Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 48, NWS Great Falls, MT

July 21, 20214 counties in Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 21, 2021, 4:45 PM MDT for 4 counties in Montana. It was in force for 45 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 21, 2021, 4:45 PM MDT (22:45 UTC)
Expired
Jul 21, 2021, 5:30 PM MDT
In force
45 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
70.0 mph

Counties Liberty County, MT, Pondera County, MT, Teton County, MT, Toole County, MT

The radar

The Great Falls radar (KTFX), 95 km from the middle of the area, began a volume at 22:48 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.

What was reported inside it

TimeReportWhereRemark
Jul 21, 5:05 PM MDTTSTM WND GST 50Galata, MTSITE DW9605.
Jul 21, 5:30 PM MDTTSTM WND GST 483 E Lothair, MTMESONET STATION EW8201 LOTHAIR 3E.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 10.8 hours before the alert went out and 127 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.

874 
WUUS55 KTFX 212245
SVRTFX
MTC051-073-099-101-212330-
/O.NEW.KTFX.SV.W.0048.210721T2245Z-210721T2330Z/

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

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Eastern Pondera County in north central Montana...
  Southwestern Liberty County in north central Montana...
  Southern Toole County in north central Montana...
  North central Teton County in north central Montana...

* Until 530 PM MDT.

* At 444 PM MDT, a severe thunderstorm was located 10 miles south of 
  Valier, or 11 miles west of Conrad, moving northeast at 35 mph. A 
  second severe thunderstorm was located east of Ledger, also moving 
  northeast at 35 mph.

  HAZARD...70 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect considerable 
           tree damage. Wind damage is also likely to mobile homes, 
           roofs, and outbuildings.

* Locations impacted include...
  Conrad, Valier, Lothair, Devon, Galata and Ledger. 

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.

&&

LAT...LON 4847 11109 4824 11114 4823 11150 4811 11185
      4807 11205 4809 11206 4809 11217 4808 11224
      4813 11233 4819 11235 4830 11228 4842 11195
      4843 11174 4861 11125
TIME...MOT...LOC 2244Z 246DEG 31KT 4816 11219 

HAIL...1.00IN
WIND...70MPH
 
$$

HART
2 follow-up statements
429 
WWUS55 KTFX 212301
SVSTFX

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

MTC051-073-099-101-212330-
/O.CON.KTFX.SV.W.0048.000000T0000Z-210721T2330Z/
Pondera MT-Liberty MT-Toole MT-Teton MT-
501 PM MDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM MDT
FOR EASTERN PONDERA...SOUTHWESTERN LIBERTY...SOUTHERN TOOLE AND
NORTHEASTERN TETON COUNTIES...

At 500 PM MDT, a severe thunderstorm was located over Conrad, moving 
east at 30 mph. A second severe thunderstorm was located across 
mainly rural areas of southern Toole county, moving northeast at 30 
mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
Conrad, Lothair, Devon, Galata and Ledger. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 4847 11109 4824 11114 4823 11150 4811 11185
      4807 11205 4809 11206 4809 11217 4831 11216
      4842 11195 4843 11174 4861 11125
TIME...MOT...LOC 2300Z 257DEG 28KT 4816 11201 

HAIL...1.00IN
WIND...70MPH
 
$$

HART
230 
WWUS55 KTFX 212309
SVSTFX

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

MTC099-212318-
/O.CAN.KTFX.SV.W.0048.000000T0000Z-210721T2330Z/
Teton MT-
509 PM MDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN TETON COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4847 11109 4824 11114 4823 11150 4811 11185
      4808 11200 4810 11203 4820 11211 4825 11207
      4833 11211 4842 11195 4843 11174 4861 11125
TIME...MOT...LOC 2308Z 246DEG 31KT 4819 11191 

$$

MTC051-073-101-212330-
/O.CON.KTFX.SV.W.0048.000000T0000Z-210721T2330Z/
Pondera MT-Liberty MT-Toole MT-
509 PM MDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM MDT
FOR EASTERN PONDERA...SOUTHWESTERN LIBERTY AND SOUTHERN TOOLE
COUNTIES...

At 508 PM MDT, a severe thunderstorm was located over Conrad, moving 
northeast at 35 mph. A second severe thunderstorm was located over 
southern Toole County, also moving northeast at 35 mph.

HAZARD...70 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect considerable 
         tree damage. Wind damage is also likely to mobile homes, 
         roofs, and outbuildings.

Locations impacted include...
Conrad, Lothair, Devon, Galata and Ledger. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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.

&&

LAT...LON 4847 11109 4824 11114 4823 11150 4811 11185
      4808 11200 4810 11203 4820 11211 4825 11207
      4833 11211 4842 11195 4843 11174 4861 11125
TIME...MOT...LOC 2308Z 246DEG 31KT 4819 11191 

HAIL...1.00IN
WIND...70MPH
 
$$

HART

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, 2:56 PM MDTSevere Thunderstorm WarningTFXGlacier34 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, 4:53 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.