Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 12, NWS Missoula, MT

August 4, 2021Lake County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Aug 4, 2021, 8:26 PM MDT for Lake County, Montana. It was in force for 34 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 4, 2021, 8:26 PM MDT (02:26 UTC)
Expired
Aug 4, 2021, 9:00 PM MDT
In force
34 min
Issued by
NWS Missoula, MT
Area
Storm-based polygon
Damage threat
Considerable
Hail
1.75 in
Wind
60.0 mph

County Lake County, MT

The radar

The Missoula radar (KMSX), 81 km from the middle of the area, began a volume at 02:26 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

Spokane, WA (KOTX), launched 00:00Z, 2.4 hours before the alert went out and 183 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, Spokane, WA at 00:00Z on 2021-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 502 joules per kilogram.LCLLFCEL10008507005003002001001 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, Spokane, WA at 00:00Z on 2021-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 square meters per square second.193958Sfc1 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
502 J/kg
Mixed-layer CIN
-9 J/kg
Mixed-layer LCL
3045 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
58 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

776 
WUUS55 KMSO 050226
SVRMSO
MTC047-050300-
/O.NEW.KMSO.SV.W.0012.210805T0226Z-210805T0300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Missoula MT
826 PM MDT Wed Aug 4 2021

The National Weather Service in Missoula has issued a

* Severe Thunderstorm Warning for...
  Northeastern Lake County in northwestern Montana...

* Until 900 PM MDT.

* At 826 PM MDT, a severe thunderstorm was located near Kings Point,
  or 8 miles northeast of Polson, moving east at 20 mph.

  HAZARD...Golf ball size hail and 60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           wind damage to roofs, siding, and trees.

* Locations impacted include...
  Finley Point.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4774 11407 4781 11406 4785 11380 4771 11377
TIME...MOT...LOC 0226Z 275DEG 18KT 4778 11403 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$
3 follow-up statements
939 
WWUS55 KMSO 050232
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
832 PM MDT Wed Aug 4 2021

MTC047-050300-
/O.CON.KMSO.SV.W.0012.000000T0000Z-210805T0300Z/
Lake MT-
832 PM MDT Wed Aug 4 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM MDT
FOR NORTHEASTERN LAKE COUNTY...

At 832 PM MDT, a severe thunderstorm was located 7 miles east of
Kings Point, or 10 miles northeast of Polson, moving east at 20 mph.

HAZARD...Ping pong ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees.

This severe thunderstorm will remain over mainly rural areas of
northeastern Lake County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4773 11397 4782 11400 4785 11380 4771 11377
TIME...MOT...LOC 0232Z 275DEG 18KT 4778 11398 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.50 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$
835 
WWUS55 KMSO 050245
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
845 PM MDT Wed Aug 4 2021

MTC047-050300-
/O.CON.KMSO.SV.W.0012.000000T0000Z-210805T0300Z/
Lake MT-
845 PM MDT Wed Aug 4 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM MDT
FOR EAST CENTRAL LAKE COUNTY...

At 845 PM MDT, a severe thunderstorm was located 11 miles south of
Swan Lake, or 13 miles northeast of Polson, moving east at 20 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.

This severe thunderstorm will remain over mainly rural areas of east
central Lake County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4775 11392 4781 11391 4785 11380 4771 11377
TIME...MOT...LOC 0245Z 275DEG 18KT 4777 11389 

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

$$
130 
WWUS55 KMSO 050253
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
853 PM MDT Wed Aug 4 2021

MTC047-050303-
/O.EXP.KMSO.SV.W.0012.000000T0000Z-210805T0300Z/
Lake MT-
853 PM MDT Wed Aug 4 2021

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL LAKE COUNTY WILL
EXPIRE AT 900 PM MDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

LAT...LON 4775 11392 4781 11391 4785 11380 4771 11377
TIME...MOT...LOC 0253Z 275DEG 18KT 4777 11385 

$$

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 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
Aug 5, 5:03 PM MDTSevere Thunderstorm WarningMSOPowell42 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.