Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 200453
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1055 PM MDT Sun Oct 19 2014

UPDATED AVIATION DISCUSSION

.DISCUSSION...

Tonight through Tuesday...Large amplitude ridge continues to
amplify over the northern Rockies tonight. This will maintain
clear skies, light winds, and mild temperatures. The ridge axis
shifts to the east on Monday with a strengthening southwesterly
flow aloft. Record high temperatures are possible Monday at some
locations even with increasing high clouds. Model solutions generally
agree that a short wave trough will amplify while moving across
the Pacific northwest. The ECMWF solution is faster than others
while the NAM feature is a bit slower and breaks off further to
the southwest. A consensus approach will bring precipitation
through the zones from southwest to northeast on Tuesday, with the
highest POPs over the southwest. Snow levels will drop to around
6000 feet Tuesday night, but with only light accumulation expected
over the peaks of southwest Montana. Nutter

Tuesday Night through Sunday...Forecast models differ on the timing
of a shortwave trough that is expected to move across Montana
Tuesday night. The ECMWF is the faster solution with the trough
exiting Tuesday night, while the GFS and Canadian solutions push the
trough across the Treasure State Tuesday night. Have gone with a
model blend and increased POPs to high chance for the mountains
across central/southwest Montana and slight chance to chance POPs
elsewhere. Snow levels will lower to around 6000 feet Tuesday
night with an inch or two of wet snow possible in the mountains
along the Continental Divide and southwest/central Montana.
Precipitation will be all rain for elevations below 6000 feet.

Drier and seasonal conditions will return for the middle to latter
part of the week under weak upper-level ridging. As the flow aloft
becomes more westerly, breezy conditions will develop along the
Rocky Mountain Front. In addition, increasing Pacific moisture will
keep chances for showers in the higher terrain along the Rocky
Mountain Front and Continental Divide. By late next week, some
forecast models hint at a chance for precipitation in the
plains/valleys associated with another trough of low pressure, but
there remains several differences between the forecast models.
Temperatures will be near to above seasonal averages through the
forecast period. MLV

&&

.AVIATION...
UPDATED 0455Z.
Expect clear skies with the exception of a few clouds near 14000 ft
MSL Monday afternoon. Winds will be 10 knots or less with the
exception of southwest winds 10 to 20 knots along the east slopes of
the Rocky Mountains Monday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  76  48  61 /   0   0  10  40
CTB  41  77  44  60 /   0   0  10  40
HLN  42  73  45  60 /   0   0  10  50
BZN  34  71  39  63 /   0   0  10  40
WEY  27  61  31  52 /   0   0  10  50
DLN  39  72  43  58 /   0   0  20  60
HVR  39  75  40  67 /   0   0   0  20
LWT  43  76  47  67 /   0   0   0  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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