Area Forecast Discussion

KEY MESSAGES

- A weak front will bring slightly cooler temperatures today, otherwise, generally milder and drier conditions prevail for much of the week.

- There may also be some patchy fog development tonight, mostly for the river valleys and higher southwest basins.

- Fast moving weather systems will bring periods of breezy to windy conditions and spotty mountain precipitation Thursday through early next week.

DISCUSSION

- Meteorological Overview:

Ridging aloft will remain over the Northern Rockies for the next 24 hours, while a weak mid-level circulation moves eastward through the Great Basin. A weak frontal passage will cool todays highs by a few degrees and will bring some nighttime and early morning patchy fog development, mostly over the north-central river valleys and the higher southwest basins along the MT/ID/WY borders.

An initial trough passage will bring increased westerly winds and spotty mountain precipitation on Thursday. This will usher in an extended period of strong westerly flow aloft that will persist into early next week despite dominant ridging building for the first half of the weekend. The trend of the strongest winds aloft staying north of the Canadian border on Friday continues to gain traction, but a tightening surface pressure gradient and mountain wave activity still looks to enhance stronger winds along the Rocky Mountain Front Friday into early Saturday.

Ensembles are favoring the ridge flattening and sending a fast moving trough into the forecast area Sunday into Monday. This will bring another round of winds, strongest along the Rocky Mountain Front, and some more light precipitation along the northern divide. Temperatures look to remain above average this weekend into early next week, with only a slight cool down following any shortwave passages. - RCG

- Forecast Confidence & Scenarios:

Periods of stronger westerly winds Thursday through early next week

NBM probabilistic guidance continues to highlight Friday into Saturday for the strongest winds, with probabilities for 55 mph wind gusts running 70 to 90% along the Rocky Mountain Front and the plains along and west of highway 89 and along and west of I15 over Glacier County. The 40 to 60% chance for 75 mph wind gusts remains confined to the immediate eastern slopes of the Northern Rocky Mountain Front and will be heavily reliant on mountain wave activity. The plains east of I15 also look windy during this time as well, especially the central MT highway 87/200 corridor where 30 to 50 mph gusts will be common. The winds for Sunday into Monday have slightly lower probabilities despite stronger winds aloft, this looks to be mostly a trough timing issue. - RCG

AVIATION

4/06Z TAF Period

VFR conditions will prevail throughout this TAF period, with the exception of KWYS and KHVR which may see periods of VLIFR conditions between 09Z and 13Z due to early morning fog development. Surface winds will remain light and variable, with cloud cover decreasing around 18Z.

PRELIMINARY POINT TEMPS/POPS

TFX WATCHES / WARNINGS / ADVISORIES

None.