Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 210928

Area Forecast Discussion
National Weather Service Great Falls MT
328 AM MDT Fri Oct 21 2016


Today through Saturday...A shortwave high pressure ridge will move
eastward over our CWA today, providing many places with partly
cloudy skies and dry conditions. The exception will be the Rocky
Mountain Front, where a few rain showers and higher-elevation
upslope snow showers may spill-over the Continental Divide.
Tonight, a weather disturbance will move onshore western WA and OR
and near the Continental Divide around daybreak Saturday. This
disturbance should then reach the MT/ND border by nightfall.
Expect mostly cloudy skies and scattered rain showers/higher-
elevation snow showers to accompany this disturbance, especially
for areas north of I-90. In addition, high-resolution models
suggest a mesoscale rain band may impact portions of North-Central
Montana Friday night into Saturday morning due to confluent flow
and frontogenesis amidst abundant moisture within the 850-500 mb
layer, ahead of the disturbance. While rainfall amounts should
generally be a few hundredths to a tenth of an inch, this
mesoscale band may produce a tenth to a quarter of an inch of
rainfall. Latest indications suggest this band will develop over
the Chouteau to Havre corridor and then impact locations such as
Great Falls, Fort Benton, Chinook, and Roy as it moves eastward.
However, confidence in the occurrence and location of this band is
low at this time. Most places will have highs in the mid 50`s to
lower 60`s today, lows in the mid 30`s to lower 40`s tonight, and
highs in the 50`s Saturday. Snow levels will vary between about
6000 and 8000 feet MSL throughout the period, with the lowest
(highest) snow levels near Glacier Park (the Idaho border and
Yellowstone Park).

Saturday Night through Sunday...Dry weather should return to our CWA
by Saturday evening and then continue through Sunday as another
shortwave high pressure ridge moves in from the Pac NW. Under partly
to mostly cloudy skies, lows should reach the low to mid 30`s for
most places Saturday night and be followed by highs in the mid 50`s
to lower 60`s Sunday afternoon. Temperature readings will be near-
normal to about 10 degrees above normal during the short-term
forecast period. Jaszka

Sunday night through Friday...Large scale weather pattern next week
generally features a trough off the west coast with a ridge
downstream over the Northern Rockies and MT. Early next week models
are in fair agreement in the upper ridge amplifying over the
region and bringing milder than average temperatures and generally
dry conditions. By Tuesday night, weakening Pacific energy ejecting
out of the offshore trough moves through the region for some showers,
though precipitation amounts look to be fairly light. Slight cooling
is anticipated behind this feature for Wednesday. Models diverge some
with the degree of ridging that will follow for latter portions of
next week with the ECMWF/CMC models bringing a quick re-
amplification of the ridge while the GFS brings several northern
stream shortwaves across the Canadian Prairies and northern Plains
states, which results in suppressed ridging and delayed warming.
Leaning more towards the ECMWF/CMC solution at this point but both
scenarios are relatively dry for the region with temperatures near
or somewhat above seasonal averages. Hoenisch


.AVIATION...Updated 0428Z.

An upper level disturbance is moving through the west flow aloft and
causing brisk and gusty winds at the surface. Widespread gusts to 30
kts will diminish during the night as the disturbance moves east of
the region. Moisture will continue to cross the Continental Divide
from the west and result in isolated showers over the Rockies. Areas
east of the Rockies will remain dry. VFR conditions will prevail
through the next 24 hours.


GTF  60  42  57  36 /  10  30  40  10
CTB  56  37  54  32 /   0  20  20   0
HLN  62  39  57  35 /  10  20  30  10
BZN  61  37  59  36 /   0  10  10  10
WEY  50  30  53  30 /   0   0  10   0
DLN  61  35  58  35 /  10  10  20   0
HVR  59  39  56  32 /   0  20  30   0
LWT  60  40  55  36 /   0  10  40  10



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