000 AXNT20 KNHC 192357 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI SEP 19 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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. ...TROPICAL WAVES... A TROPICAL WAVE IS WEST OF THE CAPE VERDE ISLANDS ALONG 28W S OF 17N MOVING W NEAR 10 KT. THIS WAVE IS BENEATH AN UPPER LEVEL RIDGE AND NO CONVECTION IS NOTED WITH THIS FEATURE. A TROPICAL WAVE IS ALONG 49W S OF 19N MOVING W NEAR 10 KT. SMALL SWIRL OF LOW CLOUDS IS ALONG THE WAVE AXIS NEAR 16N. UPPER DIFFLUENCE IS ENHANCING SOME SHOWER ACTIVITY WITHIN 220 NM E OF THE AXIS AND WITHIN 180 NM W OF AXIS FROM 13N-18N. A TROPICAL WAVE...ACCOMPANIED BY A BROAD SURFACE LOW PRESSURE SYSTEM...CONTINUES TO PRODUCE WIDESPREAD CLOUDINESS AND SHOWERS OVER THE LESSER ANTILLES...AND ADJACENT CARIBBEAN AND ATLANTIC WATERS. ITS AXIS IS ALONG 63W SOUTH OF 19N MOVING SLOWLY WWD. THIS SYSTEM HAS BECOME A LITTLE BETTER ORGANIZED TODAY...AND ALTHOUGH UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE...THEY ARE EXPECTED TO BECOME MORE CONDUCIVE FOR SOME ADDITIONAL DEVELOPMENT TO OCCUR OVER THE NEXT COUPLE OF DAYS. A TROPICAL WAVE IS ALONG 74W/75W S OF 19N MOVING W 10-15 KT. SCATTERED MODERATE CONVECTION IS ASSOCIATED WITH THE WAVE OVER THE CENTRAL CARIBBEAN. THESE SHOWERS ARE BEING SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING FROM CENTRAL CUBA TO THE SW CARIBBEAN. A TROPICAL WAVE IS OVER SE MEXICO ALONG 92W S OF 19N MOVING W NEAR 10 KT. MUCH OF THE CONVECTION ASSOCIATED WITH THIS WAVE IS ON THE PACIFIC SIDE. AS THIS WAVE MOVES W IT WILL BECOME ABSORBED INTO A LARGE AREA OF DISTURBED WEATHER SSW OF THE GULF OF TEHUANTEPEC. FOR FURTHER INFORMATION SEE THE TWDEP. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 8N13W 8N25W 7N35W 9N46W 11N60W. A LARGE AREA OF MODERATE TO STRONG CONVECTION IS APPROACHING THE WEST COAST OF AFRICA FROM THE EAST. THIS CONVECTIVE ACTIVITY IS LIKELY ASSOCIATED WITH THE A NEW TROPICAL WAVE. SCATTRED MODERATE CONVECTION IS FROM 3N-10N BETWEEN 18W-21W. THIS ACTIVITY IS MOVING WWD UNDER AN ELY WIND FLOW. SCATTERED SHOWERS ARE ALONG THE REMAINDER OF THE ITCZ AXIS WITH THE EXCEPTION OF A CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION JUST EAST OF TRINIDAD AND TOBAGO IN THE WINDWARD ISLANDS. THIS SHOWER/TSTM ACTIVITY APPEARS TO BE ASSOCIATED WITH THE TROPICAL WAVE OVER THE EASTERN CARIBBEAN. ...DISCUSSION... GULF OF MEXICO... BROAD SURFACE TROUGH COVERS THE WESTERN GULF GENERATING ABUNDANT CLOUDINESS WITH EMBEDDED SHOWERS AND ISOLATED TSTMS. THE TROUGH AXIS IS ROUGHLY ALONG 94W. SURFACE DATA CLEARLY INDICATES THE WIND SHIFT ASSOCIATED WITH THE TROUGH AXIS. A SFC RIDGE DOMINATES THE SE CONUS AND THE NE PORTION OF THE GULF. THE TROUGH IS EXPECTED TO PERSIST OVER THE WESTERN GULF DURING THE UPCOMING WEEKEND AND GRADUALLY DISSIPATE. UPPER DIFFLUENCE BETWEEN A RIDGE THAT COVERS THE ENTIRE GULF AND AN UPPER-LEVEL LOW SPINNING OVER THE EASTERN U.S. IS SUPPORTING