Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Great Falls, MT

August 8, 2021Gallatin County, Montana

NWS Great Falls, MT issued this special weather statement at Aug 8, 2021, 6:45 PM MDT for Gallatin County, Montana. It was in force for 45 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 8, 2021, 6:45 PM MDT (00:45 UTC)
Expired
Aug 8, 2021, 7:30 PM MDT
In force
45 min
Issued by
NWS Great Falls, MT
Hail
0.00 in
Wind
55

County Gallatin County, MT

The radar

The Billings radar (KBLX), 207 km from the middle of the area, began a volume at 00:47 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

Great_falls, MT (KTFX), launched 00:00Z, 0.8 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 00:00Z on 2021-08-09Temperature 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, Great_falls, MT at 00:00Z on 2021-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 42 square meters per square second.1939587897Sfc1 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
633 m above ground
0-6 km bulk shear
58 kt
0-1 km storm-relative helicity
42 m²/s²
0-3 km storm-relative helicity
-108 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

070 
WWUS85 KTFX 090045
SPSTFX

Special Weather Statement
National Weather Service Great Falls MT
645 PM MDT Sun Aug 8 2021
 
MTZ015-055-090130-
Madison MT-Gallatin MT-
645 PM MDT Sun Aug 8 2021

...A strong thunderstorm will impact portions of southeastern Madison
and central Gallatin Counties through 730 PM MDT...

At 644 PM MDT, Doppler radar was tracking a strong thunderstorm 14
miles southeast of Ennis, or 19 miles southeast of Virginia City,
moving northeast at 50 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects.

Locations impacted include...
Ennis, Jeffers, Big Sky and Cameron. 

This includes the following highways...
 Interstate 90 between mile markers 315 and 320.
 Highway 191 between mile markers 31 and 73.
 Highway 287 between mile markers 1  and 2 , between mile markers 4
and 9 , and between mile markers 8  and 52.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4537 11182 4568 11083 4560 11080 4559 11086
      4553 11086 4552 11092 4536 11092 4535 11104
      4508 11104 4511 11110 4505 11115 4501 11110
      4494 11110 4474 11171
TIME...MOT...LOC 0044Z 234DEG 46KT 4516 11158 

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

$$

HART

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 8, 6:51 PM MDTSpecial Weather StatementTFXGlacier24 min
Aug 8, 7:27 PM MDTSpecial Weather StatementTFXBeaverhead48 min
Aug 8, 7:51 PM MDTSpecial Weather StatementTFXBeaverhead39 min
Aug 8, 8:09 PM MDTSpecial Weather StatementTFXSilver Bow36 min
Aug 8, 8:39 PM MDTSpecial Weather StatementTFXJefferson51 min
Aug 8, 9:17 PM MDTSpecial Weather StatementTFXGallatin28 min
Aug 9, 3:47 AM MDTAreal Flood AdvisoryTFXGlacier, Pondera, Toole3 hr

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.