000
FXUS65 KTFX 131955
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
155 PM MDT Sat Apr 13 2024

.SYNOPSIS...

Warm and mostly dry conditions are expected through the weekend as
upper level riding remains over the area. Cooler and wetter
weather are expected for the middle of the upcoming week, with at
least some snowfall expected at all elevations. Snowfall amounts
will likely be on the light side across the plains, with modest
accumulations in the higher terrain.


&&

.DISCUSSION...

Key Points:

-Warmth continues through the weekend

-Cooler and wetter weather expected around the middle of the
upcoming week

-Overall, our upcoming weather system looking less impactful
than previously forecast

Short Term (through Sunday)... Upper level ridging will remain
the main factor in our weather the next few days, keeping us warm
and early summer like with just a few showers over the mountains
of Southwestern Montana. With this upper level ridge in place,
expect most areas to see highs in the 70s today and Sunday under
mostly sunny skies, and while any showers that do develop should
be light, there is a chance that one or two could produce some
gusty outflows, particularly as they begin to dissipate.

Extended (Monday through next Saturday)... As a notable upper
level low pressure system undercuts our ridge Sunday night and
Monday, we will notice a considerable increase in clouds across
the area as some moisture wraps around this system and makes its
way into Montana. While these clouds will limit our warming
potential on Monday, temperatures will still be on the warm side,
with many areas still reaching the upper 60s to near 70. As we
head into the evening hours, we will start to see precipitation
develop over the terrain of Southwestern Montana, which will start
out as mostly rain at all elevations. As we head into the day on
Tuesday, an upper level trough approaching from Alberta and
British Columbia will begin to pour colder air into the area,
which will result in Tuesday being notably cooler than Monday, and
some rain and snow showers will accompany this cooler air. At
this point, we are gaining confidence that this system will wind
up being far less impactful than some initial forecasts showed, as
guidance has begun to converge on the drier and warmer solution,
which results from the moisture from the tropical jet going
further south and east and not meeting up with the British
Columbia/Alberta system until it gets beyond our area. Even with
this moisture missing us, we are still looking for accumulating
snowfall at higher elevations, with most major mountain ranges
seeing the 50th percentile values come in around 6” through
Wednesday, while lower elevations seeing the 50th percentile
values around an inch or less. These values are about where the
10th or 25th percentile was yesterday and the day before, further
increasing confidence in the drier solution. I would be remiss to
mention that there still is about a 10-20% chance of the wetter
solution still happening based on the WPC cluster analysis, but
with 80-90% of models some version of the aforementioned drier
solution, it is hard to give this solution the attention that it
had yesterday.

As the core of this trough moves eastward on Thursday, expect a
drying trend as the atmospheric dynamics go along with it. While
the precipitation will wind down early Thursday, the cooler air
will have a bit of staying power as a decaying upper level trough
axis remains overhead, keeping our flow out of the northwest.
Temperatures will remain below seasonal norms through Friday, with
some hints of some warming for the weekend next week. Ludwig

&&

.AVIATION...
1136 AM MDT Sat Apr 13 2024 (13/18Z TAF Period)

VFR conditions prevail through the TAF period. Some high to mid-
level clouds have developed along the Rocky Mountain Front moving
into the Hi-Plains region along with breezy conditions with wind
gusts up to 25 knots for KCTB through the early evening hours.
Westerly winds diminish tonight becoming calmer for the overnight
period. For KEKS, there is low potential (30%) for a thunderstorm to
develop this afternoon. I have higher confidence for a vicinity
thunderstorm to impact the airfield between 0z/14 and 1z/14. Rain
shower and thunderstorm development is forecasted to be isolated and
between 23z and 3z for mainly south of the I-90 corridor and
Beaverhead County. I didn`t have confidence to include thunderstorms
in KBZN TAFs as latest model guidance continues to support
development for well south of the airport for impacts to airport
operations, but a vicinity rain shower can`t be ruled out for this
evening. Webb

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  43  76  45  70 /   0  10  30  10
CTB  36  72  42  65 /   0   0   0   0
HLN  44  78  46  69 /  20  10  20  20
BZN  38  75  39  65 /  20  10  10  40
WYS  27  63  29  60 /   0   0  10  50
DLN  38  71  37  65 /  10   0   0  20
HVR  40  75  44  74 /   0   0  10   0
LWT  41  74  43  65 /  10  20  20  40

&&

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

$$

http://www.weather.gov/greatfalls