000 AXNT20 KNHC 281750 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST THU DEC 27 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N10W 6N20W 4N30W 2N40W EQUATOR AT 47W INTO NE BRAZIL. SCATTERED MODERATE CONVECTION IS WITHIN 80 NM EITHER SIDE OF AXIS 29W-36W. CLUSTERS OF MODERATE CONVECTION ARE N OF AXIS FROM 4N-7N BETWEEN 42W-52W. UPPER DIFFLUENCE IS ENHANCING THIS CONVECTIVE ACTIVITY. ...DISCUSSION... THE GULF OF MEXICO... A NEW COLD FRONT HAS ENTERED THE NW CORNER OF THE GULF THIS MORNING. AS OF 1500 UTC...THE FRONT STRETCHES ACROSS CENTRAL LOUISIANA AND THE NW PORTION OF THE GULF TO NEAR TAMPICO MEXICO. MOSAIC DOPPLER RADAR FROM THE SE U.S. REVEALS A NARROW LINE OF SHOWERS WITH EMBEDDED TSTMS ASSOCIATED WITH THE FRONTAL BOUNDARY. THIS FRONT WILL EXTEND FROM THE FLORIDA PANHANDLE TO THE BAY OF CAMPECHE SATURDAY MORNING BEFORE BECOMING DIFFUSE AND DISSIPATE SUN. IN THE MID AND UPPER LEVELS...A JETSTREAM CUTS ACROSS THE REGION ADVECTING A PLUME OF MOISTURE FROM THE EPAC ACROSS THE DEEP SOUTH TO SE U.S..AN UPPER TROUGH OVER THE CENTRAL PLAINS IS SUPPORTING THE ABOVE MENTIONED COLD FRONT. MODERATE RETURN FLOW IS SEEN AHEAD OF THE FRONT WHILE NLY WINDS OF 20 TO 25 KT ARE BLOWING BEHIND THE FRONT. LOOKING AHEAD...A STRONGER COLD FRONT IS IN STORE FOR THE BEGINNING OF THE NEW YEAR. THIS FRONT IS EXPECTED TO MOVE RAPIDLY OFF THE TEXAS COAST LATE MON AND EXTEND FROM THE FLORIDA PANHANDLE TO BAY OF CAMPECHE EARLY TUE FOLLOWED BY STRONG NLY FLOW AND MUCH COOLER TEMPERATURES. GALE FORCE WINDS ARE EXPECTED OVER THE WESTERN GULF TUE AND PROBABLY WED WHEN THE COLD FRONT IS EXPECTED TO MOVE ACROSS SOUTH FLORIDA. THE CARIBBEAN SEA... MORE OF THE SAME...THE CARIBBEAN REMAINS TYPICALLY TRANQUIL FOR THIS TIME OF YEAR UNDER THE INFLUENCE OF A MID/UPPER-LEVEL RIDGE WHICH IS PRODUCING STRONG SUBSIDENCE. THIS RIDGE...ANCHORED ON A HIGH JUST SOUTH OF JAMAICA ALSO COVERS CENTRAL AMERICA AND SOUTHERN MEXICO...INCLUDING THE YUCATAN PENINSULA/CHANNEL. POCKETS OF LOW LEVEL MOISTURE WITH LIGHT TO MODERATE SHOWERS ARE BEING CARRIED BY THE TRADE WINDS ACROSS THE BASIN...MORE CONCENTRATED SOUTH OF PUERTO RICO AND HISPANIOLA. SCATTERED MODERATE CONVECTION HAS DEVELOPED ACROSS THE SW CARIBBEAN DUE TO SOME LOW-LEVEL CONVERGENCE...AIDED BY A DIFFLUENT PATTERN ALOFT. THIS SHOWER ACTIVITY IS SPREADING OVER PARTS OF PANAMA...COSTA RICA AND NICARAGUA. HIGH PRESSURE BUILDING N OF THE AREA WILL MAINTAIN MODERATE TO STRONG TRADE WINDS ACROSS THE SEA THROUGH MONDAY. THE GFS COMPUTER MODEL SHOWS ELY WINDS OF UP TO 30 KT JUST OFF THE COLOMBIAN COAST SAT AND SUN. THE ATLANTIC OCEAN... HIGHLY AMPLIFIED DEEP LAYER RIDGE/TROUGH/RIDGE PATTERN EXISTS ACROSS THE DISCUSSION AREA. THE W ATLC IS DOMINATED BY RIDGING WITH THE MID AND UPPER AXIS EXTENDING NWD FROM THE CARIBBEAN THROUGH BERMUDA. A SUBTROPICAL JETSTREAM IS RIDING ON THE N PERIPHERY OF THIS ANTICYCLONE BRINGING SOME UPPER LEVEL MOISTURE/HIGH CLOUDS. A DEEP LAYERED TROUGH REMAINS STUCK OVER THE CENTRAL ATLANTIC EXTENDING SW FROM A CUT-OFF LOW NEAR 26N38W TO JUST EAST OF THE WINDWARD ISLANDS. AT THE SURFACE...A 1011 MB LOW CONTINUES TO MEANDER NEAR 26N38W WITH A TROUGH EXTENDING S THEN SW TO NEAR TRINIDAD AND TOBAGO. A ROPE CLOUD DEFINES THIS TROUGH ON VIS SAT IMAGERY. A QUIKSCAT PASS FROM AROUND 1200 UTC SHOWED VERY CLEAR THE CYCLONIC CIRCULATION. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE LOW CENTER AND WITHIN 75 NM AHEAD OF THE TROUGH N OF 24N. A COUPLE OF 1026 MB HIGHS CENTERED NEAR 34N71W AND 30N57W ARE DOMINATING THE AREA W OF 50W. THE FAR E ATLC IS ALSO DOMINATED BY RIDGING ANCHORED ON A HIGH OVER THE IBERIAN PENINSULA. HOWEVER...THERE IS QUITE A BIT MORE CLOUDINESS WITH EMBEDDED SHOWERS IN THIS AREA DUE TO AN UPPER JET CROSSING THE AREA. THIS JETSTREAM LIES SE OF THE AFOREMENTIONED UPPER TROUGH. $$ GR