Helena Valley, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

938
FXUS65 KTFX 102045
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
145 PM MST Sun Nov 10 2024

.KEY MESSAGES...

 - Light snow Monday night into Tuesday and again Wed into Thu
 - Windy in the Cut Bank area Tuesday and Thursday
 - Potential for a widespread heavier snowfall Fri night into Sat

&&

.DISCUSSION...

 - Meteorological Overview:

A Canadian cold front is moving southward through North Central
MT currently. Slightly cooler air is also moving southward, but
this front will begin to retreat and move back northward tonight.
Several weather systems will affect North Central and Southwest MT
this week. Overall, generally light precipitation is expected
through Thursday, with the potential for a more impactful snowfall
Friday night into Sat. It will be windy at times, especially in
the Cut Bank area Tuesday and again on Thursday. A high wind watch
was issued for Tue.

 - Forecast Confidence & Scenarios:

A moist southwest flow aloft will continue to affect the CWA
through Thursday. As a result expect a few showers along the
divide tonight and through the day on Monday, otherwise confidence
is higher for a light snow over the Rocky Mountain Front and
Southwest MT Monday night into Tuesday. As of now, about 3 to 7
inches of snowfall is likely Monday night into Tue for the
mountains around Big Sky. There is about a 50 percent chance for
1 or 2 inches on Bozeman Pass, Raynolds Pass and in the West
Yellowstone area during this period, thus for now I am thinking
just a special weather statement will be issued for this event.
However, later shifts might decide to issue a short WSW should
impacts become higher at lower elevations. For Wednesday night
into Thursday, the snow amounts and 50 percent confidence area
looks to be confined mostly to the Rocky Mountain Front and again
only around 2 inches look possible over Marias Pass, so holding
off on a WSW for this event as well.

For Friday/Saturday...the GFS/EC have quite the different
solutions for Central/North Central MT. The GFS is almost dry over
North Central MT, with some light snow over Central MT. The EC has
over 1 inch of QPF over North Central, all falling in the form of
snow. The EC would result in major winter snowfall over North
Central MT. Thus confidence is generally less than 50 percent at
this time for the EC to pan out, but that could change quickly to
higher confidence over the next few days should the GFS start to
develop the same situation.

The other concerns this week are the wind potential. The NBM has
increased the chances for 58 mph wind gusts on Tuesday to over 80
percent for the Cut Bank area. Thus a high wind watch has been
issued. For areas further west, There is generally less than a 70
percent chance for peak wind gusts to be lower than 75 mph, thus
high wind watch for those area at this time. A special weather
statement might be needed should wind gusts go over 60 mph though.
On Thursday, a very similar pattern develops in these same areas,
with the potential for additional high wind statements. Brusda

&&

.AVIATION...
10/18Z TAF Period

Light mountain snow arrives this afternoon, with a low chance for
some brief light rain at KHLN. Other than that, mid to high
clouds will be passing through. A cold front towards the
MT/Canada border will bring MVFR/IFR ceilings to KCTB and KHVR
this afternoon. Another boundary sweeping across the region later
tonight will shift surface winds to the south. -Wilson

The KWYS TAF will not be issued until airport operations resume next
spring.

Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  36  60  38  51 /  10   0  10  10
CTB  29  57  34  47 /   0   0  10  10
HLN  32  58  34  49 /  20   0  20  20
BZN  28  57  30  45 /  10   0  30  50
WYS  18  44  21  34 /  40   0  70  90
DLN  29  53  28  43 /  10   0  30  40
HVR  27  59  34  54 /   0   0  10  10
LWT  31  59  33  49 /  10   0   0  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from Tuesday afternoon through Tuesday evening
for Eastern Glacier, Western Toole, and Central Pondera.

&&

$$
http://www.weather.gov/greatfalls