000 AXNT20 KNHC 151158 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED SEP 15 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...SPECIAL FEATURES... TROPICAL STORM KARL IS CENTERED NEAR 18.6N 87.6W AT 15/1200 UTC OR ABOUT 90 NM E OF CHETUMAL MEXICO MOVING W-NW AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT3/WTNT33 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. NUMEROUS STRONG CONVECTION IS WITHIN 30/45 NM OF THE CENTER IN THE ALL QUADRANTS WITH SCATTERED MODERATE/STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 17N-19N W OF 85W TO INLAND OVER THE YUCATAN AND SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 45 NM OF LINE FROM 21N84W TO INLAND OVER THE YUCATAN NEAR 20N87W. KARL COULD INTENSIFY BEFORE LANDFALL BUT FORTUNATELY TIME IS SHORT BEFORE THE CENTER SHOULD CROSS THE COAST. HURRICANE IGOR IS CENTERED NEAR 19.5N 54.5W AT 15/0900 UTC OR ABOUT 495 NM E OF THE NORTHERN LEEWARD ISLANDS AND ABOUT 950 NM KM SE OF BERMUDA MOVING W-NW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 935 MB. MAXIMUM SUSTAINED WIND SPEED IS 125 KT WITH GUSTS TO 155 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. SCATTERED STRONG CONVECTION IS WITHIN 15O NM FROM THE CENTER IN THE SE QUADRANT WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 16N-23N BETWEEN 50W-57W. ALTHOUGH IGOR HAS WEAKEN SLIGHTLY IT IS STILL A LARGE CATEGORY FOUR HURRICANE. HURRICANE JULIA IS CENTERED NEAR 17.3N 31.8W AT 15/0900 UTC OR ABOUT 455 NM W OF THE CAPE VERDE ISLANDS MOVING NW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 950 MB. MAXIMUM SUSTAINED WIND SPEED IS 115 KT WITH GUSTS TO 140 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. SCATTERED STRONG CONVECTION IS WITHIN 60 NM FROM THE CENTER IN THE SW QUADRANT WITH SCATTERED MODERATE/ ISOLATED STRONG CONVECTION COVERING THE REMAINDER OF THE AREA FROM 14N-21N BETWEEN 30W-34W. ALTHOUGH JULIA IS A RELATIVE SMALLER HURRICANE THAN IGOR IT IS NOW ALSO A CATEGORY FOUR HURRICANE. ...ITCZ... THE ITCZ/MONSOONAL TROUGH REMAINS ACROSS THE ATLC BASIN BEING DISTORTED SOMEWHAT BY HURRICANES IGOR AND JULIA. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 90/120 NM N OF THE AXIS FROM 16-19 AND FROM 21W-24W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 4N-9N E OF 34W TO INLAND OVER SW AFRICA AND WITHIN 120/150 NM OF LINE FROM 6N37W TO 12N42W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER LEVEL RIDGE COVERS THE GULF N OF 25N TO OVER THE SE U.S. EXTENDING E TO OVER THE FLORIDA PENINSULA ANCHORED OFF THE SE LOUISIANA COAST NEAR 29N89W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 60/75 NM OF 28N FROM 83W-88W. THE BROAD UPPER RIDGE ASSOCIATED WITH T.S. KARL COVERS THE SE GULF S OF 25N E OF 90W PROVIDING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER THE AREA. SIMILAR ACTIVITY IS BEING GENERATED BY THE SOUTHERLY FLOW ALOFT AND THE CONVERGING NORTHERLY SURFACE FLOW S OF 23N BETWEEN 90W-94W. A WEAK UPPER INVERTED TROUGH IS ALONG THE COAST OF MEXICO FROM VERACRUZ TO TUXPAN IN THE W BAY OF CAMPECHE GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF THE COAST S OF 24N W OF 94W. OTHERWISE...MOSTLY DRY STABLE AIR ALOFT DOMINATES THE REMAINDER OF THE GULF THIS MORNING WITH MOSTLY CLEAR SKIES. CARIBBEAN SEA... THE PRIMARY FOCUS FOR THE CARIBBEAN THIS MORNING IS TROPICAL STORM KARL. HEAVY RAIN HAS ALREADY MOVED ONSHORE AS KARL APPROACHES THE COAST...SEE SPECIAL FEATURES ABOVE. THE UPPER LEVELS OF THE CARIBBEAN ARE DOMINATED BY A BROAD UPPER RIDGE THAT IS ASSOCIATED WITH T.S. KARL EXTENDING AN AXIS SE FROM 20N80W TO 16N69W PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF 74W TO OVER THE GREATER ANTILLES AND CENTRAL AMERICA. A WEAKENING UPPER TROUGH REMAINS OVER THE E CARIBBEAN EXTENDING FROM THE LEEWARD/VIRGIN ISLANDS NEAR 17N63W TO 13N66W COVERING THE REMAINDER OF THE E CARIBBEAN WITH DRY STABLE AIR E OF THE HURRICANE IGOR. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 60/75 NM OF A LINE FROM 13N67W TO 15N74W. ATLANTIC OCEAN... HURRICANES IGOR AND JULIA ARE THE PRIMARY FOCUS FOR THE ATLC AGAIN THIS MORNING. THE UPPER RIDGE ASSOCIATED WITH T.S. KARL IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS S OF 25N TO OVER CUBA W OF 75W INTO THE FLORIDA STRAITS. A WEAK SURFACE RIDGE COVERS THE REMAINDER OF THE W ATLC WITH A 1020 MB HIGH NEAR 32N77W. A WEAKENING UPPER TROUGH EXTENDS FROM 22N62W ACROSS THE LEEWARD/VIRGIN ISLANDS INTO THE E CARIBBEAN NEAR 17N63W PROVIDING DRY STABLE AIR E OF HURRICANE IGOR. THE UPPER RIDGE ASSOCIATED WITH IGOR IS A LARGE NEARLY UNIFORMED IN AREA WHILE THE UPPER RIDGE ASSOCIATED WITH JULIA IS NARROW AND ELONGATED N-NE TO S-SW AND AN UPPER TROUGH BETWEEN. STRONG SUBSIDENCE/DRY STABLE AIR AND THUS MOSTLY CLEAR SKIES DOMINATE THE REMAINDER OF THE W AND CENTRAL ATLC BETWEEN IGOR AND JULIA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW