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Tropical Storm KARL Forecast Discussion Number 39
2016-09-24 04:52:58| National Hurricane Center (Atlantic)
Issued at 1100 PM AST FRI SEP 23 2016 000 WTNT42 KNHC 240252 TCDAT2 TROPICAL STORM KARL DISCUSSION NUMBER 39 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122016 1100 PM AST FRI SEP 23 2016 A few hours ago, a NOAA Hurricane Hunter aircraft reported flight-level winds of 71 kt at 7800 ft about 30 n mi to the southwest of the center, along with SFMR surface wind estimates of near 55 kt. The minimum central pressure at the time was near 990 mb. Since then, the cyclone has gotten better organized, with radar data from Bermuda showing a strong convective band west and northwest of the center. One caveat to the increased organization is that the center apparent in both radar and microwave imagery may be a little to the northwest of the surface center. Based on the earlier aircraft data, the initial intensity is set to 55 kt, and this could be a little conservative. Karl is expected to remain over sea surface temperatures of between 29-30C for the next 12-24 hours or so in an environment of moderate vertical wind shear. This should allow the cyclone to strengthen to a hurricane in about 24 hours. After that, the cyclone should undergo extratropical transition as it merges with the cold front, and this should be complete by 48 hours. The cyclone is likely to be absorbed by a larger extratropical low between 48-72 hours. The new intensity forecast is similar to the previous forecast, but it lies a little below the forecasts of the SHIPS and LGEM models. The initial motion is 020/11. Karl is about to enter strong southwesterly flow in advance of a deep-layer trough and associated surface cold front moving eastward from the northeastern United States. This should result in a turn toward the northeast during the next several hours and an increase in forward speed. The new track forecast has changed little from the previous forecast, and calls for Karl to make its closest approach to Bermuda during the next 12 hours and then move rapidly away from the island. Overall, the forecast track is near the center of the tightly clustered guidance. The wind radii have been revised based on a recent scatterometer overpass and input from the Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 24/0300Z 30.8N 65.1W 55 KT 65 MPH 12H 24/1200Z 32.5N 63.0W 60 KT 70 MPH 24H 25/0000Z 35.5N 57.8W 70 KT 80 MPH 36H 25/1200Z 39.5N 49.9W 70 KT 80 MPH 48H 26/0000Z 45.0N 40.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 72H 27/0000Z...ABSORBED BY LARGER EXTRATROPICAL LOW $$ Forecaster Beven
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