Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 220942

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


Today...A shortwave trough over eastern WA and northeast OR at
time of writing 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

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


.AVIATION...Updated 0440z.

A weak upper-level disturbance will cross the Rockies tonight and
bring a chance of showers across central and northern portions of
the region. Most areas affected by precipitation will remain VFR
although local MVFR near showers is possible as well as mountain
obscuration. Dry conditions and brisk west winds will develop
Saturday behind the associated cold front.


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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