Marine Weather and Tide Forecast for Big Sky, MT

DISCUSSION
/Issued 1250 AM MDT Mon Aug 3 2026/

- Meteorological Overview:

An upper level disturbance tracking across the region through the day today will result in quite a cool day behind a cold front moving through as of publishing this discussion. Upper level support will yield a few showers through the day today, mainly north of the I-90 corridor. Overall precipitation amounts with any shower that forms looks to be not much more than a few hundreths.

By tomorrow another upper level ridge begins to work in from the west. That said, a cyclonic northwesterly flow aloft over the Northern Rockies will act to temper the warming trend, at least for a day or two before the ridge fully moves overhead toward the latter half of the week. After today the region looks dry as the upper level ridge slowly builds in.

Friday looks to be the hottest day at this time, with breezy winds over much of the region by mid-afternoon. Should this scenario unfold, concerns for fire weather conditions would be increase.

Confidence in specifics wanes into next weekend, though there does look to be some form of zonal flow aloft in place. The uncertainty lies in whether there will be any embedded waves capable of producing additional stretches of gusty winds or precipitation should they be strong enough. -AM

- Forecast Confidence & Scenarios:

Largest source of uncertainty for this forecast will be just how breezy and dry it will be on Friday across many areas. Ensemble average 700 mb flow is on the order of 15 kts or so. Given the expected deep mixing on Friday, these winds should not struggle to mix to the surface. Should this mid level flow trend stronger, closer to the current 75th percentile (20-25 kts), there would be increased concern for at least elevated fire weather Friday. -AM

AVIATION
03/12Z TAF Period

A cold front will continue to progress southward across the region this morning. Low clouds moving in behind this front over the plains will result in some brief sub-VFR ceilings through the morning before daytime mixing helps to raise ceilings. While some showers will be around through the day today, confidence in these occurring at any TAF site at any specific time was far too low to warrant mention in TAFs at this time.

Wildfire smoke will continue to be around today, but mainly be aloft. Hence, slant-range visibility issues will remain.

For KGTF: Winds will remain more or less northwesterly through the morning today before becoming a bit more variable this afternoon.
Magnitude of winds looks to be 10 kts or less, yielding a very low probability for 15kt+ crosswind today. There does look to be some icing risk through the day today, but confidence in the depth of a layer capable of producing icing is low at this time. -AM



FIRE WEATHER

Remaining concerns through the day today will include a cold front progressing southward over the plains as of writing this discussion early this morning, resulting in a gusty wind shift to a more northerly direction through the morning. A persistent breezy northwest wind along and east of US-87 will result in elevated fire weather conditions through the early evening. -AM

PRELIMINARY POINT TEMPS/POPS
GTF 70 47 78 49 / 20 0 0 0 CTB 66 42 74 46 / 20 0 0 0 HLN 72 47 79 48 / 20 10 0 0 BZN 72 43 78 46 / 20 0 0 0 WYS 71 33 75 35 / 0 0 0 0 DLN 72 43 76 45 / 0 0 0 0 HVR 70 43 79 48 / 20 10 0 0 LWT 64 42 73 46 / 40 10 0 0

TFX WATCHES/WARNINGS/ADVISORIES
None.