Alert archive / Montana / Severe Thunderstorm Warnings in 2018
Severe Thunderstorm Warning 51, NWS Great Falls, MT
NWS Great Falls, MT issued this severe thunderstorm warning at Aug 20, 2018, 3:53 PM MDT for Beaverhead 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 counties it named.
The facts
- Issued
- Aug 20, 2018, 3:53 PM MDT (21:53 UTC)
- Expired
- Aug 20, 2018, 4:30 PM MDT
- In force
- 37 min
- Issued by
- NWS Great Falls, MT
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
County Beaverhead County, MT
The radar
The Pocatello radar (KSFX), 226 km from the middle of the area, began a volume at 21:56 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, 9.9 hours before the alert went out and 313 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1430 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- -31 m²/s²
- 0-3 km storm-relative helicity
- 127 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
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 Aug 20, 2:32 PM MDT, 1 hour 21 minutes earlier.
Area forecast discussion, Aug 20, 2:32 PM MDT, 1 hour 21 minutes before
Area Forecast Discussion National Weather Service Great Falls MT 232 PM MDT Mon Aug 20 2018 .SYNOPSIS... Scattered to numerous showers and thunderstorms are expected tonight and into the mid morning hours on Tuesday across Central and Southwest Montana. A few storms across Southwest Montana may become strong and produce damaging wind gusts. Temperatures will begin to warm through the remainder of the week. && .DISCUSSION... Rest of this Afternoon through Wednesday...An elongated, positive- tilt trough will reside over the Pacific Northwest and Northern Rockies through Tuesday. At the surface, a cool Canadian airmass will continue to push southward with scattered to numerous showers and thunderstorms expected through tonight. A few thunderstorms could become severe over southwest Montana this afternoon through this evening with the primary threat being damaging wind gusts. The upper trough weakens and sinks southward overnight with shower and thunderstorm activity affecting primarily southwest Montana tonight and Tuesday. Temperatures are expected to rebound Tuesday and Wednesday as atmospheric thickness values increase as the upper trough weakens and cuts off over far southwest Montana and Idaho. Isolated showers/thunderstorms will likely linger over the southwest zones into Wednesday due to the upper low continuing to spin and destabilize the atmosphere. Meanwhile, surface low pressure develops in Alberta with increasing southerly winds expected across north central Montana. mpj Wednesday night through Monday...Medium range models finally weaken the upper level cutoff low and eject it eastward with shortwave ridging expected over the state on Thursday. Expecting continued warm, mostly dry, and breezy to windy conditions to prevail Thursday and Friday. This could bring a return to borderline critical fire weather condition late in the week, a possibility we will continue to monitor. Models also continue to suggest that a broad upper level trough will develop over western Canada for the weekend and into early next week with west to southwest flow aloft expected over Montana. Main medium-range models appear to be closing the gap with a fair amount of moisture streaming through a southwest flow aloft. Have therefore increased PoPs/QPF beginning Sunday. Britton && .AVIATION... Updated 1740Z. Widespread smoke will keep visibility over much of the area in the high MVFR to low VFR range throughout much of the period. Increased mid level moisture associated with a Pacific weather system will continue to generate scattered to numerous showers and thunderstorms across the forecast area this morning, but slowly diminishing from the northwest this afternoon. Low pressure aloft moves southward during the period with showers becoming more widespread in southwest Montana. VFR conditions expected to prevail but areas of smoke, showers, and low clouds will generate periods of IFR/MVFR conditions with mountains obscured through the forecast period. britton && .PRELIMINARY POINT TEMPS/POPS... GTF 44 72 47 85 / 40 0 0 0 CTB 41 73 46 85 / 10 0 0 0 HLN 46 72 49 84 / 90 20 10 10 BZN 45 67 44 81 / 80 30 10 10 WEY 30 67 30 73 / 50 20 20 30 DLN 44 68 43 77 / 90 30 10 20 HVR 46 76 48 86 / 10 0 0 0 LWT 44 65 44 80 / 90 30 10 0 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && http://www.weather.gov/greatfalls
In the hours before
Special weather statement, Aug 20, 2:03 PM MDT, 1 hour 50 minutes before
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</html>Special weather statement, Aug 20, 3:08 PM MDT, 45 minutes before
Special Weather Statement
National Weather Service Great Falls MT
308 PM MDT MON AUG 20 2018
MTZ008-202200-
Beaverhead MT-
308 PM MDT MON AUG 20 2018
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN BEAVERHEAD COUNTY
UNTIL 400 PM MDT...
At 308 PM MDT, Doppler radar was tracking a strong thunderstorm near
Leadore, or 37 miles southeast of Salmon, moving east at 20 mph.
Half inch hail and wind gusts up to 50 mph will be possible with this
storm.
This storm will remain over mainly rural areas of southwestern
Beaverhead County.
LAT...LON 4487 11346 4500 11307 4473 11291 4470 11310
4477 11313 4482 11326 4479 11335 4483 11336
4484 11342
TIME...MOT...LOC 2108Z 252DEG 16KT 4477 11337
NJLSpecial weather statement, Aug 20, 3:39 PM MDT, 14 minutes before
Special Weather Statement National Weather Service Great Falls MT 339 PM MDT MON AUG 20 2018 MTZ008-015-202230- Madison MT-Beaverhead MT- 339 PM MDT MON AUG 20 2018 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN MADISON AND SOUTH CENTRAL BEAVERHEAD COUNTIES UNTIL 430 PM MDT... At 338 PM MDT, Doppler radar was tracking a strong thunderstorm 21 miles northeast of Leadore, or 30 miles southwest of Dillon, moving east at 40 mph. Half inch hail and wind gusts up to 50 mph will be possible with this storm. Locations impacted include... Dillon, Grant, Beaverhead Rock State Park and Clark Canyon. LAT...LON 4470 11304 4498 11318 4526 11254 4478 11222 TIME...MOT...LOC 2138Z 254DEG 33KT 4485 11299 NJL
The office that day
Everything else NWS Great Falls, MT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 7:27 PM MDT | Special Weather Statement | TFX | Jefferson | 33 min |
| Aug 20, 2:03 PM MDT | Special Weather Statement | TFX | Beaverhead | 42 min |
| Aug 20, 3:08 PM MDT | Special Weather Statement | TFX | Beaverhead | 52 min |
| Aug 20, 3:39 PM MDT | Special Weather Statement | TFX | Beaverhead | 51 min |
| Aug 20, 4:24 PM MDT | Special Weather Statement | TFX | Beaverhead | 51 min |
| Aug 20, 5:10 PM MDT | Special Weather Statement | TFX | Madison | 50 min |
| Aug 20, 5:40 PM MDT | Special Weather Statement | TFX | Beaverhead | 50 min |
Nearby
Severe Thunderstorm Warnings in Montana, 2018Every severe thunderstorm warning in 2018
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.