SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 AM CDT Fri Oct 03 2025 Valid 031300Z - 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 into the Central/Northern Rockies... A well-defined, slightly positively tilted shortwave trough is currently progressing through northern/central CA. Eastward progression is expected to continue throughout the day, with the shortwave forecast reach western UT by early Saturday morning with a more neutral tilt. Strong mid-level flow will extend throughout the base of this shortwave, spreading from central/southern CA into the central Intermountain West as the wave moves eastward. Strong large-scale forcing for ascent will precede this wave as well, contributing to isolated to scattered thunderstorms throughout much of the Great Basin into the western Slopes. Strong daytime heating and steep low to mid-level lapse rates will support buoyancy throughout much of this region, although the relatively scant low-level moisture will keep the overall buoyancy modest. Even with the modest buoyancy, high-based storms combined with moderate low/mid-level flow could still result in a few strong surface gusts. Greatest chance for a few gust will be later this afternoon/early evening from northern into east-central UT. Persistent forcing for ascent will result in thunderstorm development throughout the evening and overnight amid strengthening mid-level flow and cooling mid-level temperatures. Buoyancy will remain modest, but a few instances of hail are possible this evening and tonight, particularly across northern/eastern UT and vicinity. ...Elsewhere... A broad and weak upper low will remain centered over the central Gulf Coast, with lift associated with this system contributing to thunderstorms within the moist airmass in place along the Gulf Coast and FL. Southern extent of a cold front moving across Ontario will glance Upper MI and northern Lower MI, contributing to isolated storms. A few afternoon thunderstorms are also possible across Mid MS Valley amid strong heating, moderate low-level moisture, and modest low-level convergence. In each of these areas, limited shear should keep the severe potential low. An extensive low-level jet is anticipated from the southern High Plains into the Upper MS Valley tonight. A few elevated thunderstorms are possible across eastern ND and northwestern MN tonight, but warm mid-level temperatures should mitigate the overall severe potential. ..Mosier/Bentley.. 10/03/2025
