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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, September 18, 2021

SPC Sep 18, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0235 PM CDT Sat Sep 18 2021 Valid 182000Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF THE GREAT BASIN... ...SUMMARY... A few storms may produce severe wind and/or hail this afternoon and evening across parts of the Great Basin region. ...20Z Update... No changes needed to the previous outlook. As mentioned in MCD 1767, a few stronger storms remain possible across the Great Basin this afternoon. Instability has been tempered by cloud cover and rather limited low-level moisture, but deep southwesterly flow could still result in a strong wind gusts or two with any of the more robust storms. Cool mid-level temperatures could also result in isolated hail, particularly across the higher terrain. ..Mosier.. 09/18/2021 .PREV DISCUSSION... /ISSUED 1114 AM CDT Sat Sep 18 2021/ ...Great Basin... Water vapor loop shows a strong upper trough digging onto the coast of OR, with a lead shortwave trough lifting northeastward across CA/NV toward UT. Large scale forcing is overspreading parts of NV/AZ/UT, resulting in increasing coverage of thunderstorms. This activity will spread northeastward across much of UT this afternoon, and eventually into southern ID/WY. Instability will be limited due to marginal moisture values and pockets of cloudiness. However, rather strong southwesterly flow will result in fast-moving showers and thunderstorms capable of gusty and locally damaging winds. Hail will also be possible in the higher terrain of northwest AZ into central UT. Read more LIVE: