textproduct: Salt Lake City

KEY MESSAGES

- Temperatures will continue to average 10 to 20 degrees above normal today.

- A more active pattern will increase precipitation potential state-wide much of the next week.

- There is a greater than 50% chance much of northern Utah will see at least 0.25 inches of precipitation between Tuesday and Thursday mornings. For the remainder of Utah, the chance of 0.25 inches or more of precipitation has decreased to less than 30 percent.

- Across the northern mountains, locations such as the Bear River Range, western Uinta Mountains and the upper Cottonwoods have a 60% chance of 6 inches or more of snow between Tuesday morning and late Wednesday night. Elsewhere, there is a less than 20% chance of snow totals at or above 6 inches.

DISCUSSION

Temperatures more typical for early April will be the rule across the region Sunday, with highs near 60F for the Wasatch Front. The record high for the date for Salt Lake City is 64F, which isn't out of the question.

Early morning upper air and satellite analysis indicates atmospheric chaos continues in association with the northern stream...with a myriad of shortwave troughs embedded in the flow, rotating around an upper level low in the Gulf of Alaska. A prominent northern jet is noted, streaming into the Pacific Northwest. Meanwhile, an upper level low remains off the Baja California coast, with a semi-tropical tap of moisture advection shifting around this low into Mexico.

A shortwave trough associated with a stout 140+kt jet max will shift into the Pacific Northwest today...reaching the northern Intermountain Region this evening. The associated cold front will begin to cross into northern Utah after midnight tonight...reaching the central Wasatch Front around noon Monday. As was the case with last night's model runs...the dominant solution among ensemble members suggests this front will become frontolytic across northern Utah. This will limit any precipitation potential, with the highest potential across the northern mountains. The 25th to 75th percentile precipitation for the northern mountains is around 0.05-0.20" from roughly the Cottonwoods northward, with locally higher amounts in the Bear River Range...closer to the decaying atmospheric river event and more coherent front. For the valleys, amounts will struggle to exceed 0.05" south of Ogden, perhaps up to around 0.10" (75th percentile) north of Ogden to the Utah/Idaho border. Snow levels will remain high enough to reduce the threat of valley snow to less than 10% with the exception of the Cache Valley and eastern Box Elder County...where the chance of at least a brief rain/snow mix or changeover to snow is around 20% Monday night into Tuesday morning.

As the next shortwave trough approaches the region Tuesday into early Wednesday, most ensemble members retreat the front northward as a warm front. Whereas most solutions shifted this boundary south as a cold front later Tuesday into Wednesday yesterday, there has been a marked shift in the guidance...with only 15% or so of solutions showing a strong cold front Wednesday.

Forcing for precipitation will increase Wednesday as the shortwave trough approaches the region coincident with a 130kt+ jet max shifting broad upper level diffluence across the region. As mentioned earlier, there is modest potential for this system to incorporate a southern Sierra decaying atmospheric river...though currently this is around 35% of the members. Given the previously mentioned atmospheric chaos, the diversity of solutions is broad across the ensemble systems and uncertainty is high. For example, the range of 24 hour precipitation amounts for southwestern Utah is from 0.01" (10th percentile) to 0.60" (90th percentile) near Cedar City (and a similar range is noted across the northern mountains).

As far as headlines, trends toward less precipitation have decreased the likelihood of advisory amounts across the northern mountains Tuesday into Wednesday. The best chance of low end advisory criteria remains in the Bear River Range, upper Cottonwoods, and the western Uinta Mountains. Something to monitor for the next few packages.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions to prevail through the period for all regional terminals. A mid-to-high level will continue to overspread the airspace today from the north ahead of an approaching system. Winds remain generally light and terrain driven this morning, increasing out of the south this afternoon with gusts to 20 kts for most regional terminals through the evening.

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SLC WATCHES/WARNINGS/ADVISORIES

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