000 AXNT20 KNHC 111049 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT FRI JUL 11 2008 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 1015 UTC. ...SPECIAL FEATURE.... THE CENTER OF HURRICANE BERTHA AT 11/0900 UTC IS NEAR 28.0N 61.7W. IT IS MOVING NORTHWEST OR 315 DEGREES 6 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 75 KT WITH GUSTS TO 90 KT. THIS POSITION ALSO IS 305 NM/565 KM SOUTHEAST OF BERMUDA. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. SCATTERED STRONG SHOWERS AND THUNDERSTORMS ARE FROM 27N TO 30N BETWEEN 59W AND 63W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND OTHER POSSIBLE PRECIPITATION COVER THE AREA FROM 25N TO 32N BETWEEN 55W AND 66W. FORECAST TRACK GUIDANCE IS IN GOOD AGREEMENT THAT BERTHA WILL TURN NORTHWARD DURING THE NEXT 36 HOURS AS A MIDDLE LEVEL RIDGE TO THE NORTH OF THE HURRICANE MOVES EASTWARD. BERTHA IS CURRENTLY UNDER A LARGE UPPER-LEVEL ANTICYCLONE...WITH THE LARGE-SCALE MODELS FORECASTING THIS TO CONTINUE FOR AT LEAST 36 HOURS. THE INTENSITY FORECAST WILL KEEP BERTHA AT 75 KT DURING THIS TIME. A CHANCE OF SOME STRENGTHENING AT THE END OF THE EYEWALL REPLACEMENT CYCLE STILL EXISTS. IT IS EXPECTED THAT BERTHA WILL MOVE SLOWLY OUT FROM UNDER THE ANTICYCLONE AND ENCOUNTER VERTICAL WIND SHEAR STARTING IN 48 TO 72 HOURS. THIS AND DECREASING SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK SHOULD CAUSE BERTHA TO WEAKEN. OCEAN ANALYSES FROM THE ATLANTIC OCEANOGRAPHIC AND MARINE LABORATORY SHOW THAT THE WARM WATER UNDER BERTHA IS RELATIVELY SHALLOW... AND THERE IS A CHANCE THAT THIS SLOW-MOVING SYSTEM COULD UPWELL COLDER WATER UNDERNEATH IT. THIS COULD PARTICULARLY BE A FACTOR IF BERTHA STALLS FOR 24 HOURS OR MORE. THE LATEST WIND SPEED PROBABILITIES INDICATE THAT...GIVEN UNCERTAINTIES IN THE FORECASTS OF BERTHA'S TRACK...INTENSITY...AND SIZE...THERE REMAINS ROUGHLY A 50% CHANCE THAT WINDS OF TROPICAL STORM FORCE WILL AFFECT BERMUDA DURING THE NEXT FIVE DAYS. A TROPICAL STORM WATCH MAY BE ISSUED FOR THE ISLAND LATER TODAY. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 39W/40W SOUTH OF 13N MOVING WEST 15 KT. ITCZ PRECIPITATION IS CURVING NORTHWARD AT THE NORTHERN END OF THE WAVE FROM 10N TO 12N BETWEEN 34W AND 42W. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 65W/66W SOUTH OF 16N MOVING WEST 15 KT. UPPER LEVEL ANTICYCLONIC FLOW COVERS THE CARIBBEAN SEA AND THE ATLANTIC OCEAN FROM 9N TO 16N BETWEEN 55W AND 66W. BROKEN TO OVERCAST MIDDLE AND HIGH LEVEL CLOUDS ARE SOUTH OF 16N BETWEEN 56W AND 70W. SHOWERS ARE POSSIBLE IN THIS AREA. ...THE ITCZ... 11N15W 7N30W 8N51W 10N62W. SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS FROM 6N TO 10N BETWEEN 15W AND 18W...AND WITHIN 45 NM ON EITHER SIDE OF 11N43W 8N43W 8N52W 6N53W. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS FROM 11N TO 13N BETWEEN 17W AND 19W...FROM 2N TO 10N BETWEEN 20W AND 36W...AND FROM 10N TO 12N BETWEEN 34W AND 42W. SHOWERS ARE POSSIBLE ELSEWHERE SOUTH OF 10N BETWEEN 30W AND 42W. ...DISCUSSION... THE GULF OF MEXICO... MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW MOVES FROM THE ATLANTIC OCEAN ALONG THE WESTERN SIDE OF THE FLOW AROUND THE 28N69W MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER...ACROSS THE NORTHERN BAHAMAS TO THE STRAITS OF FLORIDA...INTO THE GULF OF MEXICO NORTH OF 23N...NORTHWESTWARD TO THE LOUISIANA/TEXAS BORDER. THE MIDDLE LEVEL CYCLONIC CIRCULATION CENTER/TROUGH FROM 24 HOURS AGO HAS MOVED ASHORE. IT NOW HUGS THE COASTAL PLAINS OF TEXAS FROM 30N SOUTHWARD INTO THE LOWER TEXAS COAST/ EXTREME NORTHEASTERN COASTAL MEXICO. A SECOND CYCLONIC CIRCULATION CENTER IS NEAR 21N94W IN THE SOUTHWESTERN CORNER OF THE AREA. MIDDLE TO UPPER LEVEL DRY AIR IS NORTH OF THE 21N94W CYCLONIC CENTER WEST OF 90W. ISOLATED MODERATE SHOWERS IN THE SOUTHWESTERN CORNER OF THE AREA SOUTH OF 22N. THE CARIBBEAN SEA... BROAD UPPER LEVEL ANTICYCLONIC FLOW IS SOUTH OF 18N BETWEEN 68W AND CENTRAL AMERICA. ISOLATED MODERATE SHOWERS HAVE BEEN ALTERNATELY DEVELOPING...DISSIPATING...AND POSSIBLY RE-DEVELOPING IN THE WATERS AND LAND AREAS NORTH OF 17N BETWEEN PUERTO RICO AND THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA. THIS PART OF THE CARIBBEAN SEA NORTH OF 17N IS AN AREA OF UPPER LEVEL DIFFLUENT WIND FLOW...GIVEN THE UPPER LEVEL ANTICYCLONIC FLOW IN THE EASTERN GULF OF MEXICO...THE UPPER LEVEL ANTICYCLONIC FLOW IN THE CARIBBEAN SEA SOUTH OF 18N...AND THE 28N69W 25N74W 21N77W TROUGH. MIDDLE LEVEL CYCLONIC FLOW IS IN THE SOUTHWESTERN CORNER OF THE AREA. STRONG SHOWERS AND THUNDERSTORMS ARE FROM 10N TO 14N BETWEEN 81W AND 83W AT THE COAST OF NICARAGUA. STRONG SHOWERS AND THUNDERSTORMS IN NORTHEASTERN COLOMBIA EIGHT HOURS AGO HAVE MOVED INTO THE GULF OF URABA SOUTH OF 10N BETWEEN COLOMBIA AND PANAMA...TO THE WEST OF BROAD MIDDLE LEVEL CYCLONIC FLOW. THE ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM A 28N69W CYCLONIC CIRCULATION CENTER TO 25N74W TO 21N77W IN EASTERN CUBA. BROAD UPPER LEVEL ANTICYCLONIC FLOW IS SOUTH OF 18N BETWEEN 68W AND CENTRAL AMERICA. ISOLATED MODERATE SHOWERS HAVE BEEN ALTERNATELY DEVELOPING...DISSIPATING...AND POSSIBLY RE-DEVELOPING IN THE WATERS AND LAND AREAS NORTH OF 17N BETWEEN PUERTO RICO AND THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA. CYCLONIC FLOW AROUND THIS CENTER COVERS THE ATLANTIC OCEAN FROM 26N TO 32N BETWEEN 66W AND 73W. UPPER LEVEL ANTICYCLONIC OUTFLOW FROM HURRICANE BERTHA IS MOVING ON TOP OF THE EASTERN EXTENSION OF THE CYCLONIC FLOW AROUND THE 28N69W CENTER. A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER NEAR 35N43W...ABOUT 1000 NM EAST-NORTHEAST OF HURRICANE BERTHA...THROUGH 32N44W TO 26N46W. A SURFACE TROUGH PASSES THROUGH 33N46W TO 31N47W. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS ARE NORTH OF 28N BETWEEN 40W AND 50W. A SURFACE RIDGE EXTENDS FROM A 1024 MB HIGH PRESSURE CENTER NEAR 29N72W TO 28N ALONG THE FLORIDA EAST COAST...ACROSS THE GULF OF MEXICO TO THE LOWER TEXAS COAST. BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN FROM 16N TO 30N BETWEEN AFRICA AND 52W. $$ MT