Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0219 AM CDT Wed Aug 05 2020 Valid 071200Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS... ...SUMMARY... Isolated strong to severe thunderstorms are possible Friday across parts of the northern Plains. Strong gusts and hail will be the main hazards possible with these storms. ...Northern Plains... A compact upper level shortwave trough located over the northern Rockies Friday morning will develop east/northeast across Montana to SK/MB. This will flatten the upper ridge extending northward across the Great Plains, and 35-45 kt west/southwesterly mid/upper level flow will overspread the region. At the surface, southerly low level flow will maintain 60s dewpoints across the central/northern Plains vicinity ahead of an eastward-advancing cold front. The front is forecast to be near the MT/ND border by midday and spread east/southeast through the overnight hours, extending from northwest MN into eastern SD and western NE by Saturday morning. With the strong upper high persisting over the southern Plains, warm midlevel temperatures will extend northward across much of the central Plains and mid-MO Valley vicinity. This presents some uncertainty with regards to convective initiation and coverage as capping will likely limit storm activity initially. However, as the trough ejects northeast during the afternoon/evening and the cold front begins to surge eastward, storms should be able to overcome the cap. Once convection develops, moderate to strong instability should allow storms to intensify quickly. The best vertical shear will remain closer to the Canadian border, potentially limiting storm organization with southward extent. Nevertheless, at least isolated storms capable of locally strong gusts and hail are possible Friday afternoon and evening. There is some potential that upward development along the front could occur during the late evening/overnight across parts of central/eastern ND into northern SD as a southwesterly low level jet increases. If this occurs, a greater damaging wind threat could emerge across parts of central/eastern ND/SD and into western MN during the late evening/overnight hours. However, confidence in this scenario is low due to large spread in forecast guidance with regards to the convective evolution of this system. Marginal severe probabilities have been introduced for now, and trends will be monitored for possible upgrades in subsequent outlooks. ..Leitman.. 08/05/2020Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day3otlk_0730.html
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