2PM Day 3 Convective Outlook for Tuesday, June 24. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER EASTERN WYOMING AND VICINITY
SUMMARY
Severe storms are possible Tuesday from eastern Wyoming into southwest South Dakota, the Nebraska Panhandle, and northeast Colorado. Isolated strong to severe storms will also be possible from parts of the central Plains and Midwest into the Northeast.
Synopsis
The upper ridge over the East will flatten on Tuesday as a strong upper trough moves across Ontario and Quebec, with the strongest height falls occurring overnight. To the west, shortwave ridging will occur over the northern Plains during the day, as a weakening and low-amplitude wave moves from UT into WY through 00Z. This system will continue into the northern Plains overnight, providing cooling aloft.
At the surface, high pressure will extend from the upper Great Lakes into the Southeast, with southerly winds persisting over the Plains. A boundary from Lower MI into NE will surge north as a warm front late in the day and overnight, with backed/easterly winds along this front allowing for near 60 F dewpoints as far west as eastern WY.
Late in the day, a cold front associated with the Quebec upper trough will push south across NY, PA, and New England, providing a focus for storms as the antecedent air mass will be unstable.
Northern to central High Plains
Morning thunderstorms may be ongoing from parts of NE and KS northeastward into Lower MI, but probably not severe at that time. As heating occurs, re-development is possible, both along the developing warm front or with any MCVs or residual outflow boundaries. The weak shear environment coupled with moderate instability will primarily yield sporadic clusters of strong to locally damaging wind gusts.
Farther west into eastern WY and northeast CO, supercell potential will exist late in the day and during the evening, as moist easterly flow eventually becomes uncapped generally east of a Casper to Cheyenne to Denver line. Aided by steep lapse rates/heating over the higher terrain, and the approaching upper trough, widely scattered cells are anticipated, with large hail the most likely threat. A brief tornado cannot be ruled out. While capping will be an issue after dark, the lifting warm front may support additional storms into western SD/NE.
Northeast Late Afternoon/Evening
Forecast soundings across the area depict relatively warm profiles aloft, though still unstable with 1500-2000 J/kg MUCAPE. Given this, widely scattered thunderstorms are expected from Lake Huron eastward into parts of New England late in the day. As these storms should be timed near peak heating, localized strong downbursts will be possible.