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| #888266 (Received by flhurricane at: 4:44 PM 20.Apr.2017) TCDAT1 Tropical Storm Arlene Discussion Number 6 NWS National Hurricane Center Miami FL AL012017 500 PM AST Thu Apr 20 2017 I have to add one more surprise to my long hurricane forecasting career. Unexpectedly, the subtropical cyclone became a tropical depression this morning, and then it intensified to a tropical storm. This intensity estimate is based on the cloud pattern presentation on satellite imagery which shows moderate thunderstorm activity surrounding an eye-type feature, and a convective ring in microwave imagery. Initial intensity is set at 40 kt, although estimates from TAFB suggest that the winds could have reached 45 kt around 1800 UTC. Since that time, the cloud pattern has deteriorated somewhat and winds probably have diminished. Despite the intensification, Arlene is still forecast by all global models to become absorbed by a nearby developing extratropical cyclone on Friday. Arlene is moving toward the west-northwest at 22 kt, while well embedded in the fast flow surrounding the extratropical low. This general motion around the low is expected until dissipation on Friday. Tropical storms in April are rare and Arlene is only the second one observed in this month during the satellite era. It should be noted, however, that this type of storm was practically impossible to detect prior to the weather satellite era. FORECAST POSITIONS AND MAX WINDS INIT 20/2100Z 37.7N 42.0W 40 KT 45 MPH 12H 21/0600Z 38.7N 45.9W 35 KT 40 MPH...POST-TROPICAL 24H 21/1800Z...DISSIPATED $$ Forecaster Avila |
