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DISCUSSION

KEY MESSAGES: 1) Above normal temperatures are expected to persist until a cold front arrives late Wednesday night.

2) Strong northwest winds are expected Thursday into Friday. High Wind Watches have been issued for parts of NE Montana, likely to be expanded.

3) Near average temperatures late this week through this weekend.

WEATHER PATTERN OVERVIEW:

A weak cold front along the North Dakota border is lowering temperatures slightly from the last few days. Above average temperatures can be expected through tomorrow before a cold front pushes south dropping temperatures back to near seasonably average.

Low stratus clouds along the stalled frontal boundary (east along a line from Wolf Point to Glendive) may allow for brief reductions in visibility, especially when traveling in uneven terrain. Slight chances for light snow or freezing fog are possible before dissipating during the day and increasing winds. River valley fog remains a concern over the next few nights.

Strong upper level riding over the PNW will reach its peak today but quickly give way to a Canadian surface low dropping into the Dakotas on Thursday. This low pressure center will deepen as it propagates southeast through Minnesota at the same time as ridging strengthens over the Canadian coast. This tight pressure gradient coupled with push of WAA and a quick turnover to strong CAA serves to generate strong winds over much of the CWA Thursday evening into Friday. High Wind Watches have been issued, one for eastern zones (the more prolonged, higher impact event) beginning Thursday, and one for the western zones (a terrain influenced, normal event) Friday night. Both hazards are likely to be expanded in area and time.

A forecast challenge may be snow chances tonight coupled with strong winds in eastern zones. Low end chances for light snow with the forecasted winds may create travel hazards. Current WSSI puts parts of Daniels, Sheridan, and eastern Roosevelt under moderate impacts. While this outcome is unlikely, it's worth monitoring. There is some potential for 850mb frontogenesis to develop in eastern Montana Thursday night, but dry conditions are currently limiting snowfall.

FORECAST CONFIDENCE & DEVIATIONS: Blended HiRes guidance for day 1 winds. Used 25% NBM90 for day 2 winds, 50% NBM90 day 2 wind gusts. Specifically day 2 18Z - day 3 6Z used 50% NBM90. Raised PoPs slightly in eastern zones Thursday night.

High confidence in winds, likely high wind will need to be expanded and upgraded. Low confidence in snow collocated with strong winds.

AVIATION

LAST UPDATED: 0930z

FLIGHT CAT RANGE: VFR - MVFR

DISCUSSION: Mid to high level clouds will continue to stream east across area terminals. Low stratus pushing west over KOLF, KSDY, KGDV will diminish through the morning, but may cause brief dips into MVFR or IFR. Clearing is expected during the day before mid to low level clouds return over TAF sites tonight.

WIND: W to NW winds will remain less than 10 knots through this evening. Winds will veer NW through the night tonight, becoming stronger. Gusty to strong NW winds 20 to 30 kts to begin by 12Z Thursday.

LLWS: Present over TAF sites briefly. KGGW 3 - 4Z, KGDV 5 - 7Z, KOLF 8 - 9Z

GGW WATCHES/WARNINGS/ADVISORIES

High Wind Watch from Thursday afternoon through late Thursday night for Central and Southeast Phillips-Northern Phillips- Southwest Phillips.

High Wind Watch from Thursday morning through late Thursday night for Daniels-Dawson-Eastern Roosevelt-Prairie-Richland- Sheridan-Western Roosevelt-Wibaux.