SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sat Oct 25 2025 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS AND LOUISIANA... ...SUMMARY... Scattered severe thunderstorms with a tornado threat, large hail and severe wind gusts are possible this afternoon and evening from central Texas eastward into the lower Mississippi Valley. Very large hail will be possible across parts of the middle Texas Coastal Plain. A couple of severe gusts or a brief tornado are also possible over parts of the Pacific Northwest. ...Western Gulf States... A mid-level low will move eastward into the southern Plains today, as an associated jet streak translates eastward through the base of the system. Ahead of the system, diffluent southwesterly mid-level flow will be in place over much of the western Gulf Coast states. A linear MCS will be ongoing at the start of the period across southeast Texas. A tornado and wind-damage threat will exist with the more intense segments of the line. The severe threat will continue to move eastward across central and southern Louisiana this morning, reaching the New Orleans area by early afternoon. Although the line will stabilize the airmass over much of Louisiana, moderate instability is expected to redevelop in its wake over the Texas Coastal Plain, where MLCAPE is forecast to reach the 1500 to 2500 J/kg range by afternoon. Along the western edge of the stronger instability, low-level convergence will aid scattered convective initiation this afternoon across eastern parts of the Texas Hill Country and over the middle Texas Coastal Plain. RAP forecast soundings late this afternoon from San Antonio to Houston have 0-6 km shear around 50 knots with 700-500 mb lapse rates near 7 C/km. This should support supercells with large hail. The more intense supercells could produce hailstones greater than 2 inches in diameter. In addition, 0-3 km storm relative-helicity is forecast to be in the 200 to 250 m2/s2 range over the middle Texas Coastal Plain suggesting that a few tornadoes will be possible. A potential will exist for a strong tornado, although this remains uncertain. The storms are expected to congeal into a linear convective system by early evening. A potential for damaging wind gusts will exist along the leading edge of the line, with the threat continuing into the early overnight period, along and near the coast of southern Louisiana. ...Pacific Northwest... A mid-level trough, and an associated plume of moisture, will move eastward into the Pacific Northwest today. Strong large-scale ascent will be favorable for thunderstorm development along the coast of Washington and Oregon. A brief tornado and marginally severe wind gusts will be possible as cells move inland near the coast. Further east into parts of southeast Washington and far northeast Oregon, thunderstorm development will be possible late this afternoon as a low-level jet streak moves across the region. In this area, lapse rates will be steep and flow will be strong suggesting that an isolated wind-damage threat will be possible. ..Broyles/Wendt.. 10/25/2025
