SPC Sep 13, 2017 2000 UTC Day 1 Convective Outlook

By Newsroom America Feeds at 13 Sep 2017

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0242 PM CDT Wed Sep 13 2017 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected today or tonight across the contiguous United States. ...DISCUSSION... No change is made to the outlook for this issuance. ..Broyles.. 09/13/2017 .PREV DISCUSSION... /ISSUED 1100 AM CDT Wed Sep 13 2017/ ...Northern MN... Latest surface analysis shows a cold front extending from central SD into northern MN. The air mass ahead of the front is relatively moist and unstable, with strong heating expected to yield afternoon MLCAPE values of 1500-2000 J/kg. A progressive shortwave trough now over MT will begin to approach the front this evening, leading to strengthening wind fields and weak mid-level height falls. These factors suggest there is a small area of northern MN where parameters would be favorable for organized/severe storms. However, 12z CAM guidance continues to suggest that the probability of convective initiation along the boundary is quite low, and that any storm that forms will be isolated and relatively short-lived. Therefore, will maintain the ongoing less-than-5% probability forecast for severe storms today. Read more



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