000 AXNT20 KNHC 081155 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU SEP 08 2011 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1145 UTC. ...SPECIAL FEATURES... HURRICANE KATIA IS CENTERED NEAR 32.8N 70.2W AT 08/1200 UTC OR ABOUT 325 MI...520 KM W OF BERMUDA MOVING N AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. MAXIMUM SUSTAINED WIND SPEED IS 80 KT WITH GUSTS TO 95 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/ WTNT22 KNHC FOR MORE DETAILS. KATIA REMAINS UNDER SOME WESTERLY SHEAR AND WITH DRY AIR ENTRAINING INTO THE CIRCULATION LIMITING SCATTERED MODERATE/ISOLATED STRONG CONVECTION TO WITHIN 75/90 NM OF THE CENTER OVER THE E SEMICIRLCE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER THE AREA FROM 27N-36N BETWEEN 62W-70W. LARGE SWELLS GENERATED BY HURRICANE KATIA WILL CONTINUE TO AFFECT MOST OF THE EAST COAST OF THE UNITED STATES...BERMUDA...THE GREATER ANTILLES...AND EAST FACING BEACHES OF THE BAHAMAS DURING THE NEXT FEW DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE THREATENING SURF AND RIP CURRENT CONDITIONS. PLEASE CONSULT PRODUCTS ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES FOR MORE INFORMATION. TROPICAL STORM NATE IS CENTERED NEAR 20.2N 92.4W AT 08/1200 UTC OR ABOUT 125 MI...200 KM W OF CAMPECHE MEXICO AND ABOUT 190 MI...305 KM NE OF COATZACOALCOS MEXICO MOVING SE AT 1 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT5/ WTNT25 KNHC FOR MORE DETAILS. NATE APPEARS TO BE SLOWLY BECOMING BETTER ORGANIZED. SCATTERED MODERATE/ISOLATED STRONG CONVECTION REMAINS SW OF THE CENTER OVER THE W BAY OF CAMPECHE S OF 20N TO INLAND OVER MEXICO BETWEEN 92W-96W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM OF LINE FROM 23N89W TO OVER THE YUCATAN PENINSULA ALONG 19N88W INTO THE FAR W CARIBBEAN AND THE GULF OF HONDURAS TO 15N88W. TROPICAL STORM MARIA IS CENTERED NEAR 13.0N 50.0W AT 08/1200 UTC OR ABOUT ABOUT 760 MI...1225 KM E OF THE WINDWARD ISLANDS MOVING W AT 20 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/ WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. MARIA HAS A RATHER DISORGANIZED APPEARANCE ON SATELLITE IMAGERY. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 12N-16N BETWEEN 42W-53W. ...TROPICAL WAVES... TROPICAL WAVE IN THE E TROPICAL ATLC IS ALONG 27W/28W S OF 14N WITH A 1011 MB LOW ALONG THE WAVE NEAR 9N MOVING W NEAR 15 KT. THE FIRST VISIBLE SATELLITE IMAGES SHOW THE LOW CENTER IS NO LONGER A CLOSED CIRCULATION AND MAY BE DROPPED FROM THE NEXT SURFACE ANALYSIS. WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY AND IS WELL DEFINED IN THE UPPER LEVEL SATELLITE WINDS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60/75 NM OF LINE FROM 13N24W TO 11N29W. TROPICAL WAVE IS IN THE W ATLC/NE CARIBBEAN ALONG 63W/64W S OF 22N MOVING W-NW 15-20 KT. WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY AND IS WELL DEFINED IN THE UPPER LEVEL SATELLITE WINDS. WAVE IS INTERACTING WITH AN UPPER LOW ENHANCING SCATTERED SHOWERS/THUNDERSTORMS FROM 16N-20N BETWEEN 61W-68W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 16N16W TO 15N18W. THE MONSOON TROUGH AND ITCZ AXIS HAS BEEN DISRUPTED BY THE LACK OF CONFLUENCE IN THE TRADE WINDS AND THE PRESENCE OF TROPICAL STORM MARIA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 120 NM OF COAST OF W AFRICA BETWEEN CENTRAL LIBERIA AND CENTRAL GUINEA-BISSAU. ...DISCUSSION... GULF OF MEXICO... THE