Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 230349
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
849 PM MST Sat Nov 22 2014

.UPDATE...

The surface low and upper level trof that caused widespread high
winds this afternoon is tracking further away through southern
Saskatchewan. The surface pressure gradient has weakened, as has
the post-frontal subsidence. Observed winds are now all below high
wind criteria. Strong gusty winds will continue through early
Monday, but expected to trend lower. Therefore, have dropped the
high wind warning and lowered the forecast wind speeds accordingly.
A subtle shortwave feature is producing snow over central Idaho.
Short term model guidance moves this feature with light snow
showers across south- central and southwest Montana through Monday
morning. Additional snow accumulation will be less than 2 inches.
The winter weather advisory in this area will continue through
Monday morning for snow and blowing snow. Light flurries also
continue over the Northern Rockies, but dropped the winter weather
advisory here as little, if any, new snow accumulation is
expected. Nutter

&&

.AVIATION...
UPDATED 2335Z.
Upper-level trof and its associated cold front and precipitation
that moved thru the region earlier today is now mostly in eastern
MT.  Tight surface pressure gradient and strong winds aloft from
that system will continue to generate gusty winds through 02-04Z
with area of strongest winds (G35-50kts) along/north of a KHLN-to-
KLWT line.  Winds will gradually decrease (gusts 20-25kts or less)
this evening as the trof heads further downstream.  Meanwhile,
latest radar/satellite imagery showing a second weaker disturbance
just crossing the US/Can border into north central MT, bringing
mid-level (generally above 6000 ft) ceilings and some isolated -SHRA
vcnty KHVR. Expect this system to track south-southeast this
evening, with VFR conditions continuing into tonight. Lastly, a
third system, this one currently over near WA/ID border, will arrive
early Sun morning, with scattered showers and ceilings lowering to
around 3500-4000 ft at KHLN/KLWT/KBZN around 10-12Z.
Waranauskas

&&

.PREV DISCUSSION...
/ISSUED 435 PM MST Sat Nov 22 2014/

Tonight through Monday...The cold front has moved through most of
North Central and Southwest Montana as of 3 pm. Strong gusty west
winds will continue across most of North Central Montana through
the evening, so will let the High Wind Warning continue there
through 10 pm. Spotty strong wind gusts are expected across
Southwest Montana, but they will likely remain below high wind
criteria. Overall, winds will decrease overnight, but breezy
westerly surface winds will persist into the beginning of next
week. The shortwave trough associated with the cold front is also
moving through the area, and a disturbance in the resulting
northwesterly flow aloft will keep a chance of snow showers across
much of the area overnight. Although additional snowfall in the
mountains will be only a matter of 1 to 3 inches, the fact that
snow showers will likely continue overnight is enough to keep the
Winter Weather Advisory in effect through tonight. A series of
disturbances in the northwest flow will keep at least a chance of
snow showers around through Sunday night, especially in the
mountains. However, am not anticipating enough snowfall to warrant
further winter weather highlights at this time, but the situation
will continue to be monitored. Temperatures in the wake of the
cold front will likely only cool to just below seasonal averages.
Coulston

Monday night through Saturday...Unsettled weather continues into
the long term forecast as Northwesterly flow aloft will allow for
some instability to move across the area Monday night and Tuesday.
Models have tended to come into a little better agreement with a
cooler and wetter solution for Wednesday through Friday and have
trended the forecast that way. Some decent snowfall amounts are
expected in the higher terrain at this time but models differ on
the details of how much will fall and where the heaviest snow will
be. It now appears that travel plans could be affected at least
over mountain passes and winter weather highlights might
eventually be needed. Blank/Suk

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  50  27  39  25 /  20  10  10  20
CTB  43  23  36  24 /  20  20  10  10
HLN  48  28  39  27 /  50  20  20  30
BZN  47  18  34  18 /  90  30  20  40
WEY  35  11  25  11 / 100  50  40  60
DLN  43  20  32  16 /  90  30  20  30
HVR  51  26  35  22 /  20  40  20  30
LWT  50  26  36  24 /  20  30  30  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until 5 AM MST Sunday For US 89 over
Kings Hill Pass.

WINTER WEATHER ADVISORY until 5 AM MST Sunday Beaverhead...
Gallatin...Madison.

&&

$$

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