Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
655 FXUS65 KSLC 022300 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 400 PM MST Thu Jan 2 2025 .SYNOPSIS...High pressure will briefly move in late Thursday into Friday before a fast moving storm system makes its way through the area Saturday into early Sunday, with another round of snow particularly for Utah`s northern mountains. The active pattern then continues into the early part of the upcoming week. && .SHORT TERM (Through 12Z/5AM Saturday)...Model consensus is in excellent agreement through the short term portion of the forecast in their relative depictions of building a midlevel shortwave ridge axis across Utah and SW Wyoming tonight. This will deliver a brief period of tranquil conditions to the area. As the ridge moves off to the east on Friday, this will open the door to increasing southwest flow as well as modest low to mid level warm advection through the day. Temperatures will be spring-like, with highs in the 50s for the Wasatch Front, mid to upper 50s for the central valleys and low 60s across Lower Washington County. These temperatures are generally 10F to 20F above normal for early January. By Friday afternoon, 700mb winds will increase into the 40-50kt range across the western half of Utah. This will lead to pockets of enhanced winds, especially for exposed terrain, valleys of southwest Utah and wind-prone areas of the Tooele and Salt Lake Valleys. Most likely surface gusts in the most wind prone locations are generally in the 30-40 mph range, except of course higher gusts on exposed ridgelines. Otherwise, precipitation will blossom across northern Utah in the pre-dawn hours Saturday, along and ahead of a cold front and associated mid-level trough. .LONG TERM (After 12Z/5AM Saturday)...Active weather continues at the beginning of the upcoming weekend as a cold Pacific storm system pushes into Utah and southwest Wyoming. Models have seemingly trended upwards this afternoon with regards to QPF and snowfall in the mountains of northern Utah, likely worthy of headline issuance as we head into Friday. Central and southern Utah will still see a fair hit of snowfall (1-6" for the NBM 25th-75th percentile), however, the greater impacts will be confined to the northern Utah mountains where the most likely accumulation amounts will be 6-9 inches widespread with upwards of 15-20 inches in favored terrain like the upper Cottonwoods and northern Bear River mountains. There is some uncertainty on when/if precipitation will end in the mountains before another wave moves through the region early next week, but the start time of precipitation appears pretty locked in to early Saturday morning. A cold front progressing through the region will help to intensify precipitation, which may bring a period of potentially hazardous travel conditions in the high elevation routes of northern Utah during the mid-morning to early afternoon on Saturday... will need to dial in these details as we get into tomorrow, but there is generally good consistency amongst the broad resolution models. For the valley areas of northern Utah and southwest Wyoming, not anticipating any impactful snow accumulations as antecedent temperatures will be quite warm. That said, the stout cold frontal boundary will introduce an environment cold enough for snow shortly after the period of greatest precipitation intensity, if not just on the tail end of it, which may allow for some quick snow accumulations in places like the Cache Valley, Wasatch Back, and northern Wasatch Front. Valley areas most likely to see appreciable snowfall will be in the Park City area where current 25th-75th percentile accumulations range from 4-8 inches... will certainly need to explore headline issuance for the Wasatch Back. A majority of this storm is expected to be wrapped up by Sunday morning, however, there are some models that maintain snowfall in the terrain through Sunday afternoon/ evening. It is unlikely that significant snow accumulations are produced during this post frontal period, however, areas in the upper Cottonwoods could see see another 3-6 inches of low density snow. Another trough looks to follow quickly in the heels of this upcoming storm on Monday morning, however, with a significant ridge building upstream it appears a strong moisture source will be lacking. If anything, it looks like this next storm will just be bringing a refresh of snowfall in the mountains before we shut off the moisture tap. At this point, not considering headlines for this early week storm. Heading into the middle of next week, the aforementioned significant ridge over the PacNW region will remain in place and potentially intensify, placing downstream areas under a strong blocking pattern. Any troughs that move through the region would be sourced from interior Canada, meaning that chances for significant storm systems will be quite low. Bottom line, our snowpack is going to be struggling in the long term. && .AVIATION...KSLC...Light and variable easterly winds are expected to become typical diurnal southeasterlies around 02-03z. Any lingering scattered cloud cover should dissipate by 00z, with a 30% chance of remaining into the evening, above 6kft agl. VFR conditions will persist through the TAF period before the next storm fires up early Saturday morning. .REST OF UTAH AND SOUTHWEST WYOMING...At the northern terminals, SCT/BKN cigs are expected to dissipate around 00z, lingering a bit longer at LGU. For the southern terminals, weather remains quiet with VFR conditions and some SCT/BKN layers well above 12kft agl. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ ADeSmet/Webber/Verzella For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity