Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 13, NWS Missoula, MT

August 5, 2021Powell County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Aug 5, 2021, 5:03 PM MDT for Powell County, Montana. It was in force for 42 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 5, 2021, 5:03 PM MDT (23:03 UTC)
Expired
Aug 5, 2021, 5:45 PM MDT
In force
42 min
Issued by
NWS Missoula, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Powell County, MT

The radar

The Missoula radar (KMSX), 102 km from the middle of the area, began a volume at 23:02 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, 11.1 hours before the alert went out and 181 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, Great_falls, MT at 12:00Z on 2021-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Great_falls, MT at 12:00Z on 2021-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 23 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1584 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
23 m²/s²
0-3 km storm-relative helicity
142 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

007 
WUUS55 KMSO 052303
SVRMSO
MTC077-052345-
/O.NEW.KMSO.SV.W.0013.210805T2303Z-210805T2345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Missoula MT
503 PM MDT Thu Aug 5 2021

The National Weather Service in Missoula has issued a

* Severe Thunderstorm Warning for...
  Southeastern Powell County in west central Montana...

* Until 545 PM MDT.

* At 502 PM MDT, a severe thunderstorm was located 8 miles north of
  Garrison, or 17 miles north of Deer Lodge, moving north at 35 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Garrison, Finn, Brock Creek, Goldcreek and Avon. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4646 11279 4653 11298 4696 11286 4695 11279
      4683 11279 4683 11253 4670 11253 4670 11250
TIME...MOT...LOC 2302Z 198DEG 30KT 4664 11277 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$
2 follow-up statements
700 
WWUS55 KMSO 052316
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
516 PM MDT Thu Aug 5 2021

MTC077-052345-
/O.CON.KMSO.SV.W.0013.000000T0000Z-210805T2345Z/
Powell MT-
516 PM MDT Thu Aug 5 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM MDT
FOR SOUTHEASTERN POWELL COUNTY...

At 515 PM MDT, a severe thunderstorm was located 14 miles south of
Lincoln, or 21 miles east of Drummond, moving north at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Garrison, Finn, Brock Creek, Goldcreek and Avon. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4646 11279 4653 11298 4696 11286 4695 11279
      4683 11279 4683 11253 4670 11253 4670 11250
TIME...MOT...LOC 2315Z 198DEG 30KT 4675 11272 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$
566 
WWUS55 KMSO 052341
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
541 PM MDT Thu Aug 5 2021

MTC077-052350-
/O.EXP.KMSO.SV.W.0013.000000T0000Z-210805T2345Z/
Powell MT-
541 PM MDT Thu Aug 5 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN POWELL COUNTY
WILL EXPIRE AT 545 PM MDT...
        
The storm which prompted the warning will be moving out of the area 
shortly.Therefore, the warning will be allowed to expire. However 
small hail and gusty winds are still possible with this thunderstorm.

LAT...LON 4646 11279 4653 11298 4696 11286 4695 11279
      4683 11279 4683 11253 4670 11253 4670 11250
TIME...MOT...LOC 2340Z 198DEG 30KT 4692 11264 

$$

The office that day

Everything else NWS Missoula, MT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 4, 6:21 PM MDTSpecial Weather StatementMSOFlathead24 min
Aug 4, 6:31 PM MDTSpecial Weather StatementMSOLake14 min
Aug 4, 7:57 PM MDTSpecial Weather StatementMSOLake18 min
Aug 4, 8:03 PM MDTSevere Thunderstorm WarningMSOLake27 min
Aug 4, 8:26 PM MDTSevere Thunderstorm Warning Considerable damage threatMSOLake34 min
Aug 5, 2:27 PM MDTSpecial Weather StatementMSOMineral, Ravalli33 min
Aug 5, 3:20 PM MDTSpecial Weather StatementMSOGranite, Ravalli55 min
Aug 5, 4:12 PM MDTSpecial Weather StatementMSODeer Lodge, Silver Bow48 min
Aug 5, 4:19 PM MDTSpecial Weather StatementMSORavalli56 min

Nearby

Severe Thunderstorm Warnings in Montana, 2021Every severe thunderstorm warning 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.