Aggregator | disasterassistance.gov

SPC Apr 4, 2025 0730 UTC Day 3 Severe Thunderstorm Outlook

4 months 3 weeks ago

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CDT Fri Apr 04 2025 Valid 061200Z - 071200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST AND SOUTHERN APPALACHIANS... ...SUMMARY... A wind-damage and isolated tornado threat will be likely on Sunday across parts of the Southeast and southern Appalachians. Marginally severe wind gusts will also be possible in parts of the southern Appalachians, Carolinas, and Mid-Atlantic. ...Southeast/Southern Appalachians... A mid-level trough will move slowly eastward across the central U.S. on Sunday, as an associated cold front advances eastward across the central Gulf Coast states and Tennessee Valley. Along and ahead of the front, a large MCS will be ongoing at the start of the period. This MCS will move eastward during the day. Ahead of the MCS, warming surface temperatures across a very moist airmass, and moderate deep-layer shear, will be favorable for isolated severe storms. Forecast soundings Sunday afternoon in the central Gulf Coast states near the instability axis have MLCAPE peaking in the 1000 to 1500 J/kg range with 0-6 km shear near 40 knots. In addition, low-level lapse rates are forecast to steepen during the day. This should be favorable for isolated severe storms. Supercell development will be possible along or ahead of the line, mainly in areas where instability becomes the strongest. Bowing line segments will also be possible within the line itself. The primary threat is expected to be wind damage, but an isolated tornado threat will also be possible. The greatest severe potential appears likely to shift eastward from the central Gulf Coast states into Georgia and the eastern Florida Panhandle by early evening. ...Southern Appalachians/Carolinas/Mid-Atlantic... At the start of the period, a cold front is forecast to be located from the lower Ohio Valley into the central Appalachians. The northern end of a large MCS will likely be ongoing, with this convection moving eastward across the southern and central Appalachians during the day. Ahead of the MCS, weak instability is expected to develop. Forecast soundings ahead of the front have MLCAPE peaking in the 250 to 500 J/kg range by afternoon. In addition, a 90 to 100 knot mid-level jet streak is forecast to move across the Ohio Valley. This feature will create strong deep-layer shear profiles, favorable for an isolated severe threat. As low-level lapse rates gradually steepen ahead of the front, an isolated wind-damage threat should develop. This threat may persist through the afternoon, as a broken line of storms moves eastward into the Carolinas and Mid-Atlantic. ..Broyles.. 04/04/2025 Read more