PRIMARY CONCERN FOR THE S GULF WATERS IF TROPICAL STORM NATE...SEE SPECIAL FEATURES SECTION ABOVE. A SHARP UPPER TROUGH EXTENDS FROM AN UPPER LOW OVER OHIO THROUGH GEORGIA ACROSS THE FLORIDA PANHANDLE E OF TALLAHASSEE INTO THE GULF ALONG 26N90W TO W OF NATE NEAR 22N96W SUPPORTING A QUASI-STATIONARY FRONTAL BOUNDARY THAT AT 08/0900 UTC ENTERS THE GULF WATERS NEAR TAMPA FLORIDA ALONG 26N87W TO 24N90W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 75 NM EITHER SIDE OF THE FRONT. AN UPPER RIDGE IS OVER THE FAR SE GULF EXTENDING FROM NEAR NATE ACROSS THE N YUCATAN PENINSULA TO OVER THE STRAITS OF FLORIDA AND EXTREME S FLORIDA ENHANCING THE SHOWER ACTIVITY ASSOCIATED WITH NATE. VERY DRY AIR ALOFT IS W OF THE UPPER TROUGH AXIS AND GIVING THE NW GULF REMARKABLE CLEAR SKIES THIS MORNING NW OF A LINE FROM CEDAR KEY FLORIDA ALONG 26N90W TO NEAR TUXPAN MEXICO. NATE WILL MOVE SLOWLY NE THROUGH FRI MORNING THEN WILL TURN NW EARLY SAT MORNING AND BECOME A HURRICANE BEFORE IT TURNS W TOWARD MEXICO. STATIONARY FRONT WILL WEAKEN INTO A TROUGH OVER THE E GULF LATER TODAY. CARIBBEAN SEA... TROPICAL STORM NATE IS PRODUCING SHOWERS/THUNDERSTORMS OVER THE YUCATAN PENINSULA AND IN THE GULF OF HONDURAS...SEE SPECIAL FEATURES SECTION ABOVE. WEAK UPPER FLOW DOMINATES THE CARIBBEAN. THE MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN FROM COLOMBIA NEAR 11N75W ALONG 10N80W ACROSS NICARAGUA NEAR 11N84W WITH SCATTERED SHOWERS/THUNDERSTORMS S OF 12N BETWEEN COLOMBIA AND NICARAGUA. DRY STABLE AIR ALOFT DOMINATES THE W/CENTRAL CARIBBEAN BETWEEN 75W-86W. HOWEVER...SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE OVER HAITI FROM 18N-21N BETWEEN 72W-74W. SHOWER/THUNDERSTORM ACTIVITY OVER THE NE CARIBBEAN ASSOCIATED WITH THE TROPICAL WAVE. EASTERLY TRADE WINDS ARE USHERING IN LOW LEVEL SHOWERS ACROSS THE E CARIBBEAN E OF 72W. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER REMARKABLY CLEAR SKIES AGAIN THIS MORNING. MARIA IS FORECAST TO APPROACH THE LEEWARD/VIRGIN ISLANDS EARLY SAT. THE TROPICAL WAVE OVER THE NE CARIBBEAN WILL MOVE ACROSS THE N CARIBBEAN TODAY BEFORE LIFTING N OVER THE BAHAMAS ON FRI. ATLANTIC OCEAN... A QUASI-STATIONARY FRONT ENTERS THE W ATLC NEAR 32N77W EXTENDING ACROSS FLORIDA INTO THE GULF OF MEXICO JUST S OF DAYTONA BEACH GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS NW OF THE FRONT. THE UPPER RIDGE ASSOCIATED WITH HURRICANE KATIA IS N OF 28N BETWEEN 60W-71W. A WEAKENING CUTOFF UPPER LOW IS TO THE SE OF KATIA CENTERED NEAR 22N59W GENERATING CLUSTERS OF SCATTERED SHOWERS/THUNDERSTORMS FROM 20N-28N BETWEEN 59W-68W. AN UPPER TROUGH COVERS THE REMAINDER OF THE CENTRAL AND INTO E ATLC BETWEEN 25W-45W N OF TROPICAL STORM MARIA SUPPORTING A SURFACE TROUGH THAT EXTENDS THROUGH 32N35W ALONG 26N40W TO 26N46W AND GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 28N-32N BETWEEN 30W AND THE TROUGH AXIS. A WEAKENING BROAD SURFACE RIDGE DOMINATES THE ATLC N OF 20N BETWEEN 20W-65W WITH A WEAKNESS IN THE VICINITY OF THE ABOVE SURFACE TROUGH. HURRICANE KATIA IS N OF THE DISCUSSION AREA WITH TROPICAL STORM CONDITIONS CONTINUING N OF 29N FOR TODAY. SURFACE RIDGE WILL BUILD ACROSS THE AREA IN THE WAKE OF KATIA TODAY THROUGH SAT. TROPICAL STORM MARIA WILL REACH THE BRUSH BY THE LEEWARD/VIRGIN ISLANDS SAT AND SUN BEFORE MOVING E OF THE BAHAMAS DURING THE FIRST OF THE WEEK. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW