Alert archive / Utah / Mesoscale Discussions in 2021
Mesoscale Discussion 2066
The Storm Prediction Center issued this mesoscale discussion at Dec 27, 2021, 5:13 PM MST for 8 counties in Utah; Uinta County, Wyoming. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 27, 2021, 5:13 PM MST (00:13 UTC)
- Expired
- Dec 27, 2021, 7:15 PM MST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Snow squall
Counties Morgan County, UT, Rich County, UT, Salt Lake County, UT, Summit County, UT, Tooele County, UT, Utah County, UT, Wasatch County, UT, Weber County, UT, Uinta County, WY
The radar
The Salt Lake City radar (KMTX), 76 km from the middle of the area, began a volume at 00:11 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 00:00Z, 0.2 hours before the alert went out and 14 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.
- Mixed-layer CAPE
- 33 J/kg
- Mixed-layer CIN
- -42 J/kg
- Mixed-layer LCL
- 1606 m above ground
- 0-6 km bulk shear
- 69 kt
- 0-1 km storm-relative helicity
- 219 m²/s²
- 0-3 km storm-relative helicity
- 252 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted.
090
ACUS11 KWNS 280014
SWOMCD
SPC MCD 280013
UTZ000-WYZ000-IDZ000-280215-
Mesoscale Discussion 2066
NWS Storm Prediction Center Norman OK
0613 PM CST Mon Dec 27 2021
Areas affected...Northern Utah
Concerning...Snow Squall
Valid 280013Z - 280215Z
SUMMARY...An ongoing snow squall will continue to produce heavy
snow/reduced visibility for at least the next 1-2 hours across
north-central Utah.
DISCUSSION...Radar imagery from the past hour has shown a persistent
snow squall band associated with a cold front moving east/southeast
across northern UT into the Salt Lake City area. Although
temperatures ahead of this band are in the mid/upper 30s, strong
cold advection along/behind the snow band, coupled with wet-bulb
temperatures below freezing, is driving temperature reductions into
the low 30s/upper 20s, wind gusts between 30-40 mph, and reduced
visibility down to 1/2 to 1/4 mile at times. This snow squall is
being supported by a deep layer of steep lapse rates near 8 C/km.
Latest RAP mesoanalysis shows this plume of steep lapse rates
extends well ahead of the band across north-central UT, which will
be supportive of snow squall maintenance. While interactions with
the higher terrain east of Salt Lake City may impede eastward
progress to a degree, upper tilts from KMTX show the snow squall may
extent as high as 11 kft in some locations, suggesting the potential
for continued impacts. Diurnal cooling between 01-02 UTC will likely
reduce low-level lapse rates and mitigate the mixing potential as
well as reduce instability, resulting in a gradual decay of the band
during and after this period.
..Moore.. 12/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...RIW...SLC...PIH...
LAT...LON 41531163 42061108 41811063 41321029 40801041 40341105
39971173 39891245 39981306 40171334 40501311 40971228
41531163Nearby
Mesoscale Discussions in Utah, 2021Mesoscale Discussions in Wyoming, 2021Every mesoscale discussion 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.