Helena Valley, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

974
FXUS65 KTFX 030551
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1151 PM MDT Wed Apr 2 2025

Aviation Section Updated.

.KEY MESSAGES...

- A round of accumulating snow and gusty northerly winds
  arrives tonight into Thursday, mostly impacting the Rocky
  Mountain Front, the Hi-Line, and areas over and adjacent to the
  Little Belt Mountains.

- A warming and drying trend pushes temperatures back above
  average this weekend into early next week.

- a passing disturbance may bring some breeziness and a chance
  for showers heading towards the middle of next week.

&&

.UPDATE...
/Issued 848 PM MDT Wed Apr 2 2025/

Evening update has been published, with the primary adjustment
being to increase PoPs by an additional 10-20% over the plains of
North Central Montana where confidence continues to grow in
accumulating snow through the overnight hours tonight and into
portions of the day on Thursday, especially in areas covered by
the Winter Weather Advisory. Otherwise the remaining updates
resulted in no significant changes from the previous forecast.
Current suite of Winter Weather Advisories highlight the potential
spread of snowfall accumulations and associated hazards well,
with latest radar imagery supporting and uptick in precipitation
spilling east from the Continental Divide as the upper level
shortwave approaches the Northern Rockies this evening. Latest
Hi-Res Ensemble Forecast (HREF) guidance continues to support a
period of moderate to at times heavy snow falling along and north
of the US Hwy 2 corridor from Marias Pass to Havre from midnight
tonight through 6 AM MDT Thursday, with snowfall rates of 1/4" to
3/4" per hour occurring across this region. These higher snowfall
rates will lead to snow covered and slippery roadways, which will
make for a hazardous morning commute on Thursday for these areas
and even outside of the current advisory area as even light
accumulations on roadways can lead to slippery conditions. -
Moldan

&&

.DISCUSSION...
/Issued 848 PM MDT Wed Apr 2 2025/

 - Meteorological Overview:

The steadier snows from this morning continues to wind down as
the responsible low pressure system moves away from the region;
however, a weakly unstable boundary layer has been left in its
place and is now initiating scattered rain/snow showers and even a
few rumbles of thunder. This activity looks to persist through
the afternoon before the next shortwave trough brings in the next
opportunity for accumulating snow.

The snow initially picks up along the Rocky Mountain Front and
the Hi-Line tonight and then moves southward into Central/North-
central Montana and eventually Southwest Montana on Thursday.
There will also be a brief period of gusty northerly winds behind
the front, but strong winds are not expected. This system will be
fairly quick moving with snow ending in a north to south fashion
by Thursday evening through the overnight hours.

Ridging aloft slowly builds over the Northern Rockies heading
into the weekend for warming and drying conditions. An overall
mild pattern continues into next week, though passing disturbances
may increase winds and shower chances Tuesday and Wednesday. -RCG

 - Forecast Confidence & Scenarios:

Accumulating snow tonight and on Thursday...

The shortwave that brings the next round of snow tonight will be
supported by H500/H700 temperatures down to -30/-20C respectively.
Today`s suite of model guidance has picked up on this with a
marked increase in QPF across the board, but especially along the
Rocky Mountain Front, the Hi-Line, and areas near and adjacent to
the Little Belt Mountains. Most of these locations will see
amounts in the 3 to 6 inch range with some higher amounts in the
Marias Pass and Glacier National Park areas. As mentioned above,
there will also be a period of gusty northerly winds that
accompanies the snow. I did expand the winter weather advisories
along the Rocky Mountain Front to include all of the Hi-Line and
the Bears Paw/Little Belt Mountains. Some consideration was given
for further expansion over the plains and parts of the southwest,
but the core of the shortwave`s energy does move off to the east
rather than moving directly south. additionally, most of the
forecast snow amounts were less than 2 inches. Snow ends for most
locations by Tuesday night. - RCG

&&

.AVIATION...
03/06Z TAF Period

A cold front pushing southward across Montana will bring a mix of
VFR to IFR conditions with LIFR conditions possible in heavier
snow showers. Expect snow to mainly be found around KCTB, KGTF,
and KHVR through 12z before snow spreads further south to KHLN,
KBZN, and KEKS Thursday morning. Snow showers capable of LIFR
conditions will be possible during the daylight hours on Thursday.
While they have not been put into the TAFs at this time, the
greatest threat for LIFR conditions will exist at KHLN, KEKS, and
KBZN. Ludwig

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  42  27  34  19 /  50  40  90  30
CTB  38  23  33  14 /  40  90 100  10
HLN  45  26  42  22 /  60  20  70  40
BZN  44  23  44  21 /  80  30  60  70
WYS  41  13  40  16 /  50  50  60  60
DLN  42  25  45  23 /  60  40  40  40
HVR  44  24  37  17 /  20  90 100  10
LWT  40  23  34  18 /  50  20  70  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT Thursday for East Glacier
Park Region-Eastern Glacier, Western Toole, and Central Pondera-
Northern High Plains-Southern High Plains-Southern Rocky
Mountain Front.

Winter Weather Advisory until 6 PM MDT Thursday for Bears Paw
Mountains and Southern Blaine-Eastern Toole and Liberty-Hill
County-Northern Blaine County.

Winter Weather Advisory from 9 AM Thursday to midnight MDT
Thursday night for Little Belt and Highwood Mountains.

&&

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