Tree damage, power outages, property damage, and difficult travel conditions (especially for high-profile vehicles) likely across the Upper Plains late today into the over night hours continuing until late Wednesday.
The strong atmospheric river slamming into the Pacific NW and baroclinic leaf feature trailing the atmospheric river flow located off the west coast will begin to push its way onshore and farther inland into Washington and British Columbia by tonight. Divergence aloft and a strong shortwave and PVA will help this low undergo cyclogenesis tonight into Wednesday deepening the low-pressure system. As this system crosses the Canadian Rockies and pushes into the Canadian Prairie on Wednesday, a strong deep upper-level trough will develop with westerly flow producing a high impact wind event across the region on Wednesday. This sharp contour gradient and sharp pressure gradient at the surface along with moderate instability and steep mid-level lapse rates and some convective potential will enable though strong upper-level winds with the steep contour gradient to mix down to the surface. Model reanalysis and ensemble statistics indicate the strength of these winds easily exceed the 90th percentile of a 30-year model climatology. The strongest period of high winds are expected to occur just ahead of, and a few hours behind a cold frontal passage during the daytime hours on Wednesday with the low-pressure system. There is high confidence in the timing and occurrence of the strong winds. These may be the strongest winds of the season, and localized damage should be expected in exposed areas such as some roof or tree damage, power outages, rolled trucks, or blowing dust. In addition to the winds, snow levels will drop quickly behind the passing front. Although precipitation rates will decrease, a period of snow on mountain passes could cause minor impacts to travel. Wind speeds will decrease rather quickly Wednesday night as pressure rises behind the passing front and high pressure builds back into the region.