textproduct: Great Falls

KEY MESSAGES

- Rain and cool temperatures will continue across North-central Montana through at least Tuesday.

- Across Southwestern Montana it will be mostly dry and warm up through Wednesday.

- Thursday through Saturday it will warm up with showers and thunderstorms.

UPDATE

/Issued 807 PM MDT Mon Jun 1 2026/

Slight adjustments were made to the precipitation chances in the near-term based on trending obs and the latest hi-res model guidance. But otherwise, no major changes were made to the forecast. -thor

DISCUSSION

/Issued 807 PM MDT Mon Jun 1 2026/

- Meteorological Overview:

This afternoon a closed upper-level low will continue to track northward across North-central Montana. This will continue to bring rain to north-central Montana this afternoon through this evening. It will also be breezy across North-central Montana today due to a strong surface pressure gradient. This afternoon, it will be cool (well-below seasonal averages) for temperatures across North-central Montana. Across Central Montana this afternoon and evening there will be lingering rain showers around. This afternoon it will be mostly dry across Southwestern Montana with slightly warmer temperatures than yesterday. On Tuesday the closed upper-level low continues to slowly track northward across North-central Montana. This will bring another day of light rain to North-central Montana on Tuesday. On Tuesday temperatures will warm up slightly across North-central Montana. On Tuesday across Central and Southwestern Montana it will be mostly dry with temperatures continuing to warm up. On Tuesday it will be breezy again across North-central Montana due to a strong surface pressure gradient.

On Wednesday the upper-level low slowly moves to the northeast of Montana with an upper-level ridge moving in over North-central, Central, and Southwestern Montana by Wednesday afternoon. This allows all but the Hi-Line to be dry on Wednesday. Rain showers will linger across the Hi-Line through most of the day on Wednesday. On Wednesday temperatures will warm up and be slightly below seasonal averages across North-central Montana and slightly above seasonal averages for Central and Southwestern Montana. On Thursday an upper- level trough moves over North-central, Central, and Southwestern Montana. This will bring showers and thunderstorms to the area on Thursday. Due to southwest flow aloft temperatures will warm up on Thursday across North-central, Central, and Southwestern Montana. On Friday an upper-level ridge builds in over North-central, Central, and Southwestern Montana. This will allow temperatures to continue to warm up with a few isolated showers and thunderstorms. On Saturday an upper-level trough begins to approach Montana. This will bring another day of warm temperatures with showers and thunderstorms. On Sunday a cold front associated with an upper-level trough will move through North-central, Central, and Southwestern Montana. This will bring widespread precipitation and cooler temperatures to the area. -IG

- Forecast Confidence & Scenarios:

On Tuesday there is a 30 - 70% chance for wind gusts of 40 mph or greater across North-central Montana. On Tuesday there is a 30 - 50% chance of 1 inch of snow or greater along the Rocky Mountain Front. On Tuesday across much of North-central Montana there is greater than a 60% chance for a quarter inch of rain or greater. On Tuesday there is a 50 - 70% chance for one half inch of rain or greater along most of the Hi-Line. On Thursday there is a 15 - 30% chance for a quarter of an inch of rain across most of North-central, Central, and Southwestern Montana. On Thursday there is a 40 - 60% chance for a quarter inch of rain or greater across Fergus and Judith Basin Counties.

On Thursday there is a 30 - 50% chance for thunderstorms across North-central, Central, and Southwestern Montana. On Thursday across Judith Basin and Fergus counties there is a 50 - 60% chance for thunderstorms. On Thursday there is the potential for strong thunderstorms. Uncertainty exists in the timing and location of the upper-level trough which will affect when storms move over North- central, Central, and Southwestern Montana. If thunderstorms occur in the afternoon and evening they will be on the stronger side while if they occur before noon then they will be on the weaker side. On Friday there is a 15 - 30% chance for thunderstorms across North-central, Central, and Southwestern Montana. On Saturday there is a 15 - 45% chance for thunderstorms across most of North-central, Central, and Southwestern Montana. -IG

AVIATION

02/06Z TAF Period

Southwest Montana: Mid-level clouds will persist across much of the area through the next 24 hours. There is a chance for fog to develop at KWYS and KBZN if skies remain clear with higher confidence in fog at KWYS through the overnight hours.

Central and North-Central Montana: Rain and periods of MVFR/IFR CIGs and VIS will continue through Tuesday morning before tapering off by 03/00Z except along the Hi-Line around KHVR where scattered showers are expected to persist through Tuesday night. Mountain obscuration will remain a concern through the entire TAF period. Gusty westerly winds will continue along the Rocky Mountain Front and across the Hi-Line with gusts up to 40kts and 30kts possible at KCTB and KHVR, respectively. -thor

HYDROLOGY

At this time, no areal flooding is expected across the CWA. The main concern is the St. Mary River and Badger Creek. Both streams are just below flood stage. With snow falling in the mountains today, this should slow river rises a bit, even with the lower elevation rains. That being said, it is possible that a flood statement might be need later today, or even later this week, should the streams start to go above flood stage.

Note, impacts are minor on both streams if the rivers do go just above flood stage. It is not until the streams are a few feet above stage that impacts start to become more impactful. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 42 56 42 68 / 90 90 10 10 CTB 37 50 37 64 / 90 90 20 20 HLN 42 62 42 74 / 20 60 10 10 BZN 37 65 38 75 / 30 10 10 10 WYS 29 65 31 72 / 30 0 0 0 DLN 37 68 38 75 / 10 0 10 0 HVR 39 55 40 68 / 90 90 50 20 LWT 37 56 37 67 / 70 80 10 20

TFX WATCHES/WARNINGS/ADVISORIES

None.