textproduct: Salt Lake City

KEY MESSAGES

- A transition from much warmer and drier than normal conditions to more active conditions will start Monday.

- Of the storm systems set to track into Utah through the week, one that will bring precipitation from Tuesday into Thursday will bring the majority of rain and snow.

- Precipitation from the Tuesday through Thursday storm system will be maximized throughout northern Utah. For the northern mountains, the upper Cottonwoods has a 75% chance for at least 6 inches of snow, while upper portions of the Bear River Range and western Uinta Mountains have a 40% chance for at least 6 inches of snow.

DISCUSSION

High pressure in place for southwest Wyoming and Utah will continue through Sunday. As the ridge axis has tracked downstream and a shortwave trough slides inland from the PacNW, there has been some enhancement of west to southwest flow. Valley high temperatures will be around 60F for many locations, roughly 20F warmer than normal.

Warmer than normal conditions will continue Monday, but it will also mark a changing synoptic pattern characterized by a ridge recently to one with several storm systems through the week. The first of those will be Monday, as the aforementioned shortwave trough digs into Utah. The baroclinic zone associated with it will bring a cool down of around 10F Monday. It will also bring enough forcing and moisture for valley rain and mountain snow to elevations of roughly 6000 feet and higher. Snow accumulations will range from 1-3 inches for the northern mountains, with valley rain of 0-0.10". That storm system will be in a weakening phase as is pushes through, and the boundary will lift north Tuesday as another storm system digging southward in the eastern Pacific off the coast of California transitions flow to southwest.

That atmospheric river (AR) event will bring much stronger forcing and moisture advection, particularly for California. Although a lot of moisture will downslope off the Sierra Nevada Mountains, a combination of moisture associated with that system and another in northern Mexico, upper diffluence, and eventually another baroclinic zone will result in more precipitation for southwest Wyoming and Utah. There is uncertainty on details, like how long southwest flow will last prior to a baroclinic zone tracking through and how much moisture reaches Utah from the remnant AR event. There is low confidence on snow totals because of that, with the NBM 25th-75th percentile ranging from roughly 6-16 inches for the Cottonwoods and from roughly 1-6 inches for the southern mountains.

Models are in agreement on a transient ridge after that storm system exits late Friday into Saturday, with good agreement on another storm system starting Sunday or early in the week.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions will prevail through the TAF period. Winds will remain southerly through this afternoon before becoming light/variable after sunset. Early Monday morning (after 12Z) a cold front will cross northern Utah and southwest Wyoming, switching winds to the northwest and lowering CIGs into the 5000-7000 range. The chance for rain with this front is less than 30% at northern Utah and southwest Wyoming terminals.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...None.