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AS 21
#158355 - Confirm favorable dispersion with test fire and monitor dispersion throughout burn period. End ignition if dispersion is poor. End active ignition early enough to reduce overnight settling.
Tuesday May 17 Discussion: High pressure breaks down as a weak trough of low-pressure moves across the area. This will bring some drier, but slightly cooler conditions today. It should also help to increase the transport wind.
Another ridge builds tomorrow ahead of a stronger trough for Thursday. Even with the ridge, the transport wind should remain at least moderate if not good. The trough then moves east and strengthens , wit the center skirting the area, just to the north, bringing increasing chances of showers and thunderstorms as a cold front moves through on Thursday.
TODAY, moderate surface wind away from the trough and showers moderate transport wind should bring MARGINAL to GOOD dispersion to the entire area.
WEDNESDAY, The transport and surface wind favor GOOD dispersion. Some low clouds are possible west of the Divide, which may reduce some areas to MARGINAL dispersion, mainly in Northern ID and NW MT.
THURSDAY, an upper-level system move in by the morning and spreads showers, and possibly some storms across the entire area, bringing POOR dispersion everywhere.
FRIDAY, the low is slowly moving across the area, and may bring a period of prolong precipitation and low cloud cover, keeping dispersions POOR.
Wednesday 18 MAY Dispersion Forecast:
MONTANA
Northwest (AS 1, 2): MARGINAL to GOOD
West Central (AS 3A, 3B, 4, 5, 6): GOOD
Southwest (AS 7, 8A, 8B): GOOD
Central/Eastern (AS 9, 10): GOOD
IDAHO:
North (AS 11): MARGINAL to GOOD
North Central (AS 12A, 12B, 13): MARGINAL to GOOD
West Central (AS 14, 