Hail and Damaging Winds in Montana, June 13 to 14, 2020

Name: Hail and Damaging Winds in Montana, June 13 to 14, 2020
Start: 2020-06-13T07:00
End: 2020-06-14T18:30
Location: Montana

June 13 to 14, 2020 · NWS TFX · 17 events in 9 counties and zones

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 17

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS TFX wrote it up.

With respect to wind, south to north orientated H700 jet max of 35-50kts/H500 jet max of 50-75kts remains over southwest and into central Montana through 03-06z Sunday before sliding eastward over The Northern High Plains. Deep diurnal mixing combined with terrain funneling, most notably in the north-south orientated valleys, continues to lead to sustained winds of 35-45 mph and gusts approaching 65 mph across southwest and into portions of central Montana. High Wind Warning continues for Beaverhead, |Madison, Gallatin, Jefferson, and Broadwater counties. While a few isolated wind gusts above High Wind criteria occur north of the High Wind Warning in Central Montana (Porphyry Peak in the Little Belt Mountains and Judith Peak in the Judith Mountains), have held off on expanding the High Wind Warning further north given the isolated nature of the gusts. With that being said, concern is that the H700/500 jet max slides further north between 21z Saturday and 03z Sunday that locations like Great Falls, Belt, and Stanford could briefly reach High Wind criteria.

With respect to the potential for severe weather, the Storm Prediction Center continues to maintain a slight risk for portions of northwest Montana, mainly northwest of a line from Augusta, to Choteau, to Conrad, to Cut Bank. Afternoon storms are on-going across western Montana, with additional development expected along The Continental Divide through 00z Sunday. Hi-Res models also indicate the potential for storms to develop over far eastern portions of central and north central Montana before lifting north/northeast into southern Canada, but confidence in coverage and intensity of these storms is not as high as across northwest Montana. Large hail up to the size |of half dollar and damaging winds up to 60 mph are the primary threats with any severe thunderstorm, especially across the Slight Risk area. In addition to the threat for |severe weather, the potential for locally heavy rainfall leading to flash flooding also exists, especially where storms train over complex terrain.

What forecasters said that day

The local office's own words before the first event, 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 the first event at Jun 13, 4:48 AM MST, 2 hours 12 minutes earlier.

Area forecast discussion, Jun 13, 4:48 AM MST, 2 hours 12 minutes before

Area Forecast Discussion
National Weather Service Great Falls MT
548 AM MDT Sat Jun 13 2020

...UPDATED AVIATION SECTION...

.SYNOPSIS...

A frontal boundary will move north over the region today. A few
showers and thunderstorms will move over the area this morning,
but the better chance for showers and storms will move over the
mountains this afternoon and over the Hi-Line into early this
evening. Some of these Hi-Line storms could produce strong wind
gusts and some hail. However, strong southerly winds will spread
north behind the boundary, and these downsloping winds will hinder
shower and storm development elsewhere. A broad low pressure
trough will then bring cooler temperatures early next week, along
with a good chance for showers and thunderstorms to the mountain
areas, and gusty westerly winds to the plains.

&&

.DISCUSSION...

Today and Tonight...
Isolated showers and weak thunderstorms will continue move north
over the area in the breezy southerly flow aloft, but they should
likely only produce brief heavy rain. These storms are forming
ahead of a frontal boundary over weakly unstable air. As this
boundary moves north, southerly winds will increase first over
Southwest Montana this morning, then over the plains this
afternoon. Most of the area will see wind gusts of 30 to 40 mph,
but gusts could reach 60 mph at times through some north- south
oriented valleys in Southwest Montana, as well as over ridge tops,
which could negatively impact those participating in outdoor
activities. Will therefore continue the High Wind Warning for the
area south of Helena and White Sulphur Springs. There is a chance
that winds downsloping off the Big and Little Belt Mountains
could approach a similar strength, but the mountain and valley
orientations are not as favorable for such gusts, so have
cancelled the High Wind Watch for Meagher, Cascade, and Judith
Basin Counties. Also, the mid level winds are not quite as strong
as those farther south, and the timing for potential transfer down
to the surface is not favorable and will likely be a more narrow
window. As this boundary moves north, scattered showers and
thunderstorms will move north over the mountain ridges along the
Continental Divide and from Gallatin County north to the Central
Montana mountains, but the southerly downslope winds will likely
hinder shower/storm development in between those areas. However,
scattered showers and storms will develop along the leading edge
of the boundary on the Hi-Line as it intersects with warm moist
air and winds veering off the surface. This could cause some
thunderstorms to possibly become severe with strong wind gusts and
at least small hail possible. After the showers, storms and winds
decrease this evening, a disturbance in a more southwesterly flow
aloft will increase showers, with snow above 7500 feet, over
Southwest Montana overnight. Coulston/Nutter

