000 AXNT20 KNHC 251757 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU OCT 25 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 TROPICAL WAVE IS ALONG 28W S OF 16N MOVING W 10-15 KT. THE WAVE SHOWS UP WELL IN LOW LEVEL SATELLITE DERIVED WINDS AND VORTICITY...AND THE UW-CIMSS TPW PRODUCTS. IN ADDITION...VIS SATELLITE IMAGERY SHOWS A SWIRL OF LOW CLOUDS ALONG THE WAVE AXIS NEAR 8N. SCATTERED SHOWERS AND ISOLATED TSTMS ARE RELATED TO THE WAVE. LOW AMPLITUDE TROPICAL WAVE IS NOW ALONG 43W S OF 13N MOVING W 10-15 KT. THIS WAVE ALSO SHOWS UP WELL ON THE MIMIC-TPW PRODUCT AND 850 MB VORTICITY. VIS SAT IMAGERY SHOWS A WELL DEFINED INVERTED-V PATTERN ASSOCIATED WITH THE WAVE. SCATTERED MODERATE CONVECTION IS WITHIN 250 NM E OF THE AXIS...AND NORTH OF THE ITCZ AXIS. TROPICAL WAVE IS ALONG 72W S OF 17N MOVING W 10-15 KT. THE WAVE IS GENERATING SOME SHOWER ACTIVITY OVER WESTERN VENEZUELA AND NE COLOMBIA AS WELL AS OVER HISPANIOLA. A QUIKSCAT PASS FROM THIS MORNING SHOWED SOME WIND SHIFT ASSOCIATED WITH THE WAVE. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 10N26W 10N37W 7N50W 6N59W. BESIDES FOR THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES... SCATTERED MODERATE CONVECTION IS WITHIN 100 NM S OF AXIS EAST OF 18W TO THE COAST OF AFRICA. SIMILAR CONVECTION IS WITHIN 180 NM N OF AXIS BETWEEN THE PREVIOUSLY MENTIONED TROPICAL WAVES. DISCUSSION... GULF OF MEXICO... AN OCCLUDED SURFACE LOW IS CENTERED NEAR THE ALABAMA/MISSISSIPPI WITH AN ATTENDANT STATIONARY FRONT EXTENDING S ACROSS SE FLORIDA AND THE STRAITS OF FLORIDA TO W CUBA INTO THE NW CARIBBEAN. A BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS AND TSTMS IS ASSOCIATED WITH THE FRONTAL SYSTEM. SHOWER ACTIVITY IS MORE CONCENTRATED OVER THE NW CARIBBEAN WHERE A SFC TROUGH IS ALSO ANALYZED. WV IMAGERY SHOWS A CUT-OFF LOW OVER N MISSISSIPPI WITH A DEEP LAYERED TROUGH EXTENDING SW INTO CENTRAL MEXICO. DRY UPPER AIR ROTATING AROUND THE LOW COVERS THE WESTERN GULF AND THE NE PORTION OF THE AREA WHILE ABUNDANT UPPER LEVEL MOISTURE IS SEEN OVER THE SE GULF. BROKEN STRATOCUMULUS CLOUDS ARE OVER MOST OF THE GULF EXCEPT WITH CLEAR SKIES OVER THE FAR W PORTION. THE FRONT IS FORECAST TO SLOWLY DISSIPATE TONIGHT THROUGH FRI NIGHT. WINDS OVER THE GULF WATERS ARE OUT OF THE N/NW AND HAVE DIMINISHED OVER THE PAST 24 HRS WITH THE QUIKSCAT STILL SHOWING 20 KT OVER THE NW AND SW GULF. LOOKING AHEAD...STRONG HIGH PRES WILL BUILD OVER THE SOUTHERN PLAINS ON SAT WITH INCREASING NORTHERLY WINDS OVER THE WESTERN AND MIDDLE GULF DURING THE UPCOMING WEEKEND. CARIBBEAN SEA... MAIN FEATURE IN THE CARIBBEAN SEA IS AN AREA OF LOW PRESSURE LOCATED ABOUT 130 NM EAST-NORTHEAST OF SAN JUAN PUERTO RICO. THIS 1008 MB SFC LOW IS PRODUCING A LARGE AREA OF CLOUDINESS AND SHOWERS. ALTHOUGH THIS SYSTEM HAS BECOME