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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, August 22, 2021

SPC Aug 23, 2021 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Sun Aug 22 2021 Valid 230100Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS... ...SUMMARY... Scattered strong to severe thunderstorms will move eastward across the central and northern Plains this evening. A threat for large hail and wind damage will likely accompany the stronger storms. An isolated tornado threat will also exist across parts of eastern South Dakota. ...Northern and Central Plains/Mid Missouri Valley... A negatively-tilted upper-level trough and an associated 45 to 60 kt mid-level jet are located across the northern Plains according to water vapor imagery. At the surface, a moist airmass is in place from Kansas northward into the eastern Dakotas. The RAP is analyzing a corridor of moderate to strong instability along the moist axis, with MLCAPE across eastern South Dakota estimated to be from 1500 to 3000 J/kg. Strong to severe thunderstorms are ongoing along this corridor of instability. In addition to the instability, deep-layer shear is strong across the northern Plains. The WSR-88D VWP at Aberdeen currently has 0-6 km shear near 60 kt, with veering winds with height in the lowest kilometer. This wind profile will be favorable for supercells this evening. Low-level shear will continue to increase this evening helping to maintain a tornado threat across eastern South Dakota for a few more hours. Supercells will also be capable of large hail and wind damage. Moderate instability is also present in eastern North Dakota where the RAP is estimating MLCAPE in the 1200 to 1500 J/kg range. A cluster of strong to severe thunderstorms is ongoing in eastern North Dakota along the eastern edge of the stronger instability. This combined with strong deep-layer shear, associated with a mid-level speed max, will continue to be favorable for supercells associated with large hail and wind damage. An isolated tornado threat will also be possible for another hour or so. The severe threat is expected to impact western Minnesota later this evening but weaker instability further east will make the severe threat more isolated. Further to the south into east-central Nebraska, a pocket of strong instability is analyzed by the RAP, with MLCAPE in the 3000 to 4000 J/kg range. A cluster of strong to severe thunderstorms is ongoing along the southern side of the stronger instability, from the vicinity of Grand Island southward to near the Kansas state-line. The WSR-88D VWP just to the east of the storm cluster has 0-6 km shear near 40 kt and veering winds with height in the lowest 2 kilometers. This will be favorable for supercells this evening, with a threat for large hail and wind damage. An isolated severe threat could impact part of the mid Missouri Valley later this evening. ..Broyles.. 08/23/2021 Read more LIVE:
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