Area Forecast Discussion

KEY MESSAGES

- Valley rain and mountain snow showers will continue through Thursday afternoon. Northern mountains can be expected to see an additional 1-4 inches of snow, with locally 5-8 inches over the Bear River Range.

- Freezes will impact many Utah valleys tonight and again Thursday night. Freezes are not expected to impact the Wasatch Front or lower Washington County.

- An active pattern will bring the threat of 6+ inches of snow to the northern mountains Saturday night into Monday.

- Additional freezes may impact the Sanpete and Sevier Valleys and southwest Utah Sunday night into Monday morning.

DISCUSSION

A cyclonic west to southwesterly flow aloft is in place over Utah this evening as remnants of a decaying upstream low ripples across the area. These remnants, in addition to another weak disturbance rotating in from the north, will continue to impact the area through Thursday afternoon. This will allow showery precipitation to continue across northern Utah through the night into Thursday. Snow levels will remain near 6 kft, with generally sub-advisory snow amounts except locally over the higher ridgelines of the Bear River Range.

With a cooler airmass in place, freezing temperatures are expected across the central through southwest Utah valleys tonight, provided midlevel clouds currently in place over a portion of this area clear out quickly enough to support efficient radiative cooling. With clearer skies Thursday night, temperatures in these same areas, as well as in eastern Box Elder County, are expected to see freezing temperatures once again.

Drier and slightly warmer temperatures are expected Friday into Saturday, but the break in the weather will be brief as an active weather pattern continues thereafter. The next storm system will arrive from the southwest Saturday night with a more robust moisture plume expected to bring widespread precipitation to the area through Sunday, with additional precipitation expected through at least Monday. While details are still coming together, the heaviest precipitation looks to occur over the Wasatch Front and Wasatch Mountains. Saturday night through Monday, there is a 45-70% chance of at least 0.5 inches of QPF along the Wasatch Front, while the Wasatch Mountains have a 45-75% chance of at least 1 inch. That said, model spread remains fairly significant, and 75th percentile amounts range from over 1.5-2 inches across the northern Wasatch Mountains to locally near 2.5 inches in the upper Cottonwoods. However, as this storm will be accompanied by a somewhat milder airmass, snow levels look to be in the 7-8 kft range. The snow levels and lower snow ratios will help moderate snow accumulations, but if the higher end water amounts verify, locally significant snow amounts will be possible.

AVIATION...KSLC

VFR conditions will persist for the KSLC terminal through the period. Showers and gusty northerly winds will diminish after 06Z with a lull in precip overnight and winds becoming more southerly. Scattered showers return during the morning and will be intermittent through mid afternoon with lowered CIGs and mountain obscuration possible.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions will persist for the entire airspace through the period. Showers across the northern airspace will diminish overnight, returning during the morning across the north, and remaining intermittent through the early afternoon. Lowered CIGs across the north will lead to mountain obscuration. Winds will transition to light and diurnally driven overnight. The southern terminals will remain dry.

SLC WATCHES / WARNINGS / ADVISORIES

UT...Freeze Warning from 10 PM Thursday to 9 AM MDT Friday for UTZ103- 114>116-118>120-122.

Freeze Warning until 10 AM MDT Thursday for UTZ114>116-118>120- 122.

WY...None.