A LITTLE BETTER ORGANIZED SINCE YESTERDAY...UPPER-LEVEL WINDS ARE UNFAVORABLE FOR ADDITIONAL DEVELOPMENT. HOWEVER...CONDITIONS COULD BECOME MORE FAVORABLE OVER THE NEXT SEVERAL DAYS AS THIS SYSTEM MOVES WESTWARD OR WEST-SOUTHWESTWARD INTO THE BASIN. SCATTERED MODERATE TO STRONG CONVECTION IS MAINLY SE OF THE LOW CENTER FROM 17N-19N BETWEEN 60W-63W. ACCORDING TO THE GFS MODEL... MOISTURE FROM THIS LOW WILL GRADUALLY SPREAD OVER THE UK/US VIRGIN ISLANDS AND PUERTO RICO TONIGHT THROUGH SATURDAY... INCREASING THE CHANCES OF RAIN OVER THOSE AREAS. EASTERLY WINDS HAVE INCREASED TO 20-25 KT N OF PUERTO RICO...THANKS TO A TIGHTENING PRES GRADIENT BETWEEN THE AREA OF LOW PRES AND A SFC HIGH LOCATED NE OF BERMUDAS. THIS GRADIENT IS EXPECTED TO STRENGTHEN FURTHER AND EXPAND W THROUGH AT LEAST FRI NIGHT. A FRONTAL BOUNDARY IS OVER WESTERN CUBA AND THE NW CARIBBEAN. THE FRONT COMBINED WITH A BROAD AREA OF LOW PRES OVER THE W-CENTRAL CARIBBEAN IS PRODUCING SCATTERED SHOWERS AND TSTMS OVER THE AREA...PARTICULARLY WEST OF 80W. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE AFFECTING THE ABC ISLANDS AND THE ISLANDS OFFSHORE OF VENEZUELA. SIMILAR CONVECTION IS FOUND OVER THE CARIBBEAN COAST OF COLOMBIA E OF 76W. THIS ACTIVITY IS PROBABLY ASSOCIATED WITH A SFC TROUGH AND A DIFFLUENT PATTERN ALOFT RELATED TO A BROAD UPPER-LEVEL RIDGE THAT EXTENDS FROM N SOUTH AMERICA NWWD THROUGH E CUBA...THE BAHAMAS AND THE W ATLC. AN EARLIER QUIKSCAT PASS SHOWED VERY WELL THE WIND SHIFT ASSOCIATED WITH THIS SFC TROUGH THAT EXTENDS ALONG 19N82W 15N81W 14N75W. THIS ACTIVITY IS MOVING EWD WITH THE MID LEVEL FLOW. ATLANTIC OCEAN... THE STATIONARY FRONT ASSOCIATED WITH THE UPPER TROUGH IN THE GULF OF MEXICO EXTENDS INTO THE W ATLC OFF THE COAST OF SOUTH CAROLINA THROUGH THE STRAITS OF FLORIDA AND WESTERN CUBA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALONG THE IMMEDIATE FRONTAL BOUNDARY. BROAD UPPER LEVEL RIDGE FROM THE CARIBBEAN EXTENDS A NARROW UPPER RIDGE E OF THE FRONT ACROSS CUBA...THE BAHAMAS AND THE W ATLC BEYOND 31N75W. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS HELPING TO INDUCE CONVECTIVE ACTIVITY ALONG THE FRONT. BROAD UPPER HIGH OVER THE N/CENTRAL ATLC CONTINUES TO MOVE N OF THE REGION WHILE A LARGE UPPER-LEVEL LOW CONTINUES TO SPIN OVER THE E-CENTRAL ATLC. A SURFACE RIDGE ANCHORED BY A 1024 MB HIGH LOCATED NE OF BERMUDAS IS BETWEEN THE STATIONARY FRONT AND A 1009 MB SFC LOW LOCATED NEAR 27N42W. A SFC TROUGH EXTENDS FROM THE LOW TO NEAR 21N48W. A SURFACE RIDGE REMAINS OVER THE FAR E ATLC WITH A 1017 MB SURFACE HIGH LOCATED W OF THE CANARY ISLANDS NEAR 27N22W. THE TYPICAL E/W UPPER LEVEL RIDGE EXTENDS OVER THE E TROPICAL ATLC ALONG 11N E OF 35W WITH A NARROW UPPER RIDGE AXIS EXTENDING N ALONG 23W TO 34N COVERING THE REMAINDER OF THE E ATLC. $$ GR