textproduct: Salt Lake City

KEY MESSAGES

- Ridging builds back in Saturday bringing potentially record breaking warmth and dry conditions to the forecast area through at least Monday.

- A pattern shift is expected to occur as early as Tuesday bringing wetter and cooler temperatures to the forecast area through at least Thursday.

- A prolonged valley rainfall and mountain snowfall event looks to continue from as early as late Tuesday into Friday. Additionally, gusty conditions will develop Wednesday and Thursday as a system moves into the region.

DISCUSSION

Current satellite imagery indicates modest mid-upper level moisture streaming across N UT and SW WY along the northwest periphery of a building upper level ridge. Temperatures will remain slightly above seasonal normals today across northern UT, roughly around 5-10F. For central and southern UT, temperatures will run roughly 10-15F above normal with lower Washington county seeing temperatures in excess of 20F above normal this afternoon. Temperatures areawide will continue to warm as ridging builds overhead this weekend into Monday averaging 15-20F above normal resulting in another period of record-breaking heat for March.

Mid-upper moisture will continue streaming into the region along the northwest ridge axis through Monday with a few weak shortwave troughs embedded within the flow. Dry low levels will prevent lower elevation locations from seeing precipitation, though higher terrain locations statewide may see some gusty showers develop each afternoon as orographics compensate for weak ascent. Chances across our UT high terrain for rain showers will be around 10-20% each day before increasing to around 20-30% on Monday as slightly better ascent moves into the region.

A pattern shift is expected to develop Tuesday, persisting through the end of the work week bring cooler and wetter conditions to the region. Initially, a shortwave trough embedded within the southern stream will traverse across the area with an associated cold front in the morning hours. Modest moisture will stream in ahead of the frontal boundary, moistening the PBL resulting in PoPs increasing for most lower elevation locations across UT and SW WY to around 20- 40%. Higher terrain will see chances for precipitation increase to around 50-70% due to orographic influence and higher quality mid- level moisture pushing into the region as well. Given preceding warm conditions, snow levels will generally remain above 7000ft as this frontal boundary arrives keeping most areas socked in with rain other than the Upper Cottonwoods, Bear River Range, and High Uintas, where a mix of snow and rain is expected.

A brief lull will exist Tuesday afternoon through potentially Wednesday morning as subsidence builds in behind the frontal feature. Some residual moisture aloft will linger with enhanced flow aloft, providing enough ascent to keep scattered showers in play for through the aforementioned timeframe with PoPs generally hovering around 40-60%.

Beginning Wednesday morning, a complex system begins to push into the Great Basin with the first impulse coming in the form of a broad southern stream trough. This feature will serve to provide modest ascent and moisture return ahead of a deeper upper level trough diving southeast from the PNW. PoPs will increase markedly areawide Wednesday with the West Desert, southwest UT, and southeast UT generally seeing PoPs around 30-50%, the I-15 corridor and SW WY ranging from 60-80%, and high terrain locations seeing 80%+. Most locations can expect precipitation in the form of rainfall as this initial push will remain quite warm, keeping snow levels around 8000- 8500ft into Thursday morning ahead of a cold front. Following the passage of a cold front later Thursday morning, snow levels will drop to around 5000-6000ft throughout the afternoon Thursday as colder air pushes in via northwesterly flow.

The pattern looks to remain active as we head into the weekend, though considerable uncertainty remains regarding placement and evolution of other waves that look to propagate east from the Pacific. Regardless, wet and cool conditions appear likely to continue past the long-term forecast period.

REST OF UTAH AND SOUTHWEST WYOMING

Generally light winds throughout the area are expected today under a broad area of high pressure, though high cloud cover will be prevalent in all but the farthest southern reaches of the forecast area. Expect typical diurnally driven wind shifts in the absence of much in the way of upper level flow. Cloud cover will build through the overnight hours into Saturday morning with gradually lowering CIGs, and the potential for weak and showery precipitation moving into northwestern Utah by late Saturday morning - though confidence in observing any precipitation anywhere in the forecast area is very low at this point.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...Fire Weather Watch from Saturday afternoon through Monday evening for WYZ277.