1AM Day 2 Convective Outlook for Tuesday, June 24. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR EASTERN WY NORTHEAST CO AND PARTS OF WESTERN NE/SD
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
A mid/upper-level shortwave trough is forecast to move from the Southwest into the northern Rockies on Tuesday. Downstream, a strong mid/upper-level trough will move across parts of Ontario and Quebec, resulting in some dampening of the persistent upper ridge over the East.
At the surface, a warm front will move northward across parts of the central Plains, while the eastern portion of the front will be draped somewhere from the Midwest into the southern Great Lakes vicinity. A cold front will move southward across parts of the northern Great Lakes and Northeast/New England.
WY/CO into western NE/SD
Increasing low-level moisture beneath generally steep midlevel lapse rates will support moderate destabilization across parts of eastern WY into northeast CO. Veering wind profiles will support organized storms, and isolated to widely scattered supercells may develop from late afternoon into the evening. Large to very large hail, localized severe gusts, and perhaps a tornado are all possible. Some upscale growth will be possible through the evening, which could spread at least an isolated severe threat into parts of western NE/SD. The longevity of the severe threat into Tuesday night is uncertain, due to increasing low-level stability.
Lower MO River Valley into the Midwest and Great Lakes
In the wake of morning convection, strong heating/destabilization will support development of strong to potentially severe storms from parts of eastern KS/southeast NE into the Midwest and Great Lakes, along the periphery of the upper ridge. Development will likely be focused near an outflow-influenced front, and potentially near any remnant MCVs. Deep-layer shear is expected to be relatively weak along/ahead of the front, but unidirectional southwesterly flow will support potential for outflow-driven clusters capable of locally damaging wind.
Corridors of greater severe threat may eventually evolve within the broad Marginal Risk across this region, but confidence in the placement of the front and any MCVs or other vorticity maxima precludes higher probabilities at this time.
Parts of the Northeast/New England
Midlevel lapse rates will be weak, but relatively strong heating will support moderate buoyancy by afternoon across parts of the Northeast, along and ahead of the cold front. Stronger ascent and deep-layer flow will remain north of the front, but sufficient flow and steepening of low-level lapse rates will support a threat of damaging gusts with any strong storms across the region. Storm coverage is uncertain, but greater severe probabilities may eventually be needed if trends support more than isolated storm development during the afternoon and evening.
Southeast into the Carolinas and Mid Atlantic
A remnant EML will gradually move southwestward along the periphery of the upper ridge across parts of the Carolinas, Mid Atlantic, and Southeast on Tuesday. While this will support strong buoyancy, there is a considerable amount of spread regarding storm coverage across this region Tuesday. At this time, the highest confidence in storm development is over the southern Appalachians, where deep-layer shear will be negligible underneath the upper ridge. If confidence in storm coverage increases where slightly stronger flow aloft will be present, severe probabilities may eventually be needed.