472 ACUS02 KWNS 291721 SWODY2 SPC AC 291719 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Mon Jun 29 2026 Valid 301200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN WISCONSIN AND THE UPPER PENINSULA OF MICHIGAN...PARTS OF NEW YORK AND VERMONT...AND THE CENTRAL PLAINS... ...SUMMARY... Severe thunderstorms will be possible from parts of the central High Plains into the Upper Midwest, and across parts of the Northeast on Tuesday. ...Northeast... Enhanced northwesterly flow aloft on the northeastern periphery of an amplified upper ridge will overspread the region on Tuesday. This area will also be on the southerly periphery of a strengthening southwesterly low-level jet oriented across Ontario/Quebec. This will support effective shear magnitudes around 40+ kt. Supercell structures will be possible, but most guidance suggests convection will develop into one or more forward propagating clusters/bowing segments. Damaging wind gusts will be the main hazard with this activity as it moves across a very moist and moderately unstable airmass. Given supercell wind profiles and enlarged, favorably curved hodographs, a couple of tornadoes also will be possible, especially if a more semi-discrete storm mode occurs. While details in convective evolution vary some among various guidance, a consistent signal exists (particularly across northern NY into VT) and a Slight risk (Level 2 of 5) has been included. Convection should gradually decrease in intensity with southeast extent toward southern New England and the Mid-Atlantic vicinity as instability decreases and inhibition increases. ...Upper Midwest/Great Lakes... An upper low and attendant shortwave trough initially over the Canadian Prairies and northern MN will gradually shift east/northeast through the period. Height tendencies will generally be neutral across the area given the strong upper ridge just to the east. Enhanced southwesterly deep-layer flow will persist across the region, with some intensification of a low-level jet by late afternoon/evening. At the surface, a quasi-stationary boundary is forecast to extend from near the MN Arrowhead, southward into eastern NE at midday. To the south/east of the boundary, a very moist airmass with 70s dewpoints is forecast. A corridor of strong to extreme instability is depicted by some model guidance across northern WI into the U.P. of Michigan. Convection may develop near the surface boundary and shift east across northern portions of the Great Lakes. If this occurs, damaging winds (some near 80 mph) could accompany thunderstorm clusters potentially organizing into a bowing MCS. Some guidance develops additional convection overnight across parts of southern MN/WI into northern IA and vicinity. This activity would be supported by a warm front lifting northward across the central Plains and Mid-MO Valley and an intensifying southwesterly low-level jet. While ample instability will exist across the area, it is uncertain if this activity would be surfaced-based. Nevertheless, a favorable thermodynamic and kinematic environment would support some severe wind/hail risk. ...Southern/Central High Plains... Modest height falls are forecast as a midlevel shortwave impulse ejected across the central Rockies into NE/SD from late afternoon into the overnight hours. A surface trough/dryline will sharpen as a result, and southerly low-level flow will transport low 60s dewpoints northward along the boundary beneath steep midlevel lapse rates. High-based convection is expected to develop by late afternoon and shift east/northeast through evening. Initial supercells could produce large to very large hail. With time, some upscale development could occur via consolidating outflows and as the low-level jet increases during the evening. This could bring an increasing risk for damaging winds, a few possibly approaching 80 mph. Given a consistent signal across various CAMs, deterministic and ML/AI guidance, a Slight risk (level 2 of 5) has been added. ...LA/MS/AL/GA/FL Panhandle... Forecast guidance depicts 25-35 kt midlevel northeasterly flow on the southern periphery of an upper high centered over the OH/TN Valley. A very moist airmass will be present across much of the region and strong destabilization is forecast amid strong daytime heating. Forecast soundings depict around 20-30 kt effective shear magnitudes, supporting some risk of organized cells/clusters. Isolated damaging wind gusts are possible as activity develops west/southwest through early evening. ..Leitman.. 06/29/2026 $$