000 AXNT20 KNHC 311742 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED AUG 31 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 1715 UTC. ...SPECIAL FEATURE... TROPICAL STORM KATIA IS CENTERED NEAR 14.2N 40.8W AS OF 31/1500 UTC OR ABOUT 955 NM W OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING WNW AT 18 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 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. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA FROM 11N-16N BETWEEN 39W-44W. TROPICAL WAVE IS OVER THE SE GULF OF MEXICO AND THE YUCATAN PENINSULA FROM 26N85W TO BELIZE NEAR 18N87W MOVING W-NW NEAR 15 KT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75/90 NM OF LINE FROM THE WAVE AXIS NEAR 24N86W INTO THE NW CARIBBEAN TO 20N85W. ALTHOUGH UPPER LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT DURING THE NEXT DAY OR TWO...THERE IS SOME POTENTIAL FOR TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT OVER THE CENTRAL OR WESTERN GULF OF MEXICO IN A FEW DAYS. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL OR SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... THE TROPICAL WAVE IN THE SE GULF OF MEXICO IS NOW IN THE SPECIAL FEATURES SECTION ABOVE. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA ENTERING THE E PACIFIC REGION JUST S OF DAKAR SENEGAL EXTENDING ALONG 13N20W TO 12N27W AND IS DISRUPTED TO THE W BY T.S. KATIA. CLUSTERS OF SCATTERED MODERATE CONVECTION 4N-8N BETWEEN E OF 32W TO INLAND OVER SIERRA LEONE AND LIBERIA AND FROM 9N-15N E OF 23W TO INLAND OVER GUINEA TO SENEGAL. ...DISCUSSION... GULF OF MEXICO... AN ABUNDANCE OF DEEP LAYER MOISTURE COVERS ALL BUT THE NW GULF WITH A SHORTWAVE UPPER TROUGH EXTENDING ACROSS THE N GULF FROM THE W ATLC ACROSS THE FLORIDA PANHANDLE INTO THE GULF NEAR PENSACOLA TO CORPUS CHRISTI TEXAS GENERATING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS N OF 27N E OF 87W TO INLAND OVER FLORIDA. AN UPPER RIDGE DOMINATES THE REMAINDER OF THE GULF ANCHORED INLAND OVER S/CENTRAL TEXAS EXTENDING AN AXIS TO W CUBA/THE STRAITS OF FLORIDA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE BEING ENHANCED BY THE TROPICAL WAVE MOVING THROUGH THE UPPER RIDGE COVERING THE AREA S OF 27W W OF 85W TO OVER THE FLORIDA PENINSULA AND THROUGH THE STRAITS OF FLORIDA INCLUDING THE FLORIDA KEYS. A SURFACE TROUGH OVER THE SW GULF EXTENDS FROM 23N96W TO THE W BAY OF CAMPECHE NEAR 19N95W GENERATING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM 20N94W TO 25N97W. THIS LEAVES ONLY THE NW GULF WITH CLEAR SKIES THIS AFTERNOON. CARIBBEAN SEA... AN ABUNDANCE OF DEEP LAYER MOISTURE COVERS THE W CARIBBEAN WHERE AN UPPER RIDGE EXTENDING FROM S/CENTRAL MEXICO ACROSS THE S GULF OF MEXICO TO OVER CUBA IS GIVING THE NW CARIBBEAN NE FLOW ALOFT. AN INVERTED UPPER TROUGH EXTENDS ACROSS THE CENTRAL CARIBBEAN FROM CENTRAL PANAMA TO THE WINDWARD PASSAGE ENHANCING THE NE FLOW OVER THE NW CARIBBEAN AND THE SCATTERED/HEAVY SHOWERS WITH SCATTERED THUNDERSTORMS W OF A LINE FROM 17N94W ALONG 13N81W TO CENTRAL PANAMA NEAR 9N79W TO INLAND OVER CENTRAL AMERICA. SOME ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE OVER THE REMAINDER OF THE CARIBBEAN W OF 75W LEAVING THE E CARIBBEAN UNDER MOSTLY CLEAR SKIES THIS AFTERNOON. ATLANTIC OCEAN... THE PRIMARY FEATURE OF INTEREST IS TROPICAL STORM KATIA IN THE CENTRAL TROPICAL ATLC...SEE SPECIAL FEATURES SECTION ABOVE. AN UPPER LOW IS JUST N OF THE DISCUSSION AREA NEAR 34N69W EXTENDING A SHORTWAVE UPPER TROUGH SW ACROSS SE GEORGIA/NE FLORIDA INTO THE GULF OF MEXICO GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM S OF A LINE FROM 31N71W 30N76W TO 31N81W. THE UPPER RIDGE OVER THE GULF OF MEXICO EXTENDS ACROSS THE REMAINDER OF THE W ATLC FROM W CUBA NEAR HAVANA NE ALONG 27N74W TO BEYOND 32N68W. A BROAD UPPER TROUGH COVERS THE CENTRAL ATLC RE-ENFORCING THE N FLOW BETWEEN 65W-72W WHERE A SURFACE TROUGH EXTENDS FROM 30N65W TO 22N69W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-25N BETWEEN 65W-69W AND ISOLATED SHOWERS WITHIN 200 NM W OF THE TROUGH N OF 27N. THE UPPER TROUGH MENTIONED ABOVE EXTENDS FROM AN UPPER LOW NEAR 30N55W SW TO THE VIRGIN ISLANDS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 32N52W TO 26N56W, SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 150 NM OF LINE FROM 21N55W TO 31N49W AND N OF 30N BETWEEN 50W-56W. A SURFACE RIDGE COVERS THE CENTRAL INTO THE E ATLC ANCHORED BY A 1026 MB HIGH N OF THE DISCUSSION AREA THROUGH 32N39W TO 21N34W. A BROAD UPPER TROUGH IS MOVING S INTO THE E ATLC SUPPORTING A DEVELOPING COLD FRONT JUST N OF THE REGION WITH SCATTERED SHOWERS N OF 30N BETWEEN 18W-31W. 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