SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0731 AM CDT Sat Oct 30 2021 Valid 301300Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not forecast across the contiguous United States today or tonight. ...Synopsis/Discussion... The mid/upper-level pattern over the CONUS will be dominated by three substantial perturbations this period: 1. A major synoptic-scale cyclone now over the Appalachians forecast to continue filling while pivoting northeastward to NY and Lake Ontario by 12Z tomorrow. The associated swath of elevated low-level warm advection and related destabilization above the boundary layer will support 200-800 J/kg MUCAPE and thunderstorm potential from this afternoon into tonight across roughly the eastern 3/4 of New England. Relatively stable air should remain in the boundary layer, with the surface occlusion triple point remaining just offshore, south through east of ACK. A few strong gusts may penetrate to the surface, especially over coastal southeastern MA and the nearby islands, but severe potential appears too minimal for an unconditional outlook. 2. A northern-stream synoptic trough moving eastward over central Canada and the adjoining northern Plains/Upper Midwest, with the underlying air mass too dry for thunderstorms; and 3. A compact cyclone now evident in moisture-channel imagery west of Cape Mendocino, CA. This circulation will move slowly northeastward across the northwest tip of CA and over coastal OR through the period. Downstream, strongly difluent flow aloft and several small shots of DCVA, along with marginal midlevel moisture, will continue to support sporadic thunder over portions of far northern CA to central OR today, and perhaps parts of the northern Great Basin region the last few hours of the period. ..Edwards/Mosier.. 10/30/2021 Read more LIVE: spc.noaa.gov
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