Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 221138

Area Forecast Discussion
National Weather Service Great Falls MT
537 AM MDT Sat Oct 22 2016



Today...A shortwave trough entering western MT should reach the MT/ND
border by early this evening. Mostly cloudy skies this morning will
become partly cloudy this afternoon as the disturbance exits our
region. As for precipitation, expect scattered rain showers and
higher-elevation snow showers to impact areas mainly north of a
Helena to Grass Range line this morning. Snow levels will range from
near 6000-7000 feet in North-Central MT to near 7000-9000 feet MSL in
Southwest MT. In addition, confluent flow and resulting frontogenesis
within the 850-500 mb layer along and ahead of the disturbance,
combined with ample moisture within the aforementioned layer, will
allow a mesoscale band of light to moderate rain to impact portions
of North-Central MT. While rainfall amounts will mainly reach only a
few hundredths to a tenth of an inch, still expect this rain band to
produce higher rainfall totals of a tenth to a quarter of an inch as
it moves east-northeastward. The areas most likely to receive these
higher rainfall totals extend from eastern Teton County to western
Hill County and then east-northeastward through the Havre/Fort
Benton areas to northern Blaine County. A few rain showers may linger
over northern Blaine County early this afternoon, but otherwise dry
weather is expected as a shortwave high pressure ridge begins
building-in from the Pac NW. Highs this afternoon will reach the mid
to upper 50`s in many locations.

Tonight through Monday...The aforementioned shortwave ridge will
provide most of the CWA with dry weather during this period as the
ridge axis moves eastward to the central Dakotas by early Monday
evening. However, a few rain showers and higher-elevation snow
showers may impact Southwest Montana on Monday as moist southwest
flow aloft, ahead of the next weather disturbance approaching the Pac
NW coast, becomes established over the CWA. Snow levels should
be near 9000-10000 feet MSL in Southwest MT during that time.
Partly to mostly cloudy skies are expected throughout the period
since widespread mid- to upper-level cloud cover looks to spill-
over the shortwave ridge as the aforementioned disturbance
approaches. Lows tonight will mainly reach the upper 20`s to lower
30`s, while Sunday will have highs in the 50`s to lower 60`s.
After Sunday night lows in the mid 30`s to lower 40`s, Monday will
have milder highs in the upper 50`s to mid 60`s for most. Jaszka

Monday night through Saturday...Medium range models generally
maintain a large scale trough off the west coast with ridging
downstream and inland over the Inter-mountain west through much of
next week. While the ridge extending north through the region will
keep temperatures above seasonal averages Tuesday through Thursday,
weak shortwave energy ejecting over the ridge will keep some
cloudiness and a small chance for showers, mainly over the western
Mtns. By Friday and Saturday, there is significant spread among
medium range models as pieces of the offshore trough begin to move
into Western US.  This will bring an increase in chances for
precipitation with temperatures trending back toward seasonal
average. Hoenisch


Updated 1137Z.

Predominantly VFR expected through 12Z/Sun. An eastward-moving
weather disturbance entering western MT at time of writing is
expected to reach the central third of MT around 18Z/Sat. Broken mid-
to upper-level cloud cover through about 18Z/Sat should become
scattered thereafter as a high pressure ridge builds-in behind the
disturbance. Scattered rain showers are expected before 18Z/Sat,
especially north of a KHLN to KLWT line. Brief MVFR ceilings and
visibility may accompany the more persistent showers. This includes
KGTF and KHVR. After 16Z/Sat, expect gusty southwesterly to westerly
surface winds to develop over the plains of North-Central MT before
easing around 00Z/Sun. Jaszka


GTF  58  33  58  40 /  60   0  10  10
CTB  53  28  51  35 /  20   0  10  10
HLN  57  33  60  38 /  20   0  10   0
BZN  57  33  61  40 /   0   0  10   0
WEY  51  28  55  32 /   0   0  10   0
DLN  58  32  60  37 /   0   0   0   0
HVR  56  30  56  34 /  50   0   0  10
LWT  56  33  57  39 /  10   0  10   0



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