Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Great Falls, MT

August 2, 2021Chouteau County, Hill County, Liberty County, Montana

NWS Great Falls, MT issued this special weather statement at Aug 2, 2021, 6:08 PM MDT for Chouteau County, Hill County, Liberty County, Montana. It was in force for 37 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 2, 2021, 6:08 PM MDT (00:08 UTC)
Expired
Aug 2, 2021, 6:45 PM MDT
In force
37 min
Issued by
NWS Great Falls, MT

Counties Chouteau County, MT, Hill County, MT, Liberty County, MT

The radar

The Great Falls radar (KTFX), 94 km from the middle of the area, began a volume at 00:09 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, 0.1 hours before the alert went out and 87 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 2021-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 177 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 00:00Z on 2021-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 square meters per square second.1939Sfc1 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
177 J/kg
Mixed-layer CIN
-103 J/kg
Mixed-layer LCL
1940 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
56 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

884 
WWUS85 KTFX 030008
SPSTFX

Special Weather Statement
National Weather Service Great Falls MT
608 PM MDT Mon Aug 2 2021

MTZ011-013-045-046-049-030045-
Chouteau-Liberty-Eastern Teton-Hill-Eastern Pondera-
608 PM MDT Mon Aug 2 2021

...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN 
PONDERA...LIBERTY...EAST CENTRAL TETON...HILL AND CHOUTEAU 
COUNTIES...

At 605 PM MDT, strong thunderstorms were moving northeast at 15 mph 
over much of north central Montana.

Periods of heavy rain and winds in excess of 30 mph are possible 
with this storm.

Locations impacted include...
Havre, Fort Benton, Chester, Big Sandy, Dutton, Geraldine, Beaver
Creek, Lothair, Joplin, Brady, The Knees, Azure, Inverness, Gildford,
Sangrey, Boneau, Box Elder, St. Pierre, Highwood and Carter.

This includes the following highways...
 Interstate 15 between mile markers 308 and 332.
 Highway 2 between mile markers 308 and 386.
 Highway 87 between mile markers 15 and 111.

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms, and may 
cause localized flooding. Do not drive your vehicle through flooded 
roadways.

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

Some of these storms 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.

To report severe weather, contact your nearest law enforcement
agency. They can relay your report to the National Weather Service
office in Great Falls.

LAT...LON 4871 10950 4759 11026 4762 11105 4768 11099
      4769 11142 4790 11200 4835 11169 4822 11166
      4822 11128 4900 11125 4900 10949
TIME...MOT...LOC 0005Z 217DEG 11KT 4820 11086 

$$

SC

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 2, 6:47 PM MDTSpecial Weather StatementTFXChouteau, Hill43 min
Aug 2, 7:39 PM MDTSpecial Weather StatementTFXHill, Liberty51 min
Aug 2, 7:44 PM MDTSpecial Weather StatementTFXBroadwater46 min
Aug 2, 7:47 PM MDTSpecial Weather StatementTFXJudith Basin43 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.