000 AXNT20 KNHC 312326 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SUN DEC 31 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... ITCZ AXIS IS ALONG 6N10W 2N26W 1N40W TO THE EQUATOR AND 50W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE BETWEEN 12W-16W. ISOLATED MODERATE IS WITHIN 240 NM N OF THE AXIS BETWEEN 33W-44W. ...DISCUSSION... THE GULF OF MEXICO... A COLD FRONT ENTERED THE NW CORNER OF THE GULF NEARLY 48 HOURS AGO AND CONTINUES TO SLOWLY INCH EASTWARD. AS OF 21Z...THE FRONT WAS ANALYZED FROM PENSACOLA FLORIDA TO S MEXICO ALONG 31N87W 24N91W 18N94W. DOPPLER RADAR FROM THE SE U.S. SHOWS A STRONG BAND OF NUMEROUS SHOWERS AND TSTMS AHEAD OF THE FRONT ACROSS THE FL PANHANDLE AND THE BIG BEND AREA NWD INTO GEORGIA. IR IMAGERY SUGGESTS THAT SIMILAR ACTIVITY IS LIKELY OCCURRING FURTHER SE WITHIN 90 NM EITHER SIDE OF THE FRONT BETWEEN 25N-30N. THE SE GULF AND MUCH OF THE FL PENINSULA STILL LIES UNDER MID TO UPPER LEVEL RIDGING WITH DRY AIR IN PLACE. HOWEVER...SOME MOISTENING WILL OCCUR AS THE FRONT NEARS AND THE RIDGE CONTINUES TO RETREAT E. SHIP...BUOY AND QSCAT DATA SHOWS SLY WINDS MAINLY WITHIN THE 15-20 KT RANGE WHICH IS ADVECTING A WARM AND HUMID AIRMASS FOR THE MIDDLE OF WINTER. BEHIND THE FRONT...CONSIDERABLE CLOUDINESS AND SCATTERED SHOWERS ARE LINGERING FOR ABOUT 200 NM W OF THE BOUNDARY WITH CLEARING SKIES CONFINED TO THE FAR NW PORTION. SFC WINDS ARE NLY IN THE 15-25 KT RANGE...STRONGEST CLOSEST TO THE FRONT. THE AIRMASS BEHIND THE FRONT IS NOTICEABLY COOLER BUT FAR FROM COLD WITH TEMPS GENERALLY IN THE 60'S AND LOW 70'S. DEW POINTS HAVE DROPPED OFF TO THE UPPER 30'S F ACROSS THE NW GULF COAST WHERE THE CLOUDS HAVE CLEARED. OVER THE NEXT COUPLE OF DAYS...THE FRONT WILL CONTINUE ITS SLOW MOTION...WEAKEN CONSIDERABLY AND EVENTUALLY BECOME STATIONARY DRAPED E-W ACROSS THE AREA. THE ASSOCIATED MOISTURE WILL LIKELY THIN OUT AS SFC HIGH PRES BUILDS IN. THE CARIBBEAN SEA... AN AMPLIFIED UPPER LEVEL RIDGE/TROUGH PATTERN EXISTS IN THE REGION. THE UPPER RIDGE AXIS LIES ROUGHLY ALONG 82W AND COVERS THE CARIB W OF 75W. THE REMAINDER OF THE AREA IS UNDER A WELL-DEFINED CENTRAL ATLC TROUGH. UPPER LEVEL CONFLUENCE BETWEEN THESE BROAD FEATURES IS PRODUCING WIDESPREAD DRY AND STABLE AIR IN THE MID AND UPPER LEVELS. THIS SINKING...STABLE AIR IS KEEPING THE WX CONDITIONS VERY QUIET WITH NO AREAS OF SIGNIFICANT DEEP CLOUDINESS OR SHOWER ACTIVITY NOTED ON IR IMAGERY. WHILE CONVECTION IS NOT A