SPC Sep 22, 2017 Day 4-8 Severe Weather Outlook

By Newsroom America Feeds at 22 Sep 2017

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0259 AM CDT Fri Sep 22 2017 Valid 251200Z - 301200Z ...DISCUSSION... The slow-moving longwave trough over the West will finally begin to weaken and eject northeastward toward the western Great Lakes region around D5/Tuesday. Ahead of this trough, surface cyclogenesis should occur in Wisconsin that, when combined with weak surface-based destabilization, may result in a risk for isolated severe storms during the afternoon and evening. Beyond this period, models diverge substantially with regard to a remnant cut-off low over the Southwest and a downstream trough near the Great Lakes. Despite differences in the mid/upper synoptic pattern, models generally suggest varying degrees of surface ridging across the northern Rockies and central Plains that should result in a cooler, drier airmass spreading into these areas. With modified maritime air shunted south of more active westerlies (nearer the Great Lakes and vicinity), it appears that any organized severe risk should be on the decrease. Read more



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