textproduct: Great Falls

KEY MESSAGES

- It will be warm and mostly dry today and Sunday.

- Monday through Friday there will be isolated showers and thunderstorms.

- It will be warm Sunday through Tuesday with a brief cooldown on Wednesday and Thursday.

DISCUSSION

/Issued 318 AM MDT Sat May 23 2026/

- Meteorological Overview:

Today there is zonal flow aloft with a weak upper-level shortwave moving through the flow over North-central, Central, and Southwestern Montana. This will allow temperatures to warm up with mostly dry weather. The upper-level shortwave will provide enough forcing for there to be weak and very isolated showers this afternoon and evening. On Sunday an upper-level ridge builds in over the area with another upper-level shortwave that moves through the flow. This will allow temperatures to warm up to well- above seasonal averages. The shortwave will bring weak isolated showers to Southwestern Montana Sunday afternoon.

On Monday the upper-level ridge remains over North-central, Central, and Southwestern Montana with an upper-level trough approaching the area. This will allow temperatures to warm up some more due to southerly flow aloft with warm air advection. As a result of the warm temperatures there will be isolated showers and thunderstorms around North-central, Central, and Southwestern Montana Monday afternoon/evening. On Tuesday the upper-level trough becomes a closed low and slowly moves over the Great Basin Region. This corresponds to a Pacific Cold Front moving through North-central, Central, and Southwestern Montana. This will cool temperatures down slightly and bring another round of showers and thunderstorms to the area on Tuesday. Wednesday though Thursday the closed low continues to sit over the Great Basin with a very subtle and slow eastward progression. This will cool down temperatures to around seasonal averages with afternoon showers and thunderstorms on Wednesday and Thursday. On Friday the upper-level low slowly tracks eastward across Wyoming. Temperatures will warm up slightly on Friday with another day of afternoon showers and thunderstorms. -IG

- Forecast Confidence & Scenarios:

On Monday across North-central, Central, and Southwestern Montana south of the Montana Highway 200 Corridor there is a 10 - 25% chance for thunderstorms. On Tuesday there is a 25 - 40% chance for thunderstorms across North-central, Central, and Southwestern Montana. On Wednesday there is a 30 - 50% chance for thunderstorms across Central, and Southwestern Montana and east of the I-15 corridor in North-central Montana. On Thursday and Friday across most of North-central, Central, and Southwestern Montana there is a 25 - 45% chance for thunderstorms. The biggest uncertainty with any thunderstorms for this upcoming work week is the timing of the cold front and the overall track of the upper-level low. This will have a huge impact on whether or not there are any severe thunderstorms. At this time the greatest risk for any severe thunderstorms looks to be on Tuesday and Wednesday. -IG

AVIATION

23/12Z TAF Period

VFR conditions will prevail across all terminals during this TAF Period. During this TAF Period, there will be very isolated rain showers across North-central, Central, and Southwestern Montana. At the KWYS terminal between 23/18Z and 24/06Z there is a 15 - 20% chance for rain showers. At the KLWT terminal between 23/18Z and 24/01Z there is a 15 - 20% chance for a rain shower. During any rain shower there will be a brief period of mountain obscuration. -IG

PRELIMINARY POINT TEMPS/POPS

GTF 75 46 82 50 / 10 20 0 0 CTB 73 43 77 46 / 20 20 0 0 HLN 75 44 81 48 / 10 10 10 0 BZN 73 41 81 45 / 10 10 10 0 WYS 68 34 75 37 / 20 20 20 0 DLN 73 41 79 44 / 0 10 10 0 HVR 78 47 86 50 / 10 20 0 0 LWT 70 43 78 47 / 20 20 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.