Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0346 AM CDT Tue Jul 13 2021 Valid 161200Z - 211200Z ...DISCUSSION... Medium-range guidance continues to indicate that mid/upper flow amplification across the eastern Pacific into western North America may be the most notable development late this week through next weekend. This is still forecast to include the evolution of a prominent mid-level high near/north of the Four Corners, with considerable expansion across much of the Intermountain West, Rockies, and northwestern Great Plains. Upstream, large-scale troughing appears likely to evolve to the west of the British Columbia and northern U.S. Pacific coast, before perhaps trending more progressive and migrating inland toward the Canadian and adjacent northern U.S. Rockies during the early to middle portion of next week. At the same time, another amplifying trough, to the east of the ridging, may dig across Hudson Bay toward the St. Lawrence Valley. This regime may be accompanied by periodic evolution of organized thunderstorm clusters impacting parts of the Southwest by late this weekend. Prior to the offshore larger-scale troughing accelerating northeastward, perturbations emerging from it could also contribute to increasing potential for strong to severe thunderstorm development across the Columbia Plateau into parts of the northern Rockies by early next week. Additional organized thunderstorm development is possible along/ahead of a southward advancing cold front associated with digging mid-level trough, into parts of the Northeast and lower Great Lakes region by the end of the period. Too many uncertainties remain to confidently indicate more than relatively isolated and/or marginal severe weather potential with any of these scenarios. Accordingly, severe weather probabilities are being maintained at less than 15 percent, but this could still change in later outlooks for this period. Read more LIVE: spc.noaa.gov
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