Alert archive / Idaho / Winter Weather Advisories in 2021

Winter Weather Advisory 82, NWS Missoula, MT

December 30, 2021Clearwater County, Idaho County, Idaho

NWS Missoula, MT issued this winter weather advisory at Dec 30, 2021, 7:50 AM PST for Clearwater County, Idaho County, Idaho. It took effect at Dec 30, 2021, 7:00 PM PST. It was in force for 15 hr.

The area

The counties it named.

The facts

Issued: Dec 30, 2021, 7:50 AM PST (15:50 UTC)
In effect from: Dec 30, 2021, 7:00 PM PST
Expired: Dec 31, 2021, 10:00 AM PST
In force: 15 hr
Issued by: NWS Missoula, MT

Counties Clearwater County, ID, Idaho County, ID

The radar

The Missoula radar (KMSX), 148 km from the middle of the area, began a volume at 15:52 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.

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 Dec 30, 3:00 AM PST, 4 hours 50 minutes earlier.

Area forecast discussion, Dec 30, 3:00 AM PST, 4 hours 50 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
400 AM MST Thu Dec 30 2021

.DISCUSSION...A low pressure system is currently making its way
into the Northern Rockies which will causing widespread snow.
North central Idaho is still anticipated to receive the brunt of
the storm. Clearwater and Idaho counties should expected to
receive between 4 to 7 inches over the next 24 hours, heavier
amounts in the higher terrain. The models are indicating that
gusty southerly winds could develop over the Grangeville area
later this morning into the afternoon. This wind will decrease
snow amounts on the Camas Prairie, but gusts up to 35 mph could
create localized blowing snow. The remainder of the Northern
Rockies should expected 1 to 3 inches of new snow accumulation
during the passage of this system today through tonight.

This evening another surge of arctic air appears to flow over the
Continental Divide causing gusty easterly winds from Marias Pass
to Kalispell along HWY 2 and evening from Rogers Pass to Bonner
along HWY 200 tonight. These gusty winds will create very cold
wind chill readings during the overnight hours into Friday
morning.

The upper level flow will remain northerly over the Northern
Rockies on Friday which is conducive to lingering light snow
showers with cold air remain entrenched in the valleys. A ridge
of high pressure is expected to develop over the region this
weekend. This ridge will cause a decrease in precipitation, but
uncertainty lies on how much warming will the valleys experience.

The models continue to trend towards a very active weather period
for the Northern Rockies next week.

&&

.AVIATION...A disturbance will continue to move through the
Northern Rockies for the next 24 hours bring widespread snow. KGPI
and KMSO is currently experience snow and should experience a
break around 30/17z. A second round of snow is expected this
evening for KGPI and KMSO. KBTM appears to have vicinity snow
showers throughout the event. While KSMN appears to be impacted by
snow between 30/13z to 30/21z. Clearwater and Idaho counties of
Idaho will have the biggest impacted from the snow over the next
24 hours. As for wind concerns, strong westerly winds will
continue to impact the Glacier National Park region this morning
then diminish. The Grangeville Idaho area should have gusty
southerly winds develop late this morning through the afternoon.
Finally another surge of easterly winds expected this evening
along the Continental Divide, potentially impacting KGPI by
31/03z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...     Winter Weather Advisory until 11 AM MST Friday Lower Clark Fork
     Region.

ID...Winter Weather Advisory until 10 AM PST Friday Lower Hells
     Canyon/Salmon River Region.

     Winter Weather Advisory until 10 AM PST Friday
     Orofino/Grangeville Region.

     Winter Weather Advisory until 10 AM PST Friday Southern
     Clearwater Mountains.

     Winter Weather Advisory until 10 AM PST Friday Northern
     Clearwater Mountains.

&&

In the hours before

Local storm report, Dec 30, 6:22 AM PST, 1 hour 28 minutes before

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Local storm report, Dec 30, 6:25 AM PST, 1 hour 25 minutes before

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    <section class="card" role="status" aria-live="polite">
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        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
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The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 30, 7:50 AM PST	Winter Storm Warning	MSO	Clearwater, Idaho	11 hr

Nearby

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; radar from the NEXRAD Level II archive.