Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Great Falls, MT

July 21, 2021Lewis and Clark County, Montana

NWS Great Falls, MT issued this special weather statement at Jul 21, 2021, 5:21 PM MDT for Lewis and Clark County, Montana. It was in force for 24 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, 5:21 PM MDT (23:21 UTC)
Expired: Jul 21, 2021, 5:45 PM MDT
In force: 24 min
Issued by: NWS Great Falls, MT

County Lewis and Clark County, MT

The radar

The Great Falls radar (KTFX), 99 km from the middle of the area, began a volume at 23:21 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 12:00Z, 11.4 hours before the alert went out and 145 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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.

871 
WWUS85 KTFX 212321
SPSTFX

Special Weather Statement
National Weather Service Great Falls MT
521 PM MDT Wed Jul 21 2021
 
MTZ014-212345-
Central and Southern Lewis and Clark MT-
521 PM MDT Wed Jul 21 2021

...AN AREA OF STRENGTHENING THUNDERSTORMS WILL IMPACT SOUTHEASTERN 
LEWIS AND CLARK COUNTY UNTIL 545 PM MDT...

At 520 PM MDT, Doppler radar was tracking developing strong 
thunderstorms northwest of Helena, moving northeast at 30 mph.

HAZARD...Wind gusts of 50 to 55 mph and pea size 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...
Wolf Creek, Marysville, Canyon Creek and Austin. 

This includes Interstate 15 between mile markers 205 and 227.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

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 4706 11215 4688 11186 4660 11229 4661 11231
      4665 11231 4666 11236 4670 11241
TIME...MOT...LOC 2320Z 226DEG 28KT 4676 11224 

$$

HART

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 20, 6:10 PM MDT	Special Weather Statement	TFX	Teton	35 min
Jul 20, 6:14 PM MDT	Special Weather Statement	TFX	Toole	31 min
Jul 20, 6:18 PM MDT	Special Weather Statement	TFX	Cascade	27 min
Jul 20, 6:34 PM MDT	Special Weather Statement	TFX	Teton	26 min
Jul 20, 6:48 PM MDT	Severe Thunderstorm Warning	TFX	Pondera, Teton	27 min
Jul 20, 7:01 PM MDT	Special Weather Statement	TFX	Cascade	29 min
Jul 20, 7:17 PM MDT	Special Weather Statement	TFX	Teton	28 min
Jul 20, 7:47 PM MDT	Special Weather Statement	TFX		28 min
Jul 20, 7:52 PM MDT	Special Weather Statement	TFX	Cascade	23 min
Jul 20, 8:45 PM MDT	Special Weather Statement	TFX	Chouteau, Judith Basin	30 min
Jul 21, 1:26 PM MDT	Fire Weather Watch	TFX	Broadwater, Cascade, Chouteau, Fergus, Gallatin, Jefferson and 4 more	25 hr
Jul 21, 1:26 PM MDT	Red Flag Warning	TFX	Blaine, Broadwater, Cascade, Chouteau, Fergus, Gallatin and 12 more	56 hr
Jul 21, 2:38 PM MDT	Special Weather Statement	TFX	Glacier	37 min
Jul 21, 2:48 PM MDT	Special Weather Statement	TFX	Pondera	27 min
Jul 21, 2:56 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	34 min
Jul 21, 3:16 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	29 min
Jul 21, 3:23 PM MDT	Special Weather Statement	TFX	Pondera	37 min
Jul 21, 3:49 PM MDT	Special Weather Statement	TFX	Pondera	26 min
Jul 21, 3:50 PM MDT	Severe Thunderstorm Warning	TFX	Pondera	40 min
Jul 21, 3:51 PM MDT	Special Weather Statement	TFX	Teton	24 min
Jul 21, 4:07 PM MDT	Special Weather Statement	TFX	Fergus	23 min
Jul 21, 4:07 PM MDT	Severe Thunderstorm Warning	TFX	Pondera, Teton	38 min
Jul 21, 4:24 PM MDT	Special Weather Statement	TFX	Jefferson	36 min
Jul 21, 4:29 PM MDT	Special Weather Statement	TFX	Madison	31 min
Jul 21, 4:34 PM MDT	Special Weather Statement	TFX	Silver Bow	26 min
Jul 21, 4:39 PM MDT	Special Weather Statement	TFX	Fergus	36 min
Jul 21, 4:42 PM MDT	Special Weather Statement	TFX	Lewis and Clark	33 min
Jul 21, 4:45 PM MDT	Severe Thunderstorm Warning	TFX	Liberty, Pondera, Teton, Toole	45 min
Jul 21, 4:53 PM MDT	Special Weather Statement	TFX	Teton	22 min
Jul 21, 4:54 PM MDT	Special Weather Statement	TFX	Lewis and Clark	36 min
Jul 21, 4:56 PM MDT	Special Weather Statement	TFX	Jefferson	34 min
Jul 21, 4:58 PM MDT	Special Weather Statement	TFX	Broadwater, Jefferson	32 min
Jul 21, 5:02 PM MDT	Special Weather Statement	TFX	Glacier	28 min
Jul 21, 5:04 PM MDT	Special Weather Statement	TFX	Deer Lodge	26 min
Jul 21, 5:29 PM MDT	Severe Thunderstorm Warning	TFX	Liberty, Toole	46 min
Jul 21, 5:32 PM MDT	Special Weather Statement	TFX	Cascade	43 min

Nearby

Special Weather Statements in Montana, 2021 Every 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.