Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 46, NWS Great Falls, MT

July 21, 2021Pondera County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 21, 2021, 3:50 PM MDT for Pondera County, Montana. It was in force for 40 min. 1 report 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, 3:50 PM MDT (21:50 UTC)
Expired: Jul 21, 2021, 4:30 PM MDT
In force: 40 min
Issued by: NWS Great Falls, MT
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Pondera County, MT

The radar

The Great Falls radar (KTFX), 94 km from the middle of the area, began a volume at 21:52 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 21, 4:22 PM MDT	HAIL 0.25	1 Nne Conrad, MT	REPORTED FROM JUST SOUTH OF MAIN HAIL CORE.

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, 9.8 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-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: 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.

961 
WUUS55 KTFX 212150
SVRTFX
MTC073-212230-
/O.NEW.KTFX.SV.W.0046.210721T2150Z-210721T2230Z/

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

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Southeastern Pondera County in north central Montana...

* Until 430 PM MDT.

* At 350 PM MDT, a severe thunderstorm was located 8 miles west of
  Conrad, moving northeast at 25 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...
  Conrad and Ledger. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4835 11180 4835 11175 4826 11166 4822 11167
      4822 11161 4818 11157 4809 11215 4812 11218
      4817 11227 4837 11180
TIME...MOT...LOC 2150Z 245DEG 21KT 4814 11212 

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

HART

2 follow-up statements

951 
WWUS55 KTFX 212209
SVSTFX

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

MTC073-212230-
/O.CON.KTFX.SV.W.0046.000000T0000Z-210721T2230Z/
Pondera MT-
409 PM MDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM MDT
FOR EAST CENTRAL PONDERA COUNTY...

At 409 PM MDT, a severe thunderstorm was located over Conrad, moving
northeast at 25 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...
Conrad and Ledger. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4835 11180 4835 11175 4826 11166 4822 11167
      4822 11161 4818 11157 4813 11203 4823 11213
      4837 11180
TIME...MOT...LOC 2209Z 245DEG 21KT 4819 11196 

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

HART

068 
WWUS55 KTFX 212228
SVSTFX

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

MTC073-212237-
/O.EXP.KTFX.SV.W.0046.000000T0000Z-210721T2230Z/
Pondera MT-
428 PM MDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL PONDERA COUNTY
WILL EXPIRE AT 430 PM MDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However small hail
and gusty winds are still possible with this thunderstorm.

Remember, a Severe Thunderstorm Warning still remains in effect for 
south central Pondera County until 445 PM MDT as another severe 
storm moves into the area.

LAT...LON 4835 11180 4835 11175 4826 11166 4822 11167
      4822 11161 4818 11157 4813 11203 4823 11213
      4837 11180
TIME...MOT...LOC 2227Z 245DEG 21KT 4823 11183 

$$

HART

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 6:10 PM MDT	Special Weather Statement	TFX	Teton	35 min
Jul 20, 6:14 PM MDT	Special Weather Statement	TFX	Toole	31 min
Jul 20, 6:18 PM MDT	Special Weather Statement	TFX	Cascade	27 min
Jul 20, 6:34 PM MDT	Special Weather Statement	TFX	Teton	26 min
Jul 20, 6:48 PM MDT	Severe Thunderstorm Warning	TFX	Pondera, Teton	27 min
Jul 20, 7:01 PM MDT	Special Weather Statement	TFX	Cascade	29 min
Jul 20, 7:17 PM MDT	Special Weather Statement	TFX	Teton	28 min
Jul 20, 7:47 PM MDT	Special Weather Statement	TFX		28 min
Jul 20, 7:52 PM MDT	Special Weather Statement	TFX	Cascade	23 min
Jul 20, 8:45 PM MDT	Special Weather Statement	TFX	Chouteau, Judith Basin	30 min
Jul 21, 1:26 PM MDT	Fire Weather Watch	TFX	Broadwater, Cascade, Chouteau, Fergus, Gallatin, Jefferson and 4 more	25 hr
Jul 21, 1:26 PM MDT	Red Flag Warning	TFX	Blaine, Broadwater, Cascade, Chouteau, Fergus, Gallatin and 12 more	56 hr
Jul 21, 2:38 PM MDT	Special Weather Statement	TFX	Glacier	37 min
Jul 21, 2:48 PM MDT	Special Weather Statement	TFX	Pondera	27 min
Jul 21, 2:56 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	34 min
Jul 21, 3:16 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	29 min
Jul 21, 3:23 PM MDT	Special Weather Statement	TFX	Pondera	37 min
Jul 21, 3:49 PM MDT	Special Weather Statement	TFX	Pondera	26 min
Jul 21, 3:51 PM MDT	Special Weather Statement	TFX	Teton	24 min
Jul 21, 4:07 PM MDT	Special Weather Statement	TFX	Fergus	23 min
Jul 21, 4:07 PM MDT	Severe Thunderstorm Warning	TFX	Pondera, Teton	38 min
Jul 21, 4:24 PM MDT	Special Weather Statement	TFX	Jefferson	36 min
Jul 21, 4:29 PM MDT	Special Weather Statement	TFX	Madison	31 min
Jul 21, 4:34 PM MDT	Special Weather Statement	TFX	Silver Bow	26 min
Jul 21, 4:39 PM MDT	Special Weather Statement	TFX	Fergus	36 min
Jul 21, 4:42 PM MDT	Special Weather Statement	TFX	Lewis and Clark	33 min
Jul 21, 4:45 PM MDT	Severe Thunderstorm Warning	TFX	Liberty, Pondera, Teton, Toole	45 min
Jul 21, 4:53 PM MDT	Special Weather Statement	TFX	Teton	22 min
Jul 21, 4:54 PM MDT	Special Weather Statement	TFX	Lewis and Clark	36 min
Jul 21, 4:56 PM MDT	Special Weather Statement	TFX	Jefferson	34 min
Jul 21, 4:58 PM MDT	Special Weather Statement	TFX	Broadwater, Jefferson	32 min
Jul 21, 5:02 PM MDT	Special Weather Statement	TFX	Glacier	28 min
Jul 21, 5:04 PM MDT	Special Weather Statement	TFX	Deer Lodge	26 min
Jul 21, 5:21 PM MDT	Special Weather Statement	TFX	Lewis and Clark	24 min
Jul 21, 5:29 PM MDT	Severe Thunderstorm Warning	TFX	Liberty, Toole	46 min
Jul 21, 5:32 PM MDT	Special Weather Statement	TFX	Cascade	43 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.