textproduct: Salt Lake City

KEY MESSAGES

- Weak cold frontal passage across northern Utah Monday night will bring a little bit of valley rain and mountain snow in addition to a cool down.

- A more substantial storm arrives by the end of the week into the weekend with the potential for widespread precipitation that could increase the risk of flash flooding.

DISCUSSION

An area of low pressure is centered across northeastern Utah with light rain and snow showers along the terrain of central and northern Utah. Snow levels have been hovering around 9000 feet with accumulating snow on non-paved surfaces observed at Wolf Creek Pass, although this snow has been melting as the snow showers move out. Not expecting more than a quick dusting under heavier showers at elevation. A few lightning strikes are possible this afternoon as conditions de-stabilize slightly, but most of this activity will remain in the form of brief light showers across the terrain of central and northeastern Utah.

This low will move out of the area tonight with shortwave ridging moving into the region tomorrow that will help temperatures rise back into the 60s across most valley locations and low 70s across lower Washington county. These temperatures will trend lower by 5-8 degrees across northern Utah and SW Wyoming after the passage of a shallow cold front Monday evening. Guidance has trended down on QPF totals as hi-res guidance comes into frame. Most of the hi-res guidance keeps all of the precipitation to our north, but the NBM 50th percentile still has 0.1-0.2" of QPF near the Idaho border with lesser amounts as you head down the Wasatch before tapering off to nothing basically south of Utah County. A quick dusting to an inch of snow will be possible with the frontal passage as snow levels get down to 6000-7000 feet.

We will remain in a zonal flow with a broad trough across the PNW that will keep conditions mostly dry with near normal temperatures. Being on the periphery of this trough will keep the door open for some grazing shortwaves. Guidance is starting to pick up on one of these Tuesday night that could bring another brief grazing of valley rain and mountain snow across northern Utah/SW Wyoming, but this will be brief with limited precipitation totals likely. The NBM 90th percentile gets as high as 0.5" with this round of precipitation, but the 50th keeps totals <0.25".

A more substantial storm starts to emerge towards the end of the week and into the weekend as the aforementioned broad trough starts to shift further south and begins to pull in deep moisture from the southern jet stream. The timing of this will be key to when and where the heaviest precipitation sets up. Guidance seems to have slowed down today with a bulk of the activity holding off until the ladder half of the weekend as opposed to the first half that was being advertised the past couple of days. 50% of the ensemble members keeps this trough across the west for several days. This will increase our risk of flash flooding, particularly is the trough and heaviest moisture tap merge across the Great Basin.

AVIATION

KSLC...Winds will remain light and variable continuing to transition to northwest around 5-7kts after 18-19Z. A stratus deck around 2500 feet to the east of the terminal may occasionally creep over the field through 03Z.

REST OF UTAH AND SOUTHWEST WYOMING...Light showers across southern and eastern Utah this morning will increase in coverage and continue to shift towards the northeast as an area of low pressure pushes across eastern Utah today. Showers will remain near to east of roughly KCDC-KPVU, with isolated thunderstorms developing this afternoon. MVFR conditions will occur periodically near any showers.

SLC WATCHES/WARNINGS/ADVISORIES

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