SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Fri Oct 03 2025 Valid 032000Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT BASIN/INTERMOUNTAIN WEST... ...SUMMARY... Thunderstorms capable of isolated severe wind gusts and small hail will be possible from late this afternoon into tonight across parts of the Great Basin and Intermountain West. ...20Z Update... The forecast remains on track and only minor adjustments were made with this update. In particular, the MRGL risk was extended slightly westward into far northeastern NV, driven by 5-percent wind probabilities. Despite limited moisture/buoyancy, strengthening large-scale ascent in the left-exit region of a robust midlevel jet and steepening deep-layer lapse rates amid strong low/mid-level flow could support a couple strong convectively enhanced wind gusts. See the previous discussion below for more details. ..Weinman.. 10/03/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Oct 03 2025/ ...Great Basin and Intermountain West... A prominent Western states upper trough, centered over the Sierra at midday, will continue to progress eastward toward/over the Great Basin, while taking on an increasingly neutral tilt. Consequential height falls, cooling aloft, and a strengthening of deep-layer winds will occur in association. This will support increasing and at least widely scattered thunderstorm development into the afternoon and tonight as low/mid-level lapse rates steepen and modest destabilization occurs. Even with limited buoyancy, high-based storms combined with moderate low/mid-level flow could still result in a few strong thunderstorm-enhanced surface wind gusts, with the relatively greatest chance for a few gusts this afternoon/early evening across northern/east-central Utah. Persistent forcing for ascent will result in thunderstorm development throughout the evening and overnight amid strengthening mid-level flow and cooling mid-level temperatures. Buoyancy will remain modest, but a few instances of mostly sub-severe hail may also occur.
