Winter Weather Advisory 21, NWS Great Falls, MT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1045 PM MST Sat Mar 1 2014

.UPDATE...

Next round of Pacific moisture continues to spread east into
western MT and though dynamics are weak, very light snow has
developed over western portions of north central MT as a result of
the moist flow overrunning the cold airmass in place over the
region. Expect this trend to continue through tonight with periods
of light snow or flurries spreading east across most of the
forecast area by Sunday morning with accumulations generally less
than an inch. No additional updates planned to temperatures as
cloud-cover has slowed temperature falls that occurred earlier this
evening. Hoenisch

&&

.AVIATION...
UPDATED 0545Z.
Arctic airmass remains over Montana tonight through late Sunday
evening. Pacific moisture moving over the cold airmass will bring
widespread clouds with areas of fog, snow and/or low clouds
persisting for IFR/MVFR conditions at times. Mountain obscurations
are expected through the entire forecast period. Precipitation
becomes widespread across much of the region after 12Z Sunday for
prevailing MVFR conditions with some improvement in the southwest
after 18Z. mpj

&&

.PREV DISCUSSION...
/ISSUED 634 PM MST Sat Mar 1 2014/
FXUS65 KTFX 020134
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
634 PM MST Sat Mar 1 2014

UPDATE...

Winter weather highlights for snow were allowed to expire at 6pm
with the wind chill warning for north central MT continuing
through Sunday morning. Snow has ended or diminished to very light
flurries across the region with a brief break in the moist west
flow aloft bringing a period of generally dry conditions through
this evening before the next batch of Pacific moisture moves east
into the area later tonight. Satellite imagery shows a break in
the cloud-cover over eastern and southern portions of north
central MT this evening with clouds in advance of the next system
already filling in to the west of this area. Cloud-cover will play
a major role in minimum temperatures tonight and have adjusted
clouds and temps in a swath from near Rogers Pass east to
Lewistown where temps are falling rapidly in response to the clear
skies. Hoenisch

.PREV DISCUSSION...
/ISSUED 440 PM MST Sat Mar 1 2014/
This Afternoon through Monday Evening...Latest analysis shows
light snow tapering off over central MT, but continuing over
southwest MT as upper-level trof pushes through the southern half
of the state. Some partial clearing also seen on visible satellite
imagery pushing through Great Falls and neighboring areas to the
northwest, but fairly thick haze layer produced by the strong
temperature inversion in the low levels should limit any decent
warm-up over remainder of the aftn. Current warnings and
advisories are still in effect but good chance the winter
storm/winter weather portions should end this evening, but still
expecting dangerously cold wind chills over the central and Hiline
counties overnight. Region will see a brief break from the snow
tonight but next system and accompanying moisture is due to arrive
east of the Divide tomorrow morning, bringing another round of
light snow through the day. Westerly, Chinook-type flow aloft
starts to set up on Sun which should help erode the shallow cold
airmass a bit, allowing high temps to climb a few degrees above
zero from Great Falls/Lewistown northward and teens/20s over
southwest MT. Models continue to show decent warm-up on Mon as
westerly flow strengthens slightly, with highs in 30s/low 40s from
Great Falls south to Bozeman/Dillon. Some concern these temps may
be a bit warm given the fresh snow cover and extensive cloud cover
expected Mon, but with strong majority of models in close
agreement, it's hard to argue against it at this point. Westerly
flow also should promote a fair amount of drying in the low
levels, so snow will be mainly confined to the western and
southwestern mtns, with just spotty precip coverage over the
central plains. Waranauskas

Monday night through Saturday...Models start the medium range period
in decent agreement. The combination of an upper ridge along the
west coast and a persistent closed upper low over British Columbia
results in a moist and unstable northwest flow aloft. Scattered snow
will occur over the western and southwest mountains while the plains
will see isolated light snow. The upper ridge amplifies on Wednesday
as the closed low pushes east into northern Saskatchewan. Weak short
wave energy moving through the upper ridge will continue to produce
mountain snow showers with isolated snow over the plains. A lee side
trof develops Wednesday afternoon and persists into early Thursday
resulting in breezy conditions. Thursday afternoon will see an
increased chance for light snow as an upper trof knocks down the
ridge and moves east of the Continental Divide. As the upper ridge
rebuilds over the west coast, unstable northwest flow aloft will
continue to bring scattered snow to the plains. By Friday, the upper
ridge begins to rebound but weak short wave energy moving down the
front of the ridge will allow for some lingering snow showers over
the plains. The upper ridge axis moves over the Pacific Northwest
Saturday bringing drier and warmer conditions to the area. The
models disagree on the orientation of the ridge but both maintain
generally dry conditions. Afternoon temperatures will generally be
slightly below seasonal averages through the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF -22   3  -4  31 /  60  40  60  20
CTB -26  -2 -11  24 /  50  40  60  20
HLN -16  18  13  38 /  40  50  60  30
BZN -17  26  19  39 /  20  40  60  30
WEY   6  36  24  40 /  60  70  70  50
DLN  -5  31  22  38 /  30  50  50  30
HVR -19   2  -9  16 /  30  40  60  40
LWT -26   2  -3  34 /  30  40  50  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WIND CHILL WARNING until Noon MST Sunday Blaine...Cascade...
Central and Southern Lewis and Clark...Chouteau...Eastern
Glacier...Eastern Pondera...Eastern Teton...Fergus...Hill...
Judith Basin...Liberty...Meagher...Northern Rocky Mountain
Front...Southern Rocky Mountain Front...Toole.

&&

weather.gov/greatfalls
www.twitter.com/NWSGreatFalls
www.facebook.com/US.NationalWeatherService.GreatFalls.gov

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>