Alert archive / Wyoming / Mesoscale Discussions in 2021
Mesoscale Discussion 621
The Storm Prediction Center issued this mesoscale discussion at May 15, 2021, 1:54 PM MDT for Daggett County, Summit County, Utah; 4 counties in Wyoming. It was in force for 96 min.
The area
The outline as issued.
The facts
- Issued
- May 15, 2021, 1:54 PM MDT (19:54 UTC)
- Expired
- May 15, 2021, 3:30 PM MDT
- In force
- 96 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Daggett County, UT, Summit County, UT, Lincoln County, WY, Sublette County, WY, Sweetwater County, WY, Uinta County, WY
The radar
The Riverton/Lander radar (KRIW), 132 km from the middle of the area, began a volume at 19:57 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
Riverton, WY (KRIW), launched 12:00Z, 7.9 hours before the alert went out and 135 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 933 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 50 m²/s²
- 0-3 km storm-relative helicity
- 203 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
667
ACUS11 KWNS 151954
SWOMCD
SPC MCD 151954
WYZ000-COZ000-UTZ000-152130-
Mesoscale Discussion 0621
NWS Storm Prediction Center Norman OK
0254 PM CDT Sat May 15 2021
Areas affected...Northeastern Utah and southwestern Wyoming.
Concerning...Severe potential...Watch unlikely
Valid 151954Z - 152130Z
Probability of Watch Issuance...5 percent
SUMMARY...High-based thunderstorms developing near an area of low
pressure across northern Utah may produce some severe wind gusts or
large hail. A weather watch is unlikely.
DISCUSSION...As of 1930 UTC, radar and satellite observations showed
several thunderstorms developing across northern Utah and
southwestern Wyoming ahead of an upper low across the Great Basin.
Surface observations show modest low-level moisture (dewpoints in
the mid to upper 30s F) have pooled along and north of a stalled
frontal boundary along the southern Wyoming border. To the north of
the front, SPC mesoanalysis indicates around 500 J/kg of MLCAPE has
developed, owing to steep low and mid-level lapse rates near 9 C/km.
Diffluent southwesterly flow ahead of the upper low will continue to
slowly overspread the region and support between 25 and 35 kt of
effective shear. A couple of strong/severe storms capable of severe
hail, or more likely damaging outflow winds, will be possible into
early evening. Additional storm development within thermally driven
terrain circulations along the northern crest of the Uinta Range and
across the higher terrain of western Wyoming appear possible with
continued heating and the approaching mid-level diffluence. Low
confidence in convective evolution/coverage exists, suggesting a
weather watch is unlikely.
..Lyons/Guyer.. 05/15/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CYS...RIW...GJT...SLC...
LAT...LON 41451106 42381075 42791009 42990920 43000835 42830778
42500741 41870738 41350761 40920902 40651102 41451106Nearby
Mesoscale Discussions in Wyoming, 2021Mesoscale Discussions in Utah, 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.