Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 3, NWS Missoula, MT

July 7, 20214 counties in Montana

NWS Missoula, MT issued this severe thunderstorm warning at Jul 7, 2021, 2:45 PM MDT for 4 counties in Montana. It was in force for 30 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 7, 2021, 2:45 PM MDT (20:45 UTC)
Expired
Jul 7, 2021, 3:15 PM MDT
In force
30 min
Issued by
NWS Missoula, MT
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Deer Lodge County, MT, Granite County, MT, Powell County, MT, Silver Bow County, MT

The radar

The Missoula radar (KMSX), 139 km from the middle of the area, began a volume at 20:44 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 7, 2:51 PM MDTTSTM WND GST 444 Nnw Opportunity, MTBOWMAN AIRFIELD K3U3.

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 210 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 2021-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 42 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Great_falls, MT at 12:00Z on 2021-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -61 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
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.

357 
WUUS55 KMSO 072045
SVRMSO
MTC023-039-077-093-072115-
/O.NEW.KMSO.SV.W.0003.210707T2045Z-210707T2115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Missoula MT
245 PM MDT Wed Jul 7 2021

The National Weather Service in Missoula has issued a

* Severe Thunderstorm Warning for...
  Northeastern Deer Lodge County in west central Montana...
  Southeastern Granite County in west central Montana...
  North central Silver Bow County in west central Montana...
  South central Powell County in west central Montana...

* Until 315 PM MDT.

* At 244 PM MDT, a severe thunderstorm was located over Anaconda,
  moving east at 45 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Anaconda, West Valley, Warm Springs, Galen, Gregson Hot Springs,
  Lost Creek, Crackerville, Opportunity and Racetrack.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4597 11315 4619 11325 4637 11249 4634 11248
      4633 11250 4633 11253 4630 11257 4627 11256
      4624 11260 4622 11257 4618 11257 4618 11251
      4614 11252 4609 11247 4607 11246
TIME...MOT...LOC 2044Z 254DEG 38KT 4610 11300 

HAIL...<.75IN
WIND...60MPH
 
$$
2 follow-up statements
576 
WWUS55 KMSO 072056
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
256 PM MDT Wed Jul 7 2021

MTC023-039-077-093-072115-
/O.CON.KMSO.SV.W.0003.000000T0000Z-210707T2115Z/
Deer Lodge MT-Granite MT-Silver Bow MT-Powell MT-
256 PM MDT Wed Jul 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 315 PM MDT
FOR NORTHEASTERN DEER LODGE...SOUTHEASTERN GRANITE...NORTH CENTRAL
SILVER BOW AND SOUTH CENTRAL POWELL COUNTIES...

At 256 PM MDT, a severe thunderstorm was located near Warm Springs,
or 7 miles east of Anaconda, moving east at 45 mph.

HAZARD...60 mph wind gusts and penny size hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Anaconda, West Valley, Warm Springs, Galen, Gregson Hot Springs, Lost
Creek, Crackerville, Opportunity and Racetrack.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4598 11305 4622 11311 4637 11249 4634 11248
      4633 11250 4633 11253 4630 11257 4627 11256
      4624 11260 4622 11257 4618 11257 4618 11251
      4614 11252 4609 11247 4607 11246
TIME...MOT...LOC 2056Z 254DEG 38KT 4614 11282 

HAIL...0.75IN
WIND...60MPH
 
$$
237 
WWUS55 KMSO 072110
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
310 PM MDT Wed Jul 7 2021

MTC023-039-077-093-072119-
/O.EXP.KMSO.SV.W.0003.000000T0000Z-210707T2115Z/
Deer Lodge MT-Granite MT-Silver Bow MT-Powell MT-
310 PM MDT Wed Jul 7 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN DEER LODGE...
SOUTHEASTERN GRANITE...NORTHWESTERN SILVER BOW AND SOUTH CENTRAL
POWELL COUNTIES WILL EXPIRE AT 315 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 are still possible with this thunderstorm.

LAT...LON 4598 11305 4622 11311 4637 11249 4634 11248
      4633 11250 4633 11253 4630 11257 4627 11256
      4624 11260 4622 11257 4618 11257 4618 11251
      4614 11252 4609 11247 4607 11246
TIME...MOT...LOC 2109Z 254DEG 38KT 4617 11266 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 7, 8:33 AM MDTSpecial Weather StatementMSOMineral42 min
Jul 7, 8:42 AM MDTSpecial Weather StatementMSO48 min
Jul 7, 12:56 PM MDTSpecial Weather StatementMSORavalli49 min
Jul 7, 2:18 PM MDTSpecial Weather StatementMSODeer Lodge, Granite, Powell42 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.