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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Monday, September 6, 2021

SPC Sep 6, 2021 0600 UTC Day 2 Convective Outlook

SPC 0600Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Mon Sep 06 2021 Valid 071200Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF LOWER MICHIGAN... ...SUMMARY... Strong to severe thunderstorms are possible on Tuesday across much of Michigan and adjacent portions of the Great Lakes states. The greatest threat is expected during the afternoon and early evening. ...Lower MI and adjacent Great Lakes vicinity... An upper shortwave trough will shift east across the Upper Midwest and Great Lakes region on Tuesday. Ahead of the trough, a belt of moderate to strong mid/upper southwesterly flow will overspread the region. South/southwesterly low-level flow will strengthen as a surface low deepens over Ontario, with a belt of 40-60 kt 850-700 mb flow spreading across MI during the day. A cold front will extend from western WI into central KS Tuesday morning. The front will shift east through the day, becoming positioned from southeast MI into central IL during the evening, and from central OH toward the Ozarks by Wednesday morning. Quality of low-level moisture return ahead of the front remains somewhat uncertain, but at least a narrow corridor of low 60s F surface dewpoints appears likely beneath steepening midlevel lapse rates. This should result in a narrow area of 1000-1500 J/kg MLCAPE along/near the front. Strong ascent and boundary-parallel deep-layer flow will favor any semi-discrete convection quickly developing into a line with damaging gusts being the main concern. Though any convection that can remain more discrete will have increased potential to produce hail. While directional shear is forecast to be poor, wind speeds will quickly increase with height, allowing for enlarged low level hodographs. However, given concerns over storm mode and quality of boundary-layer moisture, tornado potential remains somewhat uncertain/conditional. Vertical shear and stronger forcing will rapidly decrease with southward extent, resulting in decreasing severe potential across portions of the mid-MS/lower OH Valleys. ..Leitman.. 09/06/2021 Read more LIVE: spc.noaa.gov