Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 30, NWS Great Falls, MT

July 7, 2021Fergus County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 7, 2021, 2:46 PM MDT for Fergus County, Montana. It was in force for 29 min. 6 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 7, 2021, 2:46 PM MDT (20:46 UTC)
Expired: Jul 7, 2021, 3:15 PM MDT
In force: 29 min
Issued by: NWS Great Falls, MT
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

County Fergus County, MT

The radar

The Billings radar (KBLX), 145 km from the middle of the area, began a volume at 20:49 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 7, 2:55 PM MDT	TSTM WND GST 73	2 Wsw Lewistown, MT	MEASURED AT KLWT.
Jul 7, 2:55 PM MDT	HAIL 1	3 S Lewistown, MT	INITIAL HAILSTONES UP TO QUARTER SIZE, TAPERING TO PEA SIZE ON BACK EDGE OF STORM. MEASURED 0.27IN OF RAIN IN ONLY 7 MINUTES.
Jul 7, 2:58 PM MDT	TSTM WND DMG	1 Wnw Lewistown, MT	POWER POLE DOWN ON TRUCK BYPASS (ROUTE 87). 12 FOOT PIECE OF A ROOF ALSO DAMAGED.
Jul 7, 2:58 PM MDT	TSTM WND GST 80	Lewistown, MT	UPDATED. NWS ESTIMATES STRAIGHT LINE WINDS OF 75 TO 85 MPH THROUGHOUT LEWISTOWN AND NEARBY SURROUNDING AREA. PREVIOUS REPORT: POWER POLE DOWN ON TRUCK BYPASS (ROUTE 87). 12 FOOT PIECE OF A ROOF ALSO DAMAGED.
Jul 7, 2:59 PM MDT	TSTM WND GST 68	2 Wsw Lewistown, MT	SECOND SEVERE WIND GUST MEASURED AT KLWT ASOS.
Jul 7, 3:08 PM MDT	TSTM WND DMG	1 Sse Lewistown, MT	SPOTTER REPORTS WINDS SNAPPING OFF LARGE TREE BRANCHES, AS WELL AS PEA-SIZE HAIL.

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, 8.8 hours before the alert went out and 101 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: 42 J/kg
Mixed-layer CIN: -360 J/kg
Mixed-layer LCL: 2232 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: -61 m²/s²
0-3 km storm-relative helicity: 70 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

503 
WUUS55 KTFX 072046
SVRTFX
MTC027-072115-
/O.NEW.KTFX.SV.W.0030.210707T2046Z-210707T2115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Great Falls MT
246 PM MDT Wed Jul 7 2021

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  South central Fergus County in central Montana...

* Until 315 PM MDT.

* At 246 PM MDT, a severe thunderstorm was located near Lewistown,
  moving east at 35 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.

* Locations impacted include...
  Lewistown, Moore, Giltedge, Glengarry, Heath and Forestgrove. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This thunderstorm is capable of producing all types of severe weather
including extremely large hail, destructive straight line winds and
tornadoes. Move quickly to a safe shelter such as an interior room, a
bathroom, closet or basement.

&&

LAT...LON 4697 10969 4715 10969 4727 10901 4681 10900
TIME...MOT...LOC 2046Z 267DEG 32KT 4705 10949 

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

RCG

3 follow-up statements

187 
WWUS55 KTFX 072053
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
253 PM MDT Wed Jul 7 2021

MTC027-072115-
/O.CON.KTFX.SV.W.0030.000000T0000Z-210707T2115Z/
Fergus MT-
253 PM MDT Wed Jul 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM MDT
FOR SOUTH CENTRAL FERGUS COUNTY...

At 253 PM MDT, a severe thunderstorm was located over Lewistown,
moving east at 35 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.

Locations impacted include...
Lewistown, Giltedge, Glengarry, Heath and Forestgrove. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This thunderstorm is capable of producing all types of severe weather
including extremely large hail, destructive straight line winds and
tornadoes. Move quickly to a safe shelter, such as an interior room,
a bathroom or closet or basement.

&&

LAT...LON 4695 10960 4716 10962 4727 10901 4681 10900
TIME...MOT...LOC 2053Z 267DEG 32KT 4705 10948 

TORNADO...POSSIBLE
HAIL...1.50IN
WIND...60MPH
 
$$

RCG

577 
WWUS55 KTFX 072100
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
300 PM MDT Wed Jul 7 2021

MTC027-072115-
/O.CON.KTFX.SV.W.0030.000000T0000Z-210707T2115Z/
Fergus MT-
300 PM MDT Wed Jul 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM MDT
FOR SOUTH CENTRAL FERGUS COUNTY...

At 259 PM MDT, a severe thunderstorm was located over Lewistown,
moving east at 35 mph.

