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Subtropical Storm Ernesto Forecast Discussion Number 2
2018-08-15 17:01:37| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Wed Aug 15 2018 805 WTNT45 KNHC 151501 CCA TCDAT5 Subtropical Storm Ernesto Discussion Number 2...Corrected NWS National Hurricane Center Miami FL AL052018 1100 AM AST Wed Aug 15 2018 Convection associated with the subtropical cyclone became better organized after the release of the previous advisory, but cloud tops have warmed recently with the convection becoming somewhat fragmented. An Hebert-Poteat subtropical classification of T2.5 from TAFB suggests that they system is producing gale-force winds, and recent scatterometer data that passed over the far eastern portion of the circulation revealed 30-kt winds. Since the instrument missed the radius of maximum winds, it is assumed that stronger winds exist over the eastern portion of the circulation, and the initial intensity is increased to 35 kt, making the system a subtropical storm. Ernesto has about 24 hours over marginally warm SSTs and in a low- shear environment in which to strengthen. After that time, the cyclone will be moving over much colder water which should cause it to become post-tropical within 48 hours. The post-tropical cyclone is forecast to merge with a frontal zone associated with a larger extratropical cyclone over the North Atlantic in 3 to 4 days. The cyclone is moving northward at about 6 kt. A mid-level trough that is moving off the east coast of the United States should cause Ernesto to turn north-northeastward later today, and the cyclone is forecast to accelerate northeastward by late Thursday as it becomes embedded within the mid-latitude westerlies. The dynamical model guidance continues to be in good agreement, and the new NHC track forecast remains in the middle of the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 38.1N 46.0W 35 KT 40 MPH 12H 16/0000Z 39.3N 45.3W 40 KT 45 MPH 24H 16/1200Z 41.3N 43.5W 45 KT 50 MPH 36H 17/0000Z 43.6N 40.3W 45 KT 50 MPH 48H 17/1200Z 46.4N 35.2W 45 KT 50 MPH...POST-TROPICAL 72H 18/1200Z 52.3N 21.0W 40 KT 45 MPH...POST-TROPICAL 96H 19/1200Z...MERGED WITH LARGER EXTRATROPICAL LOW $$ Forecaster Brown
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