SPC Oct 12, 2017 0730 UTC Day 3 Severe Thunderstorm Outlook

By Newsroom America Feeds at 12 Oct 2017

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Thu Oct 12 2017 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND LOWER TO MID MISSOURI VALLEY... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE SLIGHT RISK AREA FROM PARTS OF THE SOUTHERN PLAINS NORTHEASTWARD TO THE WESTERN GREAT LAKES... ...SUMMARY... Thunderstorm development with a threat for isolated large hail and wind damage will be possible from the central Plains northeastward into the mid to upper Mississippi Valley from late Saturday afternoon into the overnight period. ...Central Plains/Lower Missouri Valley/Mid to Upper Mississippi Valley... An upper-level trough will move eastward from the Intermountain West into the Southern Rockies on Saturday. At the surface, a cold front is forecast to move southeastward into the central Plains and Lower Missouri Valley on Saturday with a moist airmass located ahead of the front. As a low-level jet strengthens during the afternoon and evening, elevated thunderstorms will likely develop to the northwest of the front from central Kansas northeastward into southwest Iowa. Surface-based development appears most likely during the evening along and to the south of the front from eastern Kansas northeastward across northwest Missouri into eastern Iowa. This activity should persist through much of the night as the front moves southeastward across the slight risk area. Concerning the severe threat, a 50 to 60 kt mid-level jet is forecast to move across the central states Saturday evening. This will contribute to strong deep-layer shear profiles favorable for storm organization. Wind profiles should be favorable for isolated supercells associated with isolated large hail and wind damage in areas that warm the most on Saturday. However, the models suggest that linear development may be preferred once the front moves into the area from northwest and low-level convergence markedly increases. The wind damage threat could become the greatest severe threat if an organized linear MCS can get going. A marginal severe threat will also be possible in the southern Plains where weaker large-scale ascent should keep convective coverage more isolated. Other marginally severe storms will be possible in northern Illinois and southern Wisconsin where instability is forecast to be weaker than in areas to the southwest. ..Broyles.. 10/12/2017 Read more



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