000 AXNT20 KNHC 171124 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SUN DEC 17 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 8N12W 7N23W 4N40W 2N52W. SCATTERED MODERATE CONVECTION IS FROM THE EQ TO 9N BETWEEN 29W-37W. ISOLATED MODERATE IS WITHIN 120 NM N AND 180 NM S OF THE AXIS BETWEEN 17W-24W. ...DISCUSSION... THE GULF OF MEXICO... THE MID/UPPER LEVEL SHORTWAVE TROUGH THAT HAS BEEN IN THE GULF OVER THE PAST FEW DAYS HAS EXITED THE REGION AND IS NOW OFF THE SE COASTLINE. HOWEVER...THE TAIL END OF IT'S MOISTURE PLUME STILL COVERS THE EXTREME SE GULF AND THE FLORIDA STRAITS ...NAMELY S OF 25N E OF 83W. DOPPLER RADAR DEPICTS A SHRINKING SHIELD OF SCATTERED SHOWERS AND ISOLATED TSTMS MOVING ACROSS S FLORIDA AND THE KEYS WHERE IT HAS BEEN PRETTY GLOOMY OVER THE PAST 24 HOURS OR SO. THE BULK OF THE DEEP MOISTURE WILL NOT LAST MUCH LONGER AS DRIER AIR IS ON ITS WAY WITH PLENTY OF IT BEING ADVECTED INTO NEARLY ALL OF THE GULF. AT THE SFC...THE HIGH PRES SYSTEM HAS SHIFTED NE AND STRENGTHENED AS PROJECTED BY THE MODELS ANALYZED AT 1026 MB NEAR THE NC/VA COASTLINE. A WEAK SMALL SFC TROUGH IS LOCATED ALONG 87W FROM 21N-26N. THIS FEATURE BROKE OFF FROM THE LARGER TROUGH/FRONTAL BOUNDARY THAT IS CURRENTLY IN THE WRN ATLC. LOW-LEVEL LIFT E OR DOWNSHEAR OF THIS SFC BOUNDARY IS ENHANCING SOME ACTIVITY IN THE MOISTURE PLUME DESCRIBED. OVER THE NEXT COUPLE DAYS...THE UNSETTLED WEATHER IN THE SE GULF WILL MOVE OUT OF THE AREA AS A WEAK UPPER RIDGE BUILDS OVERHEAD. THE SFC RIDGE WILL REMAIN NEARLY STATIONARY OFF THE SE COAST HELPING TO PRODUCE MOSTLY FAIR WEATHER ACROSS THE REGION. THE CARIBBEAN SEA... CONDITIONS IN THE CARIBBEAN ARE QUIET THIS MORNING. THE ONLY AREA OF ANY MENTIONABLE CLOUDINESS IS ACROSS CUBA AND THE YUCATAN CHANNEL WHERE THERE IS BROKEN MULTILAYERED CLOUDS AND ISOLATED SHOWERS. THIS CLOUDINESS IS MAINLY CONTRIBUTED TO A WEAK SFC TROUGH IN THE YUCATAN CHANNEL/SE GULF AND SWIFT UPPER LEVEL FLOW ON THE N PERIPHERY OF A STRONG MID/UPPER LEVEL HIGH CENTERED IN THE CENTRAL CARIBBEAN NEAR 15N74W. THE REMAINDER OF THE AREA IS VERY STABLE WITH PLENTY OF DRY AIR ALOFT NOTED ON WATER VAPOR IMAGERY. THE TYPICAL LOW-LEVEL CLOUD STREAKS...UNDERNEATH THE STRONG MID-LEVEL CAP...EVEN APPEAR RATHER THIN BASED ON SHORTWAVE IR IMAGES...EXCEPT FOR THE PATCH OVER PUERTO RICO AND THE LESSER ANTILLES WHERE EMBEDDED SCATTERED SHOWERS ARE POSSIBLE AS DEPICTED ON SAN JUAN'S 88-D. