SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Sun Jun 25 2023 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG PARTS OF THE ATLANTIC SEABOARD AND IN PARTS OF THE NORTHERN PLAINS... ...SUMMARY... A marginal severe threat is likely to develop on Tuesday along parts of the Atlantic Seaboard and in parts of the Northern Plains. Hail and isolated wind damage will be the primary threats. ...Eastern Seaboard... An upper-level trough will move eastward across the eastern U.S. on Tuesday. By afternoon, the trough is forecast to extend from the lower Great Lakes southward to the southern Atlantic Seaboard. An axis of instability is forecast to develop during the morning along and to the east of the upper-level trough. Isolated to scattered thunderstorms will likely form around midday, and move eastward toward the instability axis during the early afternoon. Model forecasts on Tuesday are in disagreement concerning how much instability will develop across the Atlantic Coastal Plain. The NAM has MLCAPE peaking around 3000 J/kg during the afternoon in the eastern Carolinas. In contrast, the ECMWF has the moist axis further east, with much of the stronger instability developing offshore. At this time, the ECMWF solution is favored. This solution would still result in a marginal severe threat, perhaps early in the day on the western edge of the stronger instability as low-level lapse rates steepen. The threat would remain relatively close to the Atlantic Coast, and marginally severe winds and hail would be the primary concern. ...Northern Plains... An upper-level ridge is forecast to move eastward across the north-central U.S. on Tuesday. In the wake of the ridge, southwest mid-level flow will become established across much of the High Plains. Moisture is forecast to return northward, with a narrow corridor setting up across the High Plains by afternoon. The ECMWF suggests that MUCAPE will peak in the 1500 to 2500 J/kg range by mid afternoon. However, the magnitude of instability could be overdone due to the relatively late timing of moisture return. Along and near the instability axis, forecast soundings have moderate deep-layer shear and steep mid-level lapse rates. This environment could support an isolated severe threat during the mid to late afternoon. The stronger cells that initiate along and near the instability axis may develop a severe threat. The threat should remain isolated in most areas, with hail and marginally severe winds possible. ..Broyles.. 06/25/2023
