000 AXNT20 KNHC 082351 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... HURRICANE KATIA IS CENTERED NEAR 34.9N 69.6W AT 08/2100 UTC OR ABOUT 330 MI...530 KM NW OF BERMUDA MOVING N AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 973 MB. MAXIMUM SUSTAINED WIND SPEED IS 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. LARGE SWELL 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. THIS SWELL IS LIKELY TO CAUSE LIFE THREATENING SURF AND RIP CURRENT CONDITIONS. PLEASE CONSULT PRODUCTS ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES FOR MORE INFORMATION. GLOBAL MODELS INDICATE THAT KATIA WILL REMAIN A POWERFUL CYCLONE OVER THE NEXT DAY OR SO. THE FORECAST TAKES THE REMNANTS OF KATIA NORTH OF THE BRITISH ISLES IN ABOUT FOUR DAYS. SCATTERED MODERATE CONVECTION IS FROM 33N-38N BETWEEN 67W-72W. TROPICAL STORM NATE IS CENTERED NEAR 19.7N 92.2W AT 09/0000 UTC OR ABOUT 110 MI...180 KM W OF CAMPECHE MEXICO...OR ABOUT 175 MI...285 KM NE OF COATZACOALCOS MEXICO...AND IS STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 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. THE OUTER CONVECTION FROM NATE ALSO COVERS IMMEDIATE COASTAL WATERS OF THE EASTERN COAST OF THE YUCATAN PENINSULA. NATE IS CURRENTLY LOCATED IN AN ENVIRONMENT OF LIGHT TO MODERATE NORTHEASTERLY SHEAR. NATE IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 2 TO 4 INCHES WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES OVER THE MEXICAN STATES OF CAMPECHE... TABASCO...AND SOUTHERN VERACRUZ. A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1 TO 3 FEET ABOVE NORMAL TIDE LEVELS ALONG THE IMMEDIATE COAST IN THE WARNING AREA. THE SHEAR IS FORECAST TO LESSEN DURING THE NEXT DAY OR SO...WHICH SHOULD ALLOW FOR GRADUAL STRENGTHENING. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION REMAINS S OF THE CENTER OVER THE W BAY OF CAMPECHE TO INLAND OVER MEXICO S OF 21N BETWEEN 91W-95W. TROPICAL STORM MARIA IS CENTERED NEAR 13.2N 53.6W AT 09/0000 UTC OR ABOUT 490 MI...790 KM E OF THE WINDWARD ISLANDS MOVING W AT 19 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 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 IS SOUTH OF A PERSISTENT AND LARGE SUBTROPICAL RIDGE THAT EXTENDS WESTWARD ACROSS THE ATLC. THIS STEERING PATTERN CALLS FOR A WEST TO WEST-NORTHWEST TRACK OVER THE NEXT TWO TO THREE DAYS. AFTER THAT...A WEAKER RIDGE NORTH OF THE CYCLONE IS EXPECTED TO ALLOW A MORE NORTHWESTWARD TRACK AT A SOMEWHAT SLOWER FORWARD SPEED. GUIDANCE IS IN VERY GOOD AGREEMENT...AND MOST OF THE MODELS ARE CLUSTERED HAVING MARIA OVER OR JUST TO THE NORTH OF THE CENTRAL BAHAMAS IN FIVE DAYS. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 12N-16N BETWEEN 48W-54W. ...TROPICAL WAVES... TROPICAL WAVE IS W OF CAPE VERDE ISLANDS FROM 18N27W TO 8N29W MOVING W 10-15 KT. THE 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 SATELLITE IMAGERY. