SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0225 AM CDT Mon Sep 19 2022 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER GREAT LAKES... ...SUMMARY... Thunderstorms associated with wind damage and hail will be possible on Wednesday across parts of the lower Great Lakes region. ...Lower Great Lakes/Central and Northern Appalachians... An upper-level trough will move eastward into the Great Lakes region on Wednesday, as a 80 to 100 knot mid-level jet moves through the based of the trough. At the surface, a fast-moving cold front will advance southeastward into the central Great Lakes. Low-level convergence will increase along the front during the day. This combined with surface heating and strong large-scale ascent associated with the upper-level trough, will result in thunderstorm development during the afternoon. These storms are forecast to move eastward into the vicinity of Lake Ontario and Lake Erie during the late afternoon and early evening. Large-scale ascent should be focused along a well-defined band of vorticity, making squall line development likely. Ahead of the front, surface dewpoints are forecast to be in mid to upper 60s F, which will contribute to the development of moderate instability. Model forecasts suggest that MLCAPE could peak in the 1500 to 2500 J/kg range by mid afternoon, along an axis from northeast Ohio into far western New York. In addition, forecast soundings along the instability axis by 00Z/Thursday have 0-6 km shear near 50 knots. Winds are forecast to be veered to the south-southwest ahead of the front but some directional shear should be present in the lowest 3 km. This environment should be favorable for wind damage along the leading edge of a squall line. The wind-damage threat should be greatest from far northern Ohio into far northwest Pennsylvania and western New York, although a marginal wind-damage threat could exist further east into central Pennsylvania and eastern New York later in the evening. Lapse rates in the mid-levels should also be steep enough for hail with the stronger updrafts. ..Broyles.. 09/19/2022
