textproduct: Salt Lake City

KEY MESSAGES

- Isolated showers and thunderstorms are possible each afternoon through Tuesday.

- Widespread precipitation returns late Wednesday across southern Utah, with coverage expanding northward through Friday. Many areas will see precipitation accumulations between 0.5-1.5" through this period, with locally up to 2.0-2.5".

- The late week storm will also bring modest snowfall to the high terrain across northern Utah on Friday, with 3-6" possible mainly above 9000 feet.

DISCUSSION

Remnants of a weakening storm system across Arizona late this evening will lift across Arizona on Monday before crossing the Four Corners area Monday night. Precipitation from earlier today associated with pieces of this weakening system has largely moved out of the area, leaving behind some patchy stratus that is expected to linger across southern and central Utah overnight. On Monday, expect mainly isolated showers and thunderstorms as lingering moisture interacts with some weak instability. Most of these showers will remain confined over/near the spine of Utah.

Tuesday into Wednesday, expect a southwesterly flow to progressively increase over Utah as a closed low slowly slides down the California coast. This southwesterly flow will maintain temperatures generally above climatological normals across the area. Showers start to increase on Tuesday owing to upper diffluence and increasing instability. Wednesday may see a bit of a lull in precipitation until around midafternoon before precipitation increases again from the south. As the storm system moves inland on Thursday and across Utah on Friday, expect more widespread precipitation to develop during this time. Eastern Utah, especially, looks to catch the western edge of a moisture plume originating near what is currently Hurricane Trudy. As such, many areas are expected to see beneficial amounts of precipitation, although some of the heavier showers and thunderstorms could bring a threat of flash flooding, especially in prone areas of southern and central Utah. The NBM continues to indicate a broad area of 0.5 to over 1 inch of QPF in the valleys and 1 to over 2 inches of QPF over the mountains for the Wednesday through Friday timeframe.

With cooler air arriving with the low late Thursday into Friday, snow levels will lower, bringing accumulating snow to the mountains. Latest deterministic GFS and EC bring H7 temperatures down as cold as -3 to -5C over northern Utah. Snow levels could potentially briefly reach 6.5kft, though most accumulations will likely remain above 8kft. Around 3-6 inches still look like a good possibility over the higher ridgelines of the northern Utah mountains (less over the central and southern mountains, given that precipitation looks to largely favor northern Utah on Friday).

Beyond Friday, model spread increases. In particular, there remains uncertainty regarding how much troughiness will linger for Saturday, as it will have implications for additional precipitation. The latest deterministic GFS and EC, however, have both trended with the drier solution on Saturday.

AVIATION

KSLC...Light southerly winds will remain in place before switching to typical northerly winds between 19-20Z. Expect a 10% chance of showers and thunderstorms in the vicinity after 20Z Monday.

REST OF UTAH AND SOUTHWEST WYOMING...Typical nocturnal winds will develop across the majority of terminals this evening. Isolated to widely scattered showers and thunderstorms will impact terminals near the higher terrain across the state and adjacent valleys Monday afternoon and evening.

SLC WATCHES/WARNINGS/ADVISORIES

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