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#778861 (Received by flhurricane at: 4:54 PM 16.Jun.2015) TCDAT2 TROPICAL STORM BILL DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL022015 400 PM CDT TUE JUN 16 2015 After an earlier westward wobble, Bill is now moving toward the north-northwest or north based on Doppler radar data. My best estimate for a storm motion is 330/08 kt. Bill is expected to move north-northwestward tonight and turn toward the north over north-central Texas on Monday as the cyclone moves through a break in the subtropical ridge. By 36-48 hours, Bill is forecast to get caught up into the mid-latitude westerlies and accelerate off to the northeast and east-northeast. By 120 hours, the remnant circulation is expected to merge with a frontal system across the Ohio Valley region. The global models are in good agreement on this developing scenario and the NHC forecast track is just an update of the previous one, and lies close to a blend of the slower GFS, ECMWF, and UKMET global models. Although the inner-core banding structure of Bill has improved in radar imagery, the cyclone is expected to slowly weaken as the system continues to move farther inland. Bill should weaken to a tropical depression by Wednesday morning and become a remnant low by Wednesday evening when the system is moving across northern Texas. The GFS, ECMWF, and UKMET models now suggest that baroclinic forcing associated with an upper-level trough will help maintain the post-tropical remnants as a distinct entity for a few days before being absorbed by a frontal system by day 5. Tropical-storm-force winds and heavy rains continue to occur well away from the center. The main hazard from Bill is expected to be heavy rainfall and flooding across portions of eastern Texas and eastern Oklahoma over the next day or two. Please see products from your local National Weather Service office for more information on the flood threat. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 28.4N 96.8W 45 KT 50 MPH...INLAND 12H 17/0600Z 29.9N 97.5W 30 KT 35 MPH...INLAND 24H 17/1800Z 32.0N 97.7W 25 KT 30 MPH...INLAND 36H 18/0600Z 33.6N 97.1W 25 KT 30 MPH...POST-TROP/INLAND 48H 18/1800Z 34.7N 95.7W 20 KT 25 MPH...POST-TROP/INLAND 72H 19/1800Z 36.7N 92.0W 15 KT 15 MPH...POST-TROP/INLAND 96H 20/1800Z 39.0N 86.0W 15 KT 15 MPH...POST-TROP/INLAND 120H 21/1800Z...ABSORBED BY FRONTAL SYSTEM $$ Forecaster Stewart |