498
FXUS65 KSLC 112123
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
223 PM MST SUN JAN 11 2026
KEY MESSAGES
- A PROLONGED INVERSION PERIOD WILL PERSIST THROUGH FRIDAY,
RESULTING IN AN INCREASE IN HAZE, NOCTURNAL FOG, AND A
DEGRADATION IN AIR QUALITY ACROSS THE NORTHERN VALLEYS.
DISCUSSION
AS HIGH PRESSURE CONTINUES TO AMPLIFY ACROSS THE
WEST, NORTHERN VALLEY INVERSIONS WILL CONTINUE TO LOWER AND
STRENGTHEN. COMPARING THE LAST SEVERAL SOUNDINGS AT KSLC SHOWS A
STOUT INVERSION, LOWERING WITH TIME.
CORRESPONDING SURFACE VISIBILITY HAS DECREASED AT KSLC (USUALLY
ONE OF THE FIRST LOCATIONS IN THE WASATCH FRONT TO SEE THIS) TO
7-8 SM THIS AFTERNOON. AIR QUALITY SENSORS SHOW A CONTINUE
INCREASE IN PM2.5 CONCENTRATIONS, WITH SEVERAL SENSORS ALONG THE
WASATCH FRONT ALREADY IN THE MODERATE/YELLOW CATEGORY. NEARLY ALL
MONITORED NORTHERN VALLEY LOCATIONS ARE FORECAST TO SHIFT TO
YELLOW/MODERATE CONDITIONS MONDAY, WITH THE SALT LAKE VALLEY
FORECAST TO REACH ORANGE/UNHEALTHY FOR SENSITIVE GROUPS BY
TUESDAY. WITH LITTLE HOPE FOR VALLEY INVERSIONS TO MIX OUT/IMPROVE
THROUGH FRIDAY, EXPECT A CONTINUE INCREASE IN PARTICULATES AS THE
WEEKDAY COMMUTES COMMENCE.
THE OTHER TWO IMPACTS WILL BE HAZE AND FOG. HAZE, IN THIS CASE
DEFINED AS VISIBILITY AT OR BELOW 6SM, INCREASES IN PROBABILITY
(ABOUT 40%) FOR MONDAY AFTERNOON AND EVENING ACROSS THE SALT
LAKE, WEBER AND DAVIS COUNTY AREAS AND THEN BECOMES WIDESPREAD
ACROSS ALL THE NORTHERN INVERSION VALLEY LOCATIONS TUESDAY
MORNING.
FOR FOG, NBM/HREF BLEND CONTINUES TO SHOW A 40% CHANCE OF DENSE
FOG AND FREEZING FOG DEVELOPMENT ACROSS CACHE AND EASTERN BOX
ELDER COUNTY EARLY MONDAY MORNING. NOTE THOUGH, THAT THIS HAS BEEN
FORECAST THE LAST FEW DAYS AND HAS NOT OCCURRED...BUT GIVEN
LOWERING AND STRENGTHENING INVERSIONS...DOES NOT SEEM TO BE
UNREASONABLE. CHANCES OF DENSE FOG WILL INCREASE THROUGH THE WEEK,
ESPECIALLY FOR THE CACHE VALLEY, EASTERN BOX ELDER AND AREAS NEAR
THE GREAT SALT LAKE IN SALT LAKE, WEBER AND DAVIS COUNTY.
THE BIGGEST QUESTION...WILL THE NORTHERN VALLEYS VENTILATE IN
ASSOCIATION WITH A BACKDOOR COLD FRONT FRIDAY? ABOUT 60% OF
MEMBERS STILL BRING THE SHORTWAVE TROUGH CLOSE ENOUGH TO THE
REGION TO BRING A COLD FRONT THROUGH NORTHERN UTAH ENOUGH COLD AIR
ADVECTION TO ALLOW FULL VALLEY MIXING BY SATURDAY. THE REMAINDER
THOUGH...INVERSIONS WOULD REMAIN IN PLACE THROUGH AT LEAST EARLY
THE NEXT WEEK.
AVIATION...KSLC
VFR CONDITIONS TO PREVAIL THROUGH THE TAF
PERIOD, THOUGH VALLEY HAZE WILL BRING SLANTWISE VIS REDUCTIONS.
THERE ARE LOW END (~20%) CHANCES FOR PATCHY FOG/LOW STRATUS
DEVELOPING OVER THE GSL BETWEEN 10-16Z, BUT IMPACTS TO THE
TERMINAL ARE UNLIKELY. LIGHT NORTHWESTERLY WINDS TRANSITION TO
SOUTHEASTERLY AFTER 04Z.
REST OF UTAH AND SOUTHWEST WYOMING
VALLEY HAZE, ESPECIALLY
ACROSS THE WASATCH FRONT, 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.
KRUSE/WHITLAM
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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