000 AXNT20 KNHC 161133 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SAT DEC 16 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... METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...THE ITCZ... ITCZ AXIS IS ALONG 7N12W 4N25W 5N37W 3N52W. SMALL CLUSTERS OF ISOLATED MODERATE CONVECTION ARE WITHIN 180 NM EITHER SIDE OF THE AXIS E OF 37W. SCATTERED MODERATE IS WITHIN 120 NM N OF THE AXIS BETWEEN 41W-46W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER LEVEL SHORTWAVE TROUGH CONTINUES TO SLOWLY MOVE E NOW LOCATED FROM MISSISSIPPI SOUTHWESTWARD TO N CENTRAL MEXICO. A SUBTROPICAL JET ORIGINATES AT THE BASE OF THE TROUGH AND RACES ACROSS SOUTH CENTRAL FLORIDA AND INTO THE W ATLC WITH CORE WINDS FROM 80 TO 100 KT...STRONGEST IN THE WRN ATLC...BASED ON CIMSS SATELLITE DERIVED WINDS. COPIOUS MOISTURE IS ASSOCIATED WITH THIS UPPER LEVEL JET COVERING THE GULF E OF 86W. A SFC TROUGH...ANALYZED FROM THE NW BAHAMAS ACROSS THE STRAITS OF FLORIDA TO THE NRN YUCATAN PENINSULA IS DEEPENING THE MOISTURE ACROSS THE SE GULF. IN FACT...DOPPLER RADAR FROM MIAMI AND KEY WEST DEPICT A LARGE SHIELD OF SCATTERED SHOWERS AND TSTMS MOVING OVER S FLORIDA WHERE IT LOOKS LIKE IT WILL BE A PRETTY RAINY DAY. BUT THE DRIER AIR IS NOT THAT FAR AWAY WITH PLENTY OF IT BEING ADVECTED INTO THE WRN AND CNTRL GULF W OF 90W. A 1020 MB SFC HIGH IS LOCATED IN THE N GULF NEAR PENSACOLA. THIS WEAK PRES PATTERN IS PRODUCING LIGHT NE TO ELY WINDS. THE SFC HIGH WILL SLIDE E...STRENGTHEN AND BECOME NEARLY STATIONARY OFF THE SE COAST LATE THIS WEEKEND INCREASING ELY WINDS SLIGHTLY. THE MOISTURE IN THE E GULF WILL CONTINUE TO MOVE E WITH THE SHORTWAVE TROUGH EVENTUALLY CLEARING THE ENTIRE REGION SOMETIME TONIGHT. THE CARIBBEAN SEA... CONDITIONS ACROSS THE CARIBBEAN ARE QUIET THIS MORNING. THE ONLY AREA OF ANY MENTIONABLE CLOUDINESS IS IN THE EXTREME NW PORTION WHERE BROKEN MULTILAYERED CLOUDS AND ISOLATED SHOWERS COVER THE AREA N OF 19N W OF 80W. THIS CLOUDINESS IS MAINLY CONTRIBUTED TO THE TAIL END OF A SFC TROUGH IN THE NRN YUCATAN PENINSULA AND STRONG UPPER LEVEL WINDS ON THE N PERIPHERY OF AN UPPER HIGH CENTERED IN THE SRN CARIBBEAN NEAR 15N77W. THE REMAINDER OF THE AREA IS STABLE WITH PLENTY OF DRY AIR ALOFT NOTED ON WATER VAPOR IMAGERY...WITH THE DRIEST AIR OVER THE ERN CARIBBEAN WHERE UPPER LEVEL CONFLUENCE IS STRONGEST. THE TYPICAL LOW-LEVEL CLOUD STREAKS...UNDERNEATH THE MID-LEVEL CAP...EVEN APPEAR RATHER THIN BASED ON SHORTWAVE IR IMAGES. