Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 7, NWS Missoula, MT

July 21, 2021Missoula County, Powell County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Jul 21, 2021, 6:01 PM MDT for Missoula County, Powell County, Montana. It was in force for 29 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, 6:01 PM MDT (00:01 UTC)
Expired
Jul 21, 2021, 6:30 PM MDT
In force
29 min
Issued by
NWS Missoula, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Missoula County, MT, Powell County, MT

The radar

The Missoula radar (KMSX), 51 km from the middle of the area, began a volume at 00:05 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 21, 6:07 PM MDTHAIL 16 Nnw Woodworth, MTHAILED FOR 20-30 MINUTES, MAX SIZE OF 1 INCH. GUSTY WINDS AROUND 40MPH, HEAVY RAIN.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Spokane, WA (KOTX), launched 00:00Z, 0.0 hours before the alert went out and 236 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, Spokane, WA at 00:00Z on 2021-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Spokane, WA at 00:00Z on 2021-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 34 square meters per square second.1939587897117Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2525 m above ground
0-6 km bulk shear
55 kt
0-1 km storm-relative helicity
34 m²/s²
0-3 km storm-relative helicity
79 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

798 
WUUS55 KMSO 220001
SVRMSO
MTC063-077-220030-
/O.NEW.KMSO.SV.W.0007.210722T0001Z-210722T0030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Missoula MT
601 PM MDT Wed Jul 21 2021

The National Weather Service in Missoula has issued a

* Severe Thunderstorm Warning for...
  Northeastern Missoula County in west central Montana...
  West central Powell County in west central Montana...

* Until 630 PM MDT.

* At 601 PM MDT, a severe thunderstorm was located near Seeley Lake,
  or 37 miles north of Drummond, moving northeast 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.

* Locations impacted include...
  Seeley Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4711 11337 4716 11346 4733 11340 4722 11316
TIME...MOT...LOC 0001Z 209DEG 16KT 4719 11334 

HAIL...1.00IN
WIND...60MPH
 
$$
2 follow-up statements
634 
WWUS55 KMSO 220007
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
607 PM MDT Wed Jul 21 2021

MTC063-077-220030-
/O.CON.KMSO.SV.W.0007.000000T0000Z-210722T0030Z/
Missoula MT-Powell MT-
607 PM MDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM MDT
FOR NORTHEASTERN MISSOULA AND WEST CENTRAL POWELL COUNTIES...

At 606 PM MDT, a severe thunderstorm was located 7 miles northeast of
Seeley Lake, or 38 miles north of Drummond, moving northeast 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
northeastern Missoula and west central Powell Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4713 11333 4717 11343 4733 11340 4722 11316
TIME...MOT...LOC 0006Z 209DEG 16KT 4721 11332 

HAIL...1.50IN
WIND...60MPH
 
$$
496 
WWUS55 KMSO 220020
SVSMSO

Severe Weather Statement
National Weather Service Missoula MT
620 PM MDT Wed Jul 21 2021

MTC063-077-220030-
/O.EXP.KMSO.SV.W.0007.000000T0000Z-210722T0030Z/
Missoula MT-Powell MT-
620 PM MDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN MISSOULA AND WEST
CENTRAL POWELL COUNTIES WILL EXPIRE AT 630 PM MDT...
    
The severe thunderstorm which prompted the warning has weakened.
moved out of the warned area. Therefore, the warning will be allowed 
to expire.

LAT...LON 4713 11333 4717 11343 4733 11340 4722 11316
TIME...MOT...LOC 0020Z 209DEG 16KT 4721 11332 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 6:38 PM MDTSpecial Weather StatementMSOGranite22 min
Jul 21, 6:54 PM MDTSevere Thunderstorm WarningMSOGranite, Missoula, Powell36 min
Jul 21, 7:20 PM MDTSpecial Weather StatementMSOGranite25 min
Jul 21, 7:30 PM MDTSevere Thunderstorm WarningMSOGranite, Missoula, Powell30 min
Jul 21, 7:51 PM MDTSpecial Weather StatementMSOPowell9 min
Jul 21, 8:02 PM MDTSpecial Weather StatementMSOPowell28 min
Jul 21, 9:04 PM MDTSpecial Weather StatementMSOGranite41 min
Jul 21, 9:18 PM MDTSevere Thunderstorm WarningMSOGranite27 min
Jul 21, 10:12 PM MDTSpecial Weather StatementMSOPowell48 min
Jul 22, 1:32 PM MDTRed Flag WarningMSOBeaverhead, Deer Lodge, Granite, Jefferson, Madison, Powell and 1 more31 hr
Jul 22, 1:59 PM MDTSpecial Weather StatementMSO46 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.