947
FXUS65 KTFX 182056
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
256 PM MDT Fri Apr 18 2025

.KEY MESSAGES...

- A Pacific cold front will bring more unsettled conditions
  late Saturday through at least the middle of next week, with
  lower elevation scattered rain showers, mountain snow, and a few
  thunderstorms.

- Temperatures warm as much as 5 to 10 degrees above average on
  Saturday before cooling closer to seasonal averages for the
  remainder of the period.

&&

.DISCUSSION...

 - Meteorological Overview:

Transient ridging quickly passes through the Northern Rockies
later through much of Saturday for mild and dry conditions before
a Pacific cold front ushers in another period of unsettled
conditions later Saturday afternoon and evening. Southwest to
westerly winds increase tonight and on Saturday along the Rocky
Mountain Front and the plains, but wind speeds will mostly stay
below 40 mph except for the normally windier spots along the Rocky
Mountain Front and the neighboring high plains.

Scattered shower activity is expected along and behind the front
along with a northerly wind shift. Snow levels will be above 6,000
ft and rainfall/snow melt equivalent amounts will generally range
from trace amounts at lower elevations to around a tenth of an
inch or so in the mountains. Additional periods of showers, mostly
mountain snow, and isolated thunderstorms are expected Sunday
through Tuesday as the main trough slowly traverses the Northern
Rockies.

Southwesterly flow head of the trough`s arrival on Sunday may
send snow levels climbing to the 7,000 to 8,000 ft level on
Sunday before the colder H700/H500 (-10C/-25C) temperatures move
in Monday and Tuesday. With this trough being more broad in nature
and having more diffuse frontogenetic forcing, snowfall amounts
and associated winter impacts are expected to on the minor side.

Most ensembles show a varying degree of troughing over the
Pacific Northwest with a weak southwesterly flow over the Northern
Rockies for the second half of next week. This should maintain
lower grade unsettled conditions with scattered shower activity
and near average temperatures. - RCG

 - Forecast Confidence & Scenarios:

Rain, snow, and isolated thunderstorms late Saturday through
Tuesday...

Although the trough will take its time passing through the
Northern Rockies, a broader, less amplified system looks to result
in less rain and snow and associated winter weather impacts. The
heaviest snow is expected Sunday night through Tuesday morning
when the trough`s cold pool is overhead and snow levels fall down
to the plains and valleys. The best chance (70 to 80%) for
rain/snow amounts in excess of a quarter inch/2 inches during this
timeframe is currently reserved for mountain areas. Roadway
impacts should be mostly confined to the late night and early
morning hours. In addition to the snow, conditions will also need
to be monitored for isolated thunderstorms, especially on Sunday
and Monday with the colder air aloft supporting at least a couple
hundred J/kg of CAPE each afternoon. - RCG

&&

.AVIATION...
18/18Z TAF Period

VFR conditions prevail (except for KBZN) with some mid level
cumulus clouds this afternoon. Lingering MVFR clouds from the
morning at KBZN will persist into the early afternoon, but is
expected to go back to VFR in the afternoon. -Wilson


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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  64  37  60 /   0  10  20  50
CTB  35  56  33  52 /   0  10  10  50
HLN  33  63  37  58 /   0   0  20  40
BZN  21  58  32  57 /   0   0  40  50
WYS  10  50  25  50 /   0   0  30  60
DLN  24  58  31  57 /   0   0  20  20
HVR  30  65  35  60 /   0   0  30  50
LWT  27  61  37  55 /   0   0  20  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

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