Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 5, NWS Missoula, MT

July 21, 2021Missoula County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Jul 21, 2021, 5:12 PM MDT for Missoula County, Montana. It was in force for 19 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, 5:12 PM MDT (23:12 UTC)
Expired
Jul 21, 2021, 5:31 PM MDT
In force
19 min
Issued by
NWS Missoula, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Missoula County, MT

The radar

The Missoula radar (KMSX), 31 km from the middle of the area, began a volume at 23:12 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, 5:28 PM MDTHAIL 11 Nw Potomac, MT

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, 11.2 hours before the alert went out and 245 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 2021-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 158 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 2021-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 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
158 J/kg
Mixed-layer CIN
-180 J/kg
Mixed-layer LCL
1952 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
33 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

042 
WUUS55 KMSO 212312
SVRMSO
MTC063-212345-
/O.NEW.KMSO.SV.W.0005.210721T2312Z-210721T2345Z/

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

The National Weather Service in Missoula has issued a

* Severe Thunderstorm Warning for...
  Southeastern Missoula County in west central Montana...

* Until 545 PM MDT.

* At 512 PM MDT, a severe thunderstorm was located 7 miles east of
  Bonner-West Riverside, or 14 miles east of Missoula, 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...
  Twin Creeks and Clinton. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4677 11372 4681 11382 4695 11373 4689 11358
TIME...MOT...LOC 2312Z 209DEG 17KT 4686 11372 

HAIL...1.00IN
WIND...60MPH
 
$$
2 follow-up statements
138 
WWUS55 KMSO 212328
SVSMSO

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

MTC063-212345-
/O.CON.KMSO.SV.W.0005.000000T0000Z-210721T2345Z/
Missoula MT-
528 PM MDT Wed Jul 21 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM MDT
FOR SOUTHEASTERN MISSOULA COUNTY...

At 527 PM MDT, a severe thunderstorm was located 10 miles east of
Bonner-West Riverside, or 17 miles east of Missoula, moving northeast
at 20 mph.

HAZARD...60 mph wind gusts and quarter size hail, are still possible 
         along highway 200 between Twin Peaks and Potomac.

SOURCE...Radar indicated.

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

Locations impacted include...
Twin Creeks.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4684 11364 4688 11377 4695 11373 4689 11358
TIME...MOT...LOC 2327Z 209DEG 17KT 4692 11367 

HAIL...1.00IN
WIND...60MPH
 
$$
673 
WWUS55 KMSO 212331
SVSMSO

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

MTC063-212341-
/O.CAN.KMSO.SV.W.0005.000000T0000Z-210721T2345Z/
Missoula MT-
531 PM MDT Wed Jul 21 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MISSOULA COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has weakened.
moved out of the warned area. Therefore, the warning has been 
cancelled.

LAT...LON 4684 11364 4688 11377 4695 11373 4689 11358
TIME...MOT...LOC 2324Z 209DEG 17KT 4694 11365 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 12:17 PM MDTFire Weather WatchMSOBeaverhead, Deer Lodge, Granite, Jefferson, Madison, Powell and 1 more25 hr
Jul 21, 12:17 PM MDTRed Flag WarningMSOFlathead, Glacier, Lake, Missoula, Powell, Sanders33 hr
Jul 21, 2:44 PM MDTSpecial Weather StatementMSORavalli31 min
Jul 21, 2:57 PM MDTSpecial Weather StatementMSO33 min
Jul 21, 3:49 PM MDTSpecial Weather StatementMSORavalli26 min
Jul 21, 3:51 PM MDTSpecial Weather StatementMSOPowell24 min
Jul 21, 4:15 PM MDTSpecial Weather StatementMSOSilver Bow15 min
Jul 21, 4:40 PM MDTSpecial Weather StatementMSOGranite35 min
Jul 21, 4:53 PM MDTSpecial Weather StatementMSOMissoula37 min
Jul 21, 5:06 PM MDTSpecial Weather StatementMSOMissoula24 min
Jul 21, 5:33 PM MDTSpecial Weather StatementMSOMissoula27 min
Jul 21, 5:36 PM MDTSevere Thunderstorm WarningMSOMissoula, Powell24 min
Jul 21, 5:43 PM MDTSpecial Weather StatementMSODeer Lodge17 min
Jul 21, 5:44 PM MDTSpecial Weather StatementMSOMissoula16 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.