Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0339 AM CDT Mon Aug 02 2021 Valid 051200Z - 101200Z ...DISCUSSION... On Thu/D4, a dwindling upper low will move from the upper OH Valley into NY, with 35-40 kt 500 mb winds across the Mid Atlantic. At the surface, a weak low will move roughly from NC toward the Delmarva as a warm front lifts north across NJ and into southern New England. While ample moisture will be available for storms, significant precipitation is expected through the period, and shear will be marginal. While isolated strong to severe storms cannot be ruled over parts of the Mid Atlantic, potential remains too low. During the Fri/D5 to Sat/D5 time frame, a weakening shortwave trough is forecast to move from the northern High Plains to the upper MS Valley, with low pressure developing over SD and moving into MN. Storms appear most likely Friday evening in a zone of warm advection from the Dakotas into MN, with marginal instability forecast. Storms are expected to persist through Sat/D5 into MN and WI as moisture and instability continue to increase. While there is potential for a few severe storms in this regime, the weakening wave decreases predictability. Behind this lead wave, a stronger shortwave trough is forecast to affect the northern Plains and upper MS Valley during the Sun/D7 to Mon/D8 period. Although predictability is low, this type of pattern may result in severe storms, as persistent southerly low-level winds bring a return of upper 60s and lower 70s F dewpoints to the region. Strong instability may develop, and the Dakotas, MN and WI remain an area of interest. If model trends persist, severe risk areas may be added in later outlooks. Read more LIVE: spc.noaa.gov
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