000 AXNT20 KNHC 302333 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT DEC 30 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 6N11W 4N23W 2N37W TO THE EQUATOR AND 50W. NO SIGNIFICANT CONVECTION. ...DISCUSSION... THE GULF OF MEXICO... A COLD FRONT MOVED INTO THE NW CORNER OF THE AREA LATE LAST NIGHT AND HAS BEEN SLOWLY MOVING EWD THRU THE DAY TODAY. AS OF 21Z...THE FRONT WAS ANALYZED FROM SE LOUISIANA TO SRN MEXICO ALONG 30N90W 25N95W 20N97W. THE AIRMASS BEHIND THE FRONT IS BY NO MEANS ARCTIC-LIKE BUT IT IS NOTICEABLY COOLER AND DRIER WITH TEMPS AND DEW POINTS FALLING INTO THE 50'S F. A CONSIDERABLE AMOUNT OF LOW CLOUDS WITH POSSIBLE EMBEDDED SCATTERED SHOWERS IS LINGERING BEHIND THE BOUNDARY. SFC WINDS BEHIND THE FRONT ARE NOT VERY STRONG WITH MOST OBS FROM COASTAL TEXAS AND BUOYS REPORTING N-NE WINDS FROM 10 TO 20 KT. MOSAIC DOPPLER RADAR FROM THE SE SHOWS A RATHER LARGE SWATH OF NUMEROUS SHOWERS AND TSTMS OCCURRING ALONG AND JUST AHEAD OF THE FRONT OVER THE COASTAL WATERS OF SE LA NWD ACROSS MS AND W AL. THIS ACTIVITY IS LIKELY ALSO OCCURRING A LITTLE FURTHER S...OUT OF RADAR RANGE...INTO THE N CENTRAL GULF WITHIN 120 NM AHEAD OF THE FRONT N OF 27N. FAIR WEATHER CONTINUES IN THE E GULF...ESPECIALLY S OF 27N...WHERE SFC PRESSURES ARE HIGH AND PLENTY OF DRY STABLE AIR IN THE MID AND UPPER LEVELS IS IN PLACE. SFC WINDS ARE QUITE BRISK IN THE AREA WITH SE WINDS MAINLY IN THE 20 T0 25 KT RANGE. OVER THE NEXT COUPLE OF DAYS...THE FRONT WILL CONTINUE ITS SLOW EWD TREK BUT IT WILL BEGIN TO FALL APART AS IT APPROACHES THE E GULF. THE ASSOCIATED MOISTURE WILL ALSO THIN OUT AS SFC HIGH PRES BUILDS INTO REGION. THE CARIBBEAN SEA... THE WX ACROSS THE CARIB REMAINS PLEASANT UNDER AN UPPER LEVEL RIDGE/TROUGH PATTERN. THE UPPER LEVEL RIDGE AXIS LIES ROUGHLY ALONG 86W. THIS RIDGE COVERS THE MAJORITY OF THE AREA EXCEPT FOR THE E PORTION WHICH LIES ON THE SW SIDE OF A LARGE CENTRAL ATLC TROUGH. THE ONLY AREA OF SIGNIFICANT CLOUDINESS...AND ITS A STRETCH TO CALL IT THAT...IS S OF THE GREATER ANTILLES FROM 15N-17N BETWEEN 65W-73W WHERE UPPER DIFFLUENCE MAY BE GENERATING ISOLATED SHOWERS. OTHERWISE...WIDESPREAD DRY AIR NOTED ON WATER VAPOR IMAGERY IS PROVIDING A STABLE ENVIRONMENT ACROSS THE CARIB. TRADE WINDS ARE QUITE STRONG WITH OBS AND QSCAT DATA SHOWING WINDS GENERALLY BETWEEN 20-30 KT. THESE WINDS ARE EXPECTED TO REMAIN ON THE STRONG SIDE THRU MUCH OF NEXT WEEK AS THE PRES GRAD REMAINS TIGHT. 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 TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE SUBTROPICAL ATLC. A VERY BROAD MID TO UPPER LEVEL TROUGH IS COVERING A LOT OF OCEAN BETWEEN 40W AND ABOUT 75W. THIS TROUGH HAS BECOME LARGER AND A BIT MORE AMPLIFIED THAN IT WAS YESTERDAY AS A COUPLE OF SHORT WAVES HAVE MOVED S DEEPENING IT A BIT. AN ASSOCIATED OLD FRONTAL BOUNDARY CLIPS THE AREA EXTENDING FROM 32N34W TO 27N47W. ANOTHER FRONTAL BOUNDARY LIES E-W ALONG 32N BETWEEN 47W-65W. MOIST SWLY UPPER LEVEL FLOW ALONG WITH SOME LOW-LEVEL LIFT NEAR THE SFC BOUNDARIES MENTIONED IS PRODUCING A SWATH OF MOISTURE...WHICH APPEARS TO BE MAINLY IN THE MID AND UPPER LEVELS...N OF 21N BETWEEN 40W-59W. GFS SHOWS THIS TROUGH REMAINING RATHER BROAD AND POSSIBLY DEEPENING FURTHER OVER THE NEXT FEW DAYS AS IT MOVES E. A LARGE MID TO UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE SUBTROPICAL ATLC E OF 40W ANCHORED BY A HIGH CENTER NEAR 26N21W. THE SW PORTION OF THIS RIDGE IS BEING ERODED BY AN NWD MOVING UPPER LOW CENTERED NEAR 20N32W. INFRARED SATELLITE IMAGERY SUGGEST THAT THERE IS LIKELY SCATTERED SHOWERS ON THE MOIST E SIDE OF THE CYCLONIC CIRCULATION BETWEEN 20W-31W MAINLY FROM 20N-25N. MAINLY FAIR WEATHER EXISTS OVER MUCH OF THE OCEAN NOT OUTLINED. IN THE DEEP TROPICS...EXTENSIVE ZONAL FLOW IS THE RULE WITH MINIMAL CONVECTION IN THE AREA...EVEN WITHIN THE ITCZ. $$ CANGIALOSI