000 AXNT20 KNHC 132359 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU DEC 13 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 5N25W 3N40W EQUATOR AT 50W. SCATTERED MODERATE CONVECTION IS WITHIN 140 NM NORTH OF AXIS BETWEEN 25W-32W...AND WITHIN 100 NM EITHER SIDE OF AXIS BETWEEN 18W-22W. DISCUSSION... GULF OF MEXICO... A SLOW MOVING COLD FRONT TRAILS FROM SE LOUISIANA TO NEAR TAMPICO MEXICO THEN CONTINUES AS A STATIONARY FRONT ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. CONSIDERABLY COOLER AND DRIER AIR IS FILTERING IN BEHIND THE FRONT. A NARROW LINE OF SCATTERED SHOWERS MARKS THE LEADING EDGE OF THIS COOLER AIR MASS. THE COLD FRONT WILL STALL OVER THE CENTRAL GULF WATERS BRIEFLY TONIGHT THEN MOVE NORTH AS A WARM FRONT FRI IN ADVANCE OF A STRONGER COLD FRONT THAT IS FORECAST TO MOVE ACROSS THE GULF ON SATURDAY BRINGING A NOTICEABLE INCREASE IN WINDS AND SEAS. AS OF 2100 UTC...A 1020 MB HIGH WAS ANALYZED OVER THE NE CORNER OF THE GULF EXTENDING A RIDGE OVER THE REMAINDER OF TH GULF INCLUDING THE YUCATAN PENINSULA. MOISTURE ASSOCIATED WITH THE REMNANTS OF T.D. OLGA IS ALREADY AFFECTING THE SE PORTION OF THE GULF AND THE FLORIDA KEYS. MOSAIC DOPPLER RADAR FROM THE SE U.S. SHOWS SCATTERED SHOWERS WITH EMBEDDED TSTMS OVER THIS AREA. A BAND OF SHOWERS WITH A FEW TSTMS IS ALSO SEEN OVER THE FLORIDA PANHANDLE AND SE LOUISIANA. ALOFT...A RIDGE IS SLOW MOVING EWD ACROSS THE EASTERN PORTION OF THE GULF WHILE SWLY WINDS AHEAD OF A CUT-OFF LOW LOCATED OVER THE SW U.S./NW MEXICO ARE INVADING THE WESTERN HALF OF THE GULF. THESE WINDS ARE TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE FROM THE EPAC THROUGH MEXICO INTO THE GULF. CARIBBEAN SEA... THE REMNANT LOW OF T.D. OLGA CONTINUES TO SPIN ACROSS THE CARIBBEAN SEA BETWEEN THE ISLE OF YOUTH CUBA AND THE CAYMAN ISLANDS. AS OF 2100 UTC...A 1010 MB LOW WAS ANALYZED NEAR 19.5N81.5W. THE LAST FEW VIS SATELLITE IMAGERY FOR THE DAY SHOWS VERY CLEAR THE LOW LEVEL CYCLONIC CIRCULATION...BUT CONVECTION IS CONFINED TO A FEW SMALL BANDS N AND NE OF THE CENTER. MOISTURE ASSOCIATED WITH THIS LOW EXTENDS NWD REACHING SOUTH FLORIDA WHERE IS GENERATING SOME SHOWER ACTIVITY. LIGHTNING DATA DEPICTS SCATTERED TSTMS OVER CENTRAL CUBA WHILE SOME SHOWER ACTIVITY IS ALSO OBSERVED EAST OF JAMAICA. THE CAYMAN ISLANDS ARE REPORTING MAINLY LIGHT SHOWERS AND SUSTAINED WINDS UP TO 22 KT. THIS LOW...REMNANTS OF OLGA IS EXPECTED TO CONTINUE TO MOVE WWD AND WILL PROBABLY BE ABSORBED BY AN APPROACHING COLD FRONT ENTERING THE NW CARIBBEAN EARLY SUN. ELSEWHERE...FRAGMENTS OF LOW LEVEL MOISTURE ARE MOVING ACROSS THE LEEWARD ISLANDS INTO THE UK/US VIRGIN ISLANDS AND PUERTO RICO UNDER THE TRADE WIND FLOW. THE SAN JUAN DOPPLER RADAR REVEALS SCATTERED SHOWERS AND ISOLATED TSTMS OVER THOSE ISLANDS AND THE SURROUNDING COASTAL WATERS. ALOFT...A RIDGE DOMINATES MOST THE WEST AND CENTRAL CARIBBEAN WITH AN UPPER TROUGH ENTERING THE EASTERN PORTION OF THE BASIN FROM THE CENTRAL ATLC. ATLANTIC OCEAN... BANDS OF SHOWERS/TSTMS...ASSOCIATED WITH THE REMNANTS OF T.D. OLGA...ARE AFFECTING THE STRAITS OF FLORIDA...THE FLORIDA KEYS AND SOUTH FLORIDA. DOPPLER RADAR DATA DEPICTS THE STRONGEST TSTMS MOVING WWD ACROSS THE UPPER/MIDDLE KEYS. AN INVERTED TROUGH EXTENDS NWD FROM THE REMNANTS OF OLGA TO SOUTH-CENTRAL FLORIDA. THIS TROUGH WILL CONTINUE TO MOVE WWD IN TANDEM WITH THE 1010 MB SFC LOW...REMNANTS OF OLGA...LOCATED OVER THE CARIBBEAN SEA. THE REMAINDER OF THE DISCUSSION AREA IS DOMINATED BY MODERATE TO STRONG SFC RIDGING SUPPORTED BY A 1026 MB HIGH CENTERED SE OF BERMUDA NEAR 29N61W. THERE IS A SLIGHT WEAKNESS IN THE RIDGE DUE TO THE PRESENCE OF A SFC TROUGH THAT EXTENDS FROM 31N33W TO 25N42W AND A LARGE INVERTED TROUGH NEAR THE MADEIRA AND CANARY ISLANDS. PATCHES OF MAINLY LOW LEVEL CLOUDS ARE ASSOCIATED WITH THESE TROUGHS. AN AREA OF MODERATE CONVECTION REMAINS BETWEEN THE WINDWARD ISLANDS AND THE N COAST OF SOUTH AMERICA COVERING FROM 6N-11N BETWEEN 55W-61W. A DIFFLUENT PATTERN ALOFT IS HELPING TO INDUCE THIS SHOWER/TSTM ACTIVITY THAT IS ALSO FOUND OVER THE GUYANAS. THE MID AND UPPER PATTERN CONSISTS OF A LONGWAVE RIDGE/TROUGH N OF 16N WITH A SERIES OF EMBEDDED SHORTWAVES E OF ABOUT 50W. IN THE DEEP TROPICS...THE FLOW ALOFT IS FAIRLY ZONAL AND QUITE STRONG. A JETSTREAM BRANCH WITH CORE WINDS OF 70-90 KT CROSS JUST N OF THE CAPE VERDE ISLANDS. $$ GR