000 AXNT20 KNHC 091807 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI SEP 09 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURES... TROPICAL STORM NATE IS CENTERED NEAR 20.0N 92.8W AT 09/1800 UTC OR ABOUT 150 MI...240 KM W OF CAMPECHE AND 305 MI...490 KM ESE OF TUXPAN MEXICO. NATE IS MOVING WSW AT 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 999MB. THE MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 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. SCATTERED HEAVY SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 23N TO INLAND OVER MEXICO AND THE YUCATAN PENINSULA BETWEEN 91W-96W. ADDITIONAL STRENGTHENING TO HURRICANE STATUS IS POSSIBLE BEFORE MAKING LANDFALL OVER MEXICO. TROPICAL STORM MARIA IS CENTERED NEAR 14.3N 57.9W AT 09/1800 UTC OR ABOUT 135 MI...220 KM NE OF BARBADOS AND 275 MI...445 KM ESE OF GUADELOUPE MOVING W-NW AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 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. SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 12N-19N BETWEEN 51W-62W INCLUDING THE WINDWARD ISLANDS. MARIA IS EXPECTED TO CONTINUE MOVING WEST-NORTHWESTWARD TO THE SOUTH OF A SUBTROPICAL RIDGE OVER THE CENTRAL AND WESTERN ATLANTIC. AT 09/1500 UTC HURRICANE KATIA WAS CENTERED NEAR 39.3N 65.8W OR ABOUT 385 MI...615 KM SSW OF HALIFAX NOVA SCOTIA MOVING NE AT 25 KT. ESTIMATED MINIMUM CENTRAL PRESSURE WAS 968 MB...WITH MAXIMUM SUSTAINED WIND SPEED OF 70 KT WITH GUSTS TO 85 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 IS FORECAST TO BECOME POST-TROPICAL IN ABOUT 24 HOURS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 37N-44N BETWEEN 60W-68W. ...TROPICAL WAVES... TROPICAL WAVE IN THE E TROPICAL ATLC IS ANALYZED FROM 17N34W TO 6N40W MOVING W NEAR 15 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 LOW LEVEL CLOUD FIELD ON VISIBLE SATELLITE IMAGERY. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 200 NM ON EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE IN THE WEST ATLC/CENTRAL CARIBBEAN IS ANALYZED FROM 25N70W TO 12N75W MOVING W-NW NEAR 15 KT. WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. THE SOUTHERN EXTENSION OF THE WAVE AXIS IS INTERACTING WITH THE MONSOON TROUGH OVER THE SW CARIBBEAN. SCATTERED SHOWERS AND THUNDERSTORMS ARE AFFECTING THE CENTRAL CARIBBEAN BETWEEN 70W-77W...AND THE ATLC WATERS E OF THE BAHAMAS S OF 27N BETWEEN 65W-72W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED OVER AFRICA INTO THE E TROPICAL ATLC ACROSS THE SOUTHERN COAST OF GUINEA-BISSAU NEAR 11N15W TO 9N18W TO 11N21W. THE OCEANIC MONSOON TROUGH HAS BEEN DISRUPTED BY THE PRESENCE OF TROPICAL STORM MARIA. HOWEVER...AS MARIA CONTINUES TO MOVE WNW...A SMALL PORTION OF THE ITCZ COULD REDEVELOP LATER THIS EVENING OVER THE W TROPICAL ATLC. