Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 25, NWS Great Falls, MT

July 6, 2021Blaine County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 6, 2021, 5:46 PM MDT for Blaine County, Montana. It was in force for 29 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 6, 2021, 5:46 PM MDT (23:46 UTC)
Expired
Jul 6, 2021, 6:15 PM MDT
In force
29 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Blaine County, MT

The radar

The Glasgow radar (KGGW), 167 km from the middle of the area, began a volume at 23:49 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

TimeReportWhereRemark
Jul 6, 5:46 PM MDTHAIL 1.7513 Nnw Hays, MTREPORT RELAYED VIA SOCIAL MEDIA, WITH PICTURES.
Jul 6, 6:15 PM MDTHAIL 1.254 Nnw Hays, MTREPORT RELAYED VIA SOCIAL MEDIA. LOCATION WAS ESTIMATED BASED UPON REPORT TIME AND RADAR.
Jul 6, 6:18 PM MDTTORNADO5 Wnw Hays, MTBROADCAST MEDIA RELAYED PHOTOS AND VIDEOS OF A LIKELY TORNADO IN THE HAYS AREA. UPDATED INFORMATION FOR THIS REPORT, INCLUDING A MORE PRECISE LAT/LON, TIME, AND EVENT INFORMATION WILL BE PROVIDED WEDNESDAY MORNING...AS NEEDED.

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, 11.8 hours before the alert went out and 144 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 2021-07-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 103 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 2021-07-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 37 square meters per square second.193958Sfc1 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
103 J/kg
Mixed-layer CIN
-251 J/kg
Mixed-layer LCL
1154 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
37 m²/s²
0-3 km storm-relative helicity
134 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

351 
WUUS55 KTFX 062346
SVRTFX
MTC005-070015-
/O.NEW.KTFX.SV.W.0025.210706T2346Z-210707T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Great Falls MT
546 PM MDT Tue Jul 6 2021

The National Weather Service in Great Falls has issued a

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

* Until 615 PM MDT.

* At 546 PM MDT, a severe thunderstorm was located 15 miles northwest
  of Hays, or 23 miles northwest of Zortman, moving southeast at 20
  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.

* This severe thunderstorm will remain over mainly rural areas of
  southeastern Blaine County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4792 10886 4792 10888 4791 10889 4791 10891
      4811 10908 4825 10886 4807 10851
TIME...MOT...LOC 2346Z 319DEG 18KT 4810 10894 

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

RCG
2 follow-up statements
155 
WWUS55 KTFX 070000
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
600 PM MDT Tue Jul 6 2021

MTC005-070015-
/O.CON.KTFX.SV.W.0025.000000T0000Z-210707T0015Z/
Blaine MT-
600 PM MDT Tue Jul 6 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM MDT
FOR SOUTHEASTERN BLAINE COUNTY...

At 600 PM MDT, a severe thunderstorm was located 10 miles west of
Hays, or 18 miles northwest of Zortman, moving southeast at 20 mph.

HAZARD...60 mph wind gusts and half dollar size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe thunderstorm will remain over mainly rural areas of
southeastern Blaine County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4792 10886 4792 10888 4791 10889 4791 10891
      4810 10901 4821 10879 4807 10851
TIME...MOT...LOC 0000Z 319DEG 18KT 4805 10887 

HAIL...1.25IN
WIND...60MPH
 
$$

RCG
602 
WWUS55 KTFX 070008
SVSTFX

Severe Weather Statement
National Weather Service Great Falls MT
608 PM MDT Tue Jul 6 2021

MTC005-070015-
/O.CON.KTFX.SV.W.0025.000000T0000Z-210707T0015Z/
Blaine MT-
608 PM MDT Tue Jul 6 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM MDT
FOR SOUTHEASTERN BLAINE COUNTY...

At 607 PM MDT, a severe thunderstorm was located 8 miles west of
Hays, or 15 miles northwest of Zortman, moving southeast at 20 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.

This severe thunderstorm will remain over mainly rural areas of
southeastern Blaine County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4792 10886 4792 10888 4791 10889 4791 10891
      4806 10896 4817 10872 4807 10851
TIME...MOT...LOC 0007Z 319DEG 18KT 4802 10883 

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

RCG

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 5, 6:29 PM MDTSpecial Weather StatementTFXGallatin, Madison31 min
Jul 5, 7:04 PM MDTSpecial Weather StatementTFXGallatin26 min
Jul 5, 7:47 PM MDTSpecial Weather StatementTFXBeaverhead28 min
Jul 5, 9:16 PM MDTSpecial Weather StatementTFXGlacier44 min
Jul 5, 9:57 PM MDTSevere Thunderstorm WarningTFXGlacier33 min
Jul 5, 10:25 PM MDTSevere Thunderstorm WarningTFXGlacier, Toole50 min
Jul 5, 11:12 PM MDTSpecial Weather StatementTFXToole63 min
Jul 6, 12:14 AM MDTSpecial Weather StatementTFXLiberty61 min
Jul 6, 12:42 AM MDTSpecial Weather StatementTFXChouteau33 min
Jul 6, 1:15 AM MDTSpecial Weather StatementTFXLiberty60 min
Jul 6, 1:18 AM MDTSpecial Weather StatementTFXChouteau27 min
Jul 6, 1:44 AM MDTSpecial Weather StatementTFXChouteau46 min
Jul 6, 2:22 AM MDTSpecial Weather StatementTFXChouteau38 min
Jul 6, 3:00 AM MDTSpecial Weather StatementTFXChouteau45 min
Jul 6, 3:42 AM MDTSpecial Weather StatementTFXFergus33 min
Jul 6, 4:15 AM MDTSpecial Weather StatementTFXFergus45 min
Jul 6, 3:37 PM MDTSpecial Weather StatementTFXGlacier23 min
Jul 6, 3:55 PM MDTSpecial Weather StatementTFXGlacier35 min
Jul 6, 4:21 PM MDTSpecial Weather StatementTFXGlacier24 min
Jul 6, 4:27 PM MDTSpecial Weather StatementTFXMusselshell33 min
Jul 6, 4:37 PM MDTSpecial Weather StatementTFXFergus23 min
Jul 6, 4:40 PM MDTSevere Thunderstorm WarningTFXGlacier35 min
Jul 6, 4:42 PM MDTSpecial Weather StatementTFXBlaine33 min
Jul 6, 5:14 PM MDTSevere Thunderstorm WarningTFXGlacier, Toole31 min
Jul 6, 5:15 PM MDTSpecial Weather StatementTFXBlaine30 min
Jul 6, 5:45 PM MDTSpecial Weather StatementTFXToole30 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.