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DISCUSSION

KEY MESSAGES:

- Very strong west winds 35 to 45 mph, gusting in excess of 60 mph are expected today. High Wind Warning in effect through 5pm this afternoon.

- Mixed precipitation this morning combined with cold ground temperatures will to lead to icy surfaces in some areas.

- Warm temperatures tomorrow then sharply falling minimum temperatures. Expect icy conditions.

- Prolonged period of snowfall through the end of the week.

WEATHER PATTERN OVERVIEW:

Strong cold air advection behind the next clipper system should help mix down the stronger winds, especially for higher elevations. NBM ensemble max wind gusts show widespread 50 to 60 mph gusts, with good chances for gusts of at least 60 mph in many areas. Conditions are favorable for high winds. Post- frontal winds will shift to the NW and decrease fairly quickly this evening. Will maintain High Wind Warning until 5 pm this afternoon in all areas.

A mix of rain and Freezing is currently occurring across parts of NE Montana. Temperatures are above freezing in most areas at 2 am with only the Wolf Point and Plentywood area reporting below freezing temperatures. However, road temperatures in many areas of NE Montana are still below freezing based on reports from MDT pavement temperature sensors. This will allow the rain to turn into ice on the ground. Will maintain the Winter Weather Advisory for now. Once the sunrises, we will assess what areas have wet pavement versus icy pavement and adjust the areal extent of the Advisory.

Temperatures will begin to fall this afternoon behind the cold front and will rapidly fall this evening. Wet roads will freeze which will lead to icy surfaces. Lows tonight will vary from the single digits NE to the 20s SW.

The front moves east as a warm front on Wednesday with an overrunning band of snow moving into the forecast area during the morning and temperatures warming enough in the west for the snow to change to rain with areas of freezing rain in between. The front moves south Wednesday night amd Thursday with the wintry mix of precipitation gradually changing back to all snow.

Models and ensembles are pointing towards significant snow between Thursday and Friday night with moisture overrunning a quasi- stationary front in SW Montana and northern Wyoming. A Winter Storm Watch is likely in the near future for this event. Forecast snow amounts between models and ensembles are highly variable at this point. NBM probability of 8+ inches of snow range from less than 10 percent in the NE corner of the state to 40 to 50 percent around Zortman, Winnett, and Jordan.

Bitter cold temperatures are expected between Thursday night and Saturday night with an arctic airmass in place.

FORECAST CONFIDENCE & DEVIATIONS:

Increased winds speeds today with mixing in the NBM 90 into the forecast. No other deviations from the NBM at this time.

High confidence on the strong winds and warm temperatures today.

High confidence of precipitation occurring on Wednesday.

Low confidence on temperature forecast and the boundary between precipitation types between Wednesday and Thursday as the frontal boundary meanders across NE Montana.

High confidence that there will be heavy snow in the SW half of the forecast area between Thursday and Saturday morning with low confidence in the NE and low confidence on specific snow amounts.

High confidence on the bitter cold Thursday night through Saturday night with low confidence on specific temperatures.

AVIATION

LAST UPDATED: 0930Z

FLIGHT CAT: VFR most of the time with areas of MVFR today.

DISCUSSION: Wintry mix of precipitation through this afternoon. Look for icing concerns from mixed precipitation this morning. A mix of low and mid level clouds this morning will bring areas of MVFR cigs at times. Skies will clear this afternoon and remain mostly clear this evening. Mid and high clouds will move in from the west late tonight. WIND: Strong west winds begin by 12z. 20 to 35 kts gusting to 50 knots, with stronger gusts possible. Low level wind shear at 2000 ft will be impacting the region until the winds aloft begin mixing to the surface around 12z. Winds will become NW this afternoon and diminish to 5 to 10 knots between 00z and 06z this evening and become light and variable late tonight.

GGW WATCHES/WARNINGS/ADVISORIES

High Wind Warning until 5 PM MST this afternoon for Central and Southeast Phillips-Central and Southern Valley-Daniels-Dawson- Eastern Roosevelt-Garfield-McCone-Northern Phillips-Northern Valley-Petroleum-Prairie-Richland-Sheridan-Southwest Phillips- Western Roosevelt-Wibaux.

Winter Weather Advisory until 2 PM MST this afternoon for Central and Southeast Phillips-Central and Southern Valley- Daniels-Dawson-Eastern Roosevelt-Garfield-McCone-Northern Phillips-Northern Valley-Petroleum-Prairie-Richland-Sheridan- Southwest Phillips-Western Roosevelt-Wibaux.