AHEAD OF FRONT TO 70W THROUGH TONIGHT DIMINISHING BY EARLY MON. STRONGEST TSTMS NOW OVER NORTHEAST BAHAMAS AND N OF AREA OFF CAROLINA COASTLINE. STATIONARY HIGH PRESSURE CENTER 1023 MB AT 28N54W SHOULD YIELD TO STRONG FRONT SHIFTING EAST AS STRONG NORTHEASTERLY FLOW DOMINATES FLOW BEHIND FRONT. BROKEN LOW TO MID LEVEL CLOUDINESS WITHOUT SIGNIFICANT CONVECTION EXPECTED AS AIR MASS BECOMES STABLE. UPPER LEVEL TROUGHING THAT CROSSES EASTERN CARIBBEAN EXTENDS FURTHER NE ACROSS CENTRAL AND EASTERN ATLANTIC WELL INTO NORTHWEST AFRICA. STRONG SW FLOW ALOFT ON LEE SIDE OF TROUGH WITH JET CORE OF 115 KT BRINGS SWATH OF ITCZ TROPICAL MOISTURE INTO CONTINENT NORTH OF 13N. WEAK LOW PRESSURE 1014 MB AT 24N21W HAS TROUGH ANALYZED ACROSS CANARY ISLANDS TO 231N16W REMAINS UNDER SUBSIDING SIDE OF UPPER TROUGH UNABLE TO UTILIZE MOISTURE FOR ANY CONVECTION. $$ WALLY BARNES