SOME SHOWER AND TSTM ACTIVITY OVER THE NE CORNER OF THE GULF NEAR THE FLORIDA PANHANDLE. A GOOD AMOUNT OF UPPER-LEVEL MOISTURE IS SEEN OVER THE GULF REGION WHILE SUBSIDENCE/DRY AIR DOMINATES THE FLORIDA PENINSULA AND THE ADJACENT ATLANTIC WATERS. CARIBBEAN SEA... ATTENTION REMAINS FOCUSED ON THE ACTIVE TROPICAL WAVE LOCATED OVER THE EASTERN CARIBBEAN THAT IS PRODUCING WIDESPREAD CLOUDINESS AND SHOWERS OVER THE LESSER ANTILLES AND ADJACENT CARIBBEAN AND ATLANTIC WATERS. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION COVER THE AREA FROM 11N-18N BETWEEN 56W-61W MORE CONCENTRATED N OF 14N. MOISTURE AHEAD OF THE WAVE AXIS HAS ALREADY REACHED THE UK/US VIRGIN ISLANDS WITH THE SAN JUAN DOPPLER RADAR SHOWING SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED TSTMS MOVING WWD ACROSS THESE ISLANDS. THE GFS COMPUTER MODEL HAS THE DEEP TROPICAL MOISTURE ASSOCIATED WITH THIS WAVE SPREADING OVER THESE ISLANDS AND THE EASTERN CARIBBEAN LATE TONIGHT INTO SATURDAY...AND OVER DOMINICAN REPUBLIC ON SUNDAY AS THE WAVE CONTINUES TO MOVE SLOWLY WWD. SEE ABOVE FOR MORE DETAILS. ELSEWHERE...CONVECTION HAS FLARED UP ONCE AGAIN OVER CUBA AND HISPANIOLA. SCATTERED MODERATE CONVECTION DOTS PARTS OF CENTRAL AMERICA AS WELL AS NORTHERN COLOMBIA AND WESTERN VENEZUELA WHERE THERE IS A TROPICAL WAVE. MOIST SOUTHWESTERLY FLOW ALOFT OVER THE CENTRAL AND E CARIBBEAN IN A BROAD UPPER LEVEL TROUGH THAT EXTENDS FROM CENTRAL CUBA TO NICARAGUA IS PROMOTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE CENTRAL CARIBBEAN. A BROAD AREA OF LOW PRESSURE HAS FORMED IN THIS AREA JUST EAST OF HONDURAS-NICARAGUA BORDER...BUT THE ABOVE MENTIONED UPPER-LEVEL WINDS/TROUGH ARE CURRENTLY NOT FAVORABLE FOR ADDITIONAL DEVELOPMENT. THE RIDGE THAT DOMINATES THE GULF OF MEXICO ALSO EXTENDS OVER THE WESTERN CARIBBEAN AND CENTRAL AMERICA HELPING TO INDUCE CONVECTION ACROSS THE AREA. MODERATE TRADE WINDS ARE NOTED ACROSS THE BASIN. ATLANTIC OCEAN... A WEAKENING FRONTAL SYSTEM EXTENDS FROM A 1014 MB LOW LOCATED NEAR 31N72W TO THE NW BAHAMAS NEAR 25N78W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 100 NM OF FRONT. THIS ACTIVITY IS BEING ENHANCED BY SOUTHWESTERLY FLOW EAST OF AN UPPER LEVEL TROUGH ALONG THE CONUS E COAST THAT ALSO SUPPORTS THE ABOVE MENTIONED FRONT. THIS TROUGH DIGS INTO THE CARIBBEAN SEA ACROSS CENTRAL CUBA. N TO NE WINDS OF 15-20 KT ARE BEHIND THE FRONT OVER THE FAR NW PORTION OF THE DISCUSSION AREA. FURTHER EAST...A BROAD UPPER-LEVEL LOW IS SPINNING OVER THE CENTRAL ATLC NEAR 26N45W. ONLY ISOLATED SHOWERS ARE RELATED TO THIS UPPER-LEVEL FEATURE. A PAIR OF TROPICAL WAVES ARE MOVING WWD ACROSS THE TROPICAL ATLC...AND A NEW ONE APPEARS TO MOVE OFF THE WEST AFRICAN COAST. N OF 20N...A SURFACE RIDGE DOMINATES THE FORECAST REGION BRINGING MOSTLY FAIR WEATHER TO MUCH OF THE AREA. STRONG UPPER-LEVEL HIGH LOCATED INLAND OVER WEST AFRICA HAS A RIDGE EXTENDING WWD TO ABOUT 38W ENVELOPING THE CAPE VERDE ISLANDS. $$ GR