Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 10, NWS Missoula, MT

July 21, 2021Granite County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Jul 21, 2021, 9:18 PM MDT for Granite County, Montana. It was in force for 27 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 21, 2021, 9:18 PM MDT (03:18 UTC)
Expired
Jul 21, 2021, 9:45 PM MDT
In force
27 min
Issued by
NWS Missoula, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Granite County, MT

The radar

The Missoula radar (KMSX), 65 km from the middle of the area, began a volume at 03:18 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

Spokane, WA (KOTX), launched 00:00Z, 3.3 hours before the alert went out and 254 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.

754 
WUUS55 KMSO 220318
SVRMSO
MTC039-220345-
/O.NEW.KMSO.SV.W.0010.210722T0318Z-210722T0345Z/

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

The National Weather Service in Missoula has issued a

* Severe Thunderstorm Warning for...
  North central Granite County in west central Montana...

* Until 945 PM MDT.

* At 918 PM MDT, a severe thunderstorm was located 17 miles northwest
  of Philipsburg, or 19 miles southwest 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...
  Nimrod and Bearmouth. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4646 11353 4650 11361 4677 11345 4671 11322
TIME...MOT...LOC 0318Z 212DEG 17KT 4654 11352 

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

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 21, 6:01 PM MDTSevere Thunderstorm WarningMSOMissoula, Powell29 min
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, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.