Helena Valley Northwest, MT 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

606
FXUS65 KTFX 310313
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
913 PM MDT Sun Mar 30 2025

.KEY MESSAGES...

- Spring storm to affect the southern half of the CWA Monday night
  into Tuesday night.

- Overall, afternoon temperatures not as warm as last week through
  at least Friday.

- Next weekend is looking nicer and a bit warmer.

&&

.UPDATE...

Tonight it will be cool and mostly cloudy across North-central,
Central, and Southwestern Montana. Tomorrow it will be warmer
than today with isolated thunderstorms in the afternoon and
evening. For the update hourly temperatures, dewpoints, and
relative humidities were refreshed. Winds were adjusted to better
reflect current observations and trends. The rest of the forecast
is on track. -IG

&&

.DISCUSSION...
/Issued 145 PM MDT Sun Mar 30 2025/

 - Meteorological Overview:
A few light snow showers/flurries continue to linger over portions
of the CWA this afternoon, as the upper level disturbance exits
the CWA to our east. The next upper level disturbance arrives on
Mon afternoon, with a chance for showers/isolated thunderstorms as
it moves northward from Southwest MT into Central MT. On Monday
night, a stronger upper level trof will move over the southern
portions of the CWA, with strong convective bands of precipitation
possible. These convective bands could produce some good snowfall
rates in the mountains. Thus a winter storm watch has been issued
for some mountain ranges of Central and Southwest MT. It is likely
that some winter weather advisories will also be needed for areas
surrounding the winter storm watch as well.

Overall, the steadier precipitation ends Tuesday night over
Southwest MT, with scattered rain/snow showers then continuing
into Friday. However, the precipitation will become more isolated
Thu/Fri. Afternoon temperatures will generally be below normal for
much of the CWA through the work week.

Looking ahead to next weekend, an upper level ridge of high
pressure will try to build into the CWA from the west, resulting
in drier/warmer conditions moving back into the CWA by next
Sunday.

 - Forecast Confidence & Scenarios:
The main concern is the snowfall potential Mon night into Tuesday
over Central and Southwest MT. There is a 60 percent chance
snowfall could exceed 6 inches in the mountains. Additionally,
there is a 10 percent chance snow amounts could exceed a foot.
This potential has lead to a winter storm watch for some mountain
areas of Central/Southwest MT. There is the potential for some
higher snowfall amounts in the Elkhorn Mountains as well, but with
no mountain passes directly affected by the higher snowfall
amounts, no watch will be issued at this time.

Of second concern, is the GFS model that has lower levels and
some convective snowfall in the Helena and Bozeman areas. This
potential will be watched closely as higher resolution models
become available for the possible need to expand the winter storm
watch. Brusda

&&

.AVIATION...
30/18Z TAF Period

The initial concern this TAF period is for lingering light snow
and low clouds. Remaining snow is forecast to diminish this
afternoon, with ceilings slowly rising in most areas. Additional
low clouds will be a concern this evening and tonight, mostly
across the plains, but in some southwest MT valleys as well. Fog
will be a concern where skies at least briefly clear a bit tonight
on the plains. -AM

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  27  49  33  46 /   0  40  60  60
CTB  25  44  29  47 /   0  30  20  30
HLN  30  50  32  44 /  10  60  60  60
BZN  26  49  27  40 /  10  50  60  70
WYS  22  40  19  36 /  70  70  70  80
DLN  27  46  28  38 /  10  40  50  50
HVR  24  50  29  46 /   0  20  30  40
LWT  25  47  28  39 /  10  40  60  70

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Monday evening through Tuesday evening
for Big Belt, Bridger and Castle Mountains-Gallatin and Madison
County Mountains and Centennial Mountains-Little Belt and
Highwood Mountains.

&&

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