000 AXNT20 KNHC 191755 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1645 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS E OF THE CAPE VERDE ISLANDS ALONG 26W/27W S OF 18N MOVING W 5-10 KT. THIS WAVE IS BENEATH AN UPPER LEVEL RIDGE AND NO CONVECTION IS NOTED WITH THIS WAVE. TROPICAL WAVE IS ALONG 48W S OF 19N MOVING W NEAR 10 KT. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE WAVE AXIS FROM 13N-17N. TROPICAL WAVE IS ALONG 63W S OF 20N MOVING W 5-10 KT. THIS WAVE IS GENERATING CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 10N-16N BETWEEN 57W AND THE WAVE AXIS. TROPICAL WAVE IS ALONG 73W S OF 19N MOVING W 5-10 KT. ISOLATED SHOWERS ARE OCCURRING WITHIN 180 NM W OF THE WAVE AXIS S OF 18N. THESE SHOWERS ARE BEING SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING FROM CUBA TO THE CENTRAL CARIBBEAN. TROPICAL WAVE IS ALONG 92W S OF 19N MOVING W NEAR 10 KT. WAVE IS ALONG THE W COAST OF YUCATAN PENINSULA WITH ANY ASSOCIATED CONVECTION INLAND OVER CENTRAL AMERICA AND THE E PACIFIC REGION. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 7N14W 8N29W 9N43W 10N55W 10N84W. MODERATE CONVECTION IS FROM 3N-12N BETWEEN 16W-19W. SCATTERED MODERATE CONVECTION IS FROM 10N-13N BETWEEN 58W-61W. CLUSTERS OF MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N-15N BETWEEN 75W-85W...ENHANCED BY UPPER LEVEL DIFFLUENCE E OF AN UPPER RIDGE OVER THE W CARIBBEAN. ...DISCUSSION... GULF OF MEXICO... A WEAK SURFACE TROUGH IS OVER THE W GULF EXTENDING FROM 27N94W TO 21N94W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO DEVELOP OVER THE WESTERN GULF IN RESPONSE TO SURFACE CONVERGENCE WITH THE TROUGH. A WEAKER SURFACE TROUGH IS FROM 29N87W TO 24N85W. UPPER LEVEL SUPPORT FROM AN UPPER LEVEL TROUGH OVER THE SOUTHEAST CONUS AND N GULF IS ENHANCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE FL AND AL COASTLINE. AN UPPER LEVEL RIDGE EXTENDS FROM AN UPPER HIGH OVER CENTRAL MEXICO TO THE NE BRINING MAINLY DRY NW FLOW TO MUCH OF THE CENTRAL AND E GULF WHERE FAIR WEATHER CONDITIONS PREDOMINATE. CARIBBEAN SEA... TWO TROPICAL WAVES ARE OVER THE CARIBBEAN SEA AND CENTRAL AMERICA. SEE ABOVE. DIFFLUENCE IN NORTHERLY FLOW ALOFT IN THE SW CARIBBEAN IS GENERATING SEVERAL CLUSTERS OF MODERATE WITH ISOLATED STRONG CONVECTION S OF 16N W OF 75W TO INLAND OVER CENTRAL AMERICA. 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/ ISOLATED THUNDERSTORMS S OF 15N W OF 75W TO INLAND OVER CENTRAL AMERICA. THE SHOWER ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE ALONG 63W IS MORE WIDESPREAD DUE TO LOW LEVEL SUPPORT E OF THE TROPICAL WAVE ALONG 63W. DEEP LAYER DRY AIR OVER THE NW CARIBBEAN IS LIMITING CONVECTION THERE. ATLANTIC OCEAN... TWO TROPICAL WAVES ARE OVER THE ATLANTIC OCEAN. SEE ABOVE. A STATIONARY FRONT EXTENDS FROM A 1014 MB LOW NEAR 31N73W SW TO 26N79W. THIS FRONT CONTINUES TO WEAKEN...WITH NO CONVECTION NOTED IN THE VICINITY OF THE FRONT. A PRE-FRONTAL SURFACE TROUGH EXTENDS FROM 29N74W TO 24N79W WITH SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF TROUGH AXIS INCLUDING THE CENTRAL AND N BAHAMA ISLANDS. THIS ACTIVITY IS FURTHER BEING ENHANCED BY SOUTHWESTERLY FLOW EAST OF AN UPPER LEVEL TROUGH ALONG THE CONUS E COAST. AN UPPER LEVEL LOW NEAR 25N45W IS GENERATING CLOUDINESS AND POSSIBLE ISOLATED SHOWERS WITHIN 100 NM OF THE LOW CENTER. AN UPPER TROUGH EXTENDING FROM A DEEP LOW NEAR 34N19W IS BRINING CLOUDY CONDITIONS N OF 24N AND E OF 19W ALONG THE NW AFRICAN COAST INCLUDING THE CANARY ISLANDS. IN THE W TROPICAL ATLC SCATTERED MODERATE CONVECTION IS WITHIN 90 NM E OF THE LESSER ANTILLES IN RESPONSE TO DIFFLUENCE W OF AN UPPER HIGH CENTERED NEAR 12N54W. OTHERWISE...THE TYPICAL LARGE E/W UPPER LEVEL RIDGE IS ACROSS THE REMAINDER OF THE TROPICAL ATLC TO 40W BRINGING FAIR WEATHER TO THE CENTRAL AND E TROPICAL ATLC. $$ COHEN/WALLACE