textproduct: Great Falls

KEY MESSAGES

- This afternoon there will be isolated snow showers across portions of North-central, Central, and Southwestern Montana with cold temperatures.

- On Friday there will be isolated snow showers around North- central, Central, and Southwestern Montana with warmer temperatures.

- Saturday through early next week it will warm up with mostly dry weather.

DISCUSSION

- Meteorological Overview:

This afternoon there is an upper-level trough over North-central, Central, and Southwestern Montana. This combined with the cold front will bring well-below seasonal averages for temperatures this afternoon. This afternoon there will be snow showers across North- central, Central, and Southwestern Montana. Tonight in any areas that clear or in areas that have snow on the ground fog has the potential to form. See the Forecast Confidence & Scenarios section for details. On Friday the upper-level trough remains over North- central, Central, and Southwestern Montana. On Friday due to the upper-level trough it will be cold in the morning with temperatures warming up some in the afternoon with mostly dry weather. During the day on Friday there will be isolated snow showers across portions of North-central, Central, and Southwestern Montana.

On Saturday and Sunday an upper-level ridge moves over North- central, Central, and Southwestern Montana. This will bring warm and dry weather to the area for the weekend. Monday through Tuesday the upper-level ridge remains over North-central, Central, and Southwestern Montana. This will maintain the warm and dry weather for Monday and Tuesday. On Wednesday the upper-level ridge remains over North-central, Central, and Southwestern Montana with an approaching upper-level trough. With there being southwest flow aloft and warm temperatures, instability will build and allow isolated showers and thunderstorms to form on Wednesday. -IG

- Forecast Confidence & Scenarios:

Tonight across portions of North-central, Central, and Southwestern Montana there is a 20 - 40% chance for fog to form. The areas that have the greatest risk for fog to form are any areas that clear tonight. A secondary risk for fog to form is in the valleys of Southwestern Montana that have snow on the ground.

On Friday across the mountains of North-central, Central, and Southwestern Montana there is a 30 - 50% chance for snow showers. On Friday across the lower-elevations between the Montana Highway 200 Corridor and the I-90 Corridor there is greater than a 50% chance for light isolated snow showers. For the Wednesday system there is high confidence in an upper-level trough moving over Montana but there is low confidence in forecast details. -IG

AVIATION

16/18Z TAF Period

The steady snow is coming to an end in the Bozeman area, with periods of snow continuing through the afternoon around West Yellowstone. Scattered snow showers currently west of the divide will move east of the divide early this afternoon, and generally reside over Central and the remainder of Southwest MT into Fri morning. Some patchy fog is possible Fri morning, but confidence is too low to have at a TAF site currently. Mountains/passes to be obscured across the CWA through the period. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 21 44 26 58 / 40 50 10 0 CTB 13 43 21 57 / 20 20 0 0 HLN 24 44 25 60 / 40 60 10 0 BZN 19 40 19 57 / 50 60 20 0 WYS 9 33 10 46 / 70 60 20 0 DLN 18 41 19 57 / 30 30 0 0 HVR 18 45 24 60 / 20 10 0 0 LWT 18 41 23 55 / 30 20 10 0

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 6 PM MDT this evening for Big Belt, Bridger and Castle Mountains-Madison River Valley.

Winter Storm Warning until midnight MDT tonight for Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains.