Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Missoula, MT

August 4, 2021Flathead County, Montana

NWS Missoula, MT issued this special weather statement at Aug 4, 2021, 5:55 PM MDT for Flathead County, Montana. It was in force for 35 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
Aug 4, 2021, 5:55 PM MDT (23:55 UTC)
Expired
Aug 4, 2021, 6:30 PM MDT
In force
35 min
Issued by
NWS Missoula, MT
Hail
0.50 in
Wind
40

County Flathead County, MT

The radar

The Missoula radar (KMSX), 173 km from the middle of the area, began a volume at 23:57 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 12:00Z, 11.9 hours before the alert went out and 201 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 12:00Z on 2021-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 18 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, Spokane, WA at 12:00Z on 2021-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 131 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
18 J/kg
Mixed-layer CIN
-391 J/kg
Mixed-layer LCL
2638 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
131 m²/s²
0-3 km storm-relative helicity
259 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

672 
WWUS85 KMSO 042355
SPSMSO

Special Weather Statement
National Weather Service Missoula MT
555 PM MDT Wed Aug 4 2021
 
MTZ002-050030-
West Glacier Region MT-
555 PM MDT Wed Aug 4 2021

...A strong thunderstorm will impact portions of north central
Flathead County through 630 PM MDT...

At 554 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles north of West Glacier, or 27 miles north of Evergreen, moving
east at 20 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects. Minor damage to outdoor objects is 
         possible.

Locations impacted include...
Lake McDonald.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4857 11418 4864 11418 4870 11385 4851 11387
TIME...MOT...LOC 2354Z 261DEG 18KT 4860 11404 

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 3, 8:55 PM MDTSpecial Weather StatementMSO65 min
Aug 4, 1:21 PM MDTRed Flag WarningMSOBeaverhead, Deer Lodge, Flathead, Granite, Jefferson, Lewis and Clark and 7 more35 hr
Aug 4, 3:57 PM MDTSpecial Weather StatementMSOPowell48 min
Aug 4, 5:30 PM MDTSpecial Weather StatementMSOFlathead30 min
Aug 4, 5:35 PM MDTSpecial Weather StatementMSOLake25 min
Aug 4, 5:50 PM MDTSpecial Weather StatementMSOLake25 min

Nearby

Special Weather Statements in Montana, 2021Every special weather statement 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.