Alert archive / Montana / Winter Weather Advisories in 2021

Winter Weather Advisory 1, NWS Missoula, MT

January 2, 20215 counties in Montana; Clearwater County, Idaho County, Idaho

NWS Missoula, MT issued this winter weather advisory at Jan 2, 2021, 1:58 PM MST for 5 counties in Montana; Clearwater County, Idaho County, Idaho. It took effect at Jan 2, 2021, 5:00 PM MST. It was in force for 20 hr.

The area

The counties it named.

The facts

Issued
Jan 2, 2021, 1:58 PM MST (20:58 UTC)
In effect from
Jan 2, 2021, 5:00 PM MST
Expired
Jan 3, 2021, 1:00 PM MST
In force
20 hr
Issued by
NWS Missoula, MT

Counties Clearwater County, ID, Idaho County, ID, Flathead County, MT, Granite County, MT, Lake County, MT, Missoula County, MT, Ravalli County, MT

The radar

The Missoula radar (KMSX), 37 km from the middle of the area, began a volume at 21:01 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, 9.0 hours before the alert went out and 178 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-pSkew-T log-p diagram, Spokane, WA at 12:00Z on 2021-01-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Spokane, WA at 12:00Z on 2021-01-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 120 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
658 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
120 m²/s²
0-3 km storm-relative helicity
147 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 Jan 2, 3:19 AM MST, 10 hours 39 minutes earlier.

Area forecast discussion, Jan 2, 3:19 AM MST, 10 hours 39 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jan 2, 3:16 AM MSTWinter Storm WarningMSOMineral, Missoula, Sanders33 hr
Jan 2, 1:37 PM MSTWind AdvisoryMSODeer Lodge, Flathead, Granite, Lake, Lincoln, Missoula and 4 more27 hr

Nearby

Winter Weather Advisories in Montana, 2021Winter Weather Advisories in Idaho, 2021Every 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.