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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.

Sunday, July 18, 2021

SPC Jul 18, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Sun Jul 18 2021 Valid 182000Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHEAST CO...SOUTHWEST KS...AND NORTHWEST OK... ...SUMMARY... Large hail and damaging wind gusts remain possible through this evening mainly across a portion of the central High Plains. A few strong wind gusts are also possible over the lower Mississippi Valley area. ...20z Update... ...Central Plains... A Slight risk has been introduced across parts of far southeast CO into southwest KS and northwest OK. Clusters of storms are developing both along an outflow boundary from roughly Cheyenne County CO to Pawnee County KS, as well as ahead of this boundary across southwest KS. Around 30 kt effective shear is noted across the region, aiding in organized cells that have already produce large hail and severe gusts through mid-afternoon. Strong heating has resulted in very steep low level lapse rates, and large DCAPE is present to the south of the outflow boundary. Aided by the modest shear environment, severe gusts and hail will continue to be possible through the evening. If storms are able to congeal/grow upscale into a forward-propagating line/cluster, damaging wind potential could increase further across the region. How far south this threat may extend is a bit uncertain as hi-res CAMs are not resolving ongoing convection very well. For more details on short-term severe potential, reference MCD 1315. Aside from the inclusion of the Slight risk, the Marginal risk has been trimmed behind the current outflow boundary/ongoing convection across parts of NE and northwest KS. No other changes to the outlook have been made. ..Leitman.. 07/18/2021 .PREV DISCUSSION... /ISSUED 1126 AM CDT Sun Jul 18 2021/ ...Central Plains... The boundary layer continues to destabilize across western KS to the south of a small complex of storms and its associated MCV currently located across northwest KS. This activity may continue to pose a risk for isolated large hail and strong wind gusts as it develops southward next few hours though some uncertainty remains regarding its longevity. Warm advection storms are forecast to develop later tonight from central NE into north central KS. Some of these storms could pose a risk for mainly isolated marginally severe hail. ...Lower Mississippi Valley... The boundary layer is recovering south of a line of scattered storms situated across southern AR. This activity might become capable of producing a few strong gusts as it develops southeast into the destabilizing boundary layer where moderate instability will reside this afternoon. Read more LIVE: