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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.

Saturday, May 21, 2022

SPC May 21, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Sat May 21 2022 Valid 212000Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NEW ENGLAND TO SOUTHERN TEXAS... ...SUMMARY... Scattered severe thunderstorms capable of producing both damaging winds and large hail should continue through evening from parts of the southern Plains into the lower Ohio Valley, lower Great Lakes and Northeast. ...20Z Update... The primary change made to the Day 1 Outlook was to trim higher severe probabilities behind the convective line across the Mid Mississippi Valley, as convective overturning has reduced surface-based buoyancy. Otherwise, the previous forecast remains on track, with scattered to numerous wind/hail producing thunderstorms developing ahead of the cold front, from New England to the lower Mississippi Valley. Please refer to MCDs 0852-0854 for more information. Likewise, damaging gusts/occasionally large hail may still accompany ongoing storms across the southeast CONUS (more details available via MCDs 0855-0856). ..Squitieri.. 05/21/2022 .PREV DISCUSSION... /ISSUED 1046 AM CDT Sat May 21 2022/ ...Southern Plains to Northeast... A complex and active convective day is anticipated for much of the central and eastern US. Several lines/clusters of strong to severe thunderstorms are expected to intensify by mid-afternoon along a cold front and associated outflow boundaries from southeast Ontario into the Great Lakes region, OH Valley, middle MS Valley and southern Plains. The air mass ahead of the boundaries is quite moist with areas of strong daytime heating already occurring. While large scale forcing mechanisms are generally weak along this broad corridor, numerous thunderstorms are expected. Strong instability combined with sufficient flow aloft and steep low-level lapse rates will result in a risk of locally damaging wind gusts and some hail along the entire frontal zone. Most areas will see multicell storm clusters and lines. However, sufficient low and deep layer shear will likely result in a few supercells moving into northern New England later today with a slightly higher risk of a tornado or two. Please reference recent MCDs #848 and #849 for further short-term details. ...Gulf Coast states into the Carolinas... There is also a broad area of potential for at least isolated strong to severe storms over much of the southern and southeastern US today. Wind fields aloft are relatively weak in most places. However, strong heating, rich low-level moisture, and relatively cool temperatures aloft will promote robust up/downdrafts capable of locally damaging wind gusts and some hail. Read more CHECK UPDATE ZOOM GRAPHIC