881 ACUS02 KWNS 070631 SWODY2 SPC AC 070630 Day 2 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0130 AM CDT Tue Jul 07 2020 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MIDWEST INTO THE CENTRAL PLAINS... CORRECTED FOR INCORRECT OUTLOOK LINE DIRECTION ...SUMMARY... Severe thunderstorms are expected from the northern/central Plains into the Upper Midwest Wednesday. Isolated severe thunderstorms are also possible across New England. ...Upper Midwest into the Central Plains... A shortwave trough is expected to be over southern Saskatchewan/Manitoba at the beginning of the period. This shortwave is expected continue northeastward into central Manitoba/western Ontario while the parent cyclone matures into a closed system over southern Saskatchewan. Another shortwave trough is expected to move through the base of this cyclone, from the northern High Plains eastward/northeastward into southern Manitoba. Showers and thunderstorms will likely be ongoing early Wednesday morning across central/eastern MN, supported by enhanced low-level southeasterly flow across a warm front. These storms are expected to gradually diminish throughout the morning as the low-level flow and resulting warm-air advection weaken. At the same time, a surface low, which was centered near the ND/MN/MB border intersection at the beginning of the period, will move northeastward. This evolution will encourage the eastward/southeastward progression of a cold front from the eastern Dakotas into NE and the Upper Midwest. Dewpoints ahead of this front are forecast to be in the upper 60s/low 70s, contributing to moderate to strong buoyancy. The strongest buoyancy is anticipated across eastern SD and southwest MN where the best combination of low-level moisture and steep mid-level lapse rates is forecast. Thunderstorm development is expected along the length of the front, which will extend from far northwest MN southwestward through central SD and into western NE by Wednesday afternoon. The better vertical shear will lag behind the front, likely limiting storm organization and promoting primarily outflow-dominant storm structures across much of the region. The only exception to this is across portions of central NE where more southerly surface winds may contribute to enough low-level shear for more persistent storm organization and a greater tornado threat. Additionally, the low-level jet is expected to strengthen south of this area during the evening, resulting in an environment that could support an organized convective line. Confidence in that scenario is increasing, which prompt the southward and eastward expansion of the severe probabilities. However, further expansion, and potentially higher probabilities, may be needed in later outlooks if this scenario appears likely. ...Mid-Atlantic into New England... Scattered to numerous thunderstorms are possible from the northern Mid-Atlantic into the Northeast as a result of pre-frontal confluence amid ample low-level moisture and modest buoyancy. Weak vertical shear should preclude organized severe thunderstorms across the majority of the region. The only exception is across New England where slightly stronger flow aloft attendant to a low-amplitude shortwave trough will increase vertical shear. This increased shear could result in a few stronger storms capable of hail and/or damaging wind gusts. Hail risk is greater with earlier, more discrete development. Wind damaging risk will be greater later after the storms have transitioned to bowing line segments. ...Carolinas... Widespread thunderstorm activity is anticipated from GA through the Carolinas in the vicinity of a surface low and associated upper cyclone that is expected to move slowly over the region. Some enhancement of the low-level flow is possible along the eastern periphery of the system, but this is currently expected to be offshore. Resulting weak vertical shear over land will keep any severe threat low. ..Mosier.. 07/07/2020 $$