Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 192050
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
250 PM MDT Sat Oct 19 2019

.SYNOPSIS...

An upper level disturbance spreading rain and mountain snow
showers into the northern Rockies Saturday afternoon will move
across the region tonight. Rain and snow showers tonight will
change to mostly snow showers at lower elevations later this
evening temperatures cool, with some snow possible across lower
elevation areas. These showers become more scattered on Sunday,
with cooler temperatures, and some breezy winds also expected.
Accumulations across mountain passes in Southwest and Central
Montana could lead to slippery conditions. Those outdoors should
prepare for winter conditions.

&&

.DISCUSSION...

Rest of Today and Tonight...

Upper level trough with vigorous embedded shortwave centered over
the ID/WA border this afternoon will race east, emerging east of
the Rockies over the S-Central MT/NW WY vicinity after midnight,
driven by a strong (160 kt) WNW upper level jet crashing onto the
Pacific NW coast. Rain and snow showers will increase over SW and
Central MT through the remainder of this afternoon as the upper
level circulation moves east with best potential for periods of
heavier precipitation over SW MT where instability is greatest.
As the circulation moves east across SW MT this evening, winds
aloft will come around to the northwest and precipitation will
increase over central MT, particularly over the central MT Mtns
and areas adjacent to the north slopes of the Little Belts. Snow
levels currently near 5000-6000 feet will lower late this
afternoon and evening as cooling aloft increases. Brief but
intense bursts of snow are possible late this afternoon over
portions of SW MT with main impacts to travel expected over Mtn
Passes where temps are already near freezing. A period of snow or
snow showers is a likely from Helena east through Great Falls and
Lewistown late this evening as moisture wrapping around the upper
low combines with nw upslope flow for mainly light accumulations
at lower elevations with several inches expected over the Mtns,
including Kings Hill. Snow accumulation is the SW will similarly
be limited at lower elevations with up to 6 inches or more
possible over some SW MT mtn ranges. Big Hole, Monida and Reynolds
passes look to see the greatest impacts through this evening with
a couple inches of snow also possible over Bozeman Pass. No
changes are planned to the ongoing winter weather advisories for
higher elevations through Sunday morning, with precipitation
still looking to gradually decrease late tonight into Sunday
morning.

Sunday and Monday...

The upper level circulation continues off to the ESE Sunday
leaving a cool and somewhat moist/unstable NW flow aloft in its
wake across the Northern Rockies and MT through Monday.
Temperatures remain about 5-10 degrees below climatological
averages with a few showers at times, mainly focused over the
Mtns. Hoenisch

Tuesday through Saturday...Tuesday looks to see some breezy to
windy conditions in strong westerly flow. These winds could bring
some warming temperatures to more normal readings. Mountain
showers may also continue on Tuesday. Tuesday night through
Wednesday may see a cold front move across the region. Models
still working out the details with some suggesting rain and snow
showers, while others suggesting a more widespread precipitation
event with some lower elevation snow. This will need to be
monitored for any impacts from potential snow. Cooler temperatures
are also likely from this cold front, although may not dip as cold
as recent fronts from the north. Thursday into Friday then sees
week ridging over the area. This may diminish shower activity and
bring some warming temperatures with perhaps some breezy winds.
Friday evening into Saturday could see a clipper type system with
an associated cold front. There is still not good agreement on
this feature. Overall cooler temperatures and perhaps some rain or
low elevation snow will again be possible. Overall the long term
appears active and will need to be monitored for any weather
impacts. Anglin

&&

.AVIATION...
Updated 1130 AM MDT Sat Oct 19 2019(19/18Z TAF Period)

VFR conditions will will begin to diminish into this afternoon and
evening as the next system tracks through central Montana today.
This system will bring mostly VFR to MVFR conditions under snow/rain
showers and lower cloud ceilings for much of Northcentral and
Southwest Montana terminals through Sunday morning. MVFR to brief
IFR conditions can be expected under any shower activity. Mountain
snow showers may also bring mountain obscuration during this same
time period. -TP

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  32  49  30  50 /  90  20  20  10
CTB  28  46  28  47 /  40  10  10   0
HLN  32  47  30  49 /  80  40  30  10
BZN  30  47  27  48 /  80  70  50  30
WEY  19  36  17  37 / 100  30  70  30
DLN  28  42  28  45 /  70  30  40  20
HVR  31  51  28  51 /  60   0   0   0
LWT  31  44  28  45 /  90  50  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM MDT Sunday above 5500 feet
for Broadwater...Cascade...Judith Basin...Meagher.

Winter Weather Advisory until 9 AM MDT Sunday above 5500 feet
for Gallatin...Madison.

Winter Weather Advisory until 9 AM MDT Sunday above 6000 feet
for Beaverhead.

&&

$$

http://www.weather.gov/greatfalls


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