Sunday through next Saturday...
A broad low pressure trough will then settle over the western
United States for much of this period. As a result, the cyclonic
westerly flow aloft will keep winds breezy out the west with
temperatures ranging from 5 to 10 degrees below normal. Weak
disturbances in the flow aloft will also keep a chance of showers
and thunderstorms over North Central and Southwest Montana through
the week. The main focus for precipitation will be over Southwest
Montana Sunday through Tuesday, while the westerly downsloping
winds hinder shower/storm development over the plains. The best
chance for strong winds will be on the Rocky Mountain Front on
Monday, but there is some uncertainty as to just how strong the
winds will be. The trough may weaken enough and shift east of the
area next Saturday to allow a weak high pressure ridge to move
into the area, which may bring drier conditions and above normal
temperatures.  Coulston

&&

.AVIATION...
Updated 548 AM MDT Sat Jun 13 2020 (13/12Z TAF Period)

VFR conditions will mostly continue across North Central and
Southwest Montana, but periods of MVFR conditions are possible
with showers/thunderstorms after 20Z. Scattered to broken mid and
high level cloudiness will move north over the area in a southerly
flow aloft, with a few embedded weak showers/thunderstorms. Easterly
winds will increase and shift more southerly with the boundary
passage starting in the southwest between 15Z and 18Z and over the
plains from 18Z over Central Montana through 00Z on the Hi- Line.
Gusts of 30 to 40 kt will be common, but gusts could reach 55 kt at
times through north-south oriented valleys in the southwest.
Otherwise, isolated showers and thunderstorms will first develop
over the western mountains after 18Z and gradually spread east to a
KCTB- KBZN by 21Z or so. Isolated storms may also develop ahead of
the frontal boundary from KCTB-KHVR between 21Z and 03Z. Winds will
shift more westerly and decrease through 06Z with decreasing
showers, but another round of showers will move into
Southwest Montana after 06Z. Coulston

NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing
runway closure.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  86  47  64  44 /   0  10  30  10
CTB  80  44  61  44 /  50  40  20  20
HLN  84  46  62  41 /  30  30  80  20
BZN  84  44  63  36 /   0  30  90  40
WYS  71  37  56  29 /  10  30  80  30
DLN  75  43  59  35 /  10  30  80  10
HVR  93  51  71  46 /  30  30  30  10
LWT  87  47  65  41 /   0  30  70  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 9 AM this morning to 8 PM MDT this
evening Beaverhead...Broadwater...Gallatin...Jefferson...Madison.

&&

http://www.weather.gov/greatfalls

The radar

The Great Falls radar (KTFX), 118 km away, was scanning. The volume nearest the first event began at 23:24 UTC.

Open the radar archive at this moment

Event by event

12 high wind, 3 thunderstorm wind, 2 hail. Local standard time, as filed.

High Wind, Madison

When: June 13, 7:00 AM MST
Where: Madison forecast zone
Measured: 52 kt (60 mph) measured gust
Reported by: Mesonet

Mesonet station yctim, 6.3 w Big Sky (avalanche) station elevation: 9399 ft.

High Wind, Madison

When: June 13, 12:57 PM MST
Where: Madison forecast zone
Measured: 55 kt (63 mph) measured gust
Reported by: Mesonet

Mesonet station mtnor, Norris Hill (mt dot). Station elevation: 5699 ft.

High Wind, Broadwater

When: June 13, 2:54 PM MST
Where: Broadwater forecast zone
Measured: 51 kt (59 mph) measured gust
Reported by: Mesonet

Mesonet station ekhm8, Elkhorn raws - 8 w Townsend. station elevation: 6010 ft.

