SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1034 AM CST Thu Nov 13 2025 Valid 141200Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms appears negligible across the U.S. Friday through Friday night. ...Discussion... A more prominent blocking regime centered across the northern Atlantic continues to evolve. Models indicate that this will include the development of a broad cyclonic regime centered across the Canadian Maritimes by early Friday, which will persist through the remainder of the period. Some amplification of large-scale troughing extending southward offshore of the remainder of the Atlantic Seaboard is forecast, downstream of a significant mid-level trough and embedded cyclone migrating northeast and east of the Canadian Maritimes, on the leading edge of a more progressive regime. Upstream, broad short wave ridging appears likely to shift inland of the British Columbia coast, across and east of the Canadian/northern U.S. Rockies, to the north of an increasingly cut-off low offshore of the central and southern California coast. Models continue to indicate that the modifying mid-level cold core of the eastern Pacific low (including coldest 500 mb temperatures warming above -24 C) will generally remain offshore through this period. While it may tend to pivot away from coastal areas near/south of San Francisco Bay, and slowly toward southern California coastal areas Friday night, the leading edge of stronger forcing for ascent/cooling aloft supportive of low-topped thunderstorm development appears likely to remain well west of the southern California coastal waters through 12Z Saturday. Potential for thunderstorm development Friday through Friday night appears largely confined to a plume of lower latitude eastern Pacific moisture return, advecting ahead of the low into the southern periphery of the stronger mid-latitude westerlies. Models suggest that this may contribute to developing layers of weak conditional instability rooted in the lower/mid-tropospheric, across the southern California coast through portions of the southern Sierra Nevada and Mojave Desert, Great Basin, northern Rockies, and northern Great Plains. Weak convection becoming briefly capable of producing a few lightning strikes may not be entirely out of the question anywhere within this corridor. However, due to likely sparse coverage and rather low predictability, probabilities for thunderstorms still appear generally less than 10 percent. ..Kerr.. 11/13/2025
