Alert archive / Montana / Winter Weather Advisories in 2021

Winter Weather Advisory 12, NWS Missoula, MT

February 5, 202110 counties in Montana; Clearwater County, Idaho County, Idaho

NWS Missoula, MT issued this winter weather advisory at Feb 5, 2021, 2:59 PM MST for 10 counties in Montana; Clearwater County, Idaho County, Idaho. It took effect at Feb 6, 2021, 9:04 AM MST. It was in force for 50 hr.

The area

The counties it named.

The facts

Issued: Feb 5, 2021, 2:59 PM MST (21:59 UTC)
In effect from: Feb 6, 2021, 9:04 AM MST
Expired: Feb 8, 2021, 11:00 AM MST
In force: 50 hr
Issued by: NWS Missoula, MT

Counties Clearwater County, ID, Idaho County, ID, Deer Lodge County, MT, Flathead County, MT, Granite County, MT, Lake County, MT, Lincoln County, MT, Missoula County, MT, Powell County, MT, Ravalli County, MT, Sanders County, MT, Silver Bow County, MT

The radar

The Missoula radar (KMSX), 19 km from the middle of the area, began a volume at 22:05 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 12:00Z, 10.0 hours before the alert went out and 190 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: 867 m above ground
0-6 km bulk shear: 82 kt
0-1 km storm-relative helicity: 413 m²/s²
0-3 km storm-relative helicity: 508 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this winter weather advisory 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 winter weather advisory went out at Feb 5, 5:05 AM MST, 9 hours 54 minutes earlier.

Area forecast discussion, Feb 5, 5:05 AM MST, 9 hours 54 minutes before

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In the hours before

Local storm report, Feb 5, 1:54 PM MST, 1 hour 5 minutes before

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Local storm report, Feb 5, 1:57 PM MST, 1 hour 2 minutes before

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Local storm report, Feb 5, 2:01 PM MST, 58 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
201 PM MST FRI FEB 5 2021

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

1100 AM     HEAVY SNOW       PIERCE                  46.49N 115.80W
02/05/2021  E12.0 INCH       CLEARWATER         ID   PUBLIC

&&

Local storm report, Feb 5, 2:05 PM MST, 54 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
205 PM MST FRI FEB 5 2021

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

1000 AM     SNOW             4 NE OROFINO            46.52N 116.20W
02/05/2021  E6.0 INCH        CLEARWATER         ID   TRAINED SPOTTER

&&

Local storm report, Feb 5, 2:11 PM MST, 48 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
211 PM MST FRI FEB 5 2021

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

0900 AM     SNOW             3 ENE OROFINO           46.50N 116.20W
02/05/2021  E0.5 INCH        CLEARWATER         ID   TRAINED SPOTTER

            THEY THINK THE SNOW LEVEL MIGHT HAVE BEEN
            AROUND 1800 FEET. THEY HAD A MIX OF RAIN AND
            SNOW.

&&

Local storm report, Feb 5, 2:20 PM MST, 39 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
Feb 5, 2:59 PM MST	Winter Storm Watch	MSO	Deer Lodge, Granite, Mineral, Missoula, Powell, Ravalli and 2 more	23 hr
Feb 5, 2:59 PM MST	Winter Storm Warning	MSO	Deer Lodge, Flathead, Granite, Lake, Mineral, Missoula and 4 more	50 hr

Nearby

Winter Weather Advisories in Montana, 2021 Winter Weather Advisories in Idaho, 2021 Every winter weather advisory 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.