000 AXNT20 KNHC 201753 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST TUE NOV 20 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. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 80W S OF 19N MOVING W 15-20 KT. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE OVER THE SW CARIBBEAN SOUTH OF 15N AND JUST W OF THE WAVE AXIS. THIS ACTIVITY IS AFFECTING THE CARIBBEAN PLAINS OF NICARAGUA. DEEP LOW LEVEL CONVERGENT FLOW AND UPPER DIFFLUENCE ARE ALSO ENHANCING THIS CONVECTIVE ACTIVITY. TROPICAL WAVE IS ALONG 93/94W S OF 21N MOVING W 10-15 KT. THE WAVE IS MOVING ACROSS THE BAY OF CAMPECHE AND THE ISTHMUS OF TEHUANTEPEC GENERATING SOME CLOUDINESS WITH MAINLY LIGHT SHOWERS. THE MIMIC-TPW SHOWS A SMALL SURGE OF MOISTURE OVER THE BAY OF CAMPECHE INDICATING THE PRESENCE OF THIS FEATURE. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 8N30W 9N40W 7N60W. SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 140 NM N OF AXIS BETWEEN 32W-37W. THIS ACTIVITY IS ALSO AHEAD OF A SFC TROUGH ANALYZED ALONG 31W/32W ON THE 1200 UTC SURFACE MAP. UPPER DIFFLUENCE IS HELPING TO INDUCE THIS SHOWER/TSTM ACTIVITY. DISCUSSION... GULF OF MEXICO... A CUT-OFF CYCLONIC CIRCULATION IS CENTERED OVER THE NW PORTION OF MEXICO COVERING NORTH-CENTRAL MEXICO AND SOUTHERN TEXAS. A PLUME OF MID/UPPER LEVEL MOISTURE IS S AND SE OF THE CUT OFF LOW CROSSING CENTRAL MEXICO INTO THE GULF. THIS PLUME OF MOISTURE IS ASSOCIATED WITH A JETSTREAM BRANCH. SATELLITE DERIVED WINDS INDICATED CORE SPEEDS OF AROUND 80 KT. BROAD UPPER RIDGE DOMINATES THE GULF AND THE SE U.S.. A SURFACE RIDGE REMAINS OVER THE GULF ANCHORED OVER GEORGIA/THE CAROLINAS BY A 1025 MB HIGH. PATCHES OF LOW LEVEL CLOUDS WITH ISOLATED SHOWERS DOTS THE ENTIRE REGION. THE NEXT COLD FRONT IS EXPECTED TO ENTER THE GULF ON THU BRINGING AN INCREASE IN SHOWER ACTIVITY AND GUSTY WINDS. CARIBBEAN SEA... CLUSTERS OF MODERATE TO STRONG CONVECTION ARE CONCENTRATED OVER THE SW CARIBBEAN DUE TO SEVERAL FACTORS. SEE THE TROPICAL WAVE SECTION FOR DETAILS. A DISSIPATING FRONTAL TROUGH FROM THE CENTRAL ATLC ENTERS THE NE CARIBBEAN THROUGH THE LEEWARD ISLANDS EXTENDING EAST TO WEST JUST SOUTH OF PUERTO RICO AND HISPANIOLA. PATCHES OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS ARE OVER THOSE ISLANDS. CURRENTLY...THE SAN JUAN DOPPLER RADAR INDICATES THAT THE SHOWER ACTIVITY IS MAINLY OVER THE COASTAL WATERS. SAN JUAN REPORTED 24 HOURS RAINFALL AMOUNT OF 1.02 INCHES THIS MORNING. A DIFFERENCE IN PRES BETWEEN THE COLOMBIAN LOW AND HIGH PRES N OF AREA IS PRODUCING BRISK TRADE WINDS OF 20 TO 25 KT OVER MUCH OF THE BASIN. AN EARLIER QUIKSCAT PASS CONFIRMED THESE WINDS. BROAD UPPER-LEVEL RIDGE COVERS THE AREA ANCHORED ON AN UPPER HIGH OVER SOUTH AMERICA. THE ITCZ AXIS EXTENDS ACROSS SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION ENHANCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PARTICULARLY OVER E PANAMA AND THE PACIFIC COAST OF COLOMBIA. DEBRIS MOISTURE FROM THIS CONVECTION EXTENDS EWD ACROSS THE ABC ISLANDS. ATLANTIC OCEAN... SATELLITE LOOPS INDICATE THAT A COLD FRONT IS PUSHING SOUTH AND SE ACROSS THE W ATLC AND THE BAHAMAS. THE FRONT EXTENDS ALONG 32N60W 27N66W 25N75W. AN EARLIER QUIKSCAT PASS AND SURFACE OBSERVATIONS INDICATED NEAR GALE FORCE WINDS BEHIND THE FRONT. A BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS N OF 27N WITHIN 200 NM AHEAD OF THIS FRONTAL SYSTEM. LIGHTNING DATA ALSO DEPICTS ISOLATED TSTM IN ASSOCIATION WITH THIS BAND. ANOTHER DRY COLD FRONT WILL ENTER THE DISCUSSION AREA TONIGHT. AHEAD OF THESE FRONTAL BOUNDARIES...THERE IS A DISSIPATING FRONTAL TROUGH EXTENDING OVER THE CENTRAL ATLC AND THE NE CARIBBEAN. FURTHER EAST...A WEAK 1018 MB HIGH CENTERED N OF THE CAPE VERDE ISLANDS NEAR 20N25W DOMINATES THE E ATLC. AN ASCAT PASS FROM THIS MORNING SHOWED VERY WELL THE ANTICYCLONE CIRCULATION. ALOFT...AN UPPER TROUGH EXTENDS OVER THE W ATLC AND THE CENTRAL BAHAMAS SUPPORTING THE ABOVE MENTIONED COLD FRONTS. DRY AIR IS ALONG THE TROUGH AXIS N OF 24N WEST OF 68W...INCLUDING N-CENTRAL FLORIDA. POCKETS OF LOW/MID CLOUDS WITH SCATTERED SHOWERS AND ISOLATED TSTMS ARE BETWEEN SOUTH FLORIDA AND WEST-CENTRAL CUBA. BROAD UPPER RIDGE WITH AXIS EXTENDING NWD ALONG 50W DOMINATES THE CENTRAL ATLC. BROAD UPPER TROUGH COVERS THE REMAINDER OF THE ATLC N OF 20N E OF 45W. $$ GR