SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Sat Oct 25 2025 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH-CENTRAL TEXAS INTO SOUTHERN LOUISIANA... ...SUMMARY... Scattered severe thunderstorms are possible today into tonight from parts of south-central Texas into the lower Mississippi Valley. ...20z Update... The previous forecast largely remains on track with only a slight northward adjustment of the 5% hail/wind probabilities across portions of central/eastern TX ahead of developing convection. Immediately downstream of these storms, temperatures have been slow to warm, resulting in a regional minimum of buoyancy. It remains unclear how intense convection will be along the I-20 corridor due to the modest buoyancy, but strong deep-layer wind shear and some degree of air mass recovery may be sufficient for an isolated hail/wind threat. Additional thunderstorm development to the south/southwest along the I-35 corridor remains likely by late afternoon/evening as ascent ahead of the upper trough increases. Temperatures across the Austin/San Antonio region (and southeastwards along the TX coast) have increased to the mid 70s to low 80s, which is eroding lingering inhibition and supporting MLCAPE values upwards of 1500 J/kg. As such, the current Slight risk area continues to highlight the best convective environment with the expectation for increasing thunderstorm coverage heading into the evening hours. Additional forecast details outlined in the previous discussion below remain on track. ..Moore.. 10/25/2025 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sat Oct 25 2025/ ...South-Central/Coastal Texas into Louisiana... Extensive convective overturning occurred overnight/early this morning across central/east TX into LA with an MCS that has decayed across coastal LA as of late this morning. Recent radar and visible satellite imagery show a band of outflow arcing from south-central LA across the northwest Gulf and into south-central TX. The degree of destabilization that can occur today from central/east TX into LA in the wake of this outflow remains uncertain. Cool mid-level temperatures will persist through the period across the southern Plains as a closed mid/upper-level low moves slowly eastward from the TX Panhandle across OK. The best potential for weak to locally moderate instability to develop this afternoon may exist over portions of central into southeast TX, where some cloud breaks are noted and generally mid 60s surface dewpoints are still in place. Current expectations are for scattered thunderstorms to redevelop this afternoon along a secondary outflow boundary extending across central into east/coastal TX, as ascent associated with a 40-50+ kt mid-level jet rounding the base of the upper trough/low overspreads this area. Deep-layer shear will be strong enough to support supercells with this initial activity. Large hail may occur with any sustained supercell. With time this evening, outflow interactions should encourage another MCS to develop across southeast TX and vicinity. Scattered damaging winds should become a greater concern as this MCS develops eastward across parts of LA overnight into early Sunday morning. Although low-level flow is not forecast to be overly strong, a few tornadoes still appear possible both with the initial supercells and embedded circulations within the MCS. Given observational trends and recent model guidance suggesting robust destabilization will struggle with northward extent, severe probabilities have been confined/adjusted southward across central/east TX into LA with this update. ...Pacific Northwest... A mid-level trough and associated strong jet will move eastward across parts of the Pacific Northwest through the period. Pronounced large-scale ascent will prove favorable for thunderstorm development along coastal WA/OR. A brief waterspout/tornado could develop/move ashore near the immediate coast, and marginally severe wind gusts will be possible as low-topped cells move inland. Separately, parts of southeast WA into northeast OR and ID may see isolated to scattered thunderstorm development late this afternoon, with occasional severe gusts possible with the more robust convection. Weak instability forecast across both areas should keep the overall severe threat rather isolated/marginal.
