Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 202025
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
225 PM MDT Mon Oct 20 2014

.DISCUSSION...

Tonight through Wednesday...Southwest flow aloft increases tonight
as an upper level trough, currently moving onto the West Coast,
moves inland. Clear skies this evening will give way to increasing
cloudiness overnight with a few showers developing along the
Continental Divide late tonight in advance of the trough. The upper
level trough takes on a negative tilt as it moves into the Great
Basin Tuesday then lifts NE across MT Tuesday night. The negative
tilt will slow the progression of the frontal boundary some and aid
in the development of a band of frontogenetic precipitation from SW
to NE across SW/W-Central MT Tuesday afternoon and evening. Frontal
boundary pushes east through the forecast area tomorrow afternoon
and evening with precipitation lingering over eastern zones through
late Tuesday night while areas further west begin to clear late
Tuesday evening behind the departing system. Drier conditions move
in Wednesday under weak upper level ridging with temperatures
cooling to near seasonal averages. Snow levels look to remain above
passes along the Continental Divide though most of the day tomorrow
then fall very late in the afternoon or evening to 5000-6000 ft. 1
to 3 inches of snow accumulation is possible above 7000 ft in the
Elkhorn, Deer Lodge, Pioneer and Beaverhead mountain ranges with a
brief change-over to snow possible as precipitation ends Tuesday
evening over passes in these Mtn Ranges, however little to no
accumulation is expected on road surfaces. Hoenisch

Wednesday Night through Monday...Overall, westerly Pacific flow will
dominate during the forecast period. This pattern will keep high
chances for rain and snow showers in the higher terrain along the
Rocky Mountain Front and Continental Divide. Breezy westerly
downslope winds will limit precipitation chances over the plains and
valleys. Long-range forecast models continue to hint at a stronger
trough of low pressure by the weekend, which could bring better
chances for precipitation, especially across southwest Montana.
Downslope conditions will continue to keep low precip chances and
breezy conditions over the north-central plains. Temperatures will
be near to slightly above seasonal averages through the forecast
period. MLV

&&

.AVIATION...
UPDATED 1720Z.
High pressure aloft will continue as will dry and stable conditions.
Winds over the plains will be light but will be breezy at times
along the Rocky Mountain Front. VFR conditions prevail.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  49  60  38  60 /   0  60  40   0
CTB  44  55  37  61 /  10  60  20   0
HLN  45  59  37  60 /  10  70  40  10
BZN  40  63  31  56 /   0  40  50  10
WEY  32  48  24  46 /  10  60  50  10
DLN  44  58  31  56 /  10  60  50   0
HVR  41  65  41  62 /   0  30  30  10
LWT  47  69  39  60 /   0  30  50  10

&&

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

$$

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