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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, October 23, 2021

SPC Oct 23, 2021 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0747 AM CDT Sat Oct 23 2021 Valid 231300Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY... ...SUMMARY... Large hail is expected with thunderstorms late tonight across portions of the central Plains and Lower Missouri Valley region. ...Central Plains/Lower Missouri Valley/Ozarks... Amplification of an increasingly prominent shortwave trough is anticipated from the Great Basin toward the central High Plains by late tonight. Downstream shortwave ridging will tend to prevail across the central/southern Plains and Missouri Valley/Ozarks much of the day, where a relatively moist air mass will otherwise accompany a northward-shifting warm front. Initially, some strong storms capable of hail will persist early today across southeast Kansas and far northeast Oklahoma into the Ozarks. The stronger updrafts will tend to remain on the west/southwest flank of the convection in closer proximity to the source region instability. These storms will continue to shift eastward and likely further weaken as the low-level jet diurnally subsides. The primary severe risk across the region, in the form of large hail, is expected to develop after sunset, and particularly through the 03Z-06Z/10pm-1am CDT time frame, mainly across east-central/northeast Kansas into northern Missouri. This will be as initial height falls begin to influence the region via the High Plains-approaching upper trough. Scenario will be meaningfully influenced by a nocturnally strengthening low-level jet and related warm advection/elevated moisture transport, with thunderstorms expected to steadily increase across the region, especially in the aforementioned spatiotemporal corridor. Forecast soundings suggest ample elevated MUCAPE of 2000-3000 J/kg will exist via steep mid-level lapse coincident with steady moistening just above the stable boundary layer. Strong shear through the cloud-bearing layer will support some elevated supercells, particularly within the first few hours of increasing thunderstorm development this evening and early overnight. A cluster of strong/locally severe thunderstorms is expected to persist across northern Missouri toward central/southern Illinois through the early morning hours of Sunday. ...Western Oklahoma and west/northwest Texas... Sufficient heating and mixing this afternoon near the surface trough/dryline may allow for thunderstorm development across western Oklahoma and/or parts of the Texas South Plains/Low Rolling Plains, although the residual influence of weak subsidence/mid-level capping is expected to keep any such development very isolated. Modestly stronger westerlies with northward extent across the region, primarily across western Oklahoma and nearby eastern Texas Panhandle/Low Rolling Plains, could support a localized severe storm risk late this afternoon/early evening. Any storms that do develop should diminish into mid/late evening. ..Guyer/Kerr.. 10/23/2021 Read more LIVE: