textproduct: Salt Lake City

KEY MESSAGES

- High pressure holds into early next week, proving dry and increasingly mild conditions through early Tuesday.

- A warm Pacific system will move through the region Tuesday through late Wednesday, bringing valley rain and mountain snow, primarily for the northern half of the forecast region.

DISCUSSION

A cool start to the day in many spots today, with some sheltered southern valley locations even seeing overnight mins near to below zero. Additionally, it does appear some localized fog developed once again in some sheltered northern valleys, especially the Cache. Otherwise, not much of to observe outside of some high level clouds continuing to filter through overhead.

Deep layer ridging will amplify into the early portion of the upcoming week, with a corresponding increase in H7 temperatures. In turn will see highs and lows trend upwards, with afternoon highs near normal by Monday across portions of south central to southeast Utah, and around 5-10F above normal elsewhere across the area. The ridge will also help to maintain dry conditions at least into early Tuesday morning.

By Tuesday an elongated Pacific trough will help to flatten the ridge. Associated strong jet flow will help to initiate moderately strong moisture advection inland with climatological IVT values above the 95th percentile across the northern half of Utah and southwest Wyoming. This decaying atmospheric river type setup will be mild in nature, and result in periods of valley rain and mountain snow starting Tuesday, peaking overnight into early Wednesday, and tapering off likely by Wednesday evening. While models still support potential for a modest cold frontal passage, timing of such passage continues to be favored after much of the moisture has exited. Snow levels will remain high for most of the duration of the event as a result, increasing from around 7000-8000 ft Tuesday morning to 8000-9000 ft or Tuesday evening through the overnight, and finally decreasing again some through the daytime Wednesday. Given the good quantity of available moisture, water amounts for the northern mountains are decent (60-70% chance of over an inch of water), but snow accumulations will largely be limited to elevations above 8000 ft or so. Amounts will be far more modest than the prior system. Given the "hose" like nature of the moisture transport, there is some question of the southern extent of precip still, but even at the 90th percentile the NBM only manages to bring precipitation as far south as the I-70 corridor or so.

Models generally support some reestablishment to the western ridge as the midweek system departs. Temperatures trend back upward, with afternoon highs by friday around 7-15F across most of the forecast region. Given the ridge won't be too sharp, still will see a little bit of moisture try to sneak through, and maintain low (around 10-30%) chances of some light northern showers at higher elevations along with some cloud cover. The latter part of the weekend on into early next week shows a pretty good spread of solutions, with a lot of variation in individual ensemble members and deterministic runs. While there is some consensus on the redevelopment of a broad trough digging east of the Rockies, there is little consensus on its western extent and any potential for a grazing cold frontal passage locally, as well as if/how much moisture is available.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions will prevail across all TAF sites except KLGU through the period. Diurnal wind shifts are expected across all sites. Another round of potentially IFR vsbys and CIGs appears likely at KLGU tomorrow morning with fog development as early as 06z.

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SLC WATCHES/WARNINGS/ADVISORIES

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