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE AND LITTLE CHANGE IS EXPECTED THRU THE WEEKEND. THE WINDS WILL LIKELY INCREASE SOME IN THE NW CARIB EARLY NEXT WEEK AS MODERATE HIGH PRES BECOMES NEARLY STATIONARY TO THE N OF THE AREA. LOW-LEVEL MOISTURE MAY INCREASE SLIGHTLY IN THE ERN CARIBBEAN LATER TODAY AND SUN BUT OVERALL MAINLY DRY CONDITIONS ARE EXPECTED TO PREVAIL. THE ATLANTIC OCEAN... THE UPPER LEVEL PATTERN HAS BECOME A LITTLE MORE AMPLIFIED TODAY AND BASICALLY CONSISTS OF A LONGWAVE RIDGE/TROUGH PATTERN. STARTING IN THE WRN AND CENTRAL ATLC...WIDESPREAD MOISTURE...PRODUCED BY STRONG UPPER LEVEL WINDS E OF A SHORTWAVE TROUGH IN THE GULF AND A WEAKENING FRONTAL BOUNDARY/SFC TROUGH DRAPED ACROSS THE BAHAMAS AND THE STRAITS OF FLORIDA...IS SPREADING TO ABOUT 55W MAINLY N OF 24N. THE ATMOSPHERE CONSIDERABLY DRIES OUT E OF 55W AS THE UPPER LEVEL FLOW DEVELOPS A NLY COMPONENT ON THE W SIDE OF A LARGE TROUGH IN THE E ATLC. THIS DRY STABLE AIR ALOFT COVERS A LARGE PORTION OF THE REGION BETWEEN 25W-55W. AT THE SFC...A 1029 MB HIGH CENTERED NEAR 38N42W DOMINATES THE REGION E OF THE OLD FRONTAL BOUNDARY HELPING TO PRODUCE MOSTLY FAIR WEATHER. COMPUTER MODELS SHOW THE MOISTURE PLUME SLOWLY THINNING AND PRESSING TO THE SE OVER THE NEXT COUPLE DAYS AS THE SHORTWAVE TROUGH MOVES THRU THE REGION. IN THE E ATLC...AN OCCLUDED 1004 MB SFC LOW IS LOCATED NEAR 33N29W. A WEAKER 1010 MB LOW HAS FORMED TO THE S OF THIS MAIN ONE NEAR 26N29W WITH A SFC TROUGH CONNECTING THESE SYSTEMS. MODELS SHOW THE WEAKER SRN LOW PULLING NWD AND BECOMING ABSORBED BY THE LARGER AND STRONGER LOW TO THE N LATER TODAY. THE ASSOCIATED COLD FRONT ENTERS THE AREA NEAR 32N26W AND EXTENDS SWD ALONG 24N27W 16N34W. MOISTURE IS MOST ORGANIZED WELL N OF THE OCCLUDED LOW...OUTSIDE OF THE DISCUSSION AREA. SCATTERED SHOWERS ARE WITHIN 150 NM AHEAD OF THE COLD FRONT N OF 20N. THE MOST SIGNIFICANT WEATHER EFFECT ASSOCIATED WITH THIS LOW PRES SYSTEM IS THE STRONG WINDS AND HIGH SEAS...AS A TIGHT PRES GRAD EXISTS BETWEEN THIS LOW AND THE HIGH TO IT'S NW PRODUCING NEAR GALE FORCE CONDITIONS IN THE REGION BETWEEN THE LOW AND 40W N OF 25N. STRONGER WINDS EXIST TO THE N OF THE AREA WHERE THE GRAD IS TIGHTER. THESE STRONG NLY WINDS HAVE CREATED SIGNIFICANT SWELL PRODUCING COMBINED SEAS OF 14-18 FT IN THE REGION OUTLINED. THE REMAINDER OF THE SUBTROPICAL E ATLC IS UNDER A NARROW UPPER RIDGE WITH THE AXIS ALONG 16W KEEPING CONDITIONS RATHER TRANQUIL ACROSS THE CANARY ISLANDS AND WRN AFRICA. IN THE TROPICAL ATLC...EXTENSIVE ZONAL FLOW ON THE N SIDE OF VERY BROAD RIDGING IS THE RULE WITH CONVECTION CONFINED TO THE ITCZ. $$ CANGIALOSI