Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 53, NWS Great Falls, MT

July 29, 2021Madison County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 29, 2021, 5:19 PM MDT for Madison County, Montana. It was in force for 41 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 29, 2021, 5:19 PM MDT (23:19 UTC)
Expired
Jul 29, 2021, 6:00 PM MDT
In force
41 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Madison County, MT

The radar

The Pocatello radar (KSFX), 237 km from the middle of the area, began a volume at 23:19 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 12:00Z, 11.3 hours before the alert went out and 276 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 2021-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 joules per kilogram.LCLLFCEL10008507005003002001001 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 2021-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.19395878Sfc1 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
1 J/kg
Mixed-layer CIN
-227 J/kg
Mixed-layer LCL
2197 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
14 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

722 
WUUS55 KTFX 292319
SVRTFX
MTC057-300000-
/O.NEW.KTFX.SV.W.0053.210729T2319Z-210730T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Great Falls MT
519 PM MDT Thu Jul 29 2021

The National Weather Service in Great Falls has issued a

* Severe Thunderstorm Warning for...
  Central Madison County in southwestern Montana...

* Until 600 PM MDT.

* At 518 PM MDT, a severe thunderstorm was located 7 miles south of
  Alder, or 8 miles southwest of Virginia City, moving east at 20
  mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Satellite indicated.

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

* Locations impacted include...
  Virginia City, Alder and Laurin. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent 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 4508 11229 4544 11218 4539 11175 4495 11171
TIME...MOT...LOC 2318Z 261DEG 19KT 4522 11208 

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

HART
2 follow-up statements
449 
WWUS55 KTFX 292338
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
538 PM MDT Thu Jul 29 2021

MTC057-300000-
/O.CON.KTFX.SV.W.0053.000000T0000Z-210730T0000Z/
Madison MT-
538 PM MDT Thu Jul 29 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM MDT
FOR CENTRAL MADISON COUNTY...

At 537 PM MDT, a severe thunderstorm was located near Virginia City,
moving east at 20 mph.

HAZARD...60 mph wind gusts.

SOURCE...Satellite indicated.

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

Locations impacted include...
Virginia City, Alder and Laurin. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4507 11224 4543 11209 4539 11175 4495 11171
TIME...MOT...LOC 2337Z 261DEG 19KT 4524 11193 

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

HART
448 
WWUS55 KTFX 292354
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
554 PM MDT Thu Jul 29 2021

MTC057-300003-
/O.EXP.KTFX.SV.W.0053.000000T0000Z-210730T0000Z/
Madison MT-
554 PM MDT Thu Jul 29 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL MADISON COUNTY WILL
EXPIRE AT 600 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 gusty
winds of 40 to 50 mph are still possible with this thunderstorm.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Great Falls.

LAT...LON 4507 11224 4543 11209 4539 11175 4495 11171
TIME...MOT...LOC 2353Z 261DEG 19KT 4525 11182 

$$

HART

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 28, 7:02 PM MDTSpecial Weather StatementTFXMadison28 min
Jul 29, 2:48 PM MDTSpecial Weather StatementTFXTeton42 min
Jul 29, 3:06 PM MDTSpecial Weather StatementTFXTeton24 min
Jul 29, 3:32 PM MDTSpecial Weather StatementTFXTeton43 min
Jul 29, 3:50 PM MDTSpecial Weather StatementTFXLewis and Clark40 min
Jul 29, 4:37 PM MDTSpecial Weather StatementTFXCascade38 min
Jul 29, 4:54 PM MDTSpecial Weather StatementTFXMadison36 min
Jul 29, 5:06 PM MDTSpecial Weather StatementTFXBroadwater, Jefferson39 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.