000 AXNT20 KNHC 011155 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU SEP 01 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 1115 UTC. ...SPECIAL FEATURES... HURRICANE KATIA IS CENTERED NEAR 15.2N 45.9W AT 01/0900 UTC OR ABOUT ABOUT 925 NM E OF THE LEEWARD ISLANDS MOVING WEST AT 17 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. PLEASE READ 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. NUMEROUS STRONG CONVECTION COVERS THE ATLANTIC OCEAN FROM 14N-16N BETWEEN 44W-49W. ELSEWHERE SCATTERED MODERATE CONVECTION EXTENDS FROM 11N-18N BETWEEN 42W-49W. A TROPICAL WAVE EXTENDS FROM THE CENTRAL GULF OF MEXICO AT 27N89W TO S MEXICO AT 16N92W MOVING W AT 10 KT. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OVER S MEXICO AND GUATEMALA FROM 14N-18N BETWEEN 91W-96W. CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE ELSEWHERE OVER THE E GULF OF MEXICO...THE YUCATAN CHANNEL...AND THE NW CARIBBEAN FROM 19N-29N BETWEEN 83W-89W. CONDITIONS ARE FORECAST TO BECOME MORE CONDUCIVE LATER TODAY...AND THE SYSTEM COULD BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES SLOWLY NORTHWESTWARD. INTERESTS ALONG THE ENTIRE NORTHERN GULF OF MEXICO COAST SHOULD MONITOR THE PROGRESS OF THIS DISTURBANCE. ...TROPICAL WAVES AND LOWS... AN ATLANTIC OCEAN 1010 MB LOW IS CENTERED NEAR 11N23W MOVING W AT 15 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY SHOWS SIGNIFICANT MOISTURE OFF THE COAST OF AFRICA S OF 20N E OF 27W. ISOLATED MODERATE CONVECTIVE IS WITHIN 120 NM OF THE LOW CENTER. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH REACHES THE AFRICAN COAST NEAR 18N16W AND TERMINATES. THE TROPICAL LOW AND HURRICANE KATIA HAVE DISRUPTED THE MONSOON TROUGH AND ITCZ AXIS OVER THE TROPICAL ATLANTIC. WIDELY SCATTERED MODERATE CONVECTION IS ALONG THE COAST OF WEST AFRICA FROM 8N-10N BETWEEN 11W-20W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS ALSO S OF THE TROPICAL LOW FROM 3N-7N BETWEEN 24W-31W. ...DISCUSSION... THE GULF OF MEXICO... A TROPICAL WAVE IS OVER THE CENTRAL GULF OF MEXICO AND S MEXICO. SEE ABOVE. ELSEWHERE ISOLATED MODERATE CONVECTION IS ALSO OVER THE W GULF OF MEXICO AND THE BAY OF CAMPECHE S OF 26N W OF 94W. MOSTLY FAIR WEATHER IS OVER THE NW GULF. IN THE UPPER LEVELS... A SMALL UPPER LEVEL LOW IS CENTERED OVER S LOUISIANA NEAR 30N90W. UPPER LEVEL DIFFLUENCE SE OF THE LOW IS ENHANCING THE CONVECTION OVER THE E GULF. EXPECT MORE TROPICAL MOISTURE AND CONVECTION TO SPREAD NW OVER THE GULF OVER THE NEXT 24 HOURS. THE CARIBBEAN SEA... A TROPICAL WAVE IS PRODUCING CONVECTION OVER THE NW CARIBBEAN. SEE ABOVE. A GOOD AMOUNT OF TROPICAL MOISTURE WITH NUMEROUS STRONG CONVECTION IS ALSO OVER N COLOMBIA AND THE SW CARIBBEAN S OF 12N DUE TO THE MONSOON TROUGH THAT EXTENDS FROM LAKE MARACAIBO VENEZUELA TO N COSTA RICA. ELSEWHERE...WIDELY SCATTERED MODERATE CONVECTION IS OVER HAITI FROM 18N-19N BETWEEN 72W-76W. THE LEEWARD AND WINDWARD ISLANDS HAVE MOSTLY FAIR WEATHER WITH STRONG SUBSIDENCE ALOFT. 15-25 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH STRONGEST WINDS ALONG THE COAST OF N COLOMBIA. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. THE ATLANTIC OCEAN... THE MAIN FEATURE OF INTEREST IS HURRICANE KATIA IN THE CENTRAL TROPICAL ATLANTIC. SEE ABOVE. ELSEWHERE A PROMINENT SURFACE TROUGH IS EVIDENT OVER THE W ATLANTIC FROM 32N66W TO 28N70W. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE TROUGH AXIS. A 1025 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 35N42W. A WEAK COLD FRONT IS OVER THE E ATLANTIC FROM 32N11W TO THE CANARY ISLANDS ALONG 29N17W 27N24W. SCATTERED SHOWERS ARE WITHIN 90 NM S OF THE FRONT. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS CENTERED OVER THE CENTRAL ATLANTIC NEAR 27N55W. WIDELY SCATTERED MODERATE CONVECTION IS N OF THE CENTER FROM 27N-35N BETWEEN 47W-56W. EXPECT KATIA TO MOVE CLOSER TO THE LEEWARD ISLANDS OVER THE NEXT 24 HOURS WITH STEADY INTENSIFICATION. ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORMOSA/PAW