textproduct: Great Falls

KEY MESSAGES

- Tonight into tomorrow morning dense fog will return to areas of the Milk River Valley in Hill and Blaine County.

- Light showers will affect Southwestern Montana on Saturday.

- It will be warm (above seasonal averages) and mostly dry through Monday with a cooldown and more widespread precipitation expected on Tuesday.

DISCUSSION

/Issued 148 PM MST Fri Nov 13 2026/

- Meteorological Overview:

This afternoon an upper-level ridge is moving eastward away from Montana with southerly flow aloft. Due to warm air advection there will be well-above seasonal average temperatures across North- central, Central, and Southwestern Montana this afternoon. Due to moist easterly winds flowing up the Milk River Valley through tomorrow morning, fog will linger in the Milk River Valley through tomorrow morning. See the Forecast Confidence & Scenarios Section for details. On Saturday the southerly flow aloft remains over North- central, Central, and Southwestern Montana. A weak upper-level shortwave trough will move through the upper-level system. This will bring light rain and snow showers to Southwestern Montana during the day on Saturday. Across North-central, Central, and Southwestern Montana it will remain well-above seasonal averages for temperatures on Saturday.

On Sunday an upper-level ridge builds in over North-central, Central, and Southwestern Montana. This will keep warm (well-above seasonal average) temperatures and mostly dry weather for the area on Sunday. On Monday the upper-level ridge remains over North- central, Central, and Southwestern Montana with strong southerly flow aloft. On Monday it will remain warm (well-above seasonal averages) and mostly dry.

On Tuesday an upper-level trough associated with a Pacific Cold Front will move over North-central, Central, and Southwestern Montana. This will bring cooler temperatures and widespread precipitation to the area on Tuesday. Wednesday through Thursday there will be upper-level troughing around. This will cool temperatures down to below seasonal averages with precipitation chances. -IG

- Forecast Confidence & Scenarios:

Across the Milk River Valley in Hill and Blaine Counties there is a 50 - 80% chance for dense fog to form. As a result a Dense Fog Advisory is in effect for Hill County through 11 AM Saturday morning and a Dense Fog Advisory goes into affect for Northern Blaine County from 9 PM tonight through 11 AM Saturday morning.

From Monday night through Wednesday morning there is considerable uncertainty in how cold it gets and precipitation amounts. However there is high certainty that beginning Monday night into Tuesday there will be a significant pattern change to colder and wetter weather. -IG

AVIATION

14/00Z TAF Period

Initial concern this TAF period will be for some instances of marginal low-level wind shear at a few terminals as surface decoupling ensues. This LLWS looks to continue intermittently through the morning Saturday. Otherwise the biggest concern will be for some fog/low clouds across portions of the Hi-Line tonight. This activity looks to diminish through the morning Saturday.

Mainly light mountain precipitation develops tonight across SW MT, though confidence was largely too low to mention anything more than a prob30 at this time. Mountain obscuring clouds are forecast with this precipitation across SW MT tonight through the day Saturday. -AM

PRELIMINARY POINT TEMPS/POPS

GTF 40 61 36 58 / 0 0 0 0 CTB 28 56 30 54 / 0 0 0 0 HLN 34 55 30 55 / 0 10 0 0 BZN 34 56 30 53 / 0 20 30 0 WYS 27 42 24 41 / 10 40 20 0 DLN 34 50 30 48 / 0 30 10 0 HVR 31 59 31 59 / 0 0 0 0 LWT 38 63 34 57 / 0 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 11 AM MST Saturday for Hill County.

Dense Fog Advisory from 9 PM this evening to 11 AM MST Saturday for Northern Blaine County.