000 AXNT20 KNHC 301203 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT AUG 30 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... HURRICANE GUSTAV IS CENTERED NEAR 20.8N 81.6W AT 30/1200 UTC OR OR ABOUT 75 NM SOUTHEAST OF THE ISLE OF YOUTH CUBA MOVING N-NW AT 10 KT. THE CENTRAL PRESSURE IS DOWN TO 965 MB...A DROP OF ABOUT 24 MB IN 24 HOURS. MAXIMUM SUSTAINED WIND SPEED IS 100 KT WITH HIGHER GUSTS. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. DATA FROM AN AIR FORCE RECONNAISSANCE AIRCRAFT INDICATE THAT GUSTAV CONTINUES TO RAPIDLY STRENGTHEN AND NOW IS A DANGEROUS CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON HURRICANE SCALE...THE SECOND MAJOR HURRICANE OF THE 2008 ATLANTIC HURRICANE SEASON. FURTHER STRENGTHENING IS POSSIBLE IN THE SOUTHERN GULF OF MEXICO. OUTFLOW REMAINS GOOD IN ALL QUADRANTS. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 60 NM IN THE NE QUADRANT AND WITHIN 90 NM OF THE CENTER ELSEWHERE. SCATTERED MODERATE/STRONG CONVECTION COVERS THE REMAINDER OF THE AREA FROM 18N-22N BETWEEN 78.5N-83.5W. OUTER RAINBANDS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER THE AREA FROM 17N-23N BETWEEN 77W-84W INCLUDING W JAMAICA AND PORTIONS OF CUBA. TROPICAL STORM HANNA IS CENTERED NEAR 21.9N 66.3W AT 30/0900 UTC OR ABOUT 210 NM NORTH OF SAN JUAN PUERTO RICO AND ABOUT 270 NM EAST OF GRAND TURK ISLAND MOVING W AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. HANNA CONTINUES TO EXPERIENCE SW SHEAR RESULTING IN A PARTIALLY EXPOSED LOW LEVEL CENTER AND THE OUTFLOW TO THE N AND E OF THE CENTER. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 45 NM OF LINE FROM 20N63W TO 23N64W WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 18N-25N BETWEEN 60W-66W. TROPICAL WAVE IS ALONG 23W S OF 20N WITH A 1005 MB SURFACE LOW ALONG THE WAVE NEAR 14.5N MOVING W 10-15 KT. A BROAD MID LEVEL CYCLONIC ROTATION IS OBSERVED ON SATELLITE IMAGERY ASSOCIATED CONVECTION MOSTLY REMOVED FROM THE LOW. SCATTERED STRONG CONVECTION IS WITHIN 30 NM EITHER SIDE OF THE N PORTION OF THE WAVE BETWEEN 17N-19N. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVER THE REMAINDER OF THE AREA WITHIN 90 NM OF LINE FROM 18N21W TO 14N27W AND SMALL CLUSTERS WITHIN45 NM OF THE LOW CENTER. CONDITIONS APPEAR CONDUCIVE FOR DEVELOPMENT AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS FROM 25N43W THROUGH A 1009 MB LOW NEAR 19N44.5W TO 16N45W MOVING WNW NEAR 10 KT. BROAD INVERTED-V SATELLITE IMAGERY CURVATURE IS OBSERVED WELL N OF THE ITCZ. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 18N-25N BETWEEN 42W-45W. TROPICAL WAVE THAT WAS ALONG 62W HAS BEEN DROPPED FROM THE ANALYSIS. IT MAY BE NECESSARY TO RE-INTRODUCED THE WAVE WHEN IT REACHES THE E PACIFIC REGION. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 16N16W 11N25W 9N32W 11N45W 10N51W 11N61W. THE ITCZ CONTINUES TO BE DISRUPTED BY THE TROPICAL WAVE IN THE SPECIAL FEATURES. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N-12N BETWEEN 20W-40W WITH CLUSTERS OF SCATTERED MODERATE CONVECTION WITHIN 150 NM OF THE SW COAST OF AFRICA BETWEEN 5N-10N. ...DISCUSSION... GULF OF MEXICO... HURRICANE GUSTAV IS BECOMING A CONCERN FOR THE SE GULF AND THE FLORIDA STRAITS AS IT CONTINUES ON ITS NW TRACK ACROSS THE NW CARIBBEAN...SEE SPECIAL FEATURES ABOVE. BROAD UPPER TROUGH DOMINATES MOST OF THE GULF EXTENDING S INTO THE GULF NEAR MOBILE ALABAMA TO THE NE YUCATAN PENINSULA. UPPER RIDGE OVER MEXICO EXTENDS ACROSS THE FAR W GULF W OF 90W AND IS PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER THE W GULF W OF 90W. THE UPPER RIDGE ASSOCIATED WITH HURRICANE GUSTAV IS PROVIDING UPPER LEVEL DIFFLUENCE E OF THE UPPER TROUGH TO GENERATE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS S OF 28N E OF 87W TO OVER THE FLORIDA PENINSULA AND THROUGH THE FLORIDA STRAITS. MODERATE SUBSIDENCE AND DRY AIR ARE NOTED WITHIN 90 NM OF THE UPPER TROUGH AXIS N OF 24N. CARIBBEAN SEA... THE MAIN CONCERN CONTINUES TO BE HURRICANE GUSTAV FOR THE NW CARIBBEAN...SEE SPECIAL FEATURES ABOVE. ISOLATED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS REMAIN OVER THE N LEEWARD ISLANDS AND THE VIRGIN ISLANDS ASSOCIATED WITH OUTER RAINBANDS OF T.S. HANNA. BROAD UPPER HIGH ASSOCIATED WITH GUSTAV IS DOMINATING THE CARIBBEAN W OF 70W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE W CARIBBEAN N OF 13N W OF 77W. AN UPPER HIGH IS CENTERED JUST E OF GUADELOUPE IN THE LEEWARD ISLANDS EXTENDING A RIDGE OVER THE E CARIBBEAN TO 70W. MODERATE SUBSIDENCE AND DRY AIR ARE OVER THE E CARIBBEAN LIMITING SHOWERS OVER THE AREA INCLUDING THE WINDWARD ISLANDS WITH THE EXCEPTION OF THE ACTIVITY ASSOCIATED T.S. HANNA OVER THE LEEWARD/VIRGIN ISLANDS. ATLANTIC OCEAN... MAIN FOCUS FOR THE ATLC IS OVER THE SW ATLC IN ASSOCIATION WITH HURRICANE GUSTAV AND IN THE VICINITY NE OF THE LEEWARD/VIRGIN ISLANDS WITH T.S. HANNA...SEE SPECIAL FEATURES ABOVE. THE UPPER HIGH ASSOCIATED WITH HURRICANE GUSTAV IN THE CARIBBEAN EXTENDS ACROSS CUBA AND THE BAHAMAS OVER THE FAR W ATLC PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 29N W OF 76W ACROSS THE N BAHAMA ISLANDS AND CUBA TO OVER THE FLORIDA PENINSULA AND THROUGH THE FLORIDA STRAITS. AN UPPER LOW REMAINS N OF THE MONA PASSAGE NEAR 23N68W AND IS RESPONSIBLE FOR THE UPPER LEVEL SHEAR ASSOCIATED WITH T.S. HANNA. A SHARP UPPER TROUGH IS IN THE CENTRAL ATLC EXTENDING THROUGH 32N49W SSE TO 19N45W. ANOTHER UPPER TROUGH CONTINUES TO DIG S OVER THE NE ATLC N OF 26N FROM 19W-32W INDUCING AND AMPLIFYING AN UPPER RIDGE TO THE W WHICH IS ENHANCING THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE IN THE CENTRAL ATLC. THE E/W UPPER RIDGE IS BEGINNING TO BREAKDOWN OVER THE E ATLC AND APPEARS TO BECOMING ASSOCIATED WITH THE TROPICAL WAVE IN THE SPECIAL FEATURES. ALSO AT THE SURFACE...A SURFACE RIDGE OF HIGH PRESSURE REMAINS OVER MUCH OF THE ATLC N OF 26N E OF 58W AND N OF 28N E OF 75W ANCHORED BY A SERIES OF HIGHS N OF THE REGION. $$ WALLACE