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#204951 NW Jungle and #205603 Black Oliver - monitor and limit impacts to McCallNo Restrictions
AS 1/AS 2 monitor smoke dispersion and watch ventilation levels.
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Tuesday October 26 Discussion: A cold front will continue to move across Montana today as an upper level trough also is over the area. This upper level feature will help support shower, and maybe a could storms across both Idaho and Montana. The wind behind the front is forecast to be westerly around 10-15 mph. The higher elevations may see around 20-25 mph. However, with the abundant cloud cover, precipitation, and low mixing heights, dispersions will be lower especially in the valleys, as the higher wind speeds will not be able to mix down to clear them out.
By Wednesday, a ridge of high pressure tries to build in from the southwest, only to meet resistance from a strong trough to the north. This will bring windy conditions to portions of the area, especially east of the Divide. This may be windy enough to allow for GOOD dispersions across the area. The areas of Northern ID and NW MT are the most questionable due to possible cloud cover and lower mixing heights. So there may be localized areas of MARGINAL for Air Sheds in those locations.
After Wednesday, the ridge continues to try to build north, encountering yet another upper level low pressure system, which will keep showers in the forecast from Central ID/SW MT, north and generally west of the Divide. However, the wind will subside substantially at the surface, lowering dispersions for Thursday and Friday, when the ridge breaks down due to a stronger low pressure system..
A quick moving trough on TODAY, will bring showers and low mixing heights to Central and North ID, as well as NW MT, keeping dispersion POOR. For Southern ID, and the rest of MT, breezy conditions will accompany the trough, bringing GOOD dispersions to the rest of the area.
Another trough moves into the area on WEDNESDAY, keeping the wind breezy and even bringing more widespread breezy conditions, but also continued showers and cloud cover. This will bring GOOD to EXCELLENT dispersions everywhere.
A ridge of high pressure is forecast to build on THURSDAY, which will bring lighter wind and POOR dispersion to all areas except eastern MT. In Eastern MT, the wind will still be breezy, allowing for MARGINAL (Central MT) to GOOD (Eastern MT) dispersions.
By FRIDAY, a ridge tries to continue, but is flattened by another trough moving into the area. This will bring more cloud cover, showers and lighter wind to ID and Western MT, where dispersion will be POOR. The wind will still be breezy for Eastern/Central MT keeping dispersions GOOD.
Wednesday 27 October Dispersion Forecast
MONTANA
Northwest (AS 1, 2): GOOD.
West Central (AS 3A, 3B, 4, 5, 6): GOOD to EXCELLENT.
Southwest (AS 7, 8A, 8B): GOOD to EXCELLENT.
Central/Eastern (AS 9, 10): GOOD to EXCELLENT.
IDAHO:
North (AS 11): GOOD.
North Central (AS 12A, 12B, 13): GOOD.
West Central (AS 14, 15): GOOD.
East Central (AS 16, 17): GOOD to EXCELLENT.
Southeast (AS 18, 19, 20): GOOD to EXCELLENT.
Southwest (AS 21, 22, 23, 24): GOOD to EXCELLENT.
Prepared by Steven Ippoliti, NRCC Predictive Services Meteorologist