000 AXNT20 KNHC 261719 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUN 26 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1645 UTC. ...TROPICAL WAVES... A NEW TROPICAL WAVE HAS MOVED OFF THE COAST OF WESTERN AFRICA AND IS NOW ALONG 18W S OF 18N. INITIAL ESTIMATES HAVE THE WAVE MOVING W AT 15-20 KTS. UPPER AIR DATA FROM DAKAR DEPICT A ENE-SE WIND SHIFT AT 850 MB SUGGESTING THAT THE WAVE PASSED THE STATION THIS MORNING. BROAD LOW TO MID LEVEL CIRCULATION IS SEEN ON VISIBLE SATELLITE IMAGERY. SOUTHEASTERLY UPPER FLOW HAS DISPLACED ASSOCIATED CONVECTION W OF THE AXIS. SCATTERED MODERATE CONVECTION IS FROM 6N-11N BETWEEN THE AXIS AND 22W. A TROPICAL WAVE IS OVER FRENCH GUIANA ALONG 53W S OF 11N MOVING W 15-20 KT. THE SOUNDING FROM CAYENNE...FRENCH GUIANA... INDICATES THAT THE WAVE PASSED THE STATION LATE WED OR EARLY THIS MORNING. SFC OBS IN SURINAME SHOW PRESSURE CONTINUING TO FALL IN ADVANCE OF THE WAVE. CLUSTERS OF SCATTERED MODERATE CONVECTION SURROUND THE NORTHERN PORTION OF THE WAVE FROM 9N-10N BETWEEN 48W-57W. A TROPICAL WAVE IS ALONG 84W S OF 20N MOVING W 15-20 KT. BROAD CIRCULATION IS SEEN ON VISIBLE SATELLITE IMAGERY. ABUNDANT DEEP-LAYERED MOISTURE LIES ALONG THE WAVE AXIS WITH SCATTERED SHOWERS AND THUNDERSTORMS IN THE SW CARIBBEAN...COSTA RICA...AND NICARAGUA. AN ADDITIONAL CLUSTER OF MODERATE TO STRONG CONVECTION IS IN THE NW CARIBBEAN FROM 15N-19N BETWEEN 83W AND THE YUCATAN PENINSULA. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N12W 9N20W 5N30W 7N40W TO S AMERICA NEAR 5N53W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 20W-30W. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH REMAINS SITUATED OVER THE GULF OF MEXICO WITH ITS AXIS EXTENDING FROM LOUISIANA TO THE BAY OF CAMPECHE. AN UPPER LEVEL RIDGE EXTENDS FROM THE NW CARIBBEAN OVER THE REMAINDER OF THE GULF REGION INTO THE W ATLC. SWLY UPPER FLOW BETWEEN THESE UPPER LEVEL FEATURES IS SUPPLYING THE E GULF WITH A DEEP LAYER OF TROPICAL MOISTURE. UPPER DIVERGENCE IN THIS REGION COUPLED WITH INSTABILITY AHEAD OF A TROPICAL WAVE IN THE NW CARIBBEAN IS SUPPORTING A BROAD BAND OF SCATTERED SHOWERS AND THUNDERSTORMS OVER THE YUCATAN PENINSULA AND SERN GULF WATERS E OF 94W AND S OF 28N. AT THE SFC...A WEAK PRESSURE PATTERN IS MAINTAINING LIGHT WINDS ACROSS THE BASIN. ONSHORE WINDS COUPLED WITH DIVERGENCE OVER THE GULF COAST STATES IS GENERATING ISOLATED THUNDERSTORMS ALONG THE COAST BETWEEN HOUSTON TEXAS AND PANAMA CITY FLORIDA. LITTLE CHANGE IS EXPECTED OVER THE WEEKEND. CARIBBEAN... AN UPPER LEVEL HIGH BETWEEN CUBA AND THE CAYMAN ISLANDS EXTENDS A RIDGE OVER THE WESTERN CARIBBEAN. STRONG SWLY UPPER FLOW AROUND THIS RIDGE IS TRANSPORTING CONVECTION ASSOCIATED WITH THE TROPICAL WAVE NORTHEASTWARD INTO THE YUCATAN CHANNEL. UPPER DIVERGENCE COUPLED WITH THE SOUTHERN EXTENT OF THE WAVE IS ENHANCING AN AREA OF SHOWERS AND THUNDERSTORMS IN SW CARIBBEAN ALONG THE COAST OF PANAMA. A UPPER HIGH IN THE ATLANTIC EXTENDS A RIDGE ACROSS THE EASTERN CARIBBEAN. IN BETWEEN...A WEAK TROUGH LIES OVER HISPANIOLA AND THE CENTRAL CARIBBEAN TO 13N. MODERATE SUBSIDENCE IS KEEPING THE CARIBBEAN MOSTLY CLEAR EAST OF 78W WITH THE EXCEPTION OF A FEW LOW-TOPPED TRADE WIND SHOWERS N OF 14N. A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE IN THE ATLANTIC AND LOWER PRESSURE OVER SOUTH AMERICA CONTINUES TO PRODUCE MODERATE TO STRONG TRADE WINDS. CONVECTION AHEAD OF AN ATLANTIC TROPICAL WAVE IS EXPECTED TO AFFECT THE WINDWARD ISLANDS LATER TODAY. ATLANTIC... AN UPPER LEVEL RIDGE EXTENDS FROM THE NW CARIBBEAN ACROSS THE FLORIDA PENINSULA AND INTO THE W ATLC. DIVERGENCE ALONG THE NORTHERN EXTENT OF THIS RIDGE IS SUPPORTING AN AREA OF SHOWERS AND THUNDERSTORMS FROM 26N-29N BETWEEN THE FLORIDA COAST AND 77W. FURTHER EAST... A DEEP-LAYERED TROUGH OVER THE N ATLC EXTENDS A COLD FRONT TO 31N60W WHERE IS BEGINS TO DISSIPATE AND CONTINUES AS A SFC TROUGH TO 28N66W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 100 NM OF THIS BOUNDARY. A CLUSTER OF THUNDERSTORMS DRIVEN BY DIVERGENCE AT THE BASE OF AN UPPER SHORTWAVE TROUGH IS FROM 24N-26N BETWEEN 59W-62W. THE REMAINDER OF THE ATLC IS DOMINATED BY A LARGE RIDGE ANCHORED BY A 1028 MB SFC HIGH NE OF THE AZORES. A MOSTLY DRY AND STABLE ATMOSPHERE IS ASSOCIATED WITH THIS RIDGE IS ALSO PRODUCING A WIDE SWATH OF MODERATE TO STRONG ELY FLOW ACROSS THE N TROPICAL ATLC INTO THE CARIBBEAN SEA. THIS HIGH WILL REMAIN NEARLY STATIONARY DURING THE NEXT 24-48 HOURS. $$ WADDINGTON