textproduct: Salt Lake City

KEY MESSAGES

- A prolonged inversion event will last through at least late in the week. This will allow for an increase in haze, nocturnal fog, and a degradation in air quality for northern valleys.

DISCUSSION

High pressure will be positioned over the western U.S. through the week, with southwest Wyoming and Utah on the eastern periphery of the ridge. That will keep conditions dry with fairly light winds. Valley inversions will strengthen, particularly for northern valleys. This will result in more haze and fog.

Regarding haze, it will be a continuous increase until the next system comes close enough or pushes through and brings sufficient cooling or wind to mix out valley inversion conditions. Haze will be most dense for the urban corridor of northern Utah, but valleys throughout Utah will likely have some reduction in visibility from haze.

Fog will be more likely for valleys with inversion conditions. Minimal fog will develop through Monday, but HREF guidance indicates higher probabilities starting Tuesday. Likelihood ranges from 40-50% for the urban corridor from Salt Lake City to Brigham City and locations west to the Great Salt Lake and for the Cache Valley. Fog will be more likely through the week for those places.

Temperatures will be near to slightly below normal for valleys affected by inversions. The ridge will bring warmer conditions elsewhere, with temperatures of 5-15F warmer than normal.

There will be an increasing trend for fog and haze until valley inversions are eliminated. Models and ensembles are in good agreement that it will take several days before a longwave trough that will track into the plains could be close enough to weaken or eliminate valley inversions. It will depend on westward extent, with a more westward track to bring more cooling and better flow to assist with eroding or eliminating valley inversions. If inversions do not mix out Friday, then they would last into next week.

REST OF UTAH AND SOUTHWEST WYOMING

Valley haze, especially across the Wasatch Front and adjacent valleys, will result in slantwise visibility reductions. Otherwise, clear skies across the airspace will allow VFR conditions to persist for all regional terminals through the period. Winds remain generally light and terrain driven.

SLC WATCHES/WARNINGS/ADVISORIES

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