FXUS65 KTFX 191703
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1103 AM MDT Tue May 19 2026

Aviation Section Updated.

.KEY MESSAGES...

 - Slight chance for afternoon showers and thunderstorms this afternoon
   across much of the region.

 - More widespread precipitation is expected on Wednesday through Thursday.

 - Temperatures will gradually warm through the week with the warmest
   temperatures expected this weekend.

&&

.DISCUSSION...
/Issued 513 AM MDT Tue May 19 2026/ 

 - Meteorological Overview

After a cool start to the morning, temperatures will warm modestly 
into the 50s and 60s. Lingering moisture on the backside of the 
upper-level trough combined with modest instability will allow for 
pop-up showers and thunderstorms through the afternoon today.

On Wednesday another upper-level trough will arrive bringing a 
chance for widespread wetting precipitation to the region. Snow will 
be generally confined to locations above 7,000 feet with the rest of 
the lower elevations seeing primarily rain through the event.

As the upper-level trough starts to slowly exit the area towards the 
end of the week, temperatures will gradually start to warm up as 
upper-level ridging begins building over the western CONUS through 
the weekend.


 - Forecast Confidence & Scenarios:

For today, hi-res models were showing pretty scattered 15-30% 
chances for precipitation across the region. In general, most 
locations will remain dry throughout the day except for where these 
pop-up showers end up developing. The highest chances for 
thunderstorm activity will be across North-Central Montana with any 
precipitation in Central and Southwest Montana expected to be more 
stratiform in nature.

There is still good agreement for widespread wetting rains. The 
heaviest amounts are currently expected along a stretch from the 
Northern Rockies down through Central Montana including Great Falls 
and Helena into Lewistown. Probabilities of more than 0.25" of 
precipitation are currently sitting at 60-80% with a 20-40% chance 
of 0.5" or more. While precipitation amounts across the remainder of 
North-Central and Southwest Montana are not expected to be quite as 
high there is still at least a 40% chance for a tenth of an inch or 
more.  -thor

&&

.AVIATION... 
19/18Z TAF Period 

Initial concern this TAF period will be for afternoon and early 
evening showers and isolated thunderstorms. Briefly gusty and 
erratic winds will accompany this showery activity. Concern then 
turns to a cold front moving from north to south late tonight into 
Wednesday, primarily impacting terminals over the plains. A mix of 
showery and stratiform precipitation will accompany the wind shift to 
a more northwesterly direction behind the front. Lowering ceilings 
over the plains Wednesday morning will result in increasing mountain 
obscuration. -AM

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  64  40  58  38 /  40  20  80  70 
CTB  62  38  55  34 /  20  10  80  40 
HLN  65  38  64  38 /  20  20  60  90 
BZN  62  34  63  35 /  10  20  40  90 
WYS  54  26  57  30 /  10  10  40  80 
DLN  61  34  62  35 /  10  20  20  70 
HVR  68  40  62  36 /  30  30  50  10 
LWT  60  36  58  35 /  30  20  80  80 

&&

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

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