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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, September 11, 2021

SPC Sep 12, 2021 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 PM CDT Sat Sep 11 2021 Valid 120100Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER WESTERN NEBRASKA...MUCH OF UTAH...AND FROM SOUTHERN MINNESOTA INTO CENTRAL WISCONSIN... ...SUMMARY... Marginally severe storms remain possible this evening over Utah, and over western Nebraska. Isolated severe storms cannot be ruled out late tonight from southeast Minnesota into Wisconsin. ...Western NE/Northeast CO... Maximized daytime heating and lift near a front is currently supporting new development over far northeast CO and into northwest NE. The 00Z LBF sounding shows very steep lapse rates through a deep layer, with marginal deep-layer shear. This may support a marginal hail threat, but more likely a few strong to severe gusts through evening. ...Central/Southern UT... Daytime heating has led to scattered storms over much of UT, with a few stronger cores notes on radar. Both shear and instability remain marginally favorable for strong to severe storms with around 35 kt deep layer shear notes on the 00Z SLC sounding and only a few hundred J/kg MLCAPE. The threat may persist through about 03Z when the cooling boundary layer leads to dissipating storms. ...Southeast MN into WI... 00Z soundings show strong northwest flow aloft over the region, while a front remains front northern IA into central WI. Strong instability is also present with 2000-3000 J/kg MLCAPE analyzed over NE and IA. Lift is expected to be weak overnight, as the low-level jet veers to due west. Given expected capping in place, only a low probability exists of thunderstorms near the front after 06Z. Conditionally, the shear and instability strongly favor severe hail, and the area will need to be monitored closely for storm development later tonight. ..Jewell.. 09/12/2021 Read more LIVE: spc.noaa.gov