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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.

Thursday, July 21, 2022

SPC Jul 21, 2022 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Thu Jul 21 2022 Valid 231200Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER MIDWEST... ...SUMMARY... Scattered severe thunderstorms should occur Saturday across parts of the Upper Midwest. A few tornadoes, large to very large hail, and significant damaging winds all appear possible. ...Upper Midwest into the Great Lakes... A notable shortwave trough is forecast to progress from the northern Plains east-southeastward across the Upper Midwest and Great Lakes on Saturday. A belt of enhanced mid/upper-level flow will likely accompany this shortwave trough and act to organize thunderstorms that develop ahead of it through the day. There is reasonably good agreement in model guidance that a very moist low-level airmass will be in place ahead of a front across the Upper Midwest Saturday morning. Steepening mid-level lapse rates and robust heating of this airmass through the early afternoon should foster moderate to strong instability. Deep-layer shear will be more than sufficient for organized updrafts, and supercells with a threat for very large hail appear possible with initial convective development across MN. Most guidance also suggests that quick upscale growth into a MCS will occur Saturday afternoon/evening with eastward extent into western/central WI and northeastern IA. Given the degree of buoyancy available, at least scattered damaging/severe winds appear probable as this mode transition occurs. Some of these winds may be significant. Have included an Enhanced Risk where MCS development and propagation appear most likely. Enough low-level shear associated with a southwesterly low-level jet is also forecast to support a threat for a few tornadoes. This severe threat should continue into the Great Lakes region Saturday night, but lesser instability forecast with eastward extent should keep the overall severe threat fairly isolated. ..Gleason.. 07/21/2022 Read more CHECK UPDATE ZOOM GRAPHIC