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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 28, 2021

SPC Jul 28, 2021 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1114 AM CDT Wed Jul 28 2021 Valid 281630Z - 291200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON THROUGH TONIGHT OVER MUCH OF WISCONSIN... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF SOUTHEAST VIRGINIA AND NORTHEAST NORTH CAROLINA... ...SUMMARY... Potentially widespread severe thunderstorms are expected late this afternoon through tonight along a corridor from northeastern Minnesota across Wisconsin into southwest Lower Michigan. A few severe storms are also expected this afternoon over parts of Virginia and North Carolina. ...Upper Midwest... Strong west/northwesterly mid-level winds stretch from southern Canada into the Great Lakes region today, with several embedded shortwave troughs and jet maxima. One of these features currently over ND/MB will track southeastward into MN this afternoon. Morning clouds and scattered convection has limited heating thus far across MN, but at least pockets of afternoon destabilization will result in MLCAPE values of 1500-2500 J/kg. Most 12z guidance suggests that the ongoing convection will not significantly impact the development of afternoon thunderstorms across northern MN, where effective shear values of 45-55 knots and large hodographs will promote supercell structures and the potential for very large hail and a few tornadoes. Storms are expected to race southeastward through the evening across northern/central WI, and into southern WI/southern LM/southwest Lower MI overnight. The primary severe concern is if storms congeal into a bowing complex, widespread and potentially significant wind damage will be possible. Most guidance suggests the MCS will weaken late tonight as it moves into a slightly less moist/unstable air mass over MI/IN/OH. However, if mesoscale organization is sufficiently high, the complex could persist longer than model depictions. ...VA/NC... Clear skies are present today from the Tidewater region of VA into northeast and central NC. This area is very moist/unstable with dewpoints in the mid 70s and 500mb temperatures cooling slightly through the day. Rather widespread thunderstorms are expected today in this region, with sufficient for organized multicell storm clusters, or even a transient supercell or two. Damaging winds may occur in the stronger cells. Therefore have added a SLGT risk to this region. ..Hart/Wendt.. 07/28/2021 Read more LIVE: spc.noaa.gov