Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Wed Aug 26 2020 Valid 271200Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE NORTHEAST STATES... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN PLAINS THROUGH THE GREAT LAKES AND NORTHEAST STATES... ...SUMMARY... Severe storms are likely Thursday from a portion of the Northeast States, Great Lakes and northern Plains. Damaging wind and large hail are the main threats though a few tornadoes are also possible. Other severe storms with a threat for tornadoes are possible over a portion of the lower Mississippi Valley region. ...Lower Great Lakes through Northeast States... Early Thursday morning a warm front will extend from northern NY southeast into southern New England. This boundary will move east during the day, while an upstream cold front advances southeast through the lower Great Lakes reaching the Northeast States by late Thursday afternoon or evening. Elevated storms should be ongoing within zone of ascent on cool side of the warm front from northern NY into New England. Overall severe threat with this activity will probably remain limited. In wake of morning storms and the passing warm front, the advection of rich low-level moisture with upper 60s to around 70F dewpoints and diabatic heating should result in moderate instability with 1500-2500 J/kg MLCAPE. Additional storms will likely develop along lake breezes and pre-frontal boundary and spread southeast through a portion of the Northeast States. This region will reside within a belt of stronger northwesterly winds aloft, with 40-50 kt effective bulk shear supporting fast-moving organized storms, including bowing segments and supercells. Most CAMs show decent updraft-helicity tracks. Initial storm mode could be dominated by supercells, but an eventual evolution to lines and bowing segments may occur. All severe hazards are possible, but the primary threats should be damaging wind and large hail from mid afternoon through early evening. ...Northern Plains through Upper Great Lakes... Storms are forecast to be ongoing over a portion of the northern High Plains early Thursday, and this activity will probably weaken during the day. Reinforcing surge of cooler, dry air will augment frontogenetic forcing along pre-existing baroclinic zone from a portion of the northern Plains into the Great Lakes where the atmosphere will likely become moderately unstable during the afternoon. While a capping inversion might inhibit surface-based storms over this region much of the day, additional storms will likely develop by late afternoon or early evening from SD into southern MN and the Great Lakes in association with increasing frontogenetic forcing and strengthening low level jet. This area will reside within belt of moderate winds aloft with 30-50 kt effective bulk shear supportive of organized storms. Primary threats will be large hail and damaging wind from late afternoon into the evening. Other storms will likely develop in upslope region of northern WY and southern MT during the afternoon and spread east into the High Plains. Strong vertical shear will support supercell structures with large hail and downburst winds the main threats. ...Lower Mississippi Valley region... Strong wind fields and large hodographs associated with the remnants of Laura will spread inland through the lower MS Valley region. The risk for a few tornadoes will likely persist with mini supercells in the outer bands east and northeast of the center, and a SLGT risk has been introduced to reflect this threat. ..Dial.. 08/26/2020Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_0600.html
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