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 120 NM ON EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE IS OVER E HISPANIOLA FROM 23N68W TO 13N68W MOVING WNW 15-20 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION IS E OF THE WAVE AXIS FROM 17N-24N BETWEEN 64W-68W. ISOLATED MODERATE CONVECTION IS W OF THE WAVE AXIS FROM 14N-20N BETWEEN 69W-72W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED OVER AFRICA INTO THE E TROPICAL ATLC ACROSS THE NORTHERN COAST OF MAURITANIA NEAR 21N16W TO 18N21W. THE MONSOON TROUGH AND ITCZ AXIS HAS BEEN DISRUPTED OVER THE REMAINDER OF THE TROPICAL ATLANTIC DUE TO THE LACK OF CONFLUENCE IN THE TRADE WINDS AND THE PRESENCE OF TROPICAL STORM MARIA. ISOLATED MODERATE CONVECTION IS OFF THE COAST OF WEST AFRICA FROM 4N-7N BETWEEN 11W-16W. SIMILAR CONVECTION IS FROM 5N-9N BETWEEN 36W-41W. ...DISCUSSION... GULF OF MEXICO... THE PRIMARY CONCERN TONIGHT IS TROPICAL STORM NATE...SEE SPECIAL FEATURES SECTION ABOVE. AS OF 2100 UTC...THE TAIL END OF A DISSIPATING STATIONARY FRONT EXTENDS FROM N FLORIDA TO THE E GULF OF MEXICO ALONG 28N80W 26N86W. SCATTERED SHOWERS ARE WITHIN 120 NM OF THE FRONT. RADAR IMAGERY SHOWS SCATTERED SHOWERS AND RAIN OVER THE SE GULF OF MEXICO FROM 25N-28N BETWEEN 27W-82W. FAIR WEATHER IS NOTED OVER THE NW GULF AND TEXAS DUE TO UPPER LEVEL DRY AIR SUBSIDENCE. IN THE NEXT 24 HOURS EXPECT NATE TO REMAIN IN THE BAY OF CAMPECHE AND GRADUALLY INTENSIFY. ALSO EXPECT THE FRONT TO DISSIPATE AND BE REPLACED BY A SURFACE TROUGH. CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE LESSER ANTILLES. SEE ABOVE. ELSEWHERE...WIDELY SCATTERED MODERATE CONVECTION IS NOTED INLAND OVER PORTIONS OF NW VENEZUELA...AND N COLOMBIA. SIMILAR CONVECTION IS OVER CENTRAL AMERICA FROM PANAMA TO S GUATEMALA. ISOLATED MODERATE CONVECTION IS OVER THE HIGHER ELEVATIONS OF HISPANIOLA...JAMAICA...AND CUBA. THE REMAINDER OF THE CARIBBEAN IS UNDER UPPER LEVEL DRY AIR SUBSIDENCE BRINGING FAIR WEATHER CONDITIONS. 10-20 KT TRADEWINDS DOMINATE THE CARIBBEAN WITH THE HIGHEST WINDS ALONG THE COAST OF N COLOMBIA. EXPECT OVER THE NEXT 24 HOURS FOR THE TROPICAL WAVE TO MOVE W TO THE CENTRAL CARIBBEAN. ALSO EXPECT ADDITIONAL CONVECTION TO BE OVER THE SW CARIBBEAN DUE TO THE MONSOON TROUGH...AND OVER THE YUCATAN PENINSULA DUE TO NATE. ATLANTIC OCEAN... TROPICAL STORM MARIA...AND THE TWO TROPICAL WAVES ARE THE DOMINANT WEATHER PRODUCERS IN THE TROPICAL ATLANTIC. A DISSIPATING STATIONARY FRONT IS OVER THE W ATLANTIC FROM 31N75W TO 28N80W. SCATTERED SHOWERS ARE WITHIN 60 NM OF THE FRONT. A 1023 MB HIGH IS CENTERED OVER THE WESTERN ATLANTIC NEAR 33N55W. A SURFACE TROUGH IS OVER THE CENTRAL ATLANTIC FROM 31N34W TO 26N40W PRODUCING SIGNIFICANT WIND SHIFTS AND NO CONVECTION. TROPICAL STORM WATCH AND WARNINGS HAVE BEEN ISSUED FOR PORTIONS OF THE LEEWARD ISLANDS DUE TO MARIA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORMOSA