SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Tue Oct 20 2020 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHWEST MISSOURI...IOWA...FAR SOUTHEAST MINNESOTA AND SOUTHWEST WISCONSIN... ...SUMMARY... Thunderstorms associated with marginally severe hail and strong wind gusts will be possible in the Upper Midwest Thursday evening. ...Upper Midwest... An upper-level trough will move into the Rockies on Thursday as southwest mid-level flow becomes established from the Great Plains to the Great Lakes. At the surface, a strong cold front will advance quickly southeastward across the central Plains and Upper Midwest. Ahead of the front, surface dewpoints should reach the lower to mid 60s F which will contribute to the development of a narrow corridor of instability during the late afternoon. As low-level convergence increases along the front during the early evening, thunderstorms are expected to develop. SBCAPE in the 1000 to 1500 J/kg range and 0-6 km shear in the 35 to 45 kt range should be sufficient for an isolated severe threat mainly from northwest Missouri into southwest Wisconsin. Hail and a few severe wind gusts will be possible with the stronger cells. However, most of the convection is expected to develop just behind the front where instability will be quite a bit weaker. For this reason, any severe threat should remain marginal Tuesday evening. ..Broyles.. 10/20/2020
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