448 FXUS65 KSLC 092147 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 347 PM MDT Tue Oct 9 2018 .SYNOPSIS...An unsettled and cool pattern will continue across the region with multiple disturbances expected to impact Utah through this week. && .SHORT TERM (Through 00Z Saturday)...A large upper level ridge is currently stretching across the eastern Pacific with an upper level trough across the Interior West into the Rocky Mountain States. A series of shortwaves will dig on the west side of the trough and bring an extended period of unsettled weather with mountain snow and valley rain to Utah. The first shortwave is currently digging southeastward across eastern Oregon and northern Nevada. The associated 115-120kt jet maxima will continue to bring synoptic scale lift to northern Utah. Widespread precipitation is filling in ahead of the main wave and associated mid-level front. Expect the mid-level front to cross northern Utah later this evening into tonight. Persistent lift combined with deep moisture should bring widespread valley rain and mountain snow through the overnight hours and into Wednesday morning. Have issued winter weather advisories for the northern mountains and Uinta County Wyoming with the afternoon package for a widespread 5 to 10 inches of snow with isolated higher amounts (less in Wyoming). All seasonal roads in Utah remain open with the exception of Guardsman Pass. In addition, some of the higher summits including Parleys and Logan may see occasional road slush overnight and into the Wednesday morning commute. Mountain snow and valley rain will wind down early Wednesday morning. The trough will become elongated to the south and west Wednesday into Thursday and several weakening shortwaves will round the southwest and then southern portion of this trough...bringing another period of precipitation to mainly central and southern Utah Thursday into early Friday. .LONG TERM (After 00Z Saturday)...The primary feature to focus on during the long term period is a progressive short wave clipper that is expected to translate south-southeast across namely the northeastern portions of the area Saturday night-Sunday. With passage of the mid level short wave, a relatively shallow and moisture starved cold front will track south across the area reaching the UT/AZ line by Sunday morning. With this, marked cooling is anticipated for all areas into early next week, while light/showery precip (largely snow) will be kicked off Saturday night into Sunday morning across the far north/east (focused mtns). The big takeaway from this short wave will be the breadth of low level CAA in the wake of the cold frontal passage, as H7 temps continue to look to fall into the -10 to -11C range across the northeast, and as low as -5 to -6C across the southwest. As such, temps are expected to fall to some 10-20 degrees below climo Sunday into Monday, with highs only in the upper 40s along the I-15 corridor from the ID line south to Cedar City (Sunday), with widespread freeze/frost conditions most all areas (Sunday night). Introduced enhanced gap winds for Washington County Sunday/Sunday night, and expect enhanced canyon winds along the Wasatch Front as well during that timeframe. Modest at best, but still notable. Heights will build across the area through the mid week period as high pressure reorients along the west coast, while bulging east into the northern Rockies region. This is likely the first signs of a pattern shift that will phase back into a drier/milder regime for the latter half of the month, but we'll see how things evolve with time. For the latter half of this forecast however, this looks to hold true with gradual warming and a dry forecast. && .AVIATION...The storm system advancing south towards northern Utah will bring steadily lowering ceilings and rain to the SLC Terminal tonight through at least Wednesday morning. VFR conditions will continue through around 03Z, with ceilings dropping below 6000 feet between 00Z and 01Z. Conditions will drop into the MVFR range as both visibilities and ceilings lower due to precipitation. South-southeast winds will remain gusty through the balance of the afternoon, then decrease and eventually turn to a light northerly direction as rain intensities peak after 03Z. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Winter Weather Advisory until 9 AM MDT Wednesday for UTZ007>010. WY...Winter Weather Advisory until 9 AM MDT Wednesday for WYZ021. && $$ Kruse/Merrill/Conger For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity For frequently asked questions about the Area Forecast Discussion visit... http://weather.gov/saltlakecity/general/afd_faqs.php