000 AXNT20 KNHC 222333 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT DEC 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 4N27W 4N38W 8N54W 9N62W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM OF THE AXIS BETWEEN 36W-45W AND WITHIN 90 NM OF THE AXIS BETWEEN 51W-55W. SIMILAR CONVECTION IS FROM 4N-6N BETWEEN 25W-26W. ...DISCUSSION... THE GULF OF MEXICO... A COLD FRONT HAS ENTERED THE NW CORNER FROM CENTRAL LOUISIANA TO THE MEXICAN COAST NEAR 23N98W THEN NWD ALONG THE E SLOPES OF THE SIERRA MADRE TO 26N100W...AT 21Z. THIS FRONT IS OBTAINING SUPPORT FROM A DEEP LAYERED LOW OVER THE SRN PLAINS WHICH IS PRODUCING WINTRY WEATHER ON IT'S BACK SIDE. DOPPLER RADAR AND LIGHTNING DATA DETECT A WELL DEFINED LINE OF SCATTERED TSTM ACTIVITY WITHIN 45 NM AHEAD OF THE FRONT N OF 28N. THIS ACTIVITY THINS OUT SUBSTANTIALLY S OF 28N. TEMPS HAVE BEEN UNSEASONABLY WARM TODAY AHEAD OF THE FRONT...AND ARE NOW FALLING BACK TO AND BELOW TYPICAL LEVELS AS THE BOUNDARY PASSES. A QUICK SHOT OF NLY GALE FORCE WINDS ARE ANTICIPATED IN THE SW GULF BEGINNING LATER TONIGHT INTO THE FIRST HALF OF TOMORROW. STILL WARM AND HUMID IN THE WARM SECTION BETWEEN THE AFOREMENTIONED COLD FRONT AND A WARM FRONT FROM 24N88W TO THE NEW ORLEANS AREA. BROKEN CLOUDINESS AND POSSIBLE ISOLATED SHOWERS ACCOMPANY THE WARM FRONT. THE E GULF IS FAIRLY TRANQUIL THIS EVENING WITH ONLY PATCHY CLOUDS AND A COUPLE OF LIGHT SHOWERS ON THE FLA E COAST BLOWING IN FROM THE ATLC. THE CARIBBEAN SEA... MID TO UPPER RIDGE IS PARKED OVER THE W CARIB WITH THE FLOW ALOFT BECOMING ZONAL E OF ABOUT 75W. ABUNDANT STRONG SUBSIDENCE IS NOTED NEARLY EVERYWHERE PROVIDING NICE WEATHER ACROSS MOST OF THE REGION. HOWEVER...THERE ARE A COUPLE EXCEPTIONS. ONE IS IN THE CENTRAL CARIB N OF VENEZUELA WHERE SCATTERED SHOWERS ARE POSSIBLE S OF 15N BETWEEN 67W-72W...ASSOCIATED WITH A WEAK SFC TROUGH. SLIGHTLY DEEPER PRECIP...ALSO SCATTERED IN NATURE...IS IN THE SW CARIB S OF 12N BETWEEN 76W-82W ENHANCED BY THE ITCZ AND SLIGHTLY DIFFLUENT FLOW ALOFT. TRADE WIND FLOW IS LIGHT TO MODERATE AREA-WIDE...EXCEPT NEAR 20 KT IN THE VICINITY OF THE COLOMBIAN COAST. THE ATLANTIC OCEAN... MAIN FEATURE IN THE W ATLC IS A COMPLEX AREA OF LOW PRES. EARLIER...WE ANALYZED THIS SYSTEM AS SERIES OF LOWS DUE TO SEVERAL SWIRLS ROTATING ABOUT A CENTER. HOWEVER...SINCE THEN A LOW APPEARS TO BE DOMINATE NEAR 29N69W...1009 MB...WITH A TROUGH HANGING WSW TO SOUTH FLORIDA. THIS LOW IS VERTICALLY STACKED AS WATER VAPOR IMAGES REVEAL AN UPPER CENTER NEARLY OVERHEAD. MOST OF THE DEEP CLOUDINESS...SCATTERED SHOWERS AND TSTMS ARE SITUATED TO THE E OF THE CENTER IN AN UPPER DIFFLUENT ZONE FROM 25N-32N BETWEEN 60W-67W. AN ASSOCIATED COLD FRONT EXTENDS FROM 30N67W TO 23N72W THEN DISSIPATING ACROSS CENTRAL CUBA. SCATTERED SHOWERS ARE TSTMS ARE WITHIN 60 NM AHEAD OF THE FRONT N OF 24N. THERE ARE A COUPLE OF WEAK FEATURES IN THE CENTRAL ATLC. ONE IS THE TAIL END OF A OLD FRONTAL BOUNDARY WHICH APPEARS TO BE LIFTING NWD ALONG 32N38W 28N48W 27N55W. LITTLE SIGNIFICANT CLOUDINESS IS ALONG THIS WEAK BOUNDARY. A SMALLER SCALE INVERTED SFC TROUGH IS IN THE TROPICS E OF THE NRN LEEWARDS ALONG 58W FROM 16N-21N. NIGHT CHANNEL VIS IMAGERY SHOWS DISTINCT TURNING IN THE LOW-LEVEL CLOUDS BUT LITTLE IN THE WAY OF DEEP CONVECTION. SCATTERED SHOWERS ARE LIKELY WITHIN 180 NM E OF THE AXIS. THE E ATLC IS THE QUIETEST PART OF THE BASIN WITH SFC HIGH PRES AND ZONAL FLOW ALOFT DOMINATING THE WX PATTERN. THIS IS PRODUCING MAINLY FAIR WEATHER...ONLY PATCHY MID-HIGH LEVEL CLOUDINESS...AND MODERATE NE TO E TRADES. $$ CANGIALOSI