SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1235 AM CDT Fri Jul 16 2021 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Isolated strong to severe thunderstorms may develop today across parts of the Mid Mississippi Valley into the Ohio Valley and the Northeast, and over portions of the northern/central Plains. ...Ozarks/Mid Mississippi Valley... An upper-level trough will move eastward across the mid Mississippi Valley and Ozarks today. At the surface, a frontal boundary will be located from the Ozarks east-northeastward into the Lower Great Lakes region. Scattered thunderstorms should be ongoing this morning in the vicinity of the front and southward across much of the mid Mississippi Valley. Surface dewpoints across this area will be in the upper 60s and lower 70s F, which will allow moderate instability to develop in areas in areas that can heat up sufficiently. Storms that form in proximity to moderate instability may be associated with a marginal wind-damage threat, especially in the mid to late afternoon when low-level lapse rates are the steepest. ...Northeast... An upper-level trough will move eastward across the Northeast today. At the surface, a cold front will advance eastward across New England with a moist airmass in place ahead of the front. As surface temperatures warm during the day, a southwest-to-northeast corridor of moderate instability will develop from far southeast New York extending northeastward across southern New England. Thunderstorms that form along the front will have access to moderate instability, with surface dewpoints of 70 to 75 F. In addition, flow at 850 mb is forecast to be west-southwesterly at 25 to 30 knots. This could aid an isolated wind-damage threat as cells develop along and near the front during the late morning and early afternoon. ..Central and Northern High Plains... An upper-level ridge will move eastward across the central Rockies and northern High Plains today. Ahead of the ridge, northwest mid-level flow will be located across much of the High Plains. Ahead of the ridge, a north-to-south corridor of moderate instability will be in place across western Kansas, western Nebraska and western South Dakota by midday. Although large-scale ascent will be weak, widely spaced thunderstorm development could occur near and to the east of a lee surface trough. Moderate instability along with 0-6 km shear in the 30 to 40 kt range and steep lapse rates should be sufficient for a marginal wind-damage and hail threat. Convective coverage is forecast to remain very isolated due to the presence of the upper-level ridge, keeping the severe threat relatively low. ..Broyles/Squitieri.. 07/16/2021 Read more LIVE: spc.noaa.gov
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