Alert archive / Montana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 23, NWS Billings, MT

July 6, 2021Big Horn County, Montana

NWS Billings, MT issued this severe thunderstorm warning at Jul 6, 2021, 6:42 PM MDT for Big Horn County, Montana. It was in force for 63 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 6, 2021, 6:42 PM MDT (00:42 UTC)
Expired: Jul 6, 2021, 7:45 PM MDT
In force: 63 min
Issued by: NWS Billings, MT
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Big Horn County, MT

The radar

The Billings radar (KBLX), 81 km from the middle of the area, began a volume at 00:43 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 6, 5:00 PM MDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Riverton, WY (KRIW), launched 00:00Z, 0.7 hours before the alert went out and 280 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: 138 J/kg
Mixed-layer CIN: -63 J/kg
Mixed-layer LCL: 3032 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: -17 m²/s²
0-3 km storm-relative helicity: 59 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

583 
WUUS55 KBYZ 070042
SVRBYZ
MTC003-070145-
/O.NEW.KBYZ.SV.W.0023.210707T0042Z-210707T0145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Billings MT
642 PM MDT Tue Jul 6 2021

The National Weather Service in Billings has issued a

* Severe Thunderstorm Warning for...
  Central Big Horn County in south central Montana...

* Until 745 PM MDT.

* At 641 PM MDT, a severe thunderstorm was located 14 miles west of
  Hardin, moving southeast at 35 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Lodge Grass, Crow Agency, St. Xavier and Crow Indian Reservation. 

This replaces the warning previously in effect for this area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4564 10803 4576 10790 4545 10705 4517 10735
TIME...MOT...LOC 0041Z 305DEG 30KT 4565 10790 

HAIL...1.00IN
WIND...60MPH
 
$$

Carrothers

2 follow-up statements

759 
WWUS55 KBYZ 070114
SVSBYZ

Severe Weather Statement
National Weather Service Billings MT
714 PM MDT Tue Jul 6 2021

MTC003-070145-
/O.CON.KBYZ.SV.W.0023.000000T0000Z-210707T0145Z/
Big Horn MT-
714 PM MDT Tue Jul 6 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM MDT
FOR CENTRAL BIG HORN COUNTY...

At 714 PM MDT, a severe thunderstorm was located 9 miles southwest of
Crow Agency, or 16 miles south of Hardin, moving southeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Lodge Grass, St. Xavier and Crow Indian Reservation. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4551 10785 4560 10765 4539 10711 4517 10735
TIME...MOT...LOC 0114Z 305DEG 30KT 4549 10758 

HAIL...1.00IN
WIND...60MPH
 
$$

Carrothers

384 
WWUS55 KBYZ 070139
SVSBYZ

Severe Weather Statement
National Weather Service Billings MT
739 PM MDT Tue Jul 6 2021

MTC003-070149-
/O.EXP.KBYZ.SV.W.0023.000000T0000Z-210707T0145Z/
Big Horn MT-
739 PM MDT Tue Jul 6 2021

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL BIG HORN COUNTY WILL
EXPIRE AT 745 PM MDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However heavy rain
is still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1100 PM MDT for
south central Montana.

LAT...LON 4551 10785 4560 10765 4539 10711 4517 10735
TIME...MOT...LOC 0139Z 305DEG 30KT 4538 10736 

$$

Carrothers

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 Billings, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 6, 5:04 PM MDT, 1 hour 38 minutes earlier.

Area forecast discussion, Jul 6, 5:04 PM MDT, 1 hour 38 minutes before

Area Forecast Discussion
National Weather Service Billings MT
504 PM MDT Tue Jul 6 2021

.DISCUSSION...

Today through Wednesday night...

Ridging to the west of the area will keep door open for
disturbances dropping in from the northwest tonight. These
disturbances will interact with a dryline/stalled front draped
across the central portion of the forecast area just east of a
Roundup to Billings to Sheridan line to produce isolated to maybe
scattered showers and thunderstorms through late tonight. Along
the boundary shear and CAPE values will support a few strong to
severe thunderstorms, with large hail, strong wind gusts and heavy
downpours. Convection will slowly shift eastward overnight but
wouldn't be surprised to see a few showers or even a lingering
thunderstorm along the eastern state line around sunrise.

Ridge axis shifts into the area tomorrow boosting temperatures to
around 100 degrees in many areas. Late in the day into the evening
hours a series of disturbances will duck under the ridge and push
through the area. Models have trended wetter with this period
bumping precipitation chances to 30-40percent for most of the area
into the late night hours. The main threat with any storms
Wednesday given the heat and lower RH values will be gusty winds
over the western half of the forecast area, further east exists
better ingredients for a strong storm but by the time the energy
gets that far east the diurnal trend will be on the downswing.
Chambers

Thursday through Tuesday...

Overall pattern through the extended continues to look fairly
active. An upper ridge will get broken down on Thursday and Friday
before building back over the region next weekend.

Latest guidance indicates the ridge will break down in a couple
different waves. The first wave will slide across southern Canada
on Thursday, with an associated cold front dropping south through
the area late in the day into Thursday evening. This will bring
the return chances for some showers and thunderstorms. Depending
on the timing of the front, the gusty northwest winds associated
with it could be a fire weather concern. The second wave, in the
form of an upper trough, looks to eject out of the Pac NW and into
the Northern Rockies Thursday night bringing cooler temperatures
and chances for showers and thunderstorms on Friday. Friday looks
to have the highest chances for precipitation during the extended.

Upper ridging builds back into the region for Saturday and Sunday
bringing a return to hot and dry conditions. Another ridge
breakdown is possible late in the day on Monday as an area of low
pressure is progged to slide east across the Canadian border,
dropping a cold front through the area and bringing chances for
showers and thunderstorms Monday and possibly Tuesday.

High temperatures look to range from the 90s on Thursday, cooling
to the upper 70s to 80s on Friday. Highs in the 80s and 90s
return for the weekend, with another cooldown next week dropping
temperatures back into the 80s. Overnight lows look to be in the
50s and 60s for most nights. STP/Hooley

&&

.AVIATION...

VFR conditions will prevail for the next 24 hours outside of
thunderstorms. Isolated to scattered thunderstorms are expected
this evening into the early morning hours. The strongest activity
will be east of Billings and a few severe storms with large hail,
damaging winds and locally heavy rainfall are possible. In the
vicinity of thunderstorms expect local MVFR conditions, and
occasional mountain and pass obscuration. Chambers

&&

.PRELIMINARY POINT TEMP/POPS...

    Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 061/097 065/095 063/082 060/090 062/097 065/092 061/090
    21/U    41/U    34/T    10/U    00/U    11/U    11/U
LVM 055/095 055/092 053/082 051/090 055/096 056/089 054/089
    22/T    32/T    33/T    10/U    00/U    11/U    11/U
HDN 058/100 062/098 060/084 056/090 057/099 062/095 059/092
    21/U    31/U    34/T    21/U    00/U    11/U    11/U
MLS 062/095 066/095 064/083 059/085 060/095 064/093 062/089
    31/U    41/U    35/T    31/U    00/U    11/U    11/U
4BQ 064/095 066/093 063/082 059/082 059/092 063/092 062/088
    31/U    31/U    35/T    32/T    00/U    01/U    11/U
BHK 056/090 059/094 059/082 056/082 055/089 058/092 059/088
    41/U    42/T    35/T    52/T    00/U    01/U    21/U
SHR 056/095 059/093 056/080 053/085 054/093 058/092 056/088
    21/U    31/U    24/T    21/U    00/U    11/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Severe Thunderstorm Watch 339 in effect until 11 PM MDT this
      evening FOR ZONES 29>32-36-57-58-138-139-169-171-173-235.
WY...None.

&&

weather.gov/billings

In the hours before

Local storm report, Jul 6, 4:37 PM MDT, 2 hours 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
437 PM MDT TUE JUL 06 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 AM     HEAVY RAIN       BURGESS JUNCTION        44.77N 107.52W
07/06/2021  M1.35 INCH       SHERIDAN           WY   CO-OP OBSERVER

0429 PM     HAIL             LAVINA                  46.30N 108.94W
07/06/2021  E0.88 INCH       GOLDEN VALLEY      MT   TRAINED SPOTTER

0433 PM     HAIL             1 ENE LAVINA            46.26N 108.92W
07/06/2021  E1.25 INCH       GOLDEN VALLEY      MT   TRAINED SPOTTER

&&

JKL

Local storm report, Jul 6, 5:23 PM MDT, 1 hour 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
523 PM MDT TUE JUL 06 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0521 PM     HAIL             MELSTONE                46.60N 107.87W
07/06/2021  E0.25 INCH       MUSSELSHELL        MT   TRAINED SPOTTER

&&

JKL

Local storm report, Jul 6, 5:42 PM MDT, 1 hour before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
542 PM MDT TUE JUL 06 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0533 PM     HAIL             4 NW SHEPHERD           45.98N 108.41W
07/06/2021  E1.00 INCH       YELLOWSTONE        MT   COCORAHS

&&

JKL

Local storm report, Jul 6, 5:47 PM MDT, 55 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
547 PM MDT TUE JUL 06 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0543 PM     HAIL             SHEPHERD                45.94N 108.35W
07/06/2021  E1.00 INCH       YELLOWSTONE        MT   TRAINED SPOTTER

&&

JKL

Local storm report, Jul 6, 6:08 PM MDT, 34 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
608 PM MDT TUE JUL 06 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0556 PM     HAIL             1 S HUNTLEY             45.88N 108.31W
07/06/2021  E1.00 INCH       YELLOWSTONE        MT   TRAINED SPOTTER

&&

JKL

Local storm report, Jul 6, 6:40 PM MDT, 2 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
640 PM MDT TUE JUL 06 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0638 PM     HAIL             13 WSW HYSHAM           46.19N 107.44W
07/06/2021  E1.75 INCH       TREASURE           MT   TRAINED SPOTTER

&&

JKL

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 6, 6:28 PM MDT	Severe Thunderstorm Warning	BYZ	Big Horn, Rosebud, Treasure, Yellowstone	62 min
Jul 6, 7:28 PM MDT	Severe Thunderstorm Warning	BYZ	Big Horn, Rosebud, Treasure	62 min
Jul 6, 8:21 PM MDT	Severe Thunderstorm Warning	BYZ	Big Horn, Powder River, Rosebud	54 min
Jul 6, 8:25 PM MDT	Severe Thunderstorm Warning	BYZ	Big Horn, Rosebud	35 min
Jul 6, 9:00 PM MDT	Severe Thunderstorm Warning	BYZ	Big Horn, Powder River, Rosebud	32 min
Jul 6, 9:43 PM MDT	Severe Thunderstorm Warning	BYZ	Rosebud	62 min
Jul 6, 10:42 PM MDT	Special Weather Statement	BYZ	Rosebud	63 min
Jul 7, 4:12 PM MDT	Severe Thunderstorm Warning	BYZ	Musselshell	33 min
Jul 7, 4:23 PM MDT	Special Weather Statement	BYZ	Park	37 min
Jul 7, 4:43 PM MDT	Severe Thunderstorm Warning	BYZ	Park	32 min
Jul 7, 5:03 PM MDT	Special Weather Statement	BYZ	Musselshell	42 min
Jul 7, 5:26 PM MDT	Special Weather Statement	BYZ	Park, Sweet Grass, Wheatland	49 min
Jul 7, 5:49 PM MDT	Severe Thunderstorm Warning	BYZ	Carbon, Golden Valley, Stillwater, Sweet Grass, Wheatland	56 min
Jul 7, 5:54 PM MDT	Special Weather Statement	BYZ	Treasure	51 min

Nearby

Severe Thunderstorm Warnings in Montana, 2021 Every severe thunderstorm warning 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.