Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0322 AM CDT Tue Sep 30 2025 Valid 031200Z - 081200Z ...DISCUSSION... Late this work week through the weekend, medium-range models continue to indicate mid/upper flow amplification across the mid-latitude eastern Pacific into North America, which may lead to the evolution of an increasingly prominent blocking high offshore of the British Columbia/Pacific Northwest coast. This would probably be flanked by persistent troughing at somewhat lower latitudes, including California coastal areas into the Great Basin. However, the spread within/among the model output is sizable concerning this and subsequent developments through early next week. Stronger and more progressive westerlies, and potential for significant surface cyclogenesis, may remain confined to the higher latitudes. However, there does appear a consensus within the medium-range output of modestly deepening surface troughing across parts of the central Great Plains into Upper Midwest (roughly along an axis from the Front Range through Minnesota) by this weekend, perhaps as one notable short wave perturbation accelerates northeastward out of the Intermountain West. In the presence of steep lower/mid-tropospheric lapse rates and strengthening flow, this could provide a focus for strong thunderstorm development Saturday and/or Sunday. However, due to the continuing lack of a substantive moist return flow off the Gulf, the potential for organized severe storms still appears low.
