Alert archive / Utah / Winter Weather Advisories in 2021

Winter Weather Advisory 17, NWS Salt Lake City, UT

October 7, 2021Duchesne County, Summit County, Wasatch County, Utah

NWS Salt Lake City, UT issued this winter weather advisory at Oct 7, 2021, 3:09 PM MDT for Duchesne County, Summit County, Wasatch County, Utah. It took effect at Oct 8, 2021, 6:00 AM MDT. It was in force for 36 hr.

The area

The counties it named.

The facts

Issued
Oct 7, 2021, 3:09 PM MDT (21:09 UTC)
In effect from
Oct 8, 2021, 6:00 AM MDT
Expired
Oct 9, 2021, 6:00 PM MDT
In force
36 hr
Issued by
NWS Salt Lake City, UT

Counties Duchesne County, UT, Summit County, UT, Wasatch County, UT

The radar

The Salt Lake City radar (KMTX), 159 km from the middle of the area, began a volume at 21:08 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 9.2 hours before the alert went out and 94 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Salt Lake City I, UT at 12:00Z on 2021-10-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 40 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Salt Lake City I, UT at 12:00Z on 2021-10-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 48 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
40 J/kg
Mixed-layer CIN
-97 J/kg
Mixed-layer LCL
1145 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
48 m²/s²
0-3 km storm-relative helicity
148 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter weather advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Salt Lake City, UT wrote its last area forecast discussion before this winter weather advisory went out at Oct 7, 12:11 PM MDT, 2 hours 58 minutes earlier.

Area forecast discussion, Oct 7, 12:11 PM MDT, 2 hours 58 minutes before
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Hazardous weather outlook, Oct 7, 6:02 AM MDT, 9 hours 7 minutes before
Hazardous Weather Outlook
National Weather Service Salt Lake City UT
602 AM MDT Thu Oct 7 2021

UTZ101>131-WYZ021-081215-
Great Salt Lake Desert and Mountains-Tooele and Rush Valleys-
Eastern Box Elder County-Northern Wasatch Front-Salt Lake Valley-
Utah Valley-Cache Valley/Utah Portion-Wasatch Back-
Bear Lake and Bear River Valley-Wasatch Mountains I-80 North-
Wasatch Mountains South of I-80-Western Uinta Mountains-
Wasatch Plateau/Book Cliffs-Western Uinta Basin-
Western Millard and Juab Counties-Eastern Juab/Millard Counties-
Central Mountains-Sanpete Valley-Sevier Valley-Castle Country-
San Rafael Swell-Southwest Utah-Lower Washington County-
Zion National Park-Southern Mountains-Upper Sevier River Valleys-
Bryce Canyon Country-South Central Utah-
Capitol Reef National Park and Vicinity-Western Canyonlands-
Glen Canyon Recreation Area/Lake Powell-Southwest Wyoming-
602 AM MDT Thu Oct 7 2021

This Hazardous Weather Outlook is for the western two thirds of
Utah and southwest Wyoming.

.DAY ONE...Today and Tonight

Showers and isolated thunderstorms are expected this afternoon and
evening across northern and central Utah. These storms will be
most numerous along the higher terrain this afternoon and early
evening, then across areas north of I-80 through the evening.
Gusty winds, occasional lightning, and brief heavy rainfall can
be expected with the strongest storms.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

The next storm system will impact much of the outlook area Friday
through Saturday. Showers and thunderstorms are expected Friday
afternoon through Friday evening. Locally heavy rainfall could
result in isolated incidents of flash flooding within slot
canyons, small streams, and normally dry washes across southern
Utah, as well as near recent burn scars. Much cooler air will
arrive Friday night lowering snow levels to near 7500 feet
Saturday. Accumulating snow can be expected across northern Utah
above 8000 feet during the day Saturday.

A colder storm system will impact the outlook area during the
first half of next week, bringing the potential for significant
mountain snowfall, as well as lowering snow levels to the benches,
and resulting in freezing overnight temperatures across most
valleys excluding the St George area beginning Monday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information
about observed severe weather to the NWS while following all
local, state, and CDC guidelines.

For more information from NOAA/s National Weather Service visit...
http://weather.gov/saltlakecity

For information on potential road travel impacts visit...
http://www.udottraffic.utah.gov/roadweatherforecast.aspx

The office that day

Everything else NWS Salt Lake City, UT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 7, 2:45 PM MDTFlood WatchSLCBox Elder, Cache, Davis, Iron, Kane, Morgan and 5 more33 hr

Nearby

Winter Weather Advisories in Utah, 2021Every winter weather advisory in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.