textproduct: Salt Lake City

KEY MESSAGES

- A strong cold front moving across the area today will bring much colder temperatures to the entire region with hard freeze conditions likely across most areas above 3,000 feet.

- A quick burst of snow will accompany the front as it moves through northern portions of the area this afternoon and central and southern Utah this evening. Snow levels will quickly fall to northern Utah valley floors, but associated accumulations will be on the light side.

- Strong northerly winds will occur overnight across lower Washington County in areas that gust strong in northerly flow, such as the Black Ridge Canyon.

- High pressure will return by the weekend, bringing dry conditions with a steady warming trend.

DISCUSSION

A cold upper trough is centered over Idaho this morning, with the associated surface boundary near a KTPH-KPVU line. Light snow associated with the storm system has developed over areas near the Utah/Idaho border such as the Cache Valley and the Bear River range. As the colder air filters in, temperatures will continue to tumble.

The main trough will move across the area later today through Friday morning. With the arrival of the mid to upper level support, will see a band of precipitation, predominately snow, develop and track roughly southeast across the area. This will bring a quick shot of snow as it passes during the afternoon for northern portions of the area. Given the cold airmass, snow levels will quickly drop to valley floors, though mild antecedent conditions will limit sticking on area roadways. Still, light accumulations, at least on grassy surface, seem likely for most valley locations. Mountains will see some higher totals but given the fast moving nature of the system, amounts will be unimpressive overall.

During the evening hours, the front will move into central and southern Utah. Overall, with decreasing moisture and instability as the front moves away from the main trough, amount of precipitation will tend to diminish. One area that has a chance to be an exception is southwest Utah during the late evening and early part of the overnight hours. The center of the trough is expected to stay much closer to the front here, with the position of the jet bringing potential frontogenesis in this area. Still indicating accumulations on the light side with this forecast package, but this is one area where some overperformance would not be surprising.

As the main trough starts to pull away during the overnight hours, north to northeasterly pressure gradient is on track to set up over southwest Utah with notable cold advection, which is the typical scenario for the development of strong gap winds in the prone areas of Washington county. Looking at the latest data, think associated gusts are most likely solidly be within advisory criteria, so have replaced the High Wind Watch with a Wind Advisory for this area.

One other area of concern is the potential for lake effect snow overnight into tomorrow morning given the warm lake temperatures and unseasonably cold nature of this system. There looks to be enough instability provided, with guidance being largely bullish on the development of a late band that would most likely be focused over the western Salt Lake valley. Potential limiting factor will be that subsidence looks to move in a bit quicker than usual as the main trough exits, which would impact the longevity of such a band. If the band does develop, would not be surprised to see those areas seeing a quick inch or two of snow.

High pressure moves back into the region quickly behind the cold trough, becoming established Friday afternoon and evening. There is high confidence that this ridge will be the dominant weather feature over the area for the weekend and into early next week, keeping conditions dry and bringing high temperatures 10-15F above seasonal normals for Sunday and Monday. Same as it ever was.

REST OF UTAH AND SOUTHWEST WYOMING

A robust cold front is currently traversing Utah, with most of the northern portion of the airspace under post-frontal northwest flow already. Southern Utah remains under gusty southwesterly flow, but will see a transition to northwest winds later this afternoon. A narrow band of precipitation is trailing behind the frontal boundary, and will bring brief periods of MVFR/IFR to brief LIFR conditions to nearly all terminals throughout the day. Flight categories improve after 22-00z for northern terminals and 06-09z for southern terminals.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Freeze Warning from 8 PM this evening to noon MDT Friday for UTZ102>106-114>116-118>122-129-130.

Freeze Warning from 8 PM Friday to noon MDT Saturday for UTZ102>106-114>116-118>122-129-130.

Wind Advisory from 9 PM this evening to 9 AM MDT Friday for UTZ123.

WY...None.