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Weather conditions on bar directly above are near Lakefront. Tabs under Moon Phases refer to O'Hare (official).

Archives for SPC Convective outlook are updated daily with a live map a the beginning of the article. Touch or click map to get possible update, and follow link at end of article for referral to NOAA/NWS Storm Prediction Center. Archives for Chicago's hourly weather data were updated 24-48 hours after end of each day prior to Dec. 2020.

Wednesday, July 27, 2022

SPC Jul 27, 2022 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0212 AM CDT Wed Jul 27 2022 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE OZARKS EASTWARD TO THE MID-ATLANTIC...AND IN PARTS OF THE CENTRAL HIGH PLAINS... CORRECTED FOR GENERAL THUNDERSTORM LINES ...SUMMARY... Thunderstorms associated with marginally severe wind gusts and hail will be possible today from parts of the Ozarks eastward to the Mid-Atlantic, and across parts of the central High Plains. ...Ozarks/Mid Mississippi Valley/Ohio and Tennessee Valleys/Southern Appalachians/Mid-Atlantic... A mid-level cyclonic flow pattern will be in place today across much of the north-central U.S., with westerly mid-level flow located from near the Mississippi River to the Atlantic coast. At the surface, a very moist airmass will be in place from the Ozarks eastward to the Mid-Atlantic, where surface dewpoints will generally be in the upper 60s and lower 70s F. As surface temperatures warm, moderate instability is expected to develop in areas that largely remain free of morning convection. In response to increasing instability, thunderstorm coverage will likely increase during the afternoon, with the greatest convective coverage located near pre-existing outflow boundaries and along corridors of enhanced low-level convergence. As low-level lapse rates become steep during the mid to late afternoon, an isolated wind-damage threat should develop. However, the greatest deep-layer shear is forecast to remain well to the north of an east-to-west axis of moderate instability, suggesting that any severe threat should remain marginal. ...Central High Plains... Northwest mid-level flow will be in place today across the central and northern High Plains. At the surface, southeasterly flow across the central High Plains will help maintain an axis of maximized low-level moisture from Kansas northwestward into western Nebraska. Surface dewpoints along this corridor should be mostly in the 60s F. This will contribute to moderate instability this afternoon, with MLCAPE likely reaching the 1500 to 2500 J/kg range. Due to increasing instability, widely scattered thunderstorms will develop in the higher terrain from eastern Wyoming southward into north-central Colorado. Other more isolated storms will develop farther east across the central High Plains. In addition to moderate instability, forecast soundings this afternoon in the central High Plains have 0-6 km shear in the 40 to 50 knot range, which is mostly be due to speed shear in the mid-levels. This should be enough for an isolated wind damage and hail threat. However, lapse rates at mid-levels are forecast to remain relatively weak, suggesting any severe threat should remain marginal. ..Broyles/Weinman.. 07/27/2022 Read more CHECK UPDATE ZOOM GRAPHIC