000 AXNT20 KNHC 140524 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST THU DEC 14 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...THE ITCZ... ITCZ AXIS IS ALONG 6N11W 4N24W 5N40W 2N50W 1N53W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N AND 180 NM S OF THE AXIS BETWEEN 24W-32W AND WITHIN 180 NM N BETWEEN 35W-42W. ISOLATED MODERATE IS WITHIN 120 NM S OF THE AXIS E OF 17W. ...DISCUSSION... THE GULF OF MEXICO... A SFC TROUGH IS LINGERING IN THE SRN GULF ALONG 87W S OF 26N EXTENDING INTO THE WRN CARIB. SCATTERED SHOWERS AND TSTMS ARE LOCATED TO THE E OF THE TROUGH AXIS TO 82W. THE ERN EDGE OF THIS MOISTURE SWATH IS SHOWING UP ON THE KEY WEST AND TAMPA BAY 88-D'S WHICH DEPICTS SOME MODERATE ECHOES AT THE EDGE OF THE RADAR RANGE. SOME OF THIS MOISTURE IS SPREADING ACROSS CENTRAL FLORIDA BETWEEN LAKE OKEECHOBEE AND ORLANDO. THE REMAINDER OF THE GULF IS RELATIVELY QUIET WITH ONLY SOME PATCHES OF CLOUDINESS AND SHALLOW SHOWERS ACROSS THE WRN AND NRN GULF COAST. THE UPPER LEVEL FLOW IS RATHER UNIFORM W-SWLY ACROSS THE AREA AHEAD OF AN APPROACHING SHORTWAVE TROUGH LOCATED ABOVE SW TEXAS AND NRN MEXICO. A PLUME OF HIGH LEVEL MOISTURE ...ASSOCIATED WITH THE BASE OF THE TROUGH...IS BEING ADVECTED FROM THE EPAC ACROSS NRN MEXICO INTO THE NW GULF. AS THIS TROUGH APPROACHES IT WILL SPREAD THIS UPPER LEVEL CLOUDINESS ACROSS THE AREA AND WILL LIKELY STEER THE SFC TROUGH IN THE SRN GULF NORTHEASTWARD ACROSS FLORIDA LATER THIS WEEK. THE CARIBBEAN SEA... THERE ARE TWO WEAK SFC TROUGHS ANALYZED IN THE WRN CARIB. ONE OF THESE IS IN THE NW PART OF THE AREA ALONG 87W N OF 17N EXTENDING INTO THE SRN GULF. MOST OF THE ASSOCIATED SHOWER ACTIVITY IS N OF THE AREA BUT ISOLATED TO SCATTERED SHOWERS ARE LIKELY OCCURRING ACROSS THE YUCATAN PENINSULA. RATHER DISTINCT LOW-LEVEL CYCLONIC TURNING IS NOTED IN SFC OBS...SATELLITE IMAGES AND SAT LOW-LEVEL DERIVED WINDS. THE OTHER IS IN THE SW PORTION ANALYZED FROM 10N83W TO 16N84W. THIS AREA TYPICAL HAS A CLIMATOLOGICAL VEERING IN THE WINDS OR TROUGH FEATURE BUT THE LOW-LEVEL TURNING IS A LITTLE MORE PRONOUNCED THAN USUAL SO IT IS ANALYZED AS A SYNOPTIC WEATHER FEATURE. SOME SFC LIFT NEAR THE WEAK BOUNDARY ALONG WITH WEAK UPPER DIFFLUENCE...BETWEEN AN UPPER HIGH CENTERED OVER NICARAGUA AND STRONGER UPPER LEVEL WLY FLOW IN THE NW CARIB...IS SPARKING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 13N-18N BETWEEN 81W-85W. THE REMAINDER OF THE AREA IS QUIET UNDER MODERATELY DRY AIR ALOFT AND NW-WLY UPPER LEVEL FLOW. TRADE WINDS ARE MOSTLY IN THE 15-20 KT RANGE AND THESE WINDS ARE EXPECTED TO CHANGE LITTLE OVER THE NEXT FEW DAYS AS THE SFC RIDGE REMAINS TO THE NE OF THE REGION. SUBTROPICAL ATLANTIC... A LONGWAVE RIDGE/TROUGH/RIDGE PATTERN IS ESTABLISHED ACROSS THE SUBTROPICAL ATLC. HIGHLY TILTED STACKED RIDGING EXISTS IN THE WRN ATLC WITH THE MEAN UPPER LEVEL AXIS EXTENDING FROM CUBA NEWARD TO BERMUDA. THE SFC HIGH IS LOCATED WELL TO THE N OF THE AREA SETTING UP A LARGE AREA OF 20 KT WINDS ON ITS SRN PERIPHERY. FOR DETAILS ON THE WINDS AND SEAS REFER TO THE HIGH SEAS FORECAST...MIAHSFAT2. PLENTY OF DRY STABLE AIR ALOFT EXISTS W OF 40W PRODUCING A STRONG MID-LEVEL CAP WHICH IS KEEPING THE PATCHES OF LOW-LEVEL MOISTURE SHALLOW. A BROAD TROUGH DOMINATES THE CENTRAL ATLC WITH THE UPPER AXIS ALONG 41W. AN ASSOCIATED OLD FRONTAL BOUNDARY EXTENDS FROM A 1014 MB LOW NEAR 33N33W SW TO 20N43W. MULTILAYERED CLOUDS AND EMBEDDED ISOLATED SHOWERS ARE LOCATED MAINLY WITHIN 180 NM E OF THE TROUGH AXIS. THE DEEPEST MOISTURE IS N OF THE AREA WHERE STRONG UPPER LEVEL WINDS ARE PROVIDING MORE SUPPORT FOR UNSETTLED WEATHER. THE E ATLC IS DOMINATED BY A STRONG VERTICALLY STACKED RIDGE WITH THE MAIN UPPER HIGH CENTER NEAR 31N21W. THE 1032 MB SFC HIGH IS CENTERED FURTHER TO THE NE IN SPAIN. THE CUT OFF UPPER LEVEL LOW THAT WAS EMBEDDED IN THIS RIDGE YESTERDAY HAS BEEN OVERTAKEN BY THE RIDGE AS ADVERTISED BY THE GFS. TROPICAL ATLANTIC... NEARLY ZONAL UPPER LEVEL FLOW ON THE N SIDE OF A BROAD FLAT RIDGE COVERS MUCH OF THE TROPICAL ATLC. WATER VAPOR IMAGERY INDICATES A FAIR AMOUNT OF MODERATE DRY AIR ALOFT ABOVE THE AREA PROVIDING A FAIRLY STABLE ENVIRONMENT LIMITING CONVECTION TO THE ITCZ. $$ CANGIALOSI