SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Sun Sep 18 2022 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER GREAT LAKES...CENTRAL TO NORTHERN APPALACHIANS AND NORTHERN PLAINS... ...SUMMARY... Thunderstorms associated with marginally severe wind gusts and hail will be possible on Monday in parts of the lower Great Lakes, central to northern Appalachians, and northern Plains. ...Lower Great Lakes/Central to Northern Appalachians... A shortwave trough is forecast to move into the central Appalachians and lower Great Lakes on Monday. At the surface, a cold front is forecast to advance quickly eastward reaching the lower Great Lakes by afternoon. Ahead of the front, elevated thunderstorms may develop across parts of New York during the morning, with this activity spreading eastward into New England by afternoon. Surface dewpoints ahead of the front are forecast to be generally in the mid 60s F. This, along with surface heating, will allow for weak instability to develop during the day. Surface-based thunderstorm development will be possible near and ahead of the front, as low-level convergence becomes maximized during the mid to late afternoon. 0-6 km shear is forecast to be in the 30 to 40 knot range across much of the region. This could be sufficient for an isolated severe threat associated with the stronger multicells. Although the wind-damage potential will likely be the greatest threat, hail could also accompany the stronger updrafts. ...Northern Plains... A shortwave trough is forecast to move eastward across the northern Rockies on Monday, as mid-level flow over much of the High Plains remain west-southwesterly. At the surface, a cold front will move across the northern High Plains on Monday. Ahead of the front, a narrow corridor of maximized low-level moisture will be in place in the central Dakotas. Surface heating along this corridor may be great enough for moderate instability by late afternoon. As instability peaks, thunderstorm development appears likely along the northern edge of the stronger instability, across southern Saskatchewan and southern Manitoba. These storms could organize into a cluster and move into parts of far northern North Dakota by early evening. In addition to the moderate instability, forecast soundings at 00Z/Tuesday in northern North Dakota show 0-6 km shear in the 55 to 65 knot range with 700-500 mb lapse rates of 7.5 to 8.0 C/km. This suggests a potential for isolated supercells with marginally severe hail. A few strong wind gusts will also be possible. ..Broyles.. 09/18/2022