High Wind, Jefferson

When: June 13, 3:27 PM MST
Where: Jefferson forecast zone
Measured: 53 kt (61 mph) measured gust
Reported by: Mesonet

Mesonet station mtbou, Boulder Hill (mt dot). Station elevation: 5592 ft.

High Wind, Beaverhead

When: June 13, 3:47 PM MST
Where: Beaverhead forecast zone
Measured: 53 kt (61 mph) measured gust
Reported by: Mesonet

Mesonet station brrm8, Brenner Raws. Station elevation: 6630 ft.

High Wind, Beaverhead

When: June 13, 3:59 PM MST
Where: Beaverhead forecast zone
Measured: 52 kt (60 mph) measured gust
Reported by: Mesonet

Mesonet station lmrm8, Antelope raws. station elevation: 6794 ft.

Thunderstorm Wind, Fergus

When: June 13, 4:22 PM MST
Where: Fergus County, 5.82 mi NE of Denton
Measured: 51 kt (59 mph) measured gust
Reported by: Other Federal Agency
Coordinates: 47.370, -109.820

Measured 59 mph thunderstorm wind gust at AW Delta.

High Wind, Southern Lewis and Clark

When: June 13, 4:49 PM MST
Where: Southern Lewis and Clark forecast zone
Measured: 51 kt (59 mph) measured gust
Reported by: ASOS

Asos station khln, Helena ap asos.

Thunderstorm Wind, Glacier

When: June 13, 4:57 PM MST
Where: Glacier County, (Ctb)cutbank Muni Ar
Measured: 51 kt (59 mph) measured gust
Reported by: ASOS
Coordinates: 48.600, -112.370

Asos station KCTB Cut Bank Airport. Likely outflow from a thunderstorm.

Hail, Glacier

When: June 13, 5:00 PM MST
Where: Glacier County, 5.03 mi NNW of Blackfoot
Measured: 1.5 in hail
Reported by: Trained Spotter
Coordinates: 48.650, -112.930

Spotter emailed a picture. Also, reported 0.25 inches of rain. Time estimated based upon radar.

High Wind, Southern Lewis and Clark

When: June 13, 5:16 PM MST
Where: Southern Lewis and Clark forecast zone
Measured: 51 kt (59 mph) measured gust
Reported by: AWOS

Awos station k1gm golf.

High Wind, Broadwater

When: June 13, 5:54 PM MST
Where: Broadwater forecast zone
Measured: 62 kt (71 mph) measured gust
Reported by: Mesonet

Mesonet station ekhm8, elkhorn raws - 8 w Townsend. station elevation: 6010 ft.

High Wind, Cascade

When: June 13, 6:06 PM MST
Where: Cascade forecast zone
Measured: 53 kt (61 mph) measured gust
Reported by: Department of Highways

Reported 61 mph wind gust at the DOT station near Dearborn.

Thunderstorm Wind, Glacier

When: June 13, 6:09 PM MST
Where: Glacier County, (Ctb)cutbank Muni Ar
Measured: 52 kt (60 mph) measured gust
Reported by: ASOS
Coordinates: 48.600, -112.370

Reported at 3 sw Cut Bank. Asos station KCTB Cut Bank Airport.

Hail, Liberty

When: June 13, 6:43 PM MST
Where: Liberty County, 0.83 mi SSE of Chester Lbrty Co Arp
Measured: 1.5 in hail
Reported by: Public
Coordinates: 48.510, -110.970

Nickel to ping pong sized hail reported.

High Wind, Madison

When: June 14, 6:30 PM MST
Where: Madison forecast zone
Measured: 50 kt (58 mph) estimated gust
Reported by: COOP Observer

Multiple trees down in the area as showers passed nearby. 1 NE Laurin. Wind speed and gust estimate not reported. Time estimated from radar.

High Wind, Madison

When: June 14, 6:30 PM MST
Where: Madison forecast zone
Measured: 56 kt (64 mph) measured gust
Reported by: Public

Reported 65mph gusts recorded on home weather station as showers passed nearby. 2 NE Laurin. Time estimated from radar.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Montana in 2020 Every state in 2020 This day in weather history Warnings in Montana, June 2020

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 906071, 906065, 906073, 906067, 906068, 906072, 906061, 906074, 906062, 906059, 906075, 906064, 906070, 906063, 906060, 906076, 906077.