textproduct: Great Falls

KEY MESSAGES

- Daily chances for showers and thunderstorms with higher rainfall amounts through the weekend, with the potential for some minor mountain snow on Sunday.

- Breezy and gusty winds on Sunday, especially along the Rocky Mountain Front and Crazy Mtns.

- Below normal temperatures for Sunday and Monday Morning.

DISCUSSION

/Issued 146 PM MDT Fri Aug 28 2026/

- Meteorological Overview: Closed upper level low off the coast of British Columbia and associated upper level trough will dig south over the Pacific Northwest by Saturday morning before tracking east along the Canadian border through the day on Sunday. Southwesterly flow aloft ahead of the approaching upper level trough will continue to transport Pacific moisture north and east over the Northern Rockies through the timeframe. Stratiform rain and showers are the predominant precipitation drivers currently however isolated embedded and air mass thunderstorms could develop this afternoon as mid level stratiform dries out and daytime heating reaches its max. High temperatures in the upper 70s to upper 80s today will fall to the 60s to low 70s by Sunday as the trough propogates through the CWA and exits Monday morning. Mid level winds will shift westerly by Sunday afternoon and create strong and gusty surface winds for most of the CWA as the low tracks eastward. Areas along the northern Rocky Mountain Front will see the highest winds due to pressure gradient forcing and cross-barrier downsloping.

Synoptic pattern next week will be primarily under the influence of longwave troughing over the Pacific Coast keeping southwesterly flow over the CWA bringing above normal PWAT's and warmer temperatures until Friday when the long wave trough propogates eastward. - Akins

- Forecast Confidence & Scenarios: EFI's indicate elevated winds above climate norms for the northern Rocky Mountain Front as well as higher than normal QPF's for the Southwest of Montana for Saturday and Sunday. NBM signals of 80%+ probabilities for wind gusts over 35 KT for Northern RMF and leeside of Crazy Mtns along Hwy 191. Confidence is lower but still worth mentioning for gusts over 50 KT with NBM signaling 30% probability in the same areas. Probabilities could increase or decrease depending on latitudinal position of the upper low's track as well as timing of the jet streak position during maximum mixed layer times on Sunday. For QPF's on Saturday, NBM is indicating a 40% probability for rainfall over 1" for the West Yellowstone area from noon Saturday until 6pm Sunday as well as 30% probabilities of over 1" in the Little Belts and Bridger Mtns. - Akins

AVIATION

28/18Z TAF Period

While VFR conditions are expected to prevail through most of the 18z TAF period (through 29/18z) -RA with embedded TSRA will continue to persist across Southern Montana through the remainder of the daylight hours today, bringing some periods of MVFR visibilities to some terminals, mainly south of a KHLN to KLWT line. Further north, a stray shower cannot be entirely ruled out around KGTF, but this probability is around 10% and therefore not mentioned in the TAF. Additional -RA will work back into the area from the southwest tomorrow, but should only reach KWYS/KEKS/KBZN by 18z. Ludwig

For KGTF: Southwest winds throughout the TAF period will yield nearly a non-zero chance for crosswinds to exceed 15kts; however, shower and thunderstorm activity moving south and east of the terminal beyond 21z this afternoon could produce gusty outflow boundaries that could move north and west across the terminal. The greatest areal coverage (within 50nm of the terminal) of these showers and storms looks to occur between 21-03z this afternoon/evening, but isolated coverage will linger into the evening and overnight hours tonight. Even during this period of greatest activity, the risk for impacts to the airfield from rain or outflows remains low (10% for rain, ~20% for winds) and any impacts should be transient. - Moldan/Ludwig

FIRE WEATHER

Elevated fire weather conditions will exist across portions of Fire Weather Zone 112 today as southwest winds peak between 15-20 mph during the afternoon and evening hours, with gusts near 30 mph. The breezy winds combined with minimum relative humidly values of 15-20% west of the I-15 corridor raises concerns for the potential of new fires to spread rapidly; however, with less than half of the fire weather zone expected to see wind gusts near 30 mph we will continue to hold off on any fire weather products. - Moldan

PRELIMINARY POINT TEMPS/POPS

GTF 58 79 50 67 / 20 60 80 60 CTB 50 74 46 62 / 10 40 60 30 HLN 54 78 48 70 / 10 90 80 50 BZN 52 77 46 69 / 20 60 80 70 WYS 40 65 35 65 / 60 90 90 80 DLN 51 75 43 71 / 50 70 70 40 HVR 56 86 50 70 / 20 40 70 60 LWT 55 79 47 67 / 20 70 60 80

TFX WATCHES/WARNINGS/ADVISORIES

None.