textproduct: Salt Lake City

KEY MESSAGES

- Inversions will remain in place for prone Utah valleys through at least Friday. The stagnant air will lead to decreasing air quality and visibility, particularly along the Wasatch Front.

DISCUSSION

Strong high pressure remains centered over the Great Basin this afternoon, resulting in a dry northerly flow aloft over Utah and southwest Wyoming. The airmass over the area remains quite mild, with 700mb temperatures in the +2C to +6C range. However, persistent inversions over the prone valleys of northern Utah are keeping temperatures much cooler, with highs near seasonal normals. Particulates are also accumulating in the valleys due to the inversions, resulting in a steady decline in air quality and visibility.

On Friday, the ridge is expected to recenter itself along the Pacific Northwest coast as a trough dives into the central United States. This system will be too far east for significant impacts over Utah and southwest Wyoming, but will cool the airmass aloft somewhat. There is a low (30 percent or so) chance that the airmass will cool sufficiently to mix out valley inversions, but it is far more likely that this will act to weaken the inversions some but not fully mix them out. This will also bring temperatures outside of inversions back closer to normal for this time of year.

There is high confidence that the Great Basin ridge will rebuild over the weekend into early next week resulting in dry conditions, light winds, and inversions continuing/re-strengthening. Ensemble guidance continues to indicating a storm system impacting the area late next Thursday into Friday with sufficient cold air to mix out inversions, but the members are trending to solutions that would bring less in the way of winds in precipitation. Confidence in any particular solution remains low this far out, however.

REST OF UTAH AND SOUTHWEST WYOMING

MVFR vsbys will continue along the Wasatch Front as haze persists. Additionally, there exists some potential for fog development at KLGU from 09-13Z, perhaps lingering somewhat if it becomes more widespread. Vsbys improve somewhat to 6SM at KLGU in the late morning, though haze will persist. For all other sites, VFR conditions will persist through the period.

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SLC WATCHES/WARNINGS/ADVISORIES

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