Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 20, NWS Great Falls, MT

July 4, 2021Gallatin County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 4, 2021, 6:44 PM MDT for Gallatin County, Montana. It was in force for 16 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 4, 2021, 6:44 PM MDT (00:44 UTC)
Expired: Jul 4, 2021, 7:00 PM MDT
In force: 16 min
Issued by: NWS Great Falls, MT
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

County Gallatin County, MT

The radar

The Billings radar (KBLX), 179 km from the middle of the area, began a volume at 00:46 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.

The nearest sounding before it

Great_falls, MT (KTFX), launched 00:00Z, 0.7 hours before the alert went out and 195 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: 2 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 4341 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 13 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

518 
WUUS55 KTFX 050044
SVRTFX
MTC031-050100-
/O.NEW.KTFX.SV.W.0020.210705T0044Z-210705T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Great Falls MT
644 PM MDT Sun Jul 4 2021

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Northeastern Gallatin County in south central Montana...

* Until 700 PM MDT.

* At 644 PM MDT, a severe thunderstorm was located 9 miles east of
  Bozeman, moving northeast at 30 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees. Brief heavy 
           rain and small hail are also possible.

* This severe thunderstorm will remain over mainly rural areas of
  northeastern Gallatin County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4576 11101 4587 11080 4562 11080 4560 11089
TIME...MOT...LOC 0044Z 241DEG 26KT 4572 11086 

HAIL...<.75IN
WIND...60MPH
 
$$

SC

1 follow-up statement

499 
WWUS55 KTFX 050057
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
657 PM MDT Sun Jul 4 2021

MTC031-050107-
/O.EXP.KTFX.SV.W.0020.000000T0000Z-210705T0100Z/
Gallatin MT-
657 PM MDT Sun Jul 4 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN GALLATIN COUNTY
WILL EXPIRE AT 700 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, gusty winds and heavy rain are still possible with this
thunderstorm.

LAT...LON 4576 11101 4587 11080 4562 11080 4560 11089
TIME...MOT...LOC 0057Z 241DEG 26KT 4572 11087 

$$

SC

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 4, 6:26 PM MDT	Severe Thunderstorm Warning	TFX	Gallatin, Madison	19 min
Jul 4, 6:34 PM MDT	Special Weather Statement	TFX	Gallatin	26 min
Jul 4, 6:48 PM MDT	Special Weather Statement	TFX	Judith Basin	27 min
Jul 4, 7:01 PM MDT	Special Weather Statement	TFX	Gallatin	44 min
Jul 4, 7:13 PM MDT	Special Weather Statement	TFX	Judith Basin	32 min
Jul 4, 7:24 PM MDT	Special Weather Statement	TFX	Fergus	36 min
Jul 4, 7:56 PM MDT	Special Weather Statement	TFX	Fergus	34 min
Jul 4, 8:28 PM MDT	Special Weather Statement	TFX	Fergus	32 min
Jul 4, 9:29 PM MDT	Special Weather Statement	TFX	Meagher	31 min
Jul 5, 2:59 PM MDT	Special Weather Statement	TFX	Jefferson	31 min
Jul 5, 3:31 PM MDT	Special Weather Statement	TFX	Jefferson	29 min
Jul 5, 4:27 PM MDT	Special Weather Statement	TFX	Jefferson	33 min
Jul 5, 5:06 PM MDT	Special Weather Statement	TFX	Silver Bow	24 min
Jul 5, 5:10 PM MDT	Special Weather Statement	TFX	Lewis and Clark	35 min
Jul 5, 5:57 PM MDT	Special Weather Statement	TFX	Madison	33 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.