000 AXNT20 KNHC 061143 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST THU DEC 06 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 CENTERED ALONG 7N12W 5N28W 7N39W 5N46W 3N51W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF THE AXIS BETWEEN 28W-33W. SIMILAR CONVECTION IS WITHIN 180 NM N AND 60 NM S OF THE AXIS BETWEEN 34W-42W. DISCUSSION... THE GULF OF MEXICO... A WEAK COLD FRONT HAS PUSHED OFF THE N GULF COAST EXTENDING FROM THE BIG BEND AREA OF FLORIDA TO S TEXAS...AS OF 09Z. THIS FRONT IS VERY DRY WITH LITTLE CLOUDS SEEN ON SAT IMAGES NEAR THE BOUNDARY. THERE IS SOME CLOUDINESS...HOWEVER...IN THE SE GULF NEAR THE TAIL END OF A PREFRONTAL TROUGH. MIAMI AND KEY WEST DOPPLER RADARS REVEAL A LINE OF SCATTERED TSTMS IN THE FL STRAITS PUSHING TOWARD THE NW BAHAMAS. ISOLATED ACTIVITY IS OVER PORTIONS OF S FLORIDA. OTHERWISE...A VERY WEAK SFC PRES PATTERN AHEAD OF THE FRONT IS RESULTING IN LIGHT AND VARIABLE WINDS ACROSS THE CENTRAL AND W PORTIONS. IN THE MID AND UPPER LEVELS...A WELL DEFINED CUT OFF LOW CONTINUES TO SIT AND SPIN OVER CENTRAL MEXICO. EXTENSIVE SWLY FLOW ALOFT TO THE E OF THE LOW IS ADVECTING A PLUME OF HIGH LEVEL CLOUDINESS ACROSS MUCH OF THE W GULF. THE CARIBBEAN SEA... QUIET CONDITIONS DOMINATE MUCH OF THE CARIB BASIN THIS MORNING WITH NIGHT CHANNEL VIS IMAGERY ONLY REVEALING TYPICAL NARROW SCATTERED STREAMS OF LOW-LEVEL CLOUDINESS. SAN JUAN DOPPLER RADAR DEPICTS SOME EMBEDDED SHOWER ACTIVITY MOSTLY S OF THE ISLAND...BUT MUCH LESS SO THAN THE PAST FEW DAYS. LIKE THE GULF OF MEXICO...WEAK SFC PRES PATTERN INDUCED BY THE SERIES OF WEAK FRONTAL TROUGHS N OF THE AREA IS ALLOWING ELY TRADES TO BE LIGHT ACROSS THE ENTIRE AREA...EVEN VARIABLE IN THE NW CARIB WHERE A WEAK SFC HIGH IS ANALYZED. ALOFT...SW TO WLY FLOW IS THE THEME ON THE NW SIDE OF A VERY BROAD RIDGE CENTERED ABOVE THE TROPICAL ATLC. A SWATH OF MID-HIGH LEVEL CLOUDINESS IS SEEN ON WV IMAGES IN THE SW CARIB S OF 15N W OF 75W AND IN THE SE CARIB S OF 14N W OF 67W...BUT NOT MUCH SENSIBLE WEATHER. THE RELAXED TRADE WIND FLOW IS NOT EXPECTED TO LAST MUCH LONGER AS STRONG RIDGING BUILDS NE OF THE AREA. WINDS ARE EXPECTED TO INCREASE FROM E-W LATER TODAY. THE ATLANTIC OCEAN... A RATHER QUICK MOVING COLD FRONT HAS PUSHED OFF THE E COAST OF THE U.S. EXTENDING FROM 32N76W THRU N CENTRAL FLORIDA. THIS FRONT IS FAIRLY WEAK AND DRY IN NATURE. A PREFRONTAL TROUGH...POSSIBLY ASSOCIATED WITH A PORTION OF AN OLD FRONT...EXTENDS FROM 32N72W ACROSS THE NW BAHAMAS AND INTO THE FLA STRAITS. LOW-LEVEL CONVERGENCE ALONG THIS BOUNDARY IS PRODUCING PATCHY CLOUDINESS AND A FEW LINES OF SCATTERED TSTM ACTIVITY IN THE FL STRAITS...EVIDENT IN KEY WEST RADAR. SIMILAR ACTIVITY IS LIKELY OCCURRING IN THE NW BAHAMAS. A CLUSTER OF TSTM ACTIVITY...WHICH APPEARS TO BE ASSOCIATED WITH MID-LEVEL VORTICITY...HAS BEEN TRAVELING NE WITH THE MID AND UPPER FLOW CURRENTLY FROM 28N-32N BETWEEN 64W-66W. A SMALL WEAK SFC TROUGH IS ALONG 55W FROM 21N-26N ONLY CAUSING SCATTERED CLOUDS AND SLIGHT CYCLONIC VEERING IN THE SFC WINDS. THE REMAINDER OF THE AREA W OF 50W IS FAIRLY QUIET UNDER MODERATELY STABLE AIR AND FAIRLY UNIFORM ZONAL UPPER FLOW. THE CENTRAL AND E ATLC IS DOMINATED BY STRONG SFC RIDGING ANCHORED BY A 1036 MB HIGH MIDWAY BETWEEN THE AZORES AND THE IBERIAN PENINSULA NEAR 38N17W. SAT IMAGES SUGGEST THAT A SFC TROUGH HAS DEVELOPED ON THE SW PERIPHERY OF THE RIDGE ALONG 41W/42W FROM 13N-26N. ASSOCIATED SCATTERED SHOWERS EXIST FROM 16N-23N BETWEEN 38W-43W. TIGHT PRES GRADIENT BETWEEN THE TROUGH AND THE MENTIONED HIGH IS CREATING A LARGE AREA OF STRONG ELY TRADES ACROSS MOST OF THE DISCUSSION AREA E OF THE TROUGH AXIS. THE MID AND UPPER PATTERN IS QUITE AMPLIFIED CONSISTING OF A LARGE ANTICYCLONE OVER THE AZORES AND A BROAD ELONGATED TROUGH TRAPPED S OF THE HIGH. THE BROAD TROUGH HAS AN EMBEDDED UPPER LOW JUST SW OF THE CAPE VERDE ISLANDS NEAR 26N21W. STRONG UPPER WINDS ON THE S SIDE OF THE TROUGH IS GENERATING AND TRANSPORTING SCATTERED SHOWERS AND TSTMS N OF THE ITCZ ROUGHLY FROM 5N-13N BETWEEN 33W-44W. $$ CANGIALOSI