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE AND LITTLE CHANGE OR SOME RELAXING IS EXPECTED OVER THE NEXT FEW DAYS. MOISTURE MAY INCREASE SLIGHTLY IN THE ERN CARIBBEAN TODAY AND TOMORROW BUT MUCH OF THIS IS EXPECTED TO BE SHALLOW IN NATURE. THE ATLANTIC OCEAN... STARTING IN THE WRN AND CENTRAL ATLC...WIDESPREAD MOISTURE...PRODUCED BY STRONG UPPER LEVEL WINDS E OF A SHORTWAVE TROUGH OFF THE SE COASTLINE AND A WEAK FRONTAL BOUNDARY/SFC TROUGH DRAPED FROM 32N56W TO THE CENTRAL BAHAMAS...IS SPREADING TO ABOUT 42W MAINLY BETWEEN 24N-32N. THE ATMOSPHERE CONSIDERABLY DRIES OUT S OF 24N AND E OF 45W AS THE UPPER LEVEL FLOW DEVELOPS A NLY COMPONENT IN RESPONSE TO A LARGE TROUGH IN THE E ATLC AND A STRONG RIDGE IN THE CARIBBEAN. THE GFS MODEL SHOWS THE MOISTURE PLUME SLOWLY THINNING AND PRESSING TO THE S OVER THE NEXT COUPLE DAYS. THE MODEL ALSO SUGGESTS THAT THE TAIL END OF THE TROUGH MAY BREAK OFF AND MOVE W WITH THE LOW-LEVEL FLOW...SIMILAR TO WHAT HAS OCCURRED IN THE GULF...WHICH MAY MAKE SOME MOISTURE LINGER IN THE BAHAMAS. IN THE E ATLC...THE MAIN FEATURE IS A LARGE OCCLUDED 1000 MB LOW LOCATED NEAR 33N32W. OVER THE PAST FEW DAYS...A FEW WEAK SMALLER SFC LOWS HAVE FORMED TO THE S OF THIS MAIN ONE AND HAVE BEEN ABSORBED BY THE LARGE CIRCULATION. THE ASSOCIATED COLD FRONT ENTERS THE AREA NEAR 32N24W AND EXTENDS S-SW ALONG 25N25W 17N32W. MOISTURE IS MOST ORGANIZED WELL N OF THE OCCLUDED LOW...OUTSIDE OF THE DISCUSSION AREA WITH LIMITED MOISTURE NEAR THE TRAILING COLD FRONT. THE MOST SIGNIFICANT WEATHER EFFECT ASSOCIATED WITH THIS LOW PRES SYSTEM CONTINUES TO BE THE STRONG WINDS AND HIGH SEAS...AS A TIGHTENED PRES GRAD EXISTS BETWEEN THIS LOW AND A 1021 MB TO IT'S NW NEAR 33N44W PRODUCING GALE FORCE CONDITIONS N OF THE DISCUSSION AREA. THESE STRONG NLY WINDS HAVE CREATED SIGNIFICANT SWELL PRODUCING COMBINED SEAS OF 12-15 FT BETWEEN THE LOW AND 40W N OF 28N. A BROAD UPPER LEVEL RIDGE COVERS THE ERN MOST ATLC AND W AFRICA WITH THE AXIS ALONG 10W. IN THE TROPICAL ATLC...THE PATTERN HAS BECOME MORE AMPLIFIED WITH EXTENSIVE SWLY FLOW OR TROPICAL JET LOCATED BETWEEN THE DEEP TROUGH...WHICH IS ASSOCIATED WITH THE LARGE OCCLUDED LOW MENTIONED...AND A BROAD RIDGE CENTERED NEAR 8N21W. THIS STRONG SWLY FLOW IS SPREADING HIGH CLOUDINESS AND LIKELY ISOLATED SHOWERS ACROSS THE E ATLC SE OF A LINE ALONG 8N40W 20N27W 27N19W. $$ CANGIALOSI