Alert archive / Montana / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 18, NWS Great Falls, MT

June 24, 20204 counties in Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jun 24, 2020, 6:38 PM MDT for 4 counties in Montana. It was in force for 33 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Jun 24, 2020, 6:38 PM MDT (00:38 UTC)
Expired
Jun 24, 2020, 7:11 PM MDT
In force
33 min
Issued by
NWS Great Falls, MT
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Broadwater County, MT, Gallatin County, MT, Jefferson County, MT, Madison County, MT

The radar

The Great Falls radar (KTFX), 182 km from the middle of the area, began a volume at 00:42 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 00:00Z, 0.6 hours before the alert went out and 416 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 00:00Z on 2020-06-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 230 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Spokane, WA at 00:00Z on 2020-06-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 30 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
230 J/kg
Mixed-layer CIN
-19 J/kg
Mixed-layer LCL
2659 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
49 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning 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 severe thunderstorm warning went out at Jun 24, 3:09 PM MDT, 3 hours 29 minutes earlier.

Area forecast discussion, Jun 24, 3:09 PM MDT, 3 hours 29 minutes before
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In the hours before

Special weather statement, Jun 24, 6:00 PM MDT, 38 minutes before
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Special weather statement, Jun 24, 6:24 PM MDT, 14 minutes before
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Special weather statement, Jun 24, 6:26 PM MDT, 12 minutes before
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Special weather statement, Jun 24, 6:30 PM MDT, 8 minutes before
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Special weather statement, Jun 24, 6:34 PM MDT, 4 minutes before
Special Weather Statement
National Weather Service Great Falls MT
634 PM MDT Wed Jun 24 2020

MTZ014-048-250100-
Southern Rocky Mountain Front-Central and Southern Lewis and Clark-
634 PM MDT Wed Jun 24 2020

...A STRONG THUNDERSTORM WILL AFFECT WEST CENTRAL LEWIS AND CLARK
COUNTY...

At 633 PM MDT, a strong thunderstorm was located 16 miles northeast
of Ovando, or 38 miles north of Drummond, moving northeast at 30 mph.

Wind gusts up to 50 mph and pea size hail are possible with this
storm.

This storm will remain over mainly rural areas of west central Lewis
and Clark County.

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

LAT...LON 4743 11274 4721 11251 4714 11279 4718 11280
      4717 11303 4721 11307 4722 11306
TIME...MOT...LOC 0033Z 238DEG 28KT 4720 11292

RCG
Special weather statement, Jun 24, 6:36 PM MDT, 2 minutes before
Special Weather Statement
National Weather Service Great Falls MT
636 PM MDT Wed Jun 24 2020

MTZ015-052-053-055-250100-
Broadwater MT-Madison MT-Jefferson MT-Gallatin MT-
636 PM MDT Wed Jun 24 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL BROADWATER...NORTH
CENTRAL MADISON...SOUTHEASTERN JEFFERSON AND NORTHWESTERN GALLATIN
COUNTIES UNTIL 700 PM MDT...

At 635 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Three Forks, or 31 miles southeast of Boulder, moving
east at 15 mph.

Pea size hail and wind gusts of 50 to 55 mph will be possible with
this storm.

Locations impacted include...
Three Forks, Trident, Willow Creek, Lewis And Clark Caverns State
Park, Madison Buffalo Jump State Park and Missouri Headwaters State
Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4577 11181 4585 11193 4595 11184 4604 11149
      4571 11143
TIME...MOT...LOC 0035Z 264DEG 11KT 4587 11172

JANGLIN

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 24, 6:00 PM MDTSpecial Weather StatementTFXBroadwater45 min
Jun 24, 6:24 PM MDTSpecial Weather StatementTFXLewis and Clark36 min
Jun 24, 6:26 PM MDTSpecial Weather StatementTFXLewis and Clark49 min
Jun 24, 6:30 PM MDTSpecial Weather StatementTFXCascade30 min
Jun 24, 6:34 PM MDTSpecial Weather StatementTFXLewis and Clark26 min
Jun 24, 6:36 PM MDTSpecial Weather StatementTFXJefferson24 min
Jun 24, 6:52 PM MDTSpecial Weather StatementTFXCascade53 min
Jun 24, 7:07 PM MDTSpecial Weather StatementTFXLiberty, Toole38 min
Jun 24, 7:21 PM MDTSpecial Weather StatementTFX24 min
Jun 24, 7:23 PM MDTSpecial Weather StatementTFXGallatin52 min
Jun 24, 7:26 PM MDTSevere Thunderstorm WarningTFXChouteau, Teton34 min
Jun 24, 7:44 PM MDTSpecial Weather StatementTFXCascade, Judith Basin31 min
Jun 24, 7:44 PM MDTSevere Thunderstorm WarningTFXChouteau, Teton31 min
Jun 24, 8:17 PM MDTSpecial Weather StatementTFXChouteau28 min
Jun 24, 8:40 PM MDTSpecial Weather StatementTFXGlacier35 min
Jun 24, 8:47 PM MDTSpecial Weather StatementTFXChouteau28 min
Jun 24, 9:17 PM MDTSpecial Weather StatementTFXFergus43 min
Jun 24, 9:21 PM MDTSpecial Weather StatementTFX39 min
Jun 24, 10:03 PM MDTSpecial Weather StatementTFXFergus42 min
Jun 24, 10:43 PM MDTSpecial Weather StatementTFXLewis and Clark32 min

Nearby

Severe Thunderstorm Warnings in Montana, 2020Every severe thunderstorm warning in 2020

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.