textproduct: Great Falls

KEY MESSAGES

- Warm, dry and windy conditions will create elevated to critical fire weather through this evening.

- Strong to locally severe thunderstorms with damaging winds develop this afternoon and track northeast across much of north-central and southwest Montana through this evening.

- Very windy conditions become widespread tonight and continue through Thursday.

- Temperatures cool to near and below seasonal averages for the rest of the week with additional cooling and chances for precipitation this weekend.

DISCUSSION

/Issued 542 PM MDT Wed May 13 2026/

- Meteorological Overview:

A vigorous and negatively tilted shortwave trough lifts from the Pacific NW across the Northern Rockies tonight with thunderstorms development underway this afternoon across southwest MT expected to increase in intensity and coverage while tracking northeast through central and north-central MT later this afternoon and evening as the shortwave moves into western MT. Strong mid-level westerly flow wraps around the potent shortwave as it emerges east of the Rockies near the AB/MT border late tonight with very windy conditions likely for much of the area through Thursday. Moisture also wraps around this circulation with enough cooling aloft for snow in the Glacier Park area tonight while an areas of rain showers accompanies the wave tracking along the Canadian border through Thursday morning. This initial system marks the beginning of an unsettled and cooler period of weather likely to last through the upcoming weekend as broad troughing sets up across the western and NW US. The next round of more widespread precipitation looks to occur later this weekend as additional shortwave energy drops into the NW US allowing the broader trough to sharpen across the Northern Rockies. There is still considerable uncertainty with the timing and extent of precipitation later this weekend, but there looks to be sufficient cooling aloft for lower snow levels. Hoenisch

- Forecast Confidence & Scenarios:

Damaging winds gusts are the primary concern with thunderstorms today with initially dry and well mixed conditions early this afternoon supporting strong downdrafts with shorter lived storms. As the upper system encroaches late this afternoon through this evening, lower level moisture increases, supporting additional buoyancy/CAPE and the potential for some organization of cells into longer lived clusters or lines. Increasing winds aloft and larger thunderstorm cold pools this evening will maintain damaging winds as the primary threat with storms. High resolution model ensembles focus the highest risk (30-50%) for wind gusts in excess of 50kts from Broadwater county north east through most central MT counties this evening.

As the threat for thunderstorm winds decreases later this evening, more widespread strong/gusty west winds will overspread the region overnight as westerly mid level flow strengthens. Thursday's wind event would be typical for fall/winter but is somewhat unusual for May and could have additional impacts due to recent leaf out of trees in some areas. Hoenisch

AVIATION

14/06Z TAF Period

Convective showers have largely left the forecast area with the primary concern shifting to strong, gusty westerly winds and mountain wave activity. The winds will generally be strongest along the Rocky Mountain Front and over central/north-central MT. There will be mountain snow, especially along the immediate eastern slopes of the Rocky Mountain Front through around 04/15Z. Moisture wrapping around the low pressure system will bring another round of lighter end showers and low VFR/MVFR clouds to the Hi-Line terminals, especially KHVR between 14/09 and 14/15Z. Otherwise, VFR conditions will generally prevail elsewhere. - RCG

FIRE WEATHER

Hot, dry, and breezy to windy condtions will bring elevated to critical fire weather conditions followed by scattered to numerous gusty thunderstorms with localized 60 to 80 mph wind gusts. Probabilities for the Hot-Dry-Windy Index (HDWI) rising to within the 95Pct of Climatology has increased to a 80% or greater across most lower elevations across Southwest Montana south of the I-90 and across Hill and Blaine Counties in North Central Montana, with Fire Weather partners indicating that fuels would be receptive to fire, especially across Southwest Montana. Red Flag Warnings remain in effect for these aforementioned areas. Other areas across the region will see localized elevated fire weather conditions, with slightly greener and wetter fuels, so no additional fire weather products are anticipated at this time. Shower and thunderstorm activity will be most numerous over north-central and southwestern areas east of I15. - RCG

PRELIMINARY POINT TEMPS/POPS

GTF 64 44 63 40 / 10 0 0 0 CTB 59 39 58 34 / 20 0 0 0 HLN 65 41 63 37 / 0 0 0 0 BZN 68 37 65 34 / 0 0 0 0 WYS 64 32 63 30 / 0 0 0 0 DLN 68 36 65 35 / 0 0 0 0 HVR 69 42 65 36 / 60 0 30 10 LWT 64 40 61 36 / 10 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning until midnight MDT tonight for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains-Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass.

Winter Weather Advisory until noon MDT today for East Glacier Park Region.

High Wind Warning until midnight MDT tonight for Bears Paw Mountains and Southern Blaine-Fergus County below 4500ft-Hill County-Northern Blaine County-Snowy and Judith Mountains-Western and Central Chouteau County.

High Wind Warning until 6 PM MDT this evening for Cascade County below 5000ft-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Gates of the Mountains-Helena Valley-Judith Basin County and Judith Gap.