Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Great Falls, MT

July 15, 2021Judith Basin County, Montana

NWS Great Falls, MT issued this special weather statement at Jul 15, 2021, 9:41 PM MDT for Judith Basin County, Montana. It was in force for 49 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 15, 2021, 9:41 PM MDT (03:41 UTC)
Expired: Jul 15, 2021, 10:30 PM MDT
In force: 49 min
Issued by: NWS Great Falls, MT

County Judith Basin County, MT

The radar

The Great Falls radar (KTFX), 140 km from the middle of the area, began a volume at 03:40 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, 3.7 hours before the alert went out and 95 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: 228 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 3908 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 34 m²/s²
0-3 km storm-relative helicity: 70 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Great Falls, MT wrote its last area forecast discussion before this special weather statement went out at Jul 15, 8:51 PM MDT, 50 minutes earlier.

Area forecast discussion, Jul 15, 8:51 PM MDT, 50 minutes before

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In the hours before

Special weather statement, Jul 15, 5:10 PM MDT, 4 hours 31 minutes before

Special Weather Statement
National Weather Service Great Falls MT
510 PM MDT Thu Jul 15 2021

MTZ053-152345-
Broadwater MT-
510 PM MDT Thu Jul 15 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN BROADWATER COUNTY
UNTIL 545 PM MDT...

At 508 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles east of Montana City, or 15 miles southeast of Helena, moving
east at 20 mph.

HAZARD...Winds in excess of 40 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...
Goose Bay and Silos.

This includes Highway 12 between mile markers 56 and 70.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

If on or near Canyon Ferry Reservoir, get out of the water and move
indoors or inside a vehicle. Remember, lightning can strike out to
10 miles from the parent thunderstorm. If you can hear thunder, you
are close enough to be struck by lightning. Move to safe shelter
now! Do not be caught on the water in a thunderstorm.

&&

LAT...LON 4657 11165 4664 11164 4669 11145 4668 11144
      4668 11142 4643 11132 4640 11179 4657 11179
TIME...MOT...LOC 2308Z 255DEG 18KT 4651 11171

mpj

Special weather statement, Jul 15, 6:04 PM MDT, 3 hours 37 minutes before

Special Weather Statement
National Weather Service Great Falls MT
604 PM MDT Thu Jul 15 2021

MTZ053-160100-
Broadwater MT-
604 PM MDT Thu Jul 15 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN BROADWATER COUNTY
UNTIL 700 PM MDT...

At 600 PM MDT, Doppler radar was tracking an area of showers and
thunderstorms 9 miles southeast of Montana City, or 15 miles
southeast of Helena, moving east at 15 mph.

HAZARD...Winds in excess of 40 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. Boaters on Canyon Ferry Reservoir could be
         affected by gusty winds and increasing wave heights.

These storms will affect the following locations... Silos and Goose
Bay.

This includes Highway 12 between mile markers 59 and 74.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If on or near Canyon Ferry Reservoir, get out of the water and move
indoors or inside a vehicle. Remember, lightning can strike out to
10 miles from the parent thunderstorm. If you can hear thunder, you
are close enough to be struck by lightning. Move to safe shelter
now! Do not be caught on the water in a thunderstorm.

&&

LAT...LON 4657 11168 4657 11165 4659 11164 4665 11144
      4639 11132 4633 11178 4654 11179
TIME...MOT...LOC 0000Z 252DEG 13KT 4643 11181

mpj

Special weather statement, Jul 15, 8:35 PM MDT, 1 hour 6 minutes before

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Special weather statement, Jul 15, 9:41 PM MDT, 0 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 15, 6:04 PM MDT	Special Weather Statement	TFX	Broadwater	56 min
Jul 15, 8:35 PM MDT	Special Weather Statement	TFX	Meagher	55 min
Jul 16, 12:10 AM MDT	Special Weather Statement	TFX		50 min
Jul 16, 2:14 PM MDT	Excessive Heat Warning	TFX		3 days
Jul 16, 2:14 PM MDT	Heat Advisory	TFX		3 days

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.