291
FXUS65 KTFX 172257
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
457 PM MDT Tue Jun 17 2025

Aviation Section Updated.

.KEY MESSAGES...

 - This afternoon there will be scattered showers and thunderstorms
   east of I-15.

 - It will be dry and warm on Wednesday with showers and
   thunderstorms returning to the area on Thursday.

 - On Friday there will be showers and strong to severe
   thunderstorms with a cool down and widespread precipitation
   expected for the weekend.

&&

.DISCUSSION...
/Issued 249 PM MDT Tue Jun 17 2025/

 - Meteorological Overview:

This afternoon an upper-level shortwave moves over North-central,
Central, and Southwestern Montana. This will bring another round of
scattered showers and thunderstorms to the area this afternoon
primarily east of the I-15 Corridor.

On Wednesday and Thursday an upper-level ridge builds in over North-
central, Central, and Southwestern Montana. This will dry out the
area and allow temperatures to warm up a few degrees on Wednesday
and Thursday. On Thursday afternoon and evening an upper-level
trough approaches Montana. This combined with southwest flow aloft
will bring showers and strong to severe thunderstorms to
Southwestern Montana Thursday afternoon and evening. Thursday
evening showers and thunderstorms will spread up to portions of
North-central Montana.

On Friday the upper-level trough begins to move over North-central,
Central, and Southwestern Montana. This combined with a surface cold
front moving through Friday evening will bring showers and
thunderstorms to the area Friday afternoon and evening. On Saturday
and Sunday the upper-level trough remains over North-central,
Central, and Southwestern Montana. This will allow temperatures to
cool down to well-below seasonal averages with widespread rain
showers on Saturday and Sunday. Snow-levels will lower to allow snow
to fall in the mountains of Southwestern Montana and along the Rocky
Mountain Front on Saturday and Sunday.

 - Forecast Confidence & Scenarios:

The Storm Prediction Center has issued a Marginal Risk (5% chance
for severe wind gusts of 58 mph or greater) across Southwestern
Montana on Thursday. On Friday there is a 35 - 70% chance for
thunderstorms across much of North-central, Central, and
Southwestern Montana. On Friday there is a 30 - 60% chance for a
half inch of rain or greater across North-central Montana.

For the overall weather pattern for Friday through the weekend,
there is high confidence in the upper-level trough moving over
Montana Friday through Sunday. There is high confidence in showers
and thunderstorms on Friday with exact locations and precipitation
amounts uncertain. There is high confidence that there will be
Mountain snow this weekend but there is medium-confidence in how low
snow-levels will get. At this time the highest snowfall amounts look
to be in Glacier National park where there is a 50% chance for 6
inches or greater. There is high uncertainty in how cold
temperatures will get on Sunday. -IG

&&

.AVIATION...
18/00Z TAF Period

The main concern this TAF period will be for scattered showers and
isolated thunderstorms across the eastern plains (KHVR & KLWT) early
this evening. Gusty winds are the primary concern from the stronger
thunderstorms that form. Otherwise, minimal impacts are forecast
through Wednesday afternoon and evening. -AM

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  50  86  52  84 /  10   0   0  10
CTB  47  81  49  78 /   0   0   0   0
HLN  52  86  54  85 /   0   0   0  10
BZN  47  86  49  88 /  10   0   0  10
WYS  37  77  38  81 /  10   0   0  10
DLN  45  82  46  85 /   0   0   0  20
HVR  51  87  54  85 /  40   0  10   0
LWT  48  79  51  80 /  30   0  10  10

&&

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

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