textproduct: Great Falls

KEY MESSAGES

- It will be windy through Sunday morning across North-central Montana.

- Widespread rain/snow will fall Sunday evening through Monday morning.

- Tuesday through the end of the week it will be warm with dry weather outside of mountain snow showers at times.

DISCUSSION

- Meteorological Overview:

This morning there is an upper-level shortwave associated with a Pacific cold front that will move over the Rocky Mountain Front. This will bring strong winds to the Rocky Mountain Front and plains through this morning. It will also bring snow to locations above pass-level along the Rocky Mountain Front. The Pacific cold front will move through North-central by this evening. This will bring rain initially to the lower-elevations of North-central Montana Sunday afternoon and early evening. The Pacific Front will stall north of the I-90 corridor Sunday evening. Monday morning the Pacific Cold Front will move through Southwestern Montana. The Pacific cold front will cool temperatures to closer to seasonal averages but still slightly above seasonal averages across North- central, Central, and Southwestern Montana. The Pacific Cold Front will lower snow-levels across North-central, Central, and Southwestern Montana. This will bring mixed precipitation to much of North-central, Central, and Southwestern Montana on Monday.

Tuesday an upepr-level ridge moves over the area. This will allow temperatures to warm up slightly with mostly dry weather. Wednesday through Saturday the upper-level ridge remains over North-central, Central, and Southwestern Montana. Wednesday through Saturday there will upper-level shortwaves that move through the upper-level ridge and will bring snow showers to the mountains with mostly dry weather for the lower-elevations. Wednesday through Saturday temperatures will be well-above seasonal averages. -IG

- Forecast Confidence & Scenarios:

For Snow Sunday through Monday there is a 60% chance for 6 inches of across the Little Belts, Southern Rocky Mountain Front, and mountains of Southwestern Montana. For snow Sunday through Monday there is a 30 - 60% chance for an inch of snow or greater between Belt and Lewistown along the Montana Highway 200 Corridor/US Highway 87 Corridor.

The snow squall risk on Monday continues to go down. Model soundings only show enough instability for snow squalls in the afternoon. In addition Monday morning the frontogenesis is modestly weak. Also the snowfall in the afternoon across North-central, Central, and Southwestern Montana looks to be isolated in nature. -IG

AVIATION

08/06Z TAF Period

Periods of strong winds will affect the Rocky Mountain Front and the Cut Bank area through about 15z Sun. Rain/Snow will also affect mountain areas along the divide through the period. The rain/snow will spread eastward over Helena, Great Falls and Lewistown on Sunday evening, spreading into the Bozeman area by Monday morning. Expect low ceilings and IFR conditions to develop in areas of snow. Mountains/pass will gradually become obscured across the CWA during the day on Sunday. Brusda

FIRE WEATHER

The main concern from today through Sunday will be the gusty winds and low afternoon humidity over North Central MT. The lowest humidity will occur today, with humidity in the teens along the I-15 corridor from Great Falls to Cut Bank. Also, winds will increase this afternoon, with strong winds in the Cut Bank area by this evening. This could result in difficult conditions to contain any new fire starts. Humidity should increase on Sunday, reducing the impact a bit. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 61 44 58 34 / 0 0 20 80 CTB 57 39 52 29 / 0 0 10 50 HLN 58 36 56 32 / 0 0 30 90 BZN 58 33 56 33 / 0 0 20 80 WYS 42 21 41 25 / 10 0 30 80 DLN 56 33 54 31 / 0 0 20 70 HVR 60 38 57 29 / 0 0 0 40 LWT 60 39 57 30 / 0 0 20 80

TFX WATCHES/WARNINGS/ADVISORIES

High Wind Warning until 10 AM MST Sunday for East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera- Northern High Plains-Southern High Plains-Southern Rocky Mountain Front.