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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.


Saturday, July 17, 2021

SPC Jul 17, 2021 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1211 PM CDT Sat Jul 17 2021 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL PLAINS... ...SUMMARY... Isolated severe thunderstorms are possible across portions of the central Plains on Sunday. ...Synopsis... The only changes to the outlook with the Day 2 Update are to general thunderstorm areas. The Plains Marginal risk remains unchanged due to large spread in forecast guidance and low confidence. Large-scale upper ridging will encompass much of the western states into the Plains. A couple of shortwave troughs embedded in larger-scale troughing from the Northeast into the Mid-MS Valley will gradually pivot east/northeast through the period. Scattered thunderstorms are expected from the southeastern U.S. northward along the Atlantic coast. Weak vertical shear will limit organized storms and severe potential will remain limited. High PW values could result in sporadic, locally damaging gusts, but the threat for any substantial, organized severe threat is low. ...Central Plains... Deep layer flow will remain weak on the eastern periphery of the upper ridge. However, a seasonally moist and unstable airmass will be in place. South/southeasterly low level flow beneath modest northwesterly flow aloft will result in sufficient vertical shear for a few organized, stronger storms. Forecast guidance varies quite a bit regarding convective evolution with some CAMs indicating storms ongoing across NE Sunday morning and shifting southward through the day. Other guidance suggests thunderstorms will develop during the afternoon into the nighttime hours through diurnal processes and along residual thunderstorm outflows. While convective evolution remains uncertain, at least a marginal threat for locally damaging gusts and perhaps some hail will exist given the instability/shear parameter space. ..Leitman.. 07/17/2021 Read more LIVE:
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