Alert archive / Idaho / Mesoscale Discussions in 2021
Mesoscale Discussion 1809
The Storm Prediction Center issued this mesoscale discussion at Oct 7, 2021, 4:07 PM MDT for 4 states. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- Oct 7, 2021, 4:07 PM MDT (22:07 UTC)
- Expired
- Oct 7, 2021, 6:00 PM MDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 21 counties
Bannock County, ID, Bear Lake County, ID, Bingham County, ID, Bonneville County, ID, Caribou County, ID, Cassia County, ID, Franklin County, ID, Jerome County, ID, Minidoka County, ID, Oneida County, ID, Power County, ID, Twin Falls County, ID, Elko County, NV, Box Elder County, UT, Cache County, UT, Davis County, UT, Morgan County, UT, Rich County, UT, Tooele County, UT, Weber County, UT, Lincoln County, WY
The radar
The Salt Lake City radar (KMTX), 91 km from the middle of the area, began a volume at 22:08 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
Elko, NV (KLKN), launched 12:00Z, 10.1 hours before the alert went out and 102 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
- 3 J/kg
- Mixed-layer CIN
- -60 J/kg
- Mixed-layer LCL
- 927 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- -9 m²/s²
- 0-3 km storm-relative helicity
- 134 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
120
ACUS11 KWNS 072208
SWOMCD
SPC MCD 072207
WYZ000-IDZ000-UTZ000-NVZ000-080000-
Mesoscale Discussion 1809
NWS Storm Prediction Center Norman OK
0507 PM CDT Thu Oct 07 2021
Areas affected...Portions of the Great Basin
Concerning...Severe potential...Watch unlikely
Valid 072207Z - 080000Z
Probability of Watch Issuance...5 percent
SUMMARY...A few strong to locally severe thunderstorms are possible
through this evening across portions of the Great Basin. Isolated
instances of gusty winds and near-severe hail are the primary severe
threats. The spotty nature of any severe threat will likely preclude
a severe weather watch.
DISCUSSION...Radar imagery over the past hour or so shows widely
scattered and mostly poorly disorganized multicell thunderstorms
across portions of the Great Basin as a mid-level shortwave trough
approaches the area. The strongest storm during this time has been
located over Cassia County in southern Idaho, where periodic updraft
organization has allowed this thunderstorm to remain near severe
limits (MRMS MESH near 1 inch). Occasional
strengthening/organization of nearby/new thunderstorm updrafts are
possible over the next several hours due to effective bulk shear
near 40 knots and modest instability (e.g., MLCAPE near 500 J/kg) --
best overlap over southern/southeastern Idaho. Isolated instances of
marginally severe hail and gusty winds will be possible with the
strongest storms through mid/late evening before instability weakens
further.
Overall, the spotty nature of any severe threat should preclude a
severe weather watch.
..Elliott/Thompson.. 10/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...RIW...SLC...PIH...BOI...LKN...
LAT...LON 41121610 41781565 42601456 43491205 43371062 43111016
42440985 41741063 40911180 39841367 39931482 40261590
40611638 41121610Nearby
Mesoscale Discussions in Idaho, 2021Mesoscale Discussions in Utah, 2021Mesoscale Discussions in Nevada, 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.