textproduct: Great Falls

KEY MESSAGES

- Warm to hot temperatures and drier weather settle in for the first half of the week.

- Warm, dry, and breezy conditions bring an elevated fire weather risk to the Hi-line Monday and Southwest MT/North-Central MT Wednesday.

- Daily chances for precipitation return Wednesday through the rest of the week.

DISCUSSION

/Issued 1054 PM MDT Sat May 9 2026/

- Meteorological Overview:

As these isolated showers wind down for the night, an upper-level ridge will build back in. As a result, warmer temperatures and dry weather are on tap for Sunday. Heading to late Sunday into Monday, this ridge breaks down. Winds aloft increases, and these breezy winds mix down to the surface Monday. The combination of warm, dry, and breezy weather bring a period of elevated fire weather conditions to the Hi-line and Southwest MT, where the greenup isn't as strong from the recent dryness Monday afternoon. This ridge breakdown and a cold front also develops a few isolated showers late Sunday into Monday morning. Dry and warm conditions persist into Tuesday. However, winds will be a little lighter than Monday.

As we head into Wednesday, a trough begins to work its way onshore the Western U.S. There is still model inconsistency in the exact timing and evolution of this trough moving across the region. However, models suggest that daily chances for precipitation returns Wednesday through the weekend. This model consistency affects the strength and timing of convection and winds. This trough will help cool temperatures down for the second half of the week, though temperatures will remain above normal.

- Forecast Confidence & Scenarios:

Winds Monday:

The 700mb jet is not particularly strong Monday, with the peak winds occurring early in the day Monday. However, this jet does linger across North-Central MT through the day Monday, which daytime mixing will help create breezy winds. The strongest winds will be along the Hi-line in Blaine county, where there is a 40-80% chance for exceeding 45 mph wind gusts. Elsewhere, there's a 20-60% chance for exceeding 40 mph wind gusts.

Hot Temperatures Wednesday:

Wednesday will have the hottest temperatures of the week due to the increased southwest flow advecting in warm, moist air. Near or record breaking temperatures are expected Wednesday as temperatures climb into the mid 80s to low 90s across lower elevations. There's a 40-70% chance for much of North-Central MT reaching or exceeding 90 degrees maximum temperatures Wednesday.

Showers and Thunderstorms Returning Wednesday:

Although there remains inconsistencies in timing and evolutions of this trough returning mid week, ensembles agree that increasing southwest flow Wednesday will develop showers and thunderstorms to the region. CAPE varies from 500 to 1,500 j/kg with models. However, with deep inverted V soundings from a very dry surface layer will bring strong winds as the primary threat. Models also hint at strong synoptic winds increasing with the trough as well Thursday/Friday. Strength of the mid-level jet varies run to run, and the timing of the trough will also ultimately determine the strength and impact of these winds. - Wilson

AVIATION

10/12Z TAF Period

General VFR conditions at all TAF sites for the duration of the TAF period; however, a fast moving shortwave trough will bring breezy to locally windy conditions, along with increased higher level cloudiness this evening through Monday. - RCG

FIRE WEATHER

Well above, to near record, high temperatures are expected across the Northern Rockies for the better part of the upcoming work week, with the hottest day occurring on Wednesday as temperatures soar into the mid-80s to near 90 degrees. Low afternoon relative humidity values will be found each day as values fall to around 15% to 25%, with dry conditions expected through Wednesday afternoon before showers and thunderstorms make a return for the second half of the work week. Breezy and gusty northwest winds develop in wake of a cold front diving south from Canada on Monday over the plains of Central and North Central Montana, with gusts of generally 30 to 45 mph occurring along and east of the US Hwy 87 corridor from Havre to Great Falls. Hot-Dry-Windy Index (HDWI) on Monday for those Fire Weather Zones east of the aforementioned region, mainly 113 and 115, only rise to within the 50-75Pct; which tends to support an elevated fire weather day for those areas that have not sufficiently green-up over the last several weeks. By Wednesday south to west surface winds increase across all of Southwest through North Central Montana, particularly along and south of the I-90 corridor in Southwest Montana and west of the I-15 corridor across Central and North Central Montana. These winds will help to push multiple GEFS members of the HDWI to between the 75-95Pct, which will need to be monitored for the potential need of fire weather highlights. - Moldan

PRELIMINARY POINT TEMPS/POPS

GTF 81 49 76 45 / 0 10 0 0 CTB 78 50 70 41 / 0 10 0 0 HLN 82 46 79 43 / 0 10 0 0 BZN 79 45 79 41 / 0 10 0 0 WYS 71 37 78 37 / 0 0 0 0 DLN 80 44 81 42 / 0 10 0 0 HVR 83 51 75 40 / 0 10 0 0 LWT 77 47 72 41 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.