000
FXUS65 KTFX 250206
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
806 PM MDT Wed Apr 24 2024

.SYNOPSIS...

Clouds will be on the increase tomorrow as our next weather
system begins to push into the area. Expect cool and wet weather
Friday and Saturday, with significant snow accumulations possible
above 7000 feet. The cooler and active weather pattern will
continue through at least the middle of next week.

&&

.UPDATE...

Only adjustment to the overnight forecast period was to speed up
the coverage of isolated to scattered showers over Southwest and
Central Montana to the current time (around 8 pm) due to increased
coverage of radar echoes. While many of these showers are likely
not reaching the ground at this time, some may start to if they
linger long enough to moisten the lower levels of the atmosphere.
Granted, am not expecting much more than a few hundredths of an
inch, but wanted to address the more rapid development of these
light showers. Overall, much of this shower activity should
diminish later tonight. Otherwise, the wind and temperature
forecasts appear to be on track, as it should be another mild
night with decreasing westerly winds. -Coulston

&&

.AVIATION...
515 PM MDT Wed Apr 24 2024 (25/00Z TAF Period)

VFR conditions are forecast to mostly continue across North
Central, Central, and Southwest Montana through at least 26/00Z.

The flow aloft will increase somewhat and become more
cyclonically southwesterly through 06Z. This will generally move
high- and mid- level cloudiness over the area and cause some
mountain wave turbulence. A disturbance in the flow will bring
isolated to scattered mainly mountain showers to portions of
Southwest (KBZN KEKS) and Central (KHLN KGTF KLWT) Montana
through 12Z, but the likelihood that showers will directly impact
those terminals is low. However, in the wake of the disturbance,
lower VFR ceilings will move into Southwest Montana ahead of
another disturbance, possibly causing some mountain top
obscuration. Overall, this disturbance will spread increasing
cloudiness northeast over the area; it will also increase shower
and thunderstorm activity over Southwest Montana after 18Z, with
the main threats being erratic wind gusts and brief heavy showers
with periods of low VFR/MVFR conditions.
-Coulston

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

&&

.PREV DISCUSSION...
/ISSUED 515 PM MDT Wed Apr 24 2024/

Key Points:

-Warmth continues through Thursday
-Cooler and wetter weather arrives Friday and Saturday with some
 higher elevation snow
-Temperatures moderate early next week, even as rain chances
remain

Short term (through Thursday)... Warm temperatures and mostly
clear skies have been the norm today as a ridge of high pressure
centered just to our east allows warm southwesterly flow to bring
warm air into North Central and Southwestern Montana today. While
skies have been clear so far, the warm southwesterly flow will
have sufficient moisture with it to kick off a few showers and
maybe a thunderstorm or two, especially across Southwestern
Montana and even onto the plains of North Central Montana.
Thursday will see warmth continue across North Central and
Southwestern Montana, though increasing clouds will hold
temperatures slightly cooler tomorrow. Expect highs tomorrow to
generally be in the 60s area wide. As we head into the evening,
the clouds will begin to result in some mountain snow and valley
rain across Southwestern Montana, mainly southeast of a line from
Dillon to White Sulphur Springs. While this will be the beginning
of our next weather event, Thursday will not see much in the way
of significant impacts, as precipitation will generally be light
and snowfall totals generally confined to the highest peaks.

Extended (Friday through next Wednesday)... As a broad and slow
moving upper level low pressure system begins to push into the
Intermountain West, precipitation will begin to become more
widespread and more intense, especially South of I-90. As this
precipitation continues, we will see a combination of dynamic
cooling, wet bulbing, and some advection of cooler air coming in
from the north. This combination of cooling effects will result
in noticeably cooler temperatures across the area, keeping highs
across the area in the 50s Friday and Saturday across the lower
terrain, with temperatures staying closer to freezing above 7000
feet. With this in mind, we will see some significant
accumulations of snow across the mountains south of I-90, with
some peaks seeing 12-18” of snowfall between Friday and Saturday.
At lower elevations, precipitation should be mostly rain, though
I cannot rule out some brief periods of snow reaching the ground
where some heavier precipitation sets up. With all of this in
mind, I have gone ahead and issued a Winter Storm Watch for the
mountains south of I-90 for this event.

As we head into the day on Sunday, we will begin to dry out as
our weather system begins to push off to the east and upper level
flow becomes southwesterly. While this will result in a dry day
on Sunday across the plains, we will see precipitation return to
the higher terrain of the southwest as our next weather system
pushes in from the west. This active weather pattern will
continue into at least the middle of next week, though there is
considerable uncertainty on the number and timing of systems next
week. Ludwig

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  43  66  41  58 /  20  10  10  50
CTB  38  60  37  51 /  10   0   0  30
HLN  44  67  42  59 /  20  10  20  70
BZN  39  64  38  55 /  20  50  70  90
WYS  33  55  32  49 /  30  80  70  90
DLN  39  63  38  53 /  20  40  50  80
HVR  43  68  40  65 /  10   0   0  10
LWT  41  63  39  54 /  20  20  40  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Friday morning through late Saturday
night for Gallatin and Madison County Mountains and Centennial
Mountains-Northwest Beaverhead County-Ruby Mountains and
Southern Beaverhead Mountains.

&&

$$

http://www.weather.gov/greatfalls