2PM Day 3 Convective Outlook for Thursday, June 26. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL PLAINS INTO THE WESTERN GREAT LAKES FROM THE MID-ATLANTIC TO THE SOUTHEAST AND NORTHEAST MONTANA VICINITY
SUMMARY
Scattered strong storms are possible from the central Plains to Lower Michigan, over parts of the Southeast, and over parts of Montana on Thursday. Scattered damaging gusts appears to be the main concern.
Synopsis
Somewhat zonal flow is expected across the northern CONUS on Friday with a broad ridge across much of the southern CONUS. A moderate mid-level jet streak will move across Montana with relatively weak flow across the remainder of the CONUS. A weak upper low will drift slowly northeast across the southeastern CONUS.
Mid-Atlantic to the Southeast
A broad area of moderate instability is forecast from the Mid-Atlantic to the Southeast on Friday. Shear is expected to be very weak through the period, but moderate instability and relatively steep mid-level lapse rates beneath the upper low will provide a thermodynamic environment favorable for some damaging wind gusts. More focused areas of strong to severe storms may exist near outflow boundaries from D2/Thursday convection.
Central Plains to the western Great Lakes
Moderate to strong instability is forecast to develop along a frontal zone from Kansas to Wisconsin on Friday afternoon/evening. Shear is expected to remain weak (20 to 25 knots), but strong instability will support the threat for some damaging wind gusts.
Northeast Montana Vicinity
Moderate mid-level flow is expected to overspread northeast Montana on Friday where a deeply mixed boundary layer (above 3km) is forecast. While instability will not be that great due to limited moisture, it should be sufficient for a few storms. Moderate shear (25 to 30 knots) and a deeply mixed boundary layer will support a threat for some severe wind gusts Friday afternoon/evening.