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| #805584 (Received by flhurricane at: 10:46 AM 05.Oct.2015) TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 32 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 AM AST MON OCT 05 2015 Joaquin's cloud pattern and overall structure has remained intact based on conventional and microwave satellite data. Recent SSMIS and SSMI microwave passes showed a well-defined small eye still exists, which is also indicated in reflectivity data from the Bermuda Doppler radar. As a result, the intensity of Joaquin is being maintained at 75 kt, which is supported by Dvorak satellite current intensity estimates of T4.5/77 kt from both TAFB and SAB. The initial motion estimate is 030/11 kt. The forecast track and reasoning basically remain unchanged. Joaquin is expected to turn northeastward today and begin moving at a slightly faster forward speed tonight and Tuesday as the hurricane rounds the northwestern periphery of a weakening ridge and begins to feel the effects of the faster flow in the mid-latitude westerlies. By 36 hours, Joaquin should begin to accelerate east-northeastward at a faster forward speed of more than 25 kt. The official forecast track is essentially just an extension of the previous advisory track guidance and lies close to the consensus models TCVA and GFEX through 48 hours. After that time, the extratropical forecast track is based on guidance provided by the NOAA Ocean Prediction Center. Deep convection has persisted and even expanded somewhat since the previous advisory, with a small area of cloud tops colder than -70C having developed just west of the center. With the vertical wind shear expected to remain between 10 to 15 kt for the next 24 hours or so, only slight weakening is forecast. By 48 hours and beyond, however, westerly vertical wind shear is forecast to increase to more than 30 kt when the cyclone will be moving over SSTs less than 23C. The result should be steady weakening and a transition to a large and expanding extratropical low pressure system over the north Atlantic. Extratropical transition could occur sooner if Joaquin interacts or merges with a frontal system currently located a few hundred n mi north of the hurricane. The NHC intensity forecast is similar to the previous advisory and follows the intensity consensus model IVCN through 48 hours, and is based on guidance provided by the Ocean Prediction Center for days 3-5. The tropical storm force wind radii were expanded outward slightly in the southwestern quadrant based on surface observation and radar data from Bermuda. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 35.0N 64.6W 75 KT 85 MPH 12H 06/0000Z 36.3N 63.0W 70 KT 80 MPH 24H 06/1200Z 38.0N 59.6W 70 KT 80 MPH 36H 07/0000Z 39.3N 54.1W 65 KT 75 MPH 48H 07/1200Z 40.5N 47.2W 60 KT 70 MPH...POST-TROP/EXTRATROP 72H 08/1200Z 42.5N 32.6W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 09/1200Z 44.0N 21.4W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 10/1200Z 45.1N 15.9W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart |
