SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0801 PM CDT Thu May 08 2025 Valid 090100Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH TEXAS...THE TENNESSEE VALLEY...SOUTHERN APPALACHIANS AND SOUTHEAST... ...SUMMARY... Scattered thunderstorms with severe wind gusts and large hail will continue this evening over parts of the Tennessee Valley, southern Appalachians and Southeast. Severe wind gusts and large hail are also expected across parts of south Texas, where hailstones of greater than 2 inches in diameter will be possible. ...Tennessee Valley/Southern Appalachians/Southeast... Latest water vapor imagery shows a positively-tilted mid-level trough over the Ohio Valley, with an east-to-west oriented plume of mid-level moisture from the mid Mississippi Valley into the south and central Appalachians. At the surface, a quasi-stationary front is analyzed in the Ohio Valley. To the south of the front over the Ohio and Tennessee Valleys, surface dewpoints are in the mid 50s to the mid 60s F. The RAP has moderate instability in place from the Tennessee Valley eastward into the southern Appalachians and southward into the Gulf Coast states. Scattered thunderstorms are ongoing, concentrated along the northern edge of moderate instability from Kentucky and Tennessee eastward into western North Carolina. RAP forecast soundings in this vicinity early this evening have 0-6 km shear ranging from 35 to 45 knots, mostly due to speed shear in the mid-levels. This, combined with 0-3 km lapse rates in the 7.5 to 8 C/km range, should be favorable for severe gusts with the stronger cells. The shear will also support supercell development with large hail possible. The severe threat should become more isolated later this evening as instability decreases across the region. ...South Texas... A shortwave trough, with multiple vorticity maximums, appears to be located in the lower Rio Grande Valley, according to water vapor imagery. Scattered strong to severe thunderstorms are ongoing ahead of the trough from near Laredo extending eastward onto the Texas Coastal Plain. From the storms southward, moderate instability is analyzed by the RAP, with MLCAPE estimated to be in the 1000 to 2000 J/kg range. The airmass is very moist with surface dewpoints in the lower to mid 70s F. Within this moist airmass, RAP forecast soundings early this evening have 0-6 km shear near 50 knots, with 700-500 mb lapse rates near 7.5 C/km. This environment will support supercells with large hail, and hailstones greater than 2 inches in diameter will be possible within the more intense cores. Isolated severe gusts may also occur within the stronger downdrafts. The ongoing severe storms will track southeastward across the remainder of south Texas this evening...see MCD 749. ..Broyles.. 05/09/2025