SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Sun Jun 27 2021 Valid 291200Z - 301200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are possible from the Four Corners/Southeast across the southern Plains and over much of the eastern CONUS. Severe thunderstorms are not currently expected. ...Synopsis... Upper ridge anchoring the Pacific Northwest/southwest Canada omega block is forecast to weaken as it gradually drifts eastward throughout the period. Farther east, subtropical ridging centered just off the northern Mid-Atlantic Coast is expected to build eastward into more of the southern Plains, and a shortwave trough will likely move through the Upper Midwest and Upper Great Lakes region. Surface pattern east of the Rockies will be characterized by weak winds and a stationary front between the more moist air mass from the MS Valley eastward and the more continental airmass over the central/northern Plains. Thunderstorm development is anticipated along this boundary from central OK/KS northeastward into the Mid MS Valley. Thunderstorms are also expected within the very moist air mass across the Southeast and Carolinas. Increasing mid-level moisture should lead to at least isolated thunderstorms from the Four Corners eastward into portions of southern/central CA. Weak shear should limit the severe threat in all of these regions. An associated surface low is forecast to precede the shortwave trough expected to move through the Upper Midwest and Upper Great Lakes. Buoyancy will be lower here than areas farther south, but thunderstorms may still develop in the vicinity of the surface low as it moves eastward. Slightly stronger mid-level flow will result in better vertical shear than areas farther south, and a few storms may become strong to severe. Even so, limited storm coverage and low predictability regarding the surface low position and strength, as well as the effects of antecedent precipitation, preclude introducing any probabilities with this outlook. ..Mosier.. 06/27/2021 Read more LIVE: spc.noaa.gov
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