textproduct: Glasgow

DISCUSSION

KEY MESSAGES: - Strong winds are expected at higher elevations this morning. Targeted High Wind Warnings are currently in place.

- isolated snow showers are expected this morning and should taper off before noon. These could briefly lower visibility and produce very local totals of 1 to 2 inches.

- A very strong push of Arctic air is expected late in the work week.

WEATHER PATTERN OVERVIEW: Forecast begins with a large amplified ridge sitting off the north american coast and a large low pressure system over the Hudson Bay. Northeast Montana sits underneath the colder side of northwest flow nestled in between the two.

Today: A long trough with Arctic air push under it extends out of the Hudson low pressure and runs from northern Manitoba to central Saskatchewan and southern Alberta. This cold front is firming up and will pass through the area mid-morning. Along this cold front are isolated convective snow showers. When combined with strong NW winds areas of low visibility in blowing snow could occur with any showers. Some locations will come close to High Wind criteria this morning. So a High Wind Warning was issued for Sheridan, SW Phillips and some of the southeast counties along the Big Sheeps. This warning expires at 11 am. It's possible a quick 1 or 2 inches could fall. WPC has highlighted the area for snow squalls but will hold off on any statements at this time.

Tonight through Monday evening: Expect calming and dry conditions.

Early Tuesday morning through Tuesday night: A second round of isolated to scattered snow with gusty to strong winds are possible similar to this morning with only 1 to 2 inches.

Wednesday & Wednesday night: Expect a brief pause with calmer winds and dry conditions.

Thursday into the early weekend: Ensemble set up appears to show the Hudson Bay low get pulled west out of the Hudson basin. This places northeast Montana under a much deeper/thicker cold air bubble after a very strong Arctic front. This front should hit northeast Montana around Thursday afternoon to Thursday night.

The orientation of the flow aloft here will be key as there is uncertainty in the ensembles with how the shortwave passes over the Arctic air. But a portion of the memebers(20-40%) are dragging in moist pacific air in to flow over this Arctic airmass and should generate at least some light snow for north central to southeastern Montana. The more aggressive members(10-20%) bring much more snow for a larger storm. The problem lies in the uncertainty of orientation of flow aloft and depth of the cold air below. If things shake out right this storm could move farther north into northeast Montana (5-15%) and be a rather strong system/ event. If not(50-70%), this will be a very cold but dry set of days. So, while the chance for a storm is low, if it does happen it could be a doozey/high impact. GAH

FORECAST CONFIDENCE & DEVIATIONS: NBM deviations this morning included hourly wind and wind gusts grids out to around 21Z in order to mesh up with the reality of RTMA/URMA data.

Confidence is MODERATE in isolated snow showers this morning.

Confidence is MODERATE in a light snow event Tuesday and Tuesday night.

Confidence is HIGH in a deep Arctic Airmass arriving Thursday.

Confidence is LOW in a large storm system roughly Thursday night.

AVIATION

UPDATED: 0915Z

FLIGHT CAT RANGE: VFR - MVFR. Possible IFR in any snow showers.

DISCUSSION: Strong winds are expected across the terminal this morning along with isolated snow showers. Ceilings will remain MVFR for KSDY through the morning and begin to lift around 21-00Z. KGGW and KGDV will be on the edge of the low cloud line through the morning and may go back and forth between MVFR and VFR.

Isolated hit-and-mostly-miss Convective snow showers are expected in the mix through the mid to late morning. These will drop visibilities to IFR or worse if and when they do pass a location for probably less than an hour due to blowing snow lower visibility.

WIND: N to NW at 10 to 25 kts gusting to 35 kts in the morning hours. Reducing to 10 to 20 gust 25 kts in the afternoon. then calming to 10 kts or less through tonight and backing to the NW to W Monday morning.

GAH

GGW WATCHES/WARNINGS/ADVISORIES

High Wind Warning until 11 AM MST this morning for Dawson-McCone- Prairie-Sheridan-Southwest Phillips.