Alert archive / Idaho / Special Weather Statements in 2021

Special Weather Statement, NWS Missoula, MT

September 10, 2021Lemhi County, Idaho

NWS Missoula, MT issued this special weather statement at Sep 10, 2021, 4:46 PM MDT for Lemhi County, Idaho. 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 outline as issued.

The facts

Issued: Sep 10, 2021, 4:46 PM MDT (22:46 UTC)
Expired: Sep 10, 2021, 5:30 PM MDT
In force: 44 min
Issued by: NWS Missoula, MT
Hail: 0.00 in
Wind: 40

County Lemhi County, ID

The radar

The Missoula radar (KMSX), 208 km from the middle of the area, began a volume at 22:46 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

Boise Airport, ID (KBOI), launched 12:00Z, 10.8 hours before the alert went out and 257 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 3036 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: -90 m²/s²
0-3 km storm-relative helicity: 125 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Sep 10, 1:29 PM MDT, 3 hours 17 minutes earlier.

Area forecast discussion, Sep 10, 1:29 PM MDT, 3 hours 17 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
129 PM MDT Fri Sep 10 2021

.DISCUSSION...Expect scattered light rain showers to continue to
stream north over the Northern Rockies this afternoon, ahead of
the main surge of moisture and energy expected to arrive this
evening. The Camas Prairie in north-central Idaho, west-central
and northwest Montana will be the prime locations for the heavier
precipitation this evening, as these locations have the best
chance for thunderstorms to develop. Northwest Montana continues
to be the favored area to receive the most rainfall out of this
system, where three to eighth tenths of an inch of rainfall is
possible in the valleys. The Mission, Swan, and Whitefish ranges,
as well as Glacier National Park, are likely to see around 1 to 2
inches of rain, with isolated higher amounts possible. As the low
passes to the northeast early tomorrow morning and during the day,
wrap around moisture will keep showers in the forecast for
northwest Montana, one reason for the higher rainfall totals
compared to the rest of the region.

Expect a cool, showery and cloudy day tomorrow for most locations
across the Northern Rockies with the development of a northwesterly
flow behind the departing low. Afternoon highs will be around 5
to 10 degrees cooler than normal for this time of the year. The
pesky smoke will also finally move out of the region with the
moisture and pattern change, greatly improving area air quality.

A zonal flow pattern will reside over the region for most of next
week, allowing for breezy afternoons, and temperatures lingering
around seasonal norms. A few isolated afternoon/evening showers
will be possible each day, but will not amount to much
precipitation.

&&

.AVIATION...Smoke will continue to impact visibility at area
terminals through the evening hours today. A surge of moisture
and energy is still expected to arrive by 11/0000Z this evening
for most terminals, bringing a chance for moderate rainfall rates
and isolated lightning strikes. The threat for thunder will be in
the forecast through the overnight hours for KGPI, with the threat
ending for KMSO, KSMN, and KBTM by 11/0600Z . Gusty and erratic
winds up to 25 kts are possible for KGPI, KMSO, KBTM, and KSMN
with any convective activity. Scattered rain showers will remain
in the forecast for KGPI for most of the day Saturday.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

In the hours before

Special weather statement, Sep 10, 4:17 PM MDT, 29 minutes before

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Special weather statement, Sep 10, 4:46 PM MDT, 0 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
Sep 10, 4:17 PM MDT	Special Weather Statement	MSO	Lemhi	43 min

Nearby

Special Weather Statements in Idaho, 2021 Every special weather statement 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.