textproduct: Great Falls

KEY MESSAGES

- Hot temperatures continue through the work week, with the hottest temperatures expected late week into the weekend.

- Isolated to widely scattered thunderstorms remain possible each day this week, with the best chances occurring midweek focused primarily on terrain.

-Wildfire smoke will continue to impact the region through Tuesday with degraded air quality and areas of reduced visibility.

DISCUSSION

/Issued 512 AM MDT Mon Jul 27 2026/

- Meteorological Overview:

Broad upper-level ridging will remain the dominant feature through much of the upcoming work week, maintaining hot temperatures across North Central and Southwest Montana. Persistent southwesterly flow on the western periphery of the ridge will also continue to assist in the transporting of wildfire smoke from the Pacific Northwest into the region through at least Tuesday, resulting in degraded air quality and reduced visibility especially across the Plains and Northern Rockies. Afternoon highs will gradually warm through the period, with the hottest conditions expected the late week. Weak disturbances embedded within the southwesterly flow will periodically move across the Northern Rockies. Aided by monsoonal moisture streaming northward, weak shortwaves moving through the southwesterly flow will support isolated evening convection each day. Tuesday and Wednesday will feature slightly increased chances as a pair of more pronounced disturbances move through the region. Convection will remain primarily terrain focused, with the highest probabilities across Southwestern Montana. Forecast soundings continue to depict inverted-V profiles, supporting gusty and erratic outflow winds as the primary hazard with any stronger thunderstorm. Friday into Saturday, the upper-level ridge axis briefly extends northward across the Rockies, supporting another round of warming and pushing temperatures back up towards the 100 degree mark across much of the plains and valleys.

Looking towards the latter half of the weekend into early next week, ensembles guidance continues to suggest a transition towards a less amplified pattern as troughing moves into Northwestern CONUS. As toughing progresses eastward, the ridge begins to weaken and is suppressed southward, supporting a modest cooling trend and breezier conditions across the region. However, ensemble guidance continues to indicate limited moisture accompanying the weakening trough and subsequent toughing, resulting in low confidence for any meaningful increase in precipitation.

-JR

- Forecast Confidence & Scenarios:

Continued Hot Temperatures...

Wildfire smoke remains the primary forecast challenge through at least Tuesday. High resolution modeling continues to depict elevated smoke concentrations across much of the region with the greatest impacts to air quality expect across the Northern Rockies and Plains. Confidence is high that wildfire smoke will continue to impact the region, though confidence in the placement and density of the thickest smoke remains lower. As a result, continued adjustments to forecast highs may be needed should smoke trends differ from current guidance.

Confidence is high that Friday into Saturday will bring the hottest temperatures of the forecast period as upper-level ridging briefly amplifies over the Northern Rockies. NBM Probabilities indicate a 30 to 50 percent chance of reaching 100 degrees across much of the plains Friday before increasing to 60 to over 90 percent by Saturday. Valley locations are less likely to reach that century mark Friday, though probabilities increase into the 40 to 50 percent range by Saturday. The primary source of uncertainty remains the extent and persistence of wildfire smoke, as thicker smoke could limit daytime heating and result in muted afternoon highs.

Weakening Ridge, Cooling, and Moisture

Confidence decreases towards the end of next weekend as ensemble guidance begins to diverge on the evolution of the upper-level pattern. While most ensemble members favor a transition towards a less amplified pattern, uncertainty remains regarding the timing of the change and any associated increase in precipitation.

-JR

AVIATION

27/18Z TAF Period

Wildfire smoke will be the primary impact across the region through the entirety of the TAF period. While surface visibility may sway between VFR and MVFR, slant-range visibilities will see greater impacts. A few showers and thunderstorms develop this afternoon and evening across Southwest Montana, bringing a gusty/erratic wind threat.

For KGTF: Recent guidance has trended more toward a light westerly wind continuing through the afternoon and evening. The probability of the cross-wind component of this wind exceeding 15 kts remains at or below 10% at this time. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 90 59 92 60 / 0 0 0 0 CTB 86 54 89 56 / 0 0 0 0 HLN 91 60 92 60 / 0 0 0 0 BZN 91 57 93 58 / 10 10 0 0 WYS 84 48 86 49 / 20 20 0 0 DLN 88 55 90 55 / 0 10 0 0 HVR 93 59 96 60 / 0 0 0 0 LWT 87 58 89 58 / 0 10 10 10

TFX WATCHES/WARNINGS/ADVISORIES

None.