textproduct: Salt Lake City

KEY MESSAGES

- Cooler conditions exist on Thursday alongside light snowfall in the northern Utah mountains.

- A warm storm system will bring valley rain and high elevation mountain snow from Friday through Saturday, as well as another round of strong winds across southwest Wyoming and the north slope of the Uinta Mountains.

- After a relative lull in active weather early next week, a late week storm will bring another potential round of valley rain and mountain snow.

LONG TERM (After 00Z Monday/5PM Sunday)

Atmospheric river (AR) moisture will be decreasing Sunday into Monday as a trough near British Columbia digs south and transitions synoptic flow to the southwest. That will result in the moisture source lifting north. Precipitation through Monday will largely be near the Idaho border, with more showery precipitation south to the western Uintas and Cottonwoods. Snow levels will be around 8000 feet at this point of the event, with light additional mountain snow accumulation.

Most GEFS, EPS, and GEPS members bring a trough from near the Gulf of Alaska into the eastern Pacific from Monday through Wednesday. That would bring dry conditions throughout southwest Wyoming and Utah from after precipitation tapers off Monday through Tuesday. There would be enhancement of southwest flow from the longwave trough with warm air advection pushing valley temperatures into the 50s for most of Utah Monday through much of the week.

The longwave trough will likely become the next AR event for the western U.S. The main difference from previous ones will be the more southward track through California of the moisture plume and forcing that ensembles are in good agreement on. For southwest Wyoming and Utah, that would result in some downslope effects from the Sierra Nevada Mountains. How much will depend on the several factors, including the track of the storm system, moisture advection, and flow with the trough. Even with downslope effects, the more south track would be much better for precipitation for southern Utah than similar storm systems further north. Like other AR events, snow levels would be high. There is uncertainty with some details like timing, with a range from early Wednesday to Thursday for a valley rain and mountain snow to build into Utah.

AVIATION...KSLC

Southeast winds will last through the day. Speeds will generally be light, but there will be gusts around 20 knots after 18Z. Scattered to broken clouds in VFR range will last through the TAF period. There is around a 20% chance for light rain showers from 20-00Z.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered to broken clouds in VFR range will prevail throughout southwest Wyoming and northern Utah. There will be scattered rain and snow showers for southwest Wyoming and northern Utah, mainly north of KSLC, from 18-03Z. Rain showers will be capable of lowering conditions into MVFR range, with snow showers at KLGU and KEVW lowering conditions into IFR range. Winds will be from southeast to southwest, with gusts around 25 knots after 18Z for southwest Wyoming and 20 knots for most of Utah.

SLC WATCHES/WARNINGS/ADVISORIES

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