Lima, MT Weather

Aviation Section Updated.

Key messages

- Breezy to windy conditions decrease tonight with seasonal temperatures through Wednesday cooling below average on Thursday.

- Snow showers affect some areas near the continental divide through Thursday, mainly near Glacier National Park.

- Next larger weather system moves into the region this weekend with rain and snow developing Saturday night through Sunday.

Discussion

/Issued 126 PM MDT Tue Oct 27 2026/

- Meteorological Overview:

A baggy upper level trough remains in place across the NW US and Northern Rockies with one of multiples embedded waves lifting out into the Canadian Prairies today while another cuts east from southern ID across WY tonight. Energy dropping south along the BC coast consolidates the trough to a closed low offshore of the Pacific NW by Friday, which eventually opens and shifts inland this weekend.

Lingering afternoon light precipitation near the Hi-line associated with the energy lifting north into AB/SK will end by this evening. Gusty winds that developed today behind the departing wave will diminish for many areas this evening though breezy winds may persist through tonight along areas immediately adjacent to the Rocky Mtn Front and central MT mountains. A cooler airmass developing across AB tonight may expand as far south as areas near the international Border by early Wednesday morning, bringing some risk for lower clouds/patchy fog there. The cooler airmass slides south across the N-central MT plains later Wednesday through Thursday, cooling daytime temperatures back to below seasonal averages with less noticeable cooling reaching SW MT.

While most of the forecast area is expected to see overall dry conditions through Thursday, a steady stream of Pacific moisture embedded within the westerly flow will support orographically enhanced showers over the continental divide with more persistent periods of snow most likely for areas along the divide north of MT-200. A few isolated rain showers may track further east across north-central and SW MT, mainly in the afternoon and early evening periods today and again tomorrow as less stable conditions offset the effects of downslope drying in westerly flow.

The upper low offshore of the Pacific NW late this week splits while moving onshore this weekend in tandem with a southern stream wave and Pacific moisture streaming into CA and the Great Basin. Southerly flow developing Friday night and Saturday ahead of the trough will bring some warming as well as increasing clouds with precipitation chances increasing from south to north late Saturday. The bulk of the precipitation looks to occur later Saturday night through Sunday with the passage of the trough axis and a slow moving Pacific cold front. Snow with this system will initially be limited to higher elevations with lowering snow levels allowing for a mix or transition to snow at lower elevations Sunday. A drier period looks to follow early next week as ridging builds in behind the weekend trough. Hoenisch

- Forecast Confidence & Scenarios:

Snow levels along northern portions of the continental Divide (N of MT-200) fluctuate around 5000 ft through Thursday. Periods of snow with some minor (<1"/12hr) accumulation may occur at Marias Pass, particularly Wednesday night, but accumulations of 2" or more are primarily expected to be limited to elevations >6000 ft in Glacier NP.

Interactions between the splitting northern stream trough and southern stream moisture/energy this weekend lead to model differences and uncertainty in the more specific details of timing and precipitation amounts/type still at this time range. Snow levels may initially be above 7000 ft Saturday night but are likely to lower at least to pass levels on Sunday. Probabilities for >4" snowfall amounts this weekend are highest (50-80%) above 7000 ft in the Little Belt, Bridger, Gallatin and Madison Ranges with a 20-40% probability for 2" or higher amounts across most central and SW MT mountain passes. Hoenisch

Aviation

28/00Z TAF Period

VFR conditions will prevail at all terminals except for the KCTB and KWYS terminals during this TAF Period. At the KWYS terminal there will be snow that reduces visibility to at least MVFR-levels for the first two hours of this TAF Period. It will be windy at the KEKS and KGTF terminals during the duration of this TAF Period. Between 28/06Z and 28/12Z there is a 30% chance for fog at the KWYS terminal. Across North-central Montana between now and 28/18Z there will be isolated instances of low-level wind shear. -IG

Preliminary point temps/pops

GTF 37 51 29 38 / 0 0 10 0 CTB 30 43 24 33 / 0 10 30 10 HLN 27 48 25 44 / 10 10 0 0 BZN 25 45 24 45 / 10 0 0 0 WYS 18 37 14 42 / 30 10 0 0 DLN 24 43 23 44 / 0 0 0 0 HVR 30 48 23 39 / 20 0 10 10 LWT 30 48 27 41 / 0 0 0 0

Watches, warnings and advisories

None.