CONCERN...STRONG TRADES WINDS ARE. SFC OBSERVATIONS SHOW WINDS BETWEEN 20-30 KT ...STRONGEST N OF THE COLOMBIAN COAST. THESE WINDS ARE PRODUCING HAZARDOUS SEAS UP TO 14 FT. THE STRONG LOW-LEVEL FLOW IS ALSO STIRRING UP ENOUGH INSTABILITY TO FORM SHALLOW QUICK MOVING SHOWERS...AS NOTED ON SAN JUAN'S 88-D. TRADE WINDS ARE EXPECTED TO REMAIN ON THE STRONG SIDE THRU MUCH OF NEXT WEEK AS THE PRES GRAD REMAINS TIGHT. MAINLY DRY CONDITIONS ARE ALSO EXPECTED TO PERSIST AS THE UPPER TROUGH IN THE CENTRAL ATLC MOVES OUT AND THE MID TO UPPER RIDGE BUILDS E. THE ATLANTIC OCEAN... A LONG WAVE RIDGE/TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE SUBTROPICAL ATLC. STARTING IN THE W ATLC...AN AMPLIFIED MID TO UPPER RIDGE IS ALIGNED FROM THE NW CARIB NWD ACROSS THE BAHAMAS INTO THE NE U.S. BROKEN CLOUDINESS...STREAMING FROM THE GULF...IS ROTATING AROUND THE THE RIDGE STAYING N OF THE DISCUSSION AREA. A VERY BROAD MID TO UPPER LEVEL TROUGH IS COVERING A LOT OF OCEAN BETWEEN 38W AND 73W. THIS TROUGH HAS SHARPENED AND BECOME MORE ELONGATED SINCE YESTERDAY AS SHORT WAVES CONTINUE TO ROTATE THRU. THERE APPEAR TO BE A FEW WEAK SFC FEATURES ASSOCIATED WITH THIS BROAD TROUGH. THE CLEAREST BOUNDARY IS A COLD FRONT WHICH IS JUST ENTERING THE AREA ALIGNED E-W ALONG 31N/32N BETWEEN 58W-71W. THIS FRONT ACTS AS A SURGE IN NLY WINDS. ANOTHER WEAK BOUNDARY IS A LINGERING SFC TROUGH WHICH IS AHEAD OF THE FRONT ALONG 29N59W 28N68W 28N74W. THIS FEATURE IS AWFULLY WEAK...GENERATING MAYBE ISOLATED SHOWERS WITHIN 90 NM BUT A CLEAR LOW CLOUD LINE AND EVEN SOME VEERING IN THE WINDS... WHICH IS THE REASON FOR ANALYZING THIS FEATURE. TWO OTHER WEAK SFC TROUGHS...WHICH ARE ILL-DEFINED...ARE LOCATED FURTHER E. LOW-LEVEL LIFTING ALONG WITH MOIST SWLY UPPER LEVEL FLOW IS GENERATING A SWATH OF MOISTURE BETWEEN 40W-51W N OF 21N. A LARGE MID TO UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE SUBTROPICAL ATLC E OF 38W ANCHORED BY A HIGH CENTER 150 NM S OF THE CANARY ISLANDS NEAR 26N18W. THE SW PORTION OF THIS RIDGE IS ERODED BY A WEAKENING...NWD MOVING UPPER LOW CENTERED NEAR 24N33W. STRONG SWLY FLOW...TO THE E OF THE UPPER LOW...IS GENERATING AND DRAWING MOISTURE NWD LIKELY PRODUCING SCATTERED SHOWERS BETWEEN 25W-31W MAINLY FROM 23N-30N. MAINLY FAIR WEATHER EXISTS OVER MUCH OF THE OCEAN NOT OUTLINED. IN THE DEEP TROPICS...EXTENSIVE WLY FLOW ON THE N SIDE OF A BROAD UPPER RIDGE IS THE RULE WITH CONVECTION CONFINED TO THE ITCZ. $$ CANGIALOSI