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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.

Tuesday, May 18, 2021

SPC May 18, 2021 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0217 AM CDT Tue May 18 2021 Valid 201200Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Severe thunderstorms with large hail and wind damage will be possible on Thursday across parts of the central High Plains. Marginally severe thunderstorms may occur outside of the slight risk area in parts of the High Plains. ...

Central and Northern High Plains... An upper-level low will be in place across the western states on Thursday as divergent south-southwesterly mid-level flow takes shape over the Rockies. At the surface, a lee trough will deepen across eastern Colorado and eastern Wyoming with southeasterly winds advecting low-level moisture northwestward toward the foothills of the Front Range and Medicine Bows. As surface temperatures warm, convection will likely initiate in the higher terrain, with thunderstorms moving eastward across the central High Plains during the afternoon. Moderate instability combined with 30 to 40 kt of deep-layer shear will be favorable for severe storms. As cells move away from the foothills, supercell development with large hail and wind damage will be possible. An isolated tornado threat will also be possible. The severe threat should persist into early evening with a gradual transition to linear mode. Further north into northeast Wyoming and southeast Montana, a north-northwest to south-southeast corridor of moderate instability is forecast to develop by Thursday afternoon. Convection will likely initiate in the higher terrain and move northeastward into the northern High Plains during the afternoon. Moderate deep-layer shear should support severe storm development. Supercells with isolated large hail will be possible. However, the degree of instability that develops will be more uncertain than in areas further to the south. A slight risk appears warranted, especially if moderate instability does develop across much of the northern High Plains, as some of the model solutions are suggesting. ..Broyles.. 05/18/2021 Read more LIVE:

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