This is a very dangerous storm.

HAZARD...80 mph wind gusts and ping pong ball size hail.

SOURCE...Radar indicated.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be heavily damaged. Expect 
         considerable damage to roofs, windows, and vehicles. 
         Extensive tree damage and power outages are likely.

Locations impacted include...
Lewistown, Giltedge, Heath and Forestgrove. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This thunderstorm is capable of producing all types of severe weather
including extremely large hail, destructive straight line winds and
tornadoes. Move quickly to a safe shelter, such as an interior room,
a bathroom or closet or basement.

&&

LAT...LON 4693 10951 4717 10955 4727 10901 4681 10900
TIME...MOT...LOC 2059Z 267DEG 32KT 4705 10939 

TORNADO...POSSIBLE
HAIL...1.50IN
WIND...80MPH
 
$$

RCG

562 
WWUS55 KTFX 072108
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
308 PM MDT Wed Jul 7 2021

MTC027-072115-
/O.CON.KTFX.SV.W.0030.000000T0000Z-210707T2115Z/
Fergus MT-
308 PM MDT Wed Jul 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM MDT
FOR SOUTH CENTRAL FERGUS COUNTY...

At 308 PM MDT, a severe thunderstorm was located near Lewistown,
moving east at 35 mph.

HAZARD...70 mph wind gusts and half dollar 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...
Giltedge, Heath and Forestgrove. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This thunderstorm is capable of producing all types of severe weather
including extremely large hail, destructive straight line winds and
tornadoes. Move quickly to a safe shelter, such as an interior room,
a bathroom or closet or basement.

&&

LAT...LON 4689 10935 4719 10943 4727 10901 4681 10900
TIME...MOT...LOC 2108Z 267DEG 32KT 4706 10928 

TORNADO...POSSIBLE
HAIL...1.25IN
WIND...70MPH
 
$$

RCG

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 6, 6:14 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	29 min
Jul 6, 6:16 PM MDT	Special Weather Statement	TFX	Toole	29 min
Jul 6, 6:50 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	40 min
Jul 6, 6:57 PM MDT	Special Weather Statement	TFX	Toole	33 min
Jul 6, 7:27 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	63 min
Jul 6, 7:30 PM MDT	Special Weather Statement	TFX	Liberty	30 min
Jul 6, 8:20 PM MDT	Tornado Warning	TFX	Blaine	25 min
Jul 6, 8:45 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	19 min
Jul 7, 1:51 PM MDT	Special Weather Statement	TFX	Beaverhead	39 min
Jul 7, 2:03 PM MDT	Special Weather Statement	TFX	Judith Basin	27 min
Jul 7, 2:18 PM MDT	Special Weather Statement	TFX	Fergus	27 min
Jul 7, 2:43 PM MDT	Special Weather Statement	TFX	Fergus	32 min
Jul 7, 2:55 PM MDT	Special Weather Statement	TFX	Madison	50 min
Jul 7, 3:06 PM MDT	Special Weather Statement	TFX	Jefferson	54 min
Jul 7, 3:13 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	47 min
Jul 7, 3:21 PM MDT	Special Weather Statement	TFX	Fergus	24 min
Jul 7, 3:26 PM MDT	Severe Thunderstorm Warning	TFX	Jefferson, Lewis and Clark	34 min
Jul 7, 3:36 PM MDT	Special Weather Statement	TFX	Fergus	24 min
Jul 7, 3:40 PM MDT	Special Weather Statement	TFX	Lewis and Clark	35 min
Jul 7, 3:46 PM MDT	Special Weather Statement	TFX	Broadwater, Jefferson	44 min
Jul 7, 3:55 PM MDT	Special Weather Statement	TFX	Gallatin	50 min
Jul 7, 3:59 PM MDT	Special Weather Statement	TFX	Fergus	46 min
Jul 7, 4:02 PM MDT	Special Weather Statement	TFX	Broadwater, Jefferson	43 min
Jul 7, 4:30 PM MDT	Severe Thunderstorm Warning	TFX	Gallatin	30 min
Jul 7, 4:36 PM MDT	Severe Thunderstorm Warning	TFX	Gallatin	15 min
Jul 7, 4:48 PM MDT	Special Weather Statement	TFX	Silver Bow	27 min
Jul 7, 4:56 PM MDT	Special Weather Statement	TFX	Meagher	34 min
Jul 7, 5:12 PM MDT	Special Weather Statement	TFX	Judith Basin	48 min
Jul 7, 5:13 PM MDT	Special Weather Statement	TFX	Blaine	62 min
Jul 7, 5:38 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	37 min
Jul 7, 5:56 PM MDT	Special Weather Statement	TFX	Blaine	34 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.