000 AXNT20 KNHC 172356 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED SEP 17 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 BETWEEN THE WEST AFRICAN COAST AND THE CAPE VERDE ISLANDS ALONG 21W S OF 18N MOVING W 10-15 KT. NO DEEP CONVECTION IS ASSOCIATED WITH THE WAVE. A VORTICITY MAXIMUM IS SEEN NEAR THE NORTHERN END OF THE WAVE AXIS WHILE THE TPW PRODUCT FROM CIMSS INDICATES A BULGE OF MOISTURE IN THIS AREA. A LOW AMPLITUDE TROPICAL WAVE IS ALONG 40W S OF 14N MOVING W 10 KT. ISOLATED SHOWERS ARE OCCURRING NEAR THE INTERSECTION OF THE WAVE AND THE ITCZ. THE TROPICAL WAVE THAT WAS PREVIOUSLY ALONG 64W IS RELOCATED FURTHER WEST BASED ON SURFACE DATA AND SATELLITE PICTURES. ITS AXIS IS CURRENTLY ALONG 68W EXTENDING FROM THE MONA PASSAGE TO NORTHERN VENEZUELA NEAR 10N68W MOVING W NEAR 15 KT. NOAA BUOY 42059 IS REPORTING SE WINDS INDICATING THE PASSAGE OF THE WAVE AXIS. THE WAVE IS ENHANCING SCATTERED MODERATE CONVECTION OVER NORTHERN VENEZUELA AND ACROSS THE WESTERN PORTION OF PUERTO RICO. A TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 85W S OF 20N MOVING W NEAR 10 KT. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE ALONG THE WAVE AXIS NE HONDURAS...PARTS OF NICARAGUA AND NORTHERN COSTA RICA. THE WAVE EXTENDS INTO THE EPAC. A TROPICAL WAVE IS OVER SE MEXICO ALONG 95 S OF 18N MOVING W NEAR 10 KT. ALL CONVECTION IS IN THE E PACIFIC REGION ALONG THE COAST OF MEXICO IN THE GULF OF TEHUANTEPEC. SEE THE TWDEP FOR FURTHER INFORMATION. A RAINFALL AMOUNT OF 4.94 INCHES/24 HOURS WAS REPORTED THIS MORNING IN MERIDA MEXICO WITH THE PASSAGE OF THIS WAVE YESTERDAY EVENING. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 10N25W 10N38W 10N43W 10N62W. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 7N-14N W OF 50W. SIMILAR CONVECTION IS NOTED FROM NORTHERN SURINAME TO NE VENEZUELA. ...DISCUSSION... GULF OF MEXICO... A STATIONARY FRONT IS DRAPED FROM THE W ATLC ACROSS NE FLORIDA INTO THE GULF N OF TAMPA ALONG 27N90W INTO THE BAY OF CAMPECHE. MODERATE NLY WINDS ARE N AND W OF THE FRONT ESPECIALLY OFF THE SE MEXICAN COAST...WITH MORE EASTERLY WINDS AHEAD OF THE FRONT WHERE A WEAK SURFACE RIDGE IS IN PLACE. SCATTERED SHOWERS ARE ASSOCIATED WITH THE FRONTAL BOUNDARY PARTICULARLY SOUTH OF 25N AND W OF 90W. UPPER DIFFLUENCE ASSOCIATED WITH AN UPPER-LEVEL HIGH LOCATED NEAR TAMPICO MEXICO IS HELPING TO INDUCE THIS CONVECTIVE ACTIVITY. A DEEP LAYERED TROUGH OVER THE EASTERN CONUS DIPS INTO THE NE CORNER OF THE GULF. THIS TROUGH SUPPORTS THE AFOREMENTIONED FRONT. MOSAIC DOPPLER RADAR FROM THE SE U.S. INDICATES SCATTERED SHOWERS AND TSTMS ALONG THE FRONTAL BOUNDARY OVER N FLORIDA WITH SOME SHOWERS AND TSTMS OVER THE