Show Selection: |
#908603 (Received by flhurricane at: 10:40 AM 29.Oct.2017) TCDAT3 Tropical Storm Philippe Discussion Number 8 NWS National Hurricane Center Miami FL AL182017 1100 AM EDT Sun Oct 29 2017 Philippe looks the best it ever has, possessing a well-defined low-level center as seen in high-resolution GOES-16 visible imagery, along with at least 45-kt sustained winds based on several recent ship reports. However, the cyclone is sheared with the bulk of the convective cloud shield having been displaced northeast of the center due to southwesterly mid-/upper-level winds of 45-75 kt. Although the exact center of Philippe was difficult to track overnight, the current position is actually on the previous forecast track. Philippe has been moving due east at about 25-27 kt for the past few hours. However, the NHC model guidance is in decent agreement that the cyclone will turn toward the northeast by this afternoon ahead of an approaching frontal system and a powerful deep-layer trough moving quickly eastward across the eastern Gulf of Mexico and Florida. The cold front is currently located only 90-100 nmi west of Philippe`s center, and merger with the front along with transition to a extratropical low pressure system is expected by 12 hours, if not sooner. As the aforementioned trough becomes more negatively tilted over the next 24 hours, a strong extratropical low is forecast to develop near or just east of the North Carolina Outer Banks, pulling Philippe`s circulation north-northeastward to northward in the 12-24-hour period well offshore of the U.S east coast. Absorption of Philippe`s circulation into the larger extratropical low is expected to be completed by 24 hours when the larger low is located over New England. The official forecast track lies to the right of the previous advisory track, mainly due to the recent eastward jog, and lies along the eastern edge of the guidance envelope near a blend of the HCCA and TVCN consensus models. Some additional slight strengthening is possible during the next 12 hours or so, mainly due weak baroclinic forcing and the faster forward speed that is forecast. However, most of the baroclinic energy associated with the negatively tilted mid-latitude trough is expected to remain to the west, triggering the development of the above-mentioned significant extratropical coastal low. In fact, some of the latent heat from Philippe`s circulation will likely get drawn into the larger extratropical low developing to its northwest, aiding in that intensification process and increasing the demise of Philippe after 12 hours. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 27.8N 77.5W 45 KT 50 MPH 12H 30/0000Z 32.5N 72.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 24H 30/1200Z...ABSORBED BY LARGER EXTRATROPICAL LOW $$ Forecaster Stewart |