Alert archive / Montana / Mesoscale Discussions in 2021
Mesoscale Discussion 1075
The Storm Prediction Center issued this mesoscale discussion at Jun 24, 2021, 1:11 PM MDT for 6 counties in Montana. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 24, 2021, 1:11 PM MDT (19:11 UTC)
- Expired
- Jun 24, 2021, 3:15 PM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Cascade County, MT, Flathead County, MT, Glacier County, MT, Lewis and Clark County, MT, Pondera County, MT, Teton County, MT
The radar
The Great Falls radar (KTFX), 120 km from the middle of the area, began a volume at 19:10 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
Great_falls, MT (KTFX), launched 12:00Z, 7.2 hours before the alert went out and 172 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
- 10 J/kg
- Mixed-layer CIN
- -138 J/kg
- Mixed-layer LCL
- 2437 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 105 m²/s²
- 0-3 km storm-relative helicity
- 109 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
639
ACUS11 KWNS 241912
SWOMCD
SPC MCD 241911
MTZ000-242115-
Mesoscale Discussion 1075
NWS Storm Prediction Center Norman OK
0211 PM CDT Thu Jun 24 2021
Areas affected...Portions of northwest Montana into west-central
Montana
Concerning...Severe potential...Watch unlikely
Valid 241911Z - 242115Z
Probability of Watch Issuance...5 percent
SUMMARY...A few strong to severe storms possible through the
evening.
DISCUSSION...The boundary layer has destabilized in a region
extending from near Glacier National Park southeastward to near
Great Falls. A few stronger updrafts have started to show more
lightning within the past 30 minutes. Expect storm coverage to
increase as the compact mid-level shortwave trough drops south out
of Canada. In addition, as the boundary layer continues to warm,
expect MLCAPE to increase to around 1000 J/kg. The KTFX VWP shows
around 30 knots of effective shear. This shear combined with the
weak to moderate instability, should be sufficient for organized
updrafts, with some weak supercells possible. Isolated severe hail
and a severe wind gust or two will be possible. Relatively weak
instability, less than 30 knots of flow in the lowest 6km, and
limited coverage of strong to severe storms will likely preclude the
need for a severe thunderstorm watch.
..Bentley/Hart.. 06/24/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...TFX...MSO...
LAT...LON 49141390 49091470 48161418 46921251 46811194 46771173
47001112 47651099 49051212 49031281 49141390SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 24, 2:37 PM MDT | Mesoscale Discussion | SPC | Carter, Custer, Dawson, Fallon, Garfield, McCone and 5 more | 83 min |
Nearby
Mesoscale Discussions in Montana, 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.