SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 PM CST Tue Dec 16 2025 Valid 170100Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE PACIFIC NORTHWEST... ...SUMMARY... Sporadic severe gusts may accompany low-topped convection across parts of the Pacific Northwest tonight into early Wednesday morning. ...Pacific Northwest... A vigorous shortwave trough will reach coastal WA by late tonight and spread inland through 12Z Wednesday. This trough will be accompanied by an intense tropospheric wind field, characterized by 70-90 kts at 700 mb, that will spread across WA and OR during 06-12Z. A surface cyclone will move onshore in BC and occlude, as downstream lee cyclogenesis occurs over southern AB. Low-topped convection is expected to increase along the trailing cold front attendant to the occluded cyclone, initially reaching coastal WA towards 06Z. Surface-based buoyancy will be scant along the front, but sporadic lightning flashes and occasional strong to severe-caliber wind gusts may accompany the passage of this low-topped convective line. Low-topped convection should also increase ahead of this line overnight, as strong large-scale ascent coincides with peak low to mid-level flow. With minimal instability, low confidence exists in the degree of convective enhancement beyond the gradient winds. Thus, the level 1-MRGL risk has been maintained with no changes. ..Grams.. 12/17/2025
