SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Mon Jul 26 2021 Valid 271200Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHERN MINNESOTA...WEST-CENTRAL WISCONSIN... ...SUMMARY... Isolated thunderstorms are possible late Tuesday across the upper Mississippi Valley. A conditional risk for large hail and damaging gusts will accompany the stronger storms. Strong to locally severe gusts will be possible mainly Tuesday afternoon and evening for parts of the Northeast. ...Synopsis... A mid-level anticyclone will be centered over the central High Plains on Tuesday while a mid-level low will reside over central Quebec. A belt of strong northwesterly mid-level flow will extend from south-central Canada into the upper Great Lakes and into the Northeast. Model guidance indicates a disturbance will move from the western Great Lakes eastward into NY during the day. ...Upper MS Valley... A reservoir of low-level moisture will reside over the region Tuesday to the south of a residual frontal zone draped northwest-southeast. The airmass is forecast to become very unstable by late afternoon as a cap weakens due to strong heating. However, the lack of appreciable large-scale forcing for ascent will likely limit convective coverage with a weak cap remaining through the early evening. However, weak 850 mb theta-e advection near the boundary may aid in isolated storm development by early evening in a corridor from eastern SD to central WI. Strong shear/large CAPE would conditionally support a hail risk with any sustained storm. ...Northeast... Broad cyclonic mid-level flow will encompass the Northeast to the south of a primary disturbance over Canada. Models show strong westerly mid-level flow moving through the base of the large-scale trough. Strong heating through midday and into the afternoon will result in steepened low-level lapse rates. The arrival of the aforementioned disturbance into the lower Great Lakes by mid afternoon will probably aid in storm development across NY with activity spreading/developing east into southern New England. As a few clusters develop during peak heating, a gradual intensification is expected as storms move through an environment characterized with upper 50-lower 60s surface dewpoints. Strong to locally severe gusts capable of damaging gusts are possible with the stronger clusters before this activity weakens during the evening as it approaches the coast. ..Smith.. 07/26/2021
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