Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 39, NWS Great Falls, MT

July 11, 2021Toole County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 11, 2021, 3:40 PM MDT for Toole County, Montana. It was in force for 50 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 11, 2021, 3:40 PM MDT (21:40 UTC)
Expired
Jul 11, 2021, 4:30 PM MDT
In force
50 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
1.75 in
Wind
60.0 mph

County Toole County, MT

The radar

The Great Falls radar (KTFX), 113 km from the middle of the area, began a volume at 21:42 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 11, 4:00 PM MDTTSTM WND GST 60Toole County Airport, MTMEASURED AT TOOLE COUNTY AIRPORT, VIA AMBIENT WEATHER.
Jul 11, 4:16 PM MDTTSTM WND GST 53Galata, MTMESONET STATION DW9605 GALATA.

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, 9.7 hours before the alert went out and 138 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 2021-07-11Temperature 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°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 2021-07-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -10 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3738 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-10 m²/s²
0-3 km storm-relative helicity
104 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

926 
WUUS55 KTFX 112140
SVRTFX
MTC101-112230-
/O.NEW.KTFX.SV.W.0039.210711T2140Z-210711T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Great Falls MT
340 PM MDT Sun Jul 11 2021

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Southern Toole County in north central Montana...

* Until 430 PM MDT.

* At 339 PM MDT, a severe thunderstorm was located 8 miles south of
  Kevin, or 9 miles northwest of Shelby, moving southeast at 55 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...
  Shelby, Kevin, Devon, Ethridge, Dunkirk and Galata. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail, 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 4850 11127 4830 11128 4824 11145 4833 11167
      4835 11167 4835 11172 4838 11180 4840 11180
      4843 11193 4857 11219 4867 11219 4881 11210
TIME...MOT...LOC 2139Z 300DEG 47KT 4862 11197 

HAIL...1.75IN
WIND...60MPH
 
$$

HART
2 follow-up statements
136 
WWUS55 KTFX 112200
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
400 PM MDT Sun Jul 11 2021

MTC101-112230-
/O.CON.KTFX.SV.W.0039.000000T0000Z-210711T2230Z/
Toole MT-
400 PM MDT Sun Jul 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM MDT
FOR SOUTHERN TOOLE COUNTY...

At 358 PM MDT, a severe thunderstorm was located 9 miles east of
Shelby, moving southeast at 55 mph.

HAZARD...60 mph wind gusts and half dollar size hail. Severe wind 
         gusts may still occur well after the storm has passed.

SOURCE...Radar indicated.

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

Locations impacted include...
Shelby, Kevin, Devon, Ethridge, Dunkirk and Galata. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This storm is producing prolonged widespread strong winds behind the 
storm. Wind gusts of 50 to 60 mph may occur for up to 30 minutes 
after the storm has passed. Seek shelter inside a sturdy structure 
and stay away from windows.

&&

LAT...LON 4850 11127 4830 11128 4824 11145 4833 11167
      4835 11167 4835 11172 4838 11180 4840 11180
      4843 11193 4857 11219 4867 11219 4881 11210
TIME...MOT...LOC 2158Z 296DEG 46KT 4852 11166 

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

HART
535 
WWUS55 KTFX 112220
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
420 PM MDT Sun Jul 11 2021

MTC101-112230-
/O.CON.KTFX.SV.W.0039.000000T0000Z-210711T2230Z/
Toole MT-
420 PM MDT Sun Jul 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM MDT
FOR SOUTHEASTERN TOOLE COUNTY...

At 419 PM MDT, a severe thunderstorm was located near Lothair, or 16
miles southwest of Chester, moving east at 55 mph.

HAZARD...60 mph wind gusts and quarter size hail. Severe wind gusts 
         may occur well to the south and southwest of the main storm.

SOURCE...Radar indicated.

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

Locations impacted include...
Shelby, Devon, Dunkirk and Galata. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4850 11127 4830 11128 4824 11145 4833 11167
      4835 11167 4835 11172 4838 11180 4840 11180
      4848 11186 4868 11174
TIME...MOT...LOC 2219Z 293DEG 45KT 4842 11129 

HAIL...1.00IN
WIND...60MPH
 
$$

HART

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 11, 12:33 AM MDTRed Flag WarningTFXBlaine, Broadwater, Cascade, Chouteau, Fergus, Gallatin and 12 more20 hr
Jul 11, 2:18 PM MDTSpecial Weather StatementTFXGlacier42 min
Jul 11, 2:28 PM MDTSevere Thunderstorm WarningTFXGlacier50 min
Jul 11, 2:58 PM MDTSpecial Weather StatementTFXGlacier32 min
Jul 11, 3:03 PM MDTSevere Thunderstorm WarningTFXGlacier, Toole42 min
Jul 11, 4:18 PM MDTSevere Thunderstorm WarningTFXLiberty, Toole27 min
Jul 11, 4:36 PM MDTSpecial Weather StatementTFXPondera24 min
Jul 11, 4:47 PM MDTSpecial Weather StatementTFXChouteau28 min
Jul 11, 5:05 PM MDTSpecial Weather StatementTFXPondera25 min
Jul 11, 5:11 PM MDTSevere Thunderstorm WarningTFXChouteau, Hill49 min
Jul 11, 5:55 PM MDTSevere Thunderstorm WarningTFXBlaine, Chouteau, Hill65 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.