REMAINDER OF THE FLORIDA PENINSULA IN RESPONSE TO SEA BREEZE CONVERGENCE PROCESSES. THE FRONT IS FORECAST TO BECOME DIFFUSE ON THU...BUT A SFC TROUGH WILL PERSIST OVER THE WESTERN GULF THROUGH AT LEAST SAT. HIGH PRES BEHIND THE FRONT WILL BUILT IN DURING THE UPCOMING WEEKEND PRODUCING MODERATE ELY WINDS. CARIBBEAN SEA... A COUPLE OF TROPICAL WAVE ARE MOVING WWD ACROSS THE AREA. SEE TROPICAL WAVE SECTION FOR DETAILS. ABUNDANT CLOUDINESS WITH EMBEDDED SHOWERS IS OVER THE CENTRAL CARIBBEAN. THIS ACTIVITY IS BEING AIDED BY A DIFFLUENT PATTERN ALOFT BETWEEN AN UPPER-LEVEL RIDGE WHICH DOMINATES THE WESTERN CARIBBEAN AND CENTRAL AMERICA AND AN UPPER-LEVEL LOW SPINNING JUST N OF PUERTO RICO. THIS PATTERN ALOFT IS ALSO ENHANCING CONVECTION OVER HISPANIOLA AND PUERTO RICO. AN UPPER-LEVEL TROUGH EXTENDS FROM THE LOW LOCATED NEAR 21N67W THROUGH PUERTO RICO INTO THE E CARIBBEAN ALONG 66W. MOIST SOUTHWESTERLY FLOW DOWNSTREAM OF THIS TROUGH AXIS IS SUPPORTING SCATTERED SHOWERS OVER THE LESSER ANTILLES. MODERATE TRADE WINDS ARE BLOWING ACROSS THE BASIN WITH THE STRONGEST WINDS UP TO 20 KT...PER AN EARLIER QSCAT PASS OVER THE SOUTH-CENTRAL CARIBBEAN. ATLANTIC OCEAN... WEAK PRES GRADIENT CONTINUES TO DOMINATE THE W ATLC DUE TO THE PRESENCE OF A FRONTAL ZONE NEAR THE SE COAST OF U.S. AND A WEAK SFC TROUGH THAT ENTERS THE AREA NEAR 31N66W...THEN CONTINUES MAINLY SW TO NEAR 24N72W. ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. MOISTURE ASSOCIATED WITH THIS TROUGH IS FORECAST TO REACH SOUTH FLORIDA ON SAT. E OF THIS TROUGH...THERE IS AN AREA OF MODERATE CONVECTION WHICH COVERS FROM 26N-31N BETWEEN 59W-62W. THIS ACTIVITY IS ON THE EAST SIDE OF AN UPPER-LEVEL LOW LOCATED NEAR 32N65W. AN UPPER-LEVEL TROUGH CONNECTS THIS LOW WITH THE ONE LOCATED N OF PUERTO RICO. ANOTHER SFC TROUGH IS ALONG 64W FROM 21N-25N GENERATING SCATTRED MODERATE CONVECTION. A VORTICITY MAXIMUM IS ASSOCIATED WITH THIS TROUGH. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS NEAR 20N61W. UPPER DIFFLUENCE BETWEEN THE UPPER LOW SITUATED NORTH OF PUERTO RICO AND AN UPPER-LEVEL HIGH LOCATED EAST OF THE LESSER ANTILLES IS ENHANCING ALL THIS CONVECTIVE ACTIVITY. A SFC RIDGE ANCHORED ON A HIGH SITUATED NEAR THE AZORES ENVELOPS THE CENTRAL AND EASTERN ATLC RESULTING IN MOSTLY FAIR WEATHER ACROSS THE AREA WITH THE EXCEPTION OF A FRONTAL BOUNDARY THAT ENTERS THE AREA NEAR 31N19W THEN CONTINUES SW TO NEAR 26N25W. SOME SHOWER ACTIVITY IS ASSOCIATED WITH THIS FRONT. SCATTERED MODERATE CONVECTION IS SEEN BETWEEN 51W AND THE LESSER ANTILLES LIKELY ASSOCIATED WITH A WIND SURGE AT LOW LEVEL AND UPPER DIFFLUENCE RELATED TO THE ABOVE MENTIONED UPPER-LEVEL HIGH CENTERED NEAR 15N54W. $$ GR