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 170 NM OF COAST OF LIBERIA AND SIERRA LEONE. SIMILAR ACTIVITY OF FROM 3N-10N BETWEEN 40W-50W. ...DISCUSSION... GULF OF MEXICO... THE PRIMARY CONCERN THIS AFTERNOON IS TROPICAL STORM NATE AFFECTING THE WATERS OVER THE BAY OF CAMPECHE...SEE SPECIAL FEATURES SECTION ABOVE FOR MORE DETAILS. AN UPPER LEVEL LOW SPINNING OVER SOUTHERN ILLINOIS SLOWLY PUSHES AN UPPER TROUGH OFF THE EASTERN CONUS SUPPORTING A WEAK NEARLY STATIONARY FRONTAL BOUNDARY EXTENDING ACROSS CENTRAL FLORIDA INTO THE GULF WATERS ALONG TAMPA BAY TO NEAR 24N87W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 70 NM EITHER SIDE OF THE FRONT. VERY DRY AIR AND SUBSIDENCE ALOFT COVERS THE NW AND N CENTRAL BASINS ...GIVING THIS REGION REMARKABLE CLEAR SKIES AND FAIR WEATHER CONDITIONS NW OF A LINE FROM THE COAST OF FLORIDA NEAR 30N83W THE COAST OF MEXICO NEAR TAMPICO. CONSEQUENTLY NO SIGNIFICANT WEATHER IS OCCURRING OVER THE FAR SE AND N OF THE YUCATAN PENINSULA. NATE IS FORECAST TO SLOWLY INTENSIFY AND DRIFT NW THROUGH THE WEEKEND INTO MEXICO LATE SUN/EARLY MON. THE FRONT WILL DISSIPATE OVER THE NEXT 24-36 HOURS. CARIBBEAN SEA... THE MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN FROM WESTERN PANAMA TO NORTHERN COLOMBIA...GENERATING SCATTERED HEAVY SHOWERS AND THUNDERSTORMS WITHIN 80-100 NM ON EITHER SIDE OF THE AXIS. A TROPICAL WAVE MOVING ACROSS THE CENTRAL BASIN IS GRADUALLY INTERACTING WITH THE MONSOON TROUGH. THEREFORE...THE CONVECTION ASSOCIATED TO THIS FEATURE HAS INCREASED AND SPREAD OVER THE LAST 6 HOURS. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS BETWEEN 70W-77W. DRY STABLE AIR ALOFT AND FAIR WEATHER CONDITIONS DOMINATE ELSEWHERE ACROSS THE DISCUSSION AREA... ESPECIALLY OVER THE NW BASIN. A FEW ISOLATED LOW TOP SHOWERS ARE POSSIBLE EMBEDDED IN THE EASTERLY TRADE WIND FLOW E OF 69W. HOWEVER...THE OUTER BANDS ASSOCIATED TO MARIA ARE STARTING TO AFFECT THE LESSER ANTILLES. MARIA IS EXPECTED TO MOVE ACROSS THE NE CARIBBEAN FRI NIGHT THROUGH SAT NIGHT AFFECTING THE COASTAL WATERS NEAR PUERTO RICO AND ADJACENT ISLANDS. ATLANTIC OCEAN... A NEARLY STATIONARY/WEAKENING FRONT ENTERS THE DISCUSSION AREA OVER THE WEST ATLC NEAR 32N72W EXTENDING SW INTO CENTRAL FLORIDA ALONG CAPE CANAVERAL GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 70 NM EITHER SIDE OF THE FRONT. TO THE SE OF THIS BOUNDARY...A TROPICAL WAVE IS APPROACHING THE FAR EAST BAHAMAS GENERATING SIMILAR CONVECTION S OF 27N BETWEEN 65W-72W. A WEAK CUTOFF UPPER LOW IS NE OF THE VIRGIN ISLANDS CENTERED NEAR 23N61W GENERATING NO SIGNIFICANT CONVECTION. AN UPPER TROUGH MOVES ACROSS THE NE CENTRAL ATLC SUPPORTING A WEAK SURFACE TROUGH EXTENDING FROM 31N35W TO 26N40W GENERATING WITHOUT ANY CONVECTION. A REINFORCING COLD FRONT NW OF THE SURFACE TROUGH WILL SWING INTO THE DISCUSSION AREA WITH VERY WEAK ISOLATED CONVECTION OVER THE NEXT 6-12 HOURS. BROAD SURFACE RIDGE DOMINATES ELSEWHERE ACROSS THE ATLC N OF 20N E OF 65W. THE SURFACE RIDGE WILL CONTINUE TO BUILD ALONG 27N TONIGHT...THEN LIFT N OF THE AREA ON MON. TROPICAL STORM MARIA WILL MOVE THROUGH THE BAHAMAS EARLY NEXT WEEK. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA