000 AXNT20 KNHC 300557 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0345 UTC. ...SPECIAL FEATURES... HURRICANE GUSTAV IS CENTERED NEAR 19.7N 80.7W AT 30/0600 UTC OR OR ABOUT 43 NM NORTHEAST OF GRAND CAYMAN AND ABOUT 275 NM EAST-SOUTHEAST OF THE WESTERN TIP OF CUBA MOVING NW AT 10 KT. AN AIR FORCE RESERVE HURRICANE HUNTER PLANE RECENTLY REPORTED A MINIMUM CENTRAL PRESSURE OF 971 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. 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. GUSTAV REMAINS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. GUSTAV RECENTLY HAS DEVELOPED A 25 NM WIDE EYE AS REPORTED BY AIR FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT. WHILE GUSTAV HAS GOOD OUTFLOW IN ALL QUADRANTS...WATER VAPOR IMAGERY SUGGESTS WESTERLY FLOW ASSOCIATED WITH THE GULF OF MEXICO TROUGH UNDERCUTTING THE OUTFLOW. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 75 NM IN THE NW QUADRANT WITH SCATTERED MODERATE/STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 18N-21N BETWEEN 77W-82W. OUTER RAINBANDS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER THE AREA FROM 16N-22N BETWEEN 75W-85W INCLUDING JAMAICA AND PORTIONS OF CUBA. TROPICAL STORM HANNA IS CENTERED NEAR 22.1N 65.3W AT 30/0300 UTC OR ABOUT 226 NM NORTH OF SAN JUAN PUERTO RICO AND ABOUT 326 NM EAST OF GRAND TURK ISLAND MOVING WNW AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 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 WESTERLY SHEAR RESULTING IN A PARTIALLY EXPOSED LOW LEVEL CENTER AND THE OUTFLOW TO THE E OF THE CENTER. LARGE AREA OF SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 21N-23N BETWEEN 61W-64W WITH SCATTERED MODERATE/STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 19N-24N BETWEEN 60W-65W WHICH IS JUST NE OF THE LEEWARD ISLANDS. TROPICAL WAVE IS ALONG 22W/23W S OF 19N WITH A 1008 MB SURFACE LOW ALONG THE WAVE NEAR 14N MOVING W NEAR 15 KT. A BROAD MID LEVEL CYCLONIC ROTATION IS OBSERVED ON SATELLITE IMAGERY ASSOCIATED CONVECTION REMOVED FROM THE LOW. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90/120 NM OF LINE FROM 18N20W TO 14N26W. CONDITIONS APPEAR CONDUCIVE FOR DEVELOPMENT AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 44W FROM 13N TO 22N WITH A 1011 MB LOW ALONG THE WAVE AXIS NEAR 19N MOVING WNW NEAR 10 KT. HIGH AMPLITUDE WAVE WITH A BROAD INVERTED-V SATELLITE IMAGERY SIGNATURE OBSERVED WELL N OF THE ITCZ. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 17N-24N BETWEEN 39W-47W. TROPICAL WAVE IS ALONG 62W S OF 12N MOVING W NEAR 15-20 KT. THIS WAVE IS INLAND OVER SOUTH AMERICA AND REMAINS ILL-DEFINED WHILE LACKING ANY SHOWERS OR DEEP CONVECTION. THIS WAVE MAY BE DROPPED FROM THE SURFACE ANALYSIS AT 0600 UTC BUT IT MAY BE NECESSARY TO RE-INTRODUCED THE WAVE WHEN IT REACHES THE E PACIFIC REGION. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 8N25W 12N40W 10N53W 11N60W. THE ITCZ CONTINUES TO BE DISRUPTED BY THE TROPICAL WAVES. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 5N-14N BETWEEN 20W-39W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER TROUGH DOMINATES MOST OF THE GULF EXTENDING S ACROSS THE FLORIDA NEAR PENSACOLA TO THE NE YUCATAN PENINSULA. UPPER RIDGE OVER MEXICO EXTENDS ACROSS THE FAR W GULF W OF 94W 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 E OF 85W TO OVER THE FLORIDA PENINSULA. MODERATE SUBSIDENCE/DRY AIR ARE NOTED WITHIN 120 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. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE OVER THE LEEWARD AND VIRGIN ISLANDS ASSOCIATED WITH OUTER RAINBANDS OF T.S. HANNA. BROAD UPPER HIGH ASSOCIATED WITH GUSTAV IS DOMINATING THE W CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE GULF OF HONDURAS S OF 17N TO THE COAST OF HONDURAS BETWEEN 84W-87W AND BETWEEN 10N-15N W OF 82W TO INLAND OVER N COSTA RICA AND NICARAGUA. AN UPPER HIGH IS CENTERED OVER THE LEEWARD ISLANDS EXTENDING A RIDGE OVER THE E CARIBBEAN TO 66W. MODERATE SUBSIDENCE AND DRY AIR ARE OVER THE SE CARIBBEAN LIMITING SHOWERS OVER THE AREA INCLUDING THE WINDWARD ISLANDS. ATLANTIC OCEAN... MAIN FOCUS FOR THE ATLC IS IN THE VICINITY NE OF THE LEEWARD/ VIRGIN ISLANDS AS T.S. HANNA CONTINUES TRACKING WNW...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 28N ACROSS THE BAHAMAS AND CUBA W OF 74W TO OVER THE FLORIDA PENINSULA AND THROUGH THE FLORIDA STRAITS. AN UPPER LOW IS N OF THE MONA PASSAGE NEAR 23N68W WHICH IS GENERATING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS WITHIN 75/90 NM OF LINE FROM 30N65W TO 25N71W. THIS UPPER LOW IS RESPONSIBLE FOR THE UPPER LEVEL SHEAR ASSOCIATED WITH T.S. HANNA. A SHARP UPPER TROUGH IS IN THE CENTRAL ATLC EXTENDING THROUGH 32N47W SSE TO 19N44W INDUCING AN UPPER RIDGE TO THE W FROM NEAR T.S. HANNA NNE TO BEYOND 32N55W. ANOTHER UPPER TROUGH IS BEGINNING TO DIG S OVER THE NE ATLC N OF 27N FROM 20W-35W 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 THAT COVERS THE REMAINDER OF THE E ATLC IS BEING SUPPRESSED TO S OF WITH THE AXIS ALONG 20N TO 30W. AT THE SURFACE...A SURFACE RIDGE OF HIGH PRESSURE REMAINS OVER MUCH OF THE ATLC N OF 25N E OF 60W ANCHORED BY A PAIR 1025 MB HIGHS CENTERED N OF THE REGION AND N OF 30N FROM 60W-75W WITH A 1018 MB HIGH N OF BERMUDA. $$ WALLACE