textproduct: Salt Lake City

KEY MESSAGES

- Winter weather advisories remain in effect for the northern and southern mountains through Thursday.

- Two periods of moderate to heavy northern mountain snow, with periodic rates at or above 1 inch an hour at times, will occur between 5 AM and noon Wednesday and again between 5 PM Wednesday through 3 AM Thursday.

- Across the southern mountains, the heaviest snowfall rates in excess of 1 inch per hour will occur between 4 AM and 10 PM Wednesday, particularly near the Brian Head and Tushar range areas.

- After a break this weekend, another storm cycle will begin Monday and last through much of the next week. This storm cycle will trend colder than the previous week...with increasing potential for valley snow.

DISCUSSION

After a very long period of upper level ridging and dry conditions, the next 7 to 10 days (and perhaps beyond) look to remain in an active pattern with multiple storms to discuss in this forecast package.

Early morning upper air and satellite analysis indicates a series of upper level lows rotating around a midpoint near the central California coast. A strong jet shifting from southwest to northeast on the south side of this trough is noted, along with an associated long fetch, landfalling atmospheric river.

Current radar trends indicate the first area of precipitation associated with a shortwave trough across northern Utah is shifting north of the Idaho/Utah border. The next round is beginning across southwestern Utah and will shift north and east with time through 12Z.

With IVT anomalies in excess of 95-97th percentile shifting across the region, broad upper level diffluence and a series of subtle, embedded shortwave troughs will support two rounds of moderate to heavy precipitation across the region. The first, already beginning across southwestern Utah, will shift north and east into northern Utah by 12Z...and cross the Utah/Idaho border after 18Z. Showers will continue through the afternoon before the next round of heavier precipitation reaches northern Utah once again around 00Z Thursday...continuing through around midnight Thursday night.

Winter weather advisories continue for the mountains of northern and southern Utah through Thursday...with total snow accumulations holding steady around 6 to 12 inches for both areas, locally higher amounts up to 15 inches for the upper Cottonwoods, high Uintas, and Brian Head areas. No changes were made to the going headlines with this package.

Through the day today, the western upper level low will shift south and east well off the California coast, while the eastern upper level low will near the Bay Area. The majority of ensemble members evolve these two separate upper level lows into a consolidated trough by Thursday afternoon, with the strongest forcing on the southern side of the trough offshore the Baja California Coast. This trough will move across the Desert Southwest Friday into early Saturday.

The majority of the ensemble members support light precipitation along the north/west side of this feature across central and southern Utah later Thursday into Friday, with amounts around 0.05-0.10" through Friday evening.

A brief period of shortwave ridging will build into the region this weekend, with another series of shortwave troughs shifting into the western United States Monday. Not to get the hype train started this early, but around 70% of ensemble members show at least an inch of snow for the valley floors next Tuesday into next Wednesday. This is quite a bit out there...but something to monitor moving forward...and perhaps to look forward to ending the snow drought for KSLC. The only measurable snow at the SLC Airport for this winter season occurred on December 27, so it's been quite awhile.

REST OF UTAH AND SOUTHWEST WYOMING

Rain and high elevation snow showers moving into southwest Utah this morning will become more widespread across the airspace after ~12z. Most terminals will see periods of MVFR/IFR conditions developing under heavier precipitation due to CIG and VIS reductions. Terrain obscuration will also be a concern for most regional terminals through Thursday morning. Southerly winds prevail for all terminals, with gusty winds to 20-25kts developing mainly across western Utah after 18z. Expect winds to taper this evening, with periods of variable winds resulting from shower activity.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Winter Weather Advisory until 11 AM MST Thursday for UTZ110>113.

Winter Weather Advisory until 5 AM MST Thursday for UTZ125.

WY...None.