000 AXNT20 KNHC 261749 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED DEC 26 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 7N12W 3N25W 4N35W EQUATOR AT 48W... INTO NE BRAZIL. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF AXIS BETWEEN 16W-19W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE FROM 2N-5N BETWEEN 31W-37W. ...DISCUSSION... THE GULF OF MEXICO... AS OF 1500 UTC...A NEW COLD FRONT HAS ENTERED THE NW CORNER OF THE GULF. DOPPLER RADAR DEPICTS A WELL DEFINED LINE OF STRONG SHOWERS AND TSTMS ALONG THE COLD FRONT THAT TRAILS ACROSS EASTERN TEXAS...THE NW PORTION OF THE GULF AND NE MEXICO. THE FRONT IS ATTACHED TO A 1007 MB LOW LOCATED OVER SE TEXAS. THIS FRONTAL SYSTEM WILL EXTEND FROM THE MISSISSIPPI COAST TO NEAR TAMPICO MEXICO TONIGHT. THE FRONT IS FORECAST TO WEAKEN AND BECOME DIFFUSE ON THURSDAY. AT THE SAME TIME...A SFC HIGH IS SETTLING OVER SOUTH GEORGIA/N FLORIDA USHERING A COOL AND DRIER AIRMASS OVER FLORIDA AND THE EASTERN GULF. THE LEADING EDGE OF THIS AIRMASS IS A COLD FRONT THAT CROSSES JUST N OF LAKE OKEECHOBEE. A MID/UPPER-LEVEL TROUGH WITH AXIS ALONG THE TEXAS PANHANDLE SUPPORTS THE AFOREMENTIONED COLD FRONT. TROPICAL MOISTURE IS SEEN STREAMING NORTHEASTWARD BY A JETSTREAM BRANCH FROM THE E PACIFIC NE ACROSS THE CENTRAL MEXICO AND THE GULF REACHING TO ACROSS NORTH-CENTRAL FLORIDA INTO THE W ATLC. SATELLITE-DERIVED WINDS INDICATE A CORE WINDS OF 70-110 KT ASSOCIATED WITH THIS JETSTREAM. LOOKING AHEAD...ANOTHER COLD FRONT WILL ENTER THE NW GULF LATE THURSDAY NIGHT. THE CARIBBEAN SEA... AMPLIFIED MID TO UPPER LEVEL RIDGING IS PRESENT OVER THE NW AND CENTRAL PORTIONS OF THE SEA CREATING ABUNDANT MODERATE TO STRONG SUBSIDENCE IN THESE AREAS. THE TAIL END OF A MID/UPPER LEVEL TROUGH EXTENDS FROM THE E ATLC SW ENTERING THE EASTERN CARIBBEAN THROUGH THE LESSER ANTILLES. PRETTY QUIET CONDITIONS ARE FOUND ACROSS THE BASIN UNDER THE INFLUENCE OF THIS STABLE ENVIRONMENT. TYPICAL PATCHES OF LOW LEVEL CLOUDS WITH LIGHT RAIN SHOWERS DOT THE AREA. BRISK NELY WINDS ARE TRANSPORTING PATCHES OF LOW LEVEL MOISTURE WITH SHALLOW CONVECTION ACROSS THE CARIBBEAN PLAINS OF NICARAGUA AND COSTA RICA. FRAGMENTS OF MOISTURE IN THE TRADE WIND FLOW ARE ALSO MOVING ACROSS THE NE CARIBBEAN AFFECTING THE NORTHERN LEEWARD ISLANDS. THIS CLOUDINESS IS SPREADING ACROSS THE UK/US VIRGIN ISLANDS AND PUERTO RICO WHERE ISOLATED TO SCATTERED SHOWER ACTIVITY IS EXPECTED. MODERATE EASTERLY WINDS WILL PERSIST ACROSS THE BASIN THIS AFTERNOON THROUGH SUNDAY. THE ATLANTIC OCEAN... A COLD FRONT ENTERS THE AREA NEAR 31N76W THEN CONTINUES SW TO OVER N-CENTRAL FLORIDA. AN INVERTED SFC TROUGH REMAINS JUST OFF THE SE COAST OF FLORIDA GENERATING ISOLATED SHOWERS ACROSS THE STRAITS OF FLORIDA. A RIDGE IS BUILDING BEHIND THE FRONT ACROSS THE SE U.S. AND THE FLORIDA PENINSULA BRINGING IN A COOL AND DRIER ATMOSPHERE. A 1025 MB HIGH LOCATED NEAR 31N55W EXTENDS A RIDGE INTO THE DISCUSSION AREA BETWEEN 50W AND 75W. ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE FORECAST REGION. A BROAD UPPER RIDGE COVERS W OF 60W ACCOMPANIED BY DRY UPPER AIR. A DEEP LAYERED TROUGH REMAINS STUCK OVER THE CENTRAL ATLC EXTENDING SW TO THE EASTERN CARIBBEAN. AMPLE UPPER LEVEL MOISTURE IS EVIDENT WITHIN 600 NM E OF THE TROUGH. A CUT-OFF LOW HAS DEVELOPED ALONG THE TROUGH AXIS NEAR 27N40W. THESE UPPER FEATURES SUPPORT AN OCCLUDED 1014 MB SFC LOW THAT HAS A COLD FRONT EXTENDING ALONG 31N37W 23N40W 20N52W. A 120-140 NM WIDE BAND OF SHOWERS WITH ISOLATED TSTMS IS RELATED TO THE FRONTAL BOUNDARY N OF 23N WHILE A BAND OF BROKEN LOW CLOUDS IS ASSOCIATED WITH THE TAIL END OF THE FRONTAL SYSTEM. TIGHT PRES GRADIENT BETWEEN THIS FRONT AND THE RIDGE TO THE W OF THE FRONT IS PRODUCING MODERATE TO STRONG NLY WINDS OF 25 TO 30 KT OVER THE OCEAN...WITHIN 240 NM W SEMICIRCLE OF LOW. RIDGING ALSO DOMINATES THE E ATLC ANCHORED ON A 1033 HIGH LOCATED WEST OF PORTUGAL. THE UPPER FLOW IS GENERALLY ZONAL OVER THE TROPICAL ATLC W OF 45W. STRONG SWLY FLOW TO THE E AND SE OF THE FRONT/TROUGH IS ADVECTING UPPER LEVEL MOISTURE NEWD E OF 45W...REACHING THE CAPE VERDE ISLANDS. $$ GR