textproduct: Great Falls

KEY MESSAGES

-Unseasonably warm conditions persist through Friday with a few locations flirting with record highs. Breezy conditions shift from the Plains/RMF to Southwest Montana.

-A weaker weekend system brings increased chances for light precipitation, high snow levels (>7kft), and more seasonable temperatures.

-An active pattern develops early next week with a trend toward cooler temperatures and multiple weak systems to monitor, though uncertainty is high and no large or high-impact systems are favored.

DISCUSSION

-Meteorological Overview:

A strong upper-level ridge builds overhead through Friday, driving temperatures well above seasonal averages with a few climate locations approaching daily records. Over the next couple of days, a weak to moderate pressure gradient will sustain breezy conditions across the Rocky Mountain Front and Central Plains. However, as a powerful Pacific trough approaches the West Coast on Thursday, downstream amplification will pump the ridge axis and associated surface high pressure well north into Canada, creating a pattern resembling an omega block. As the surface high shifts northward, the cross-barrier gradient along the RMF relaxes, decreasing winds. Simultaneously, the shifting gradient reorients to favor breezy conditions funneling through the valleys of SW Montana Friday and Saturday.

The omega block pattern will be short-lived as a sequence of energetic low-pressure systems begins an assault on the West Coast and especially the Pacific Northwest. This initiates the breakdown of our ridging through this weekend. By Saturday, the ridge axis shifts east into the Central Plains as Montana transitions to weak southwesterly flow aloft ahead of a weaker shortwave trough. Moisture with the weekend wave will be sparse, resulting in isolated chances of light precipitation largely focused across SW Montana and the Rockies. Temperatures will remain marginal, keeping snow-levels high above 7kft. The primary synoptic role of this initial system is knocking down regional heights and helping usher in some more seasonal conditions ahead of potential systems next week.

Forecast confidence struggles heading into next week, with guidance pointing toward an increasingly uncertain yet active pattern. Rather than a singular high-impact storm, recent trends favor more of a split-flow setup early in the week, shunting the deepest moisture and strongest dynamic forcing to our south while ushering a return to near- seasonal temperatures across our region. Behind this initial transition, the broader pattern remains quite chaotic. While multiple weak Pacific waves are likely to traverse the region through the week, bringing periodic low-end chances for precipitation and mountain snow, ensemble spread remains very high, and no large or high-impact systems are favored at this time. -JR

- Forecast Confidence & Scenarios:

High confidence surrounds the unseasonable warmth through Friday, as well as the transition toward ridge breakdown and cooler temperatures this weekend. Confidence is medium to high (50-60%) that Saturday into Sunday will feature low-impact light precipitation largely across SW Montana and the Rockies. Snow levels will remain well above pass levels, and the scattered nature of the precipitation indicates most lower-elevation locations will remain dry.

Confidence has lowered regarding any significant or high-impact storm system early next week. While there is moderate confidence in a return toward seasonable temperatures, model spread is substantial regarding how individual waves track and interact:

Scenario 1 (Active, Chaotic Pattern): A split-flow regime keeps the primary moisture tap and strongest dynamics displaced to the south, while a series of weaker northern-branch shortwaves cross the Northern Rockies. This brings periodic light precipitation and minor pass-level snow chances, but overall impacts remain minimal.

Scenario 2 (More Amplified or Consolidated Wave): A shortwave digs more aggressively or consolidates into a broader trough over the Plains. This would allow a stronger push of Canadian cold air and wrap-around moisture into Central Montana, potentially introducing a brief window for more organized precipitation, though confidence in this evolution remains low. -JR

AVIATION

11/18Z TAF Period

VFR conditions will prevail throughout the entire 1118/1218 TAF period; however, passing mid-level cloudiness may at times obscure ridgetops, most notably along the Continental Divide. Otherwise gusty surface winds will persist through along the immediate eastern slopes of the Rocky Mountain Front and the KGTF terminal over the next 18-24 hours. - Moldan

PRELIMINARY POINT TEMPS/POPS

GTF 43 68 38 65 / 0 0 0 0 CTB 38 65 32 55 / 0 0 0 0 HLN 34 58 32 60 / 0 0 0 0 BZN 32 60 31 61 / 0 0 0 0 WYS 24 55 25 52 / 0 0 0 0 DLN 32 58 31 57 / 0 0 0 0 HVR 38 64 32 57 / 0 0 0 0 LWT 41 71 39 67 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

None.