000 AXNT20 KNHC 212356 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUN 21 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... TROPICAL WAVE IS ALONG 36W S OF 16N MOVING W NEAR 20 KT. BROAD LOW-MID LEVEL CYCLONIC TURNING IS EVIDENT ON SATELLITE IMAGERY. UPPER LEVEL FEATURES CONTINUE TO KEEP MOST OF THE CONVECTION W OF THE AXIS. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 4N-10N BETWEEN 35W-42W. TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 75W FROM FAR ERN CUBA TO NRN COLOMBIA MOVING W NEAR 20-25 KT. SATELLITE IMAGERY SHOWS LOW-LEVEL TURNING NEAR 15N. SCATTERED SHOWERS AND TSTMS ARE FROM 15N-17N BETWEEN 70W-73W. THIS CONVECTIVE ACTIVITY IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N12W 7N23W 8N34W 7N38W 5N53W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 5N-7N BETWEEN 20W-26W. ASIDE FROM CONVECTION ASSOCIATED WITH TROPICAL WAVE ALONG 36W...CLUSTERS OF SCATTERED MODERATE ARE WITHIN 200 NM ON EITHER SIDE OF THE ITCZ BETWEEN 41W-48W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL FEATURES DOMINATE THE WEATHER PATTERN IN THE GULF. AN UPPER-LEVEL RIDGE OVER MEXICO EXTENDS INTO THE FAR W GULF. STRONG SUBSIDENCE AROUND THE RIDGE IS MAINTAINING MOSTLY CLEAR CONDITIONS IN THE WRN GULF W OF 95W. A SECOND UPPER RIDGE OVER THE YUCATAN PENINSULA EXTENDS OVER THE SE GULF AND STRAITS OF FLORIDA. IN BETWEEN...A SHORTWAVE TROUGH COVERS THE NRN GULF WITH ITS AXIS STRETCHING FROM THE LOWER MISSISSIPPI VALLEY TO THE BAY OF CAMPECHE. DIVERGENCE BETWEEN THIS TROUGH AND THE RIDGE TO THE SOUTH IS GENERATING A LARGE AREA OF SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE CENTRAL AND EAST GULF EAST OF 95W. MOST INTENSE AREA OF TSTMS ACCORDING TO LIGHTNING DATA IS FROM 25N-28N BETWEEN THE FLORIDA COAST AND 88W. INSTABILITY AHEAD OF A SHORTWAVE TROUGH IS PRODUCING SIMILAR CONVECTIVE ACTIVITY WITHIN 100 NM OF THE COASTLINE FROM GALVESTON TEXAS TO MOBILE ALABAMA. A WEAK PRESSURE PATTERN IS PROVIDING LIGHT AND VARIABLE WINDS ACROSS THE REGION. CARIBBEAN... UPPER LEVEL MOISTURE FROM THE PACIFIC IS STREAMING ACROSS THE YUCATAN PENINSULA AND THE NW CARIBBEAN IN SWLY FLOW AROUND AN UPPER RIDGE LOCATED OVER GUATEMALA. MODERATE TO STRONG SUBSIDENCE ON THE EAST SIDE OF THE RIDGE IS KEEPING THE WRN CARIBBEAN SEA RELATIVELY CLOUD FREE WITH THE EXCEPTION OF CONVECTIVE ACTIVITY IN THE SW CARIBBEAN AS UPPER LEVEL DIFFLUENCE ALOFT IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 12N-15N BETWEEN 81W-83W. TROPICAL WAVE ALONG 75W CONTINUES TO PROPAGATE WESTWARD WITH 20-25 KT SURFACE WINDS REMAINING ACROSS MUCH OF THE CENTRAL AND ERN CARIBBEAN SEA. HIGH PRESSURE BUILDING IN THE W ATLC IS PRODUCING THESE MODERATE TRADE WINDS ACROSS THE BASIN...WITH THE STRONGEST WINDS UP TO 30 KT ALONG THE COAST OF COLOMBIA. ATLANTIC... SCATTERED SHOWERS AND THUNDERSTORMS ARE ACROSS SRN FLORIDA AND INTO THE W ATLC N OF 26N BETWEEN 78W-81W AHEAD OF AN APPROACHING SHORTWAVE TROUGH CURRENTLY OVER THE SERN CONUS AND GULF OF MEXICO. A DEEP-LAYERED TROUGH OVER THE W ATLC EXTENDS A FRONTAL BOUNDARY NORTH OF THE DISCUSSION AREA...HOWEVER...REMNANT ISOLATED SHOWERS AND THUNDERSTORMS REMAIN IN THE ATLC N OF 28N BETWEEN 61W-66W. A LARGE SURFACE RIDGE COVERS THE ENTIRE ATLC BASIN FROM AFRICA TO THE ERN GULF OF MEXICO. THIS RIDGE IS ANCHORED ON A QUASI-STATIONARY 1028 MB HIGH CENTERED NEAR 32N46W. AN E-W ELONGATED UPPER RIDGE EXTENDS FROM THE CAPE VERDE ISLANDS TO THE EAST AND THE FAR SE CARIBBEAN SEA TO THE WEST OVER THE TROPICAL ATLC AND CONTINUES TO ENHANCE CONVECTION ALONG THE ITCZ. $$ HUFFMAN