Alert archive / Montana / Severe Thunderstorm Warnings in 2025

Severe Thunderstorm Warning 1, NWS Missoula, MT

May 11, 2025Sanders County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at May 11, 2025, 7:01 PM MDT for Sanders County, Montana. It was in force for 44 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: May 11, 2025, 7:01 PM MDT (01:01 UTC)
Expired: May 11, 2025, 7:45 PM MDT
In force: 44 min
Issued by: NWS Missoula, MT
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

County Sanders County, MT

The radar

The Missoula radar (KMSX), 111 km from the middle of the area, began a volume at 01:03 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, 1.0 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: 16 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 1120 m above ground
0-6 km bulk shear: 64 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 93 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.1

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 Missoula, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at May 11, 2:04 PM MDT, 4 hours 57 minutes earlier.

Area forecast discussion, May 11, 2:04 PM MDT, 4 hours 57 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
204 PM MDT Sun May 11 2025

.DISCUSSION...

KEY MESSAGES:

- Scattered thunderstorms are expected today with a 5 percent
  chance of severe storms in portions of southwest Montana and
  Lemhi County, ID.

- Snow levels will start to decrease tomorrow adding more snow in
  the Anaconda and Pintlar mountains as well as along the
  Continental Divide.

- Cooler and showery conditions continue through the week and
  into next weekend.

Current mesoanalysis depicts the best instability across southwest
Montana, generally east of the the Bitterroot Mountains. Radar has
shown that storms have formed and are generally tracking to the
northeast at 35 mph. High resolution models depict more storms
firing up across north-central Idaho and northwest Montana this
evening. The main threats are lightning, small hail, gusty winds
and brief heavy rain. One thing that we have noticed is that the
HRRR and other models have been similar (from run-to-run) with a
few storms tracking from Sanders County to the Flathead Valley and
Glacier Region between 5 and 8 pm MDT this evening.

Persistent showers will continue over Idaho into northwest Montana
on Monday. Later in the evening steady precipitation will form
across southwest Montana and Lemhi County. Snow levels will fall
to around 5500 feet by Tuesday. Wet snow will impact Lost Trail
Pass, Georgetown Lake, and passes along the Divide in Lemhi
County through Tuesday evening. Also there is a chance for several
inches of snowfall in the higher elevations of Glacier National
Park...40 percent chance for greater than 2 inches at Logan Pass.
There continues to be discrepancies with the placement of the
deformation snowfall in southwest Montana later Tuesday into
Tuesday night. The NBM ranges for precipitation is from several
hundredths up to 0.15 of an inch Tuesday night. If the deformation
precip is able to make it further north and west, then there still
could be a short period of snowfall at Homestake Pass and I-15
south of Butte.

The rest of the week through next weekend will be unsettled with
a chance for showers each day. Daytime highs will be running 5 to
10 degrees cooler than average which is in the 60s. At night,
thanks to increased cloud cover temperatures in the lower valleys
could range in the 40s and 30s in the higher valleys.

&&

.AVIATION...Showers and thunderstorms will continue to fire across
Lemhi county into southwest Montana this afternoon into the early
evenings affecting KSMN and KGPI. Showers and thunderstorms are
anticipated to fire this evening across northwest Montana
potentially impacting KGPI between 12/00z to 12/03z. All storms
will be capable of producing gusty and erratic winds along with
small hail. KMSO and KHRF will be mainly in the dry slot between
these two storms this evening, but can not rule out a light shower
impacting the terminals. Steady precipitation is expected to move
over north central Idaho into northwest Montana by Monday morning
causing lowering ceilings for KGPI.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...Wind Advisory until 9 PM MDT this evening for Eastern Lemhi
     County...Western Lemhi County.

&&

In the hours before

Special weather statement, May 11, 4:49 PM MDT, 2 hours 12 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
May 11, 7:33 PM MDT	Special Weather Statement	MSO	Sanders	27 min
May 11, 8:09 PM MDT	Special Weather Statement	MSO	Lincoln	51 min
May 12, 12:27 AM MDT	Severe Thunderstorm Warning	MSO	Flathead	48 min
May 12, 1:07 AM MDT	Special Weather Statement	MSO	Flathead	53 min
May 12, 12:48 PM MDT	Winter Weather Advisory	MSO	Lemhi	23 hr

Nearby

Severe Thunderstorm Warnings in Montana, 2025 Every severe thunderstorm warning in 2025

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.