Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 41, NWS Great Falls, MT

July 11, 2021Chouteau County, Hill County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 11, 2021, 5:11 PM MDT for Chouteau County, Hill County, Montana. It was in force for 49 min. 3 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, 5:11 PM MDT (23:11 UTC)
Expired: Jul 11, 2021, 6:00 PM MDT
In force: 49 min
Issued by: NWS Great Falls, MT
Area: Storm-based polygon
Hail: 0.88 in
Wind: 60.0 mph

Counties Chouteau County, MT, Hill County, MT

The radar

The Great Falls radar (KTFX), 117 km from the middle of the area, began a volume at 23:13 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

Time	Report	Where	Remark
Jul 11, 5:14 PM MDT	TSTM WND GST 77	13 W Big Sandy, MT	VIA AMBIENT WEATHER MESONET.
Jul 11, 5:24 PM MDT	TSTM WND DMG	Verona, MT	POWERLINES DOWN ON US 87 NEAR VERONA.
Jul 11, 5:30 PM MDT	TSTM WND DMG	1 Sw Big Sandy, MT	SEMI BLOWN OF HIGHWAY 87, NEAR MILE MARKER 78. POWER LINES BLOWN DOWN IN THE AREA. UNKNOWN NUMBER OF INJURIES. REPORT VIA MT HIGHWAY PATROL. TIME OF EVENT IS ESTIMATED.

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, 11.2 hours before the alert went out and 85 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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.

702 
WUUS55 KTFX 112311
SVRTFX
MTC015-041-120000-
/O.NEW.KTFX.SV.W.0041.210711T2311Z-210712T0000Z/

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

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Southern Hill County in north central Montana...
  Northeastern Chouteau County in north central Montana...

* Until 600 PM MDT.

* At 511 PM MDT, a severe thunderstorm was located 10 miles west of
  Big Sandy, moving east at 50 mph.

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

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Big Sandy, Azure, Parker School, Agency, Sangrey, St. Pierre,
  Boneau, Box Elder, Rocky Boy and Kenilworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4816 11067 4844 11053 4828 10962 4792 10980
TIME...MOT...LOC 2311Z 286DEG 42KT 4821 11034 

HAIL...0.88IN
WIND...60MPH
 
$$

HART

2 follow-up statements

306 
WWUS55 KTFX 112327
SVSTFX

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

MTC015-041-120000-
/O.CON.KTFX.SV.W.0041.000000T0000Z-210712T0000Z/
Hill MT-Chouteau MT-
527 PM MDT Sun Jul 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM MDT
FOR SOUTHERN HILL AND NORTHEASTERN CHOUTEAU COUNTIES...

At 526 PM MDT, a severe thunderstorm was located over Big Sandy,
moving east at 50 mph.

HAZARD...60 mph wind gusts and nickel size hail. Severe wind gusts 
         may occur well after the heaviest rain and hail end. 

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Big Sandy, Azure, Parker School, Agency, Sangrey, St. Pierre, Boneau,
Box Elder, Rocky Boy and Kenilworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4816 11067 4844 11053 4828 10962 4792 10980
TIME...MOT...LOC 2326Z 286DEG 42KT 4816 11009 

HAIL...0.88IN
WIND...60MPH
 
$$

HART

729 
WWUS55 KTFX 112347
SVSTFX

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

MTC015-041-120000-
/O.CON.KTFX.SV.W.0041.000000T0000Z-210712T0000Z/
Hill MT-Chouteau MT-
547 PM MDT Sun Jul 11 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM MDT
FOR SOUTHEASTERN HILL AND NORTHEASTERN CHOUTEAU COUNTIES...

At 546 PM MDT, a severe thunderstorm was located 10 miles south of
Parker School, or 17 miles east of Big Sandy, moving east at 50 mph.

HAZARD...60 mph wind gusts and penny size hail. Although the 
         heaviest part of the storm is moving east of the warning, 
         strong wind gusts around 60 mph may still occur.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Big Sandy, Azure, Parker School, Agency, Sangrey, St. Pierre, Boneau,
Box Elder and Rocky Boy.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4807 11033 4836 11009 4828 10962 4792 10980
TIME...MOT...LOC 2346Z 286DEG 42KT 4809 10975 

HAIL...0.75IN
WIND...60MPH
 
$$

HART

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 11, 12:33 AM MDT	Red Flag Warning	TFX	Blaine, Broadwater, Cascade, Chouteau, Fergus, Gallatin and 12 more	20 hr
Jul 11, 2:18 PM MDT	Special Weather Statement	TFX	Glacier	42 min
Jul 11, 2:28 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	50 min
Jul 11, 2:58 PM MDT	Special Weather Statement	TFX	Glacier	32 min
Jul 11, 3:03 PM MDT	Severe Thunderstorm Warning	TFX	Glacier, Toole	42 min
Jul 11, 3:40 PM MDT	Severe Thunderstorm Warning	TFX	Toole	50 min
Jul 11, 4:18 PM MDT	Severe Thunderstorm Warning	TFX	Liberty, Toole	27 min
Jul 11, 4:36 PM MDT	Special Weather Statement	TFX	Pondera	24 min
Jul 11, 4:47 PM MDT	Special Weather Statement	TFX	Chouteau	28 min
Jul 11, 5:05 PM MDT	Special Weather Statement	TFX	Pondera	25 min
Jul 11, 5:55 PM MDT	Severe Thunderstorm Warning	TFX	Blaine, Chouteau, Hill	65 min

Nearby

Severe Thunderstorm Warnings in Montana, 2021 Every 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.