Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
757 FXUS65 KSLC 200925 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 325 AM MDT Sun Apr 20 2025 .SYNOPSIS...A progressive pattern will result in weak grazing systems bringing limited impacts/precipitation primarily to the northern portion of the area. Despite the active pattern, day to day temperatures are generally favored to remain above normal. && .SHORT TERM (Through 12Z/6AM Tuesday)...A very weak and largely moisture starved shortwave impulse is translating through overhead here early Sunday morning. Area radars are picking up on some high based echoes, but based upon little to no observing sites indicating any measurable precipitation, assuming very little of this is actually making it to the ground. Could still potentially see a few spits of drizzle, especially at the higher northern terrain, but the system remains very non-impactful. After sunrise, this system will be exiting the region, leaving little evidence of its presence outside of some gradually clearing skies. Deeper layer flow will trend more zonal through the day, and H7 temperatures will in turn gradually warm. As a result, Sunday afternoon highs will jump by around 5-10 degrees in comparison to Saturday, and given the mostly sunny skies and stronger April sun angle, it`ll undoubtedly feel more mild to most. Sunday evening onward into monday will see a grazing shortwave trough approach and pass through the northern portion of the forecast region. Moisture remains limited with this feature, but overall synoptic forcing looks a bit better in comparison to the weak system currently passing through the area. Shower chances will increase through Sunday night as the shortwave moves in, particularly along an associated cold frontal boundary that will be advancing southward through northern Utah by around sunrise Monday morning. Given the grazing nature of the system, and in turn the cold frontal boundary stalling out somewhere across central Utah, precipitation is not really expected across southern Utah. Total water amounts have changed minimally from prior forecasts. Maybe up to 0.05" or so for low elevation areas mostly along/north of the I-80 corridor, around 0.05-0.15" for the high terrain of the northern mountains, and locally a bit more (up to 0.25" or so) for the Bear River Range. While some cooler post- frontal H7 temps will slightly lower snow levels and improve snow to liquid ratios, they`re still pretty unfavorable for much in the way of northern mountain snow, and any sort of impactful snow remains unlikely. Aside from the precipitation potential, areas behind the front across the northern half or so of the forecast region will fall a few degrees, whereas southern Utah will continue a warming trend. .LONG TERM (After 12Z/6AM Tuesday)... Zonal flow aloft fills in following the departure of an upper trough bringing calm and benign conditions to the forecast area through Wednesday. On Wednesday, a weak upper trough is progged to slide east across northern Utah. The trough is expected to deepen somewhat as it traverses across northern Utah with ample moisture resulting in scattered valley rain showers and scattered snow showers at higher elevations across northeastern Utah and southwest Wyoming. This flow pattern will also result in a gradual warming trend through Saturday with winds clocking to southwesterly. This will yield valley temperatures ranging from 70-80 degrees with lower Washington county likely seeing temperatures in the mid to upper 80s. Come Thursday evening, model consensus appears quite favorable for a digging upper trough to push in from the eastern Pacific. This trough is expected to be quite diffluent aloft with upper level flow clocking to southwesterly Thursday evening. This pattern will be favorable for scattered rain showers across the majority of our valleys and snow showers at higher elevations as more favorable moisture is advected over the area. As of now, accumulations are not expected to be impactful in nature. Guidance does, however, begin to diverge as the trough moves inland with respect to how far north/south it will push inland along the Pacific coast. Regardless, guidance appears favorable across the board for a windy weekend with gusts greater than 20mph across southern Utah materializing Thursday evening. Gusts will then make their way north Friday evening reaching around 20-30mph across northern Utah and southwest Wyoming with gusts across southern Utah increasing further, likely exceeding 35mph. Additionally, scattered showers will persist each day from Thursday on into the weekend across northern Utah. && .AVIATION...KSLC...VFR conditions will prevail through the TAF period. A shift to southeasterly is expected around 09z this morning before clocking to northwesterly around 18z. Later in the evening, winds will clock back to southeasterly as the diurnal pattern persists. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail across all TAF sites through the period. Gusty northerly winds around 18-20kts may develop at KCDC around 18z, subsiding around 03z. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Warthen/Worster For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity