SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1254 AM CDT Fri Oct 03 2025 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE INTERMOUNTAIN WEST INTO THE CENTRAL AND NORTHERN ROCKIES... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible from late this afternoon into tonight from parts of the Intermountain West into the central and northern Rockies. ...Intermountain West/Central and Northern Rockies... Mid-level southwesterly flow will be in place today across much of the western U.S., as a trough moves into the Intermountain West. At the surface, a low will deepen across western Utah. Surface dewpoints in many areas to the east and north of the low will be in the mid 30s and mid 40s F. As surface temperatures warm today, pockets of weak instability will develop from eastern Utah and western Colorado northward into western Wyoming and eastern Idaho. As large-scale ascent increases due to the approaching trough, scattered thunderstorms are expected to develop within this instability corridor. RAP forecast soundings near the areas of strongest instability have substantial speed shear in the low to mid-levels with nearly dry adiabatic lapse rates in the low-levels. This could be conducive for isolated severe wind gusts with multicells that develop during the late afternoon and evening. In addition, 500 mb temperatures are forecast to be -12C to -15C which could support a marginal hail threat. The severe threat could continue into the overnight period as a band of strong large-scale ascent moves from west to east across the region. ..Broyles/Lyons.. 10/03/2025
