SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Sat Jul 10 2021 Valid 121200Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS MONDAY AFTERNOON AND EVENING ACROSS PARTS OF NORTHERN ALABAMA...MIDDLE AND EASTERN TENNESSEE...CENTRAL AND EASTERN KENTUCKY...EASTERN INDIANA...OHIO...PARTS OF WESTERN WEST VIRGINIA AND PENNSYLVANIA...SOUTHWESTERN NEW YORK STATE...SOUTHEASTERN LOWER MICHIGAN...AS WELL AS PARTS OF CENTRAL AND SOUTHERN ARIZONA... ...SUMMARY... Strong thunderstorms may impact a corridor from the Tennessee Valley into the lower Great Lakes region, as well as parts of central and southern Arizona, Monday afternoon and evening, accompanied by at least some risk for severe weather. ...Synopsis... As a short wave trough within the westerlies progresses east of the Canadian Prairies, downstream mid-level ridging may continue to build across the Northeast and Quebec, to the north of an increasingly prominent subtropical high becoming centered just east of the Mid Atlantic coast. As this occurs, initially amplified mid-level troughing over the Mississippi Valley is forecast to become increasingly sheared, with a remnant embedded cyclonic circulation migrating north-northeastward through the Upper Midwest/upper Great Lakes region by late Monday into Monday night. At the same time, an increasingly suppressed, but still prominent, mid-level high will remain centered over portions of the southern Great Basin. In the wake of the Mississippi Valley mid-level troughing, warm elevated mixed-layer air is forecast to advect east of the Rockies through the higher central and southern Great Plains. Otherwise, seasonably moist air and weak capping along and east of the remnant troughing may allow for considerable thunderstorm development Monday into Monday evening. ...Eastern U.S... Thermodynamic profiles across and east of the Mississippi Valley will mostly remain characterized by generally weak lapse rates. However, in a corridor from roughly middle Tennessee into the lower Great Lakes region, a lingering belt of 20-30+ kt southerly flow in the 850-700 mb layer is expected to coincide with a deep moist boundary layer, within a plume of precipitable water on the order of 1.75-2 inches. This environment may become conducive to thunderstorms in which heavy precipitation loading and downward mixing of momentum contribute to a few damaging downbursts. ...Arizona... Around the southeastern periphery of the southern Great Basin mid-level high, another short wave perturbation may aid afternoon thunderstorm development along the Mogollon Rim and higher terrain of southeastern Arizona. It appears that a belt of northeasterly mid-level flow as strong as 20-30 kt may contribute to propagation of activity off the higher terrain toward the lower deserts, where a hot and deeply-mixed boundary layer will be conducive to downbursts and developing cold pools. It remains a bit unclear whether storm development will be maintained into the lower deserts due to possible strong mid-level inhibition/modest boundary-layer moisture. ..Kerr.. 07/10/2021 Read more LIVE: spc.noaa.gov
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