SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Sat Oct 25 2025 Valid 251300Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF TEXAS AND LOUISIANA... ...SUMMARY... Scattered severe thunderstorms are possible today into tonight from central Texas eastward into the lower Mississippi Valley. ...TX-LA... Water-vapor imagery shows a mid- to upper-level low over the southern High Plains and it is forecast to move east across much of OK by early Sunday morning. Strong cyclonic 500-mb flow (40-60 kt) will move through the base of the larger scale trough over TX and eventually moving into the lower MS Valley. An ongoing MCS across southwestern LA and the northwest Gulf of America will likely progress eastward across southern LA through early afternoon. An isolated risk for damaging gusts (55-65 mph) and a brief tornado may continue east but be increasingly confined to the coastal parishes as the squall line's eastward movement outpaces appreciable inland destabilization. High uncertainty is apparent farther west across central into east and coastal portions of TX. Earlier shower/thunderstorm activity across much of the mid and upper coastal plain of TX has rendered substantial convective overturning of the airmass from the coastal plain northwestward towards the I-35 corridor north of a composite outflow boundary. Models vary regarding destabilization and this signal in model data is congruent with forecaster experience in placing low confidence in potential storm evolution later this afternoon into the evening across central and east TX. Nonetheless, there will probably exist a window of opportunity for diurnal destabilization arcing around the south and west portions of the mesoscale surface high. Some forecast soundings show moderate instability in the presence of strong mid to high-level westerly flow---supporting supercells and storm organization with accompanying potential for damaging gusts. Have adjusted the northern bounds of tornado probabilities farther south in closer proximity to richer moisture, and removed 15-percent hail probabilities across southeast TX and LA where lapse rates will likely remain stunted through early Sunday morning. The tornado risk correspondingly will tend to favor any supercell development in proximity to richer moisture and mesovortex structures within parent QLCSs, but low confidence exists regarding this forecast given aforementioned convective-related concerns. ...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 risk could develop near the immediate coast and marginally severe wind gusts will be possible as cells move inland. Farther east into parts of southeast Washington and far northeast Oregon, thunderstorm development will be possible late this afternoon with perhaps isolated severe gusts associated with the stronger thunderstorms. ..Smith/Weinman.. 10/25/2025
