Flhurricane.com - Central Florida Hurricane Center - Tracking Storms since 1995Hurricanes Without the Hype! Since 1995
The Atlantic is quiet
|
Show Selection: |
| #906431 (Received by flhurricane at: 10:40 AM 09.Oct.2017) TCDAT2 Tropical Storm Ophelia Discussion Number 2 NWS National Hurricane Center Miami FL AL172017 1100 AM AST Mon Oct 09 2017 The convective pattern of the small cyclone has continued to improve since the previous advisory, with some thunderstorm activity having developed near or over the center, along with an increase in curved banding features in the eastern semicircle. The Dvorak intensity estimate at 1200Z from TAFB was T2.0/30 kt, but given the aforementioned improvement in the curved-band structure since that time, the initial intensity is increased to 35 kt. This makes Ophelia the fifteenth named storm of the 2017 Atlantic hurricane season. The initial motion estimate is 030/04 kt. The steering flow surrounding Ophelia is expected to continue to be weak for the next day or so while the cyclone remains entangled with a weak upper-level low located just to its north and northwest. As a result, only a slow drift toward the northeast and and east is forecast. By 36 h, increased mid-level ridging to the northwest of Ophelia should induce a motion toward the east-southeast and southeast through 72 h, after which a broad mid-latitude trough is expected to gradually accelerate the cyclone toward the northeast at a forward speed of near 10 kt. The official forecast remains down the middle of the guidance envelope, in close agreement with the previous forecast track, and the HCCA and TVCX consensus models. Ophelia should remain far away from land for the next 5 days. Although Ophelia is forecast to remain over marginally warm SSTs of 26.5-27 deg C, much colder-than-normal temperatures aloft should offset the relatively cool ocean temperatures and produce sufficient instability to generate moderate to strong convection for the next 120 h. The GFS-based SHIPS model is currently assessing 25 kt of westerly vertical wind shear, which obviously isn`t occuring based on the recent development of anticyclonic outflow over the low-level center and across most of Ophelia`s circulation. In contrast, the UW-CIMSS shear analyses indicate lower shear values near 15 kt. However, both shear assessments are likely too high given the large domains that they use to calculate environmental wind shear. Based on recent trends noted in water vapor imagery showing the shear decreasing, along with the overall favorable upper-level wind fields forecast by the GFS and ECMWF, especially after 36 hours, slow but steady strengthening is expected for the next 5 days, with only occasional intrusions of dry mid-level air being the primary inhibiting factor to the intensification process. The official intensity forecast is close to the NOAA HCCA consensus model, is about midway between the more aggressive IVCN consensus model that makes Ophelia a hurricane in about 72 h, and the more conservative statistical SHIPS and LGEM models. However, even the SHIPS and LGEM models have increased their peak intensity forecasts by at least 15 kt since the previous advisory. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 31.4N 39.9W 35 KT 40 MPH 12H 10/0000Z 31.7N 39.5W 40 KT 45 MPH 24H 10/1200Z 31.6N 38.7W 45 KT 50 MPH 36H 11/0000Z 31.3N 38.1W 45 KT 50 MPH 48H 11/1200Z 30.7N 37.7W 50 KT 60 MPH 72H 12/1200Z 29.8N 36.7W 55 KT 65 MPH 96H 13/1200Z 30.5N 34.5W 65 KT 75 MPH 120H 14/1200Z 32.0N 31.0W 65 KT 75 MPH $$ Forecaster Stewart |
