textproduct: Salt Lake City

SYNOPSIS

A significant winter storm will impact northern and central Utah late Thursday into Sunday morning. The potential for unsettled weather continues through the middle of next week.

LONG TERM (After 12Z/5AM Sunday)

By Sunday morning, a broad ridge over the Pacific will be nudging into the western US, with overall northwesterly flow persisting across the Great Basin. Residual low- to mid-level moisture across northern Utah will result in some light showers through Sunday and into Monday, particularly towards the early morning hours as a shortwave trough quickly passes through the region. However, any QPF will be minimal, likely <0.10" even across the northern mountains.

Uncertainty in the longwave pattern increases beyond Monday; model guidance disagrees with the amplitude of this ridge to our west, which will ultimately steer the trajectory of a landfalling atmospheric river. For example, the GFS suggests more zonal flow which would allow this moisture to stream into northern Utah/southwest Wyoming. However, the majority of model guidance (85% by Wednesday, and still 65% by Thursday) favors a more amplified ridge, which would orient this moisture well to our north. Still, this lower-chance scenario is producing a fairly high tail in the QPF distribution (i.e. a 90th percentile QPF of 1.00" in the northern mountains), so will be something to watch. Regarding temperatures and snow levels, although we could see a cold front sag southwards later in the week, most model guidance suggests a gradual warming trend through the week, with temperatures potentially reaching 10-15 degrees above normal by late next week. Southern Utah will remain dry alongside these warming temperatures through the week.

AVIATION

Low clouds have mostly dissipated early this morning, with clearing skies expected through the day before CIGs drop once again after ~01-03z with the next storm system, resulting in mountain obscuration and MVFR CIGs, particularly after 06z. Winds will be light and variable through roughly 15-16z when southerly winds around 5-10kts will pick up. These southerlies could persist through the day (25% chance), though northwesterly winds will likely return anytime between 20-23z.

REST OF UTAH AND SOUTHWEST WYOMING...Expect light and variable winds through the morning, with westerly winds with gusts up to 25kts expected to persist after ~18z. SCT-BKN low clouds over and adjacent to higher terrain will begin to dissipate after roughly 15z, and may produce periods of MVFR CIGs until then. CIGs will dip again across northern/central UT and southwest WY later this evening.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Winter Storm Watch from late tonight through late Saturday night for UTZ108-110>112.

WY...None.