textproduct: Salt Lake City

KEY MESSAGES

- Localized downslope and gap winds over 40 mph can be expected in Washington County tonight.

- Temperatures will warm through the weekend into early next week and will be accompanied by dry conditions.

- A storm system grazing northern Utah on Tuesday will push a mostly dry cold front into the area, with gusty winds expected across northern Utah and southwest Wyoming.

DISCUSSION

The storm system that has impacted the forecast area since Wednesday has transitioned into a mean elongated, positively tilted trough with the northern stream wave moving east of the area while the southern stream splits off to the southwest. High pressure centered off the PacNW and NorCal coast is nudging inland, and will move into northwest Utah by tomorrow morning. As such, increasing stabilization of the airmass will lead to a continued reduction in shower activity this evening, with most showers ending by midnight.

With a northeasterly flow in place owing to the splitting nature of the storms and combined with continued cold advection especially across southwest Utah, expect gusty canyon and downslope winds across Washington County. While localized wind gusts in the low to mid 40 mph range are currently observed, over the past 3 hours, the winds have been running on the lower end (below the 50th percentile) of the probabilistic guidance from both the HREF and NBM. As such, will continue to hold off on any wind highlights, especially given generally low impacts in this area. Winds should be peaking through around 2 AM before gradually decreasing into the morning hours.

With the high pressure continuing to build into the area over the weekend, expect temperatures to trend warmer. Temperatures are expected to peak on Monday even as the ridge flattens in response to a low-amplitude trough moving into the PacNW. Max temperatures on Monday are forecast to rise to around 8-15 degrees above climatological normals. For SLC, the NBM has a 25th-75th percentile range of 64-66F for a max temperature.

The aforementioned trough will graze northern Utah for Tuesday, with models being in good agreement outside of some slight timing differences. This trough is expected to push a dry cold front into Utah. Some models do spread precipitation into northern Utah with the cold front, but if this occurs, any amounts will be light. Even at the 90th percentile, the NBM has less than 0.2 inches of QPF, and that's just across the northern Wasatch Mountains (northern valleys have less than 0.10 inches in the Cache and less than 0.05 inches elsewhere). The main weather concern with this cold front will be gusty near-westerly winds, especially along exposed ridgelines across the northern Utah mountains and in Uinta County, WY, where gusts over 40 mph will be common. Models are hinting at another round of gusty winds for the late Thursday through Friday timeframe with another low- amplitude trough moving by to the north, although there is a bit more model spread this far out. However, will just note that the ECMWF Extreme Forecast Index has a stronger signal for anomalous winds during this timeframe than with the Tuesday storm.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions will prevail across the area through the TAF period. Lingering CIGS in the 6-8 kft range will scatter out overnight. General north to northeast winds will persist through Saturday across southern and central Utah, while diurnally driven wind flows can be expected across northern areas.

SLC WATCHES/WARNINGS/ADVISORIES

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