textproduct: Great Falls

KEY MESSAGES

- Warm temperatures are expected today with temperatures cooling down to well-below seasonal averages on Thursday and Friday across North-central Montana.

- Snow is expected through Thursday morning in the East Glacier area.

- Widespread precipitation is expected this weekend through Monday.

DISCUSSION

- Meteorological Overview:

Today an upper-level ridge briefly builds in over North-central, Central, and Southwestern Montana. This will allow warm temperatures to persist with a few showers around. The showers will be primarily confined to the Northern Rocky Mountain Front and will be primarily snow. On Thursday there is an upper-level ridge over North- central, Central, and Southwestern Montana. However cold air will slide south from Canada and bring well-below seasonal average temperatures to North-central Montana on Thursday. On Thursday morning snow lingers in the East Glacier area. Everywhere else on Thursday it will be mostly dry. On Friday the upper-level ridge remains over North-central, Central, and Southwestern Montana. This will bring mostly dry weather to the area on Friday. On Friday the cool air from Canada remains over North-central Montana which will keep below seasonal average temperatures in place on Friday across North-central Montana.

On Saturday an upper-level trough begins to approach North-central, Central, and Southwestern Montana. There will be warm air advection due to southerly flow aloft which will warm temperatures up to near seasonal averages. Through the day on Saturday it will be mostly dry. Saturday evening through Monday an upper-level trough moves over North-central, Central, and Southwestern Montana. This will bring widespread precipitation to the area Saturday evening through Monday. This will keep cool (slightly below seasonal average) temperatures for North-central, Central, and Southwestern Montana on Sunday and Monday. Tuesday an upper-level ridge moves over North- central, Central, and Southwestern Montana this will allow temperatures to warm up with mostly dry weather. -IG

- Forecast Confidence & Scenarios:

Today through Thursday morning along the higher elevations of the Rocky Mountain Front there is a 50 - 70% chance for 6 inches of snow or greater. Today through Thursday morning at Marias Pass there is a 50 - 70% chance for 2 inches of snow or greater. Wednesday afternoon through Thursday morning there is a 50% chance for one half inch per hour snowfall rates and a 20% chance for snowfall rates of one inch per hour. As a result a Winter Weather Advisory has been issued for the East Glacier Park area from 3 PM Wednesday through 6 AM Thursday.

Confidence is increasing that for next Wednesday through at least next Friday there will be a strong upper-level ridge over North- central, Central, and Southwestern Montana. This would bring well- above seasonal averages for temperatures with a period of dry weather for next Wednesday through Friday. -IG

AVIATION

28/06Z TAF Period

Light rain showers will affect areas along/north of Highway 2 overnight from east of Cut Bank to Harlem. Also, expect rain/snow to affect the Rocky Mountain Front. On Wednesday, most of the precipitation will be confined to the Rocky Mountain Front. Mid and high clouds will affect much of Southwest MT through through period. Do expect some mountain ranges across the CWA to be obscured by clouds/precip through the period. Cloud cover will limit the chances of fog for most areas through the period as well. Brusda

PRELIMINARY POINT TEMPS/POPS

GTF 50 37 51 29 / 20 0 0 10 CTB 46 30 43 24 / 40 0 10 30 HLN 49 27 48 25 / 10 10 10 0 BZN 47 25 45 24 / 0 10 0 0 WYS 38 18 37 14 / 40 30 10 0 DLN 45 24 43 23 / 0 0 0 0 HVR 50 30 48 23 / 90 20 0 10 LWT 48 30 48 27 / 20 0 0 0

TFX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 3 PM Wednesday to 6 AM MDT Thursday for East Glacier Park Region.