Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 44, NWS Great Falls, MT

July 21, 2021Glacier County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 21, 2021, 2:56 PM MDT for Glacier 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
Jul 21, 2021, 2:56 PM MDT (20:56 UTC)
Expired
Jul 21, 2021, 3:30 PM MDT
In force
34 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
1.25 in
Wind
60.0 mph

County Glacier County, MT

The radar

The Great Falls radar (KTFX), 188 km from the middle of the area, began a volume at 20:59 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, 8.9 hours before the alert went out and 226 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 2021-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 158 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Great_falls, MT at 12:00Z on 2021-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 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
158 J/kg
Mixed-layer CIN
-180 J/kg
Mixed-layer LCL
1952 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
33 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

664 
WUUS55 KTFX 212056
SVRTFX
MTC035-212130-
/O.NEW.KTFX.SV.W.0044.210721T2056Z-210721T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Great Falls MT
256 PM MDT Wed Jul 21 2021

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Northeastern Glacier County in north central Montana...

* Until 330 PM MDT.

* At 255 PM MDT, a severe thunderstorm was located 15 miles north of
  North Browning, or 33 miles west of Cut Bank, moving northeast at
  25 mph.

  HAZARD...60 mph wind gusts and half dollar 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
  northeastern Glacier County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4881 11255 4867 11306 4883 11320 4900 11286
      4900 11271
TIME...MOT...LOC 2055Z 240DEG 23KT 4879 11304 

HAIL...1.25IN
WIND...60MPH
 
$$

SC
2 follow-up statements
359 
WWUS55 KTFX 212118
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
318 PM MDT Wed Jul 21 2021

MTC035-212130-
/O.CON.KTFX.SV.W.0044.000000T0000Z-210721T2130Z/
Glacier MT-
318 PM MDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 330 PM MDT
FOR NORTHEASTERN GLACIER COUNTY...

At 317 PM MDT, a severe thunderstorm was located 21 miles north of
North Browning, or 28 miles northwest of Cut Bank, moving northeast
at 25 mph.

HAZARD...60 mph wind gusts and half dollar 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
northeastern Glacier County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Great Falls.

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4881 11255 4875 11281 4894 11299 4900 11286
      4900 11271
TIME...MOT...LOC 2117Z 240DEG 23KT 4886 11285 

HAIL...1.25IN
WIND...60MPH
 
$$

SC
449 
WWUS55 KTFX 212131
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
331 PM MDT Wed Jul 21 2021

MTC035-212139-
/O.EXP.KTFX.SV.W.0044.000000T0000Z-210721T2130Z/
Glacier MT-
331 PM MDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN GLACIER COUNTY
WILL EXPIRE AT 330 PM MDT...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.  However small
hail, gusty winds and heavy rain are still possible with this 
thunderstorm, which is covered by another Severe Thunderstorm 
Warning for the area.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Great Falls.

Remember, a Severe Thunderstorm Warning still remains in effect for 
northeastern Glacier County until 345 pm MDT.

LAT...LON 4881 11255 4875 11281 4894 11299 4900 11286
      4900 11271
TIME...MOT...LOC 2129Z 240DEG 23KT 4889 11276 

$$

SC

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 6:10 PM MDTSpecial Weather StatementTFXTeton35 min
Jul 20, 6:14 PM MDTSpecial Weather StatementTFXToole31 min
Jul 20, 6:18 PM MDTSpecial Weather StatementTFXCascade27 min
Jul 20, 6:34 PM MDTSpecial Weather StatementTFXTeton26 min
Jul 20, 6:48 PM MDTSevere Thunderstorm WarningTFXPondera, Teton27 min
Jul 20, 7:01 PM MDTSpecial Weather StatementTFXCascade29 min
Jul 20, 7:17 PM MDTSpecial Weather StatementTFXTeton28 min
Jul 20, 7:47 PM MDTSpecial Weather StatementTFX28 min
Jul 20, 7:52 PM MDTSpecial Weather StatementTFXCascade23 min
Jul 20, 8:45 PM MDTSpecial Weather StatementTFXChouteau, Judith Basin30 min
Jul 21, 1:26 PM MDTFire Weather WatchTFXBroadwater, Cascade, Chouteau, Fergus, Gallatin, Jefferson and 4 more25 hr
Jul 21, 1:26 PM MDTRed Flag WarningTFXBlaine, Broadwater, Cascade, Chouteau, Fergus, Gallatin and 12 more56 hr
Jul 21, 2:38 PM MDTSpecial Weather StatementTFXGlacier37 min
Jul 21, 2:48 PM MDTSpecial Weather StatementTFXPondera27 min
Jul 21, 3:16 PM MDTSevere Thunderstorm WarningTFXGlacier29 min
Jul 21, 3:23 PM MDTSpecial Weather StatementTFXPondera37 min
Jul 21, 3:49 PM MDTSpecial Weather StatementTFXPondera26 min
Jul 21, 3:50 PM MDTSevere Thunderstorm WarningTFXPondera40 min
Jul 21, 3:51 PM MDTSpecial Weather StatementTFXTeton24 min
Jul 21, 4:07 PM MDTSpecial Weather StatementTFXFergus23 min
Jul 21, 4:07 PM MDTSevere Thunderstorm WarningTFXPondera, Teton38 min
Jul 21, 4:24 PM MDTSpecial Weather StatementTFXJefferson36 min
Jul 21, 4:29 PM MDTSpecial Weather StatementTFXMadison31 min
Jul 21, 4:34 PM MDTSpecial Weather StatementTFXSilver Bow26 min
Jul 21, 4:39 PM MDTSpecial Weather StatementTFXFergus36 min
Jul 21, 4:42 PM MDTSpecial Weather StatementTFXLewis and Clark33 min
Jul 21, 4:45 PM MDTSevere Thunderstorm WarningTFXLiberty, Pondera, Teton, Toole45 min
Jul 21, 4:53 PM MDTSpecial Weather StatementTFXTeton22 min
Jul 21, 4:54 PM MDTSpecial Weather StatementTFXLewis and Clark36 min
Jul 21, 4:56 PM MDTSpecial Weather StatementTFXJefferson34 min
Jul 21, 4:58 PM MDTSpecial Weather StatementTFXBroadwater, Jefferson32 min
Jul 21, 5:02 PM MDTSpecial Weather StatementTFXGlacier28 min
Jul 21, 5:04 PM MDTSpecial Weather StatementTFXDeer Lodge26 min
Jul 21, 5:21 PM MDTSpecial Weather StatementTFXLewis and Clark24 min
Jul 21, 5:29 PM MDTSevere Thunderstorm WarningTFXLiberty, Toole46 min
Jul 21, 5:32 PM MDTSpecial Weather StatementTFXCascade43 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.