SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1244 AM CDT Wed Jul 07 2021 Valid 071200Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN FLORIDA...FAR SOUTHEAST GEORGIA...THE LOWER GREAT LAKES AND NORTHERN HIGH PLAINS... ...SUMMARY... A tornado threat is expected this morning across parts of northern Florida and far southeast Georgia, with storms associated with Hurricane Elsa. Storms with large hail and wind damage could develop this afternoon and evening across parts of the northern High Plains. Storms with isolated wind damage may also develop in parts of the lower Great Lakes. ...Northern Florida/Far Southeast Georgia... Hurricane Elsa is forecast to weaken to a tropical storm today and move north-northeastward across northern Florida. Rainbands to the north and east of the center will overspread the northern Florida Peninsula and southeast Georgia this morning. RAP forecast soundings from 12Z to 18Z across the northern Florida Peninsula maintain strong low-level shear to the northeast of Elsa's center, with 0-1 km shear in the 35 to 40 kt range. This will be favorable for an isolated tornado threat associated with cells that remain semi-discrete within the outer rainbands of the tropical storm. A marginal tornado threat could spread across eastern Georgia and eastern South Carolina this afternoon and evening as Elsa moves north-northeastward. ...Lower Great Lakes/Northeast... An upper-level trough will move eastward into the mid to upper Mississippi Valley today as mid-level flow remains west-southwesterly across much of the Great Lakes region. At the surface, a quasi-stationary front will be in place across southern Lower Michigan extending eastward into southwest Ontario. Thunderstorms are forecast to develop this morning across parts of the Ohio Valley with this convection spreading northeastward into the lower Great Lakes region during the afternoon. Ahead of these storms, the airmass will be very moist with moderate instability developing by afternoon. MLCAPE could peak in the 2000 to 3000 J/kg range across parts of northeastern Ohio and northwest Pennsylvania. This area is forecast to have 0-6 km shear in the 25 to 30 kt range suggesting an isolated wind-damage threat will be possible this afternoon. Further east into parts eastern Pennsylvania and southern New England, a moist airmass will be in place today. This will result in the development of moderate instability by midday. Thunderstorms that develop within this east-to-west corridor of instability will have a potential for strong gusty winds, especially as low-level lapse rates become the steepest during the early afternoon. ...Northern High Plains/Northern Rockies... Northwest mid-level flow will be located across parts of the northern High Plains today as an upper-level ridge moves eastward across the northern Rockies. Ahead of the ridge, upslope flow will be in place across much of the northern High Plains. Moderate instability is forecast to develop by late afternoon along an axis from near the Black Hills north-northwestward into northern Montana. Thunderstorms should develop in the higher terrain of north-central Montana and spread southeastward across parts of eastern Montana during the afternoon and evening. Additional storms may develop across parts of the Black Hills. Although an isolated severe threat will be possible in much of the northern High Plains this afternoon, the highest potential should exist in north-central Montana where convective coverage is forecast to be the greatest. ..Broyles/Moore.. 07/07/2021 Read more LIVE: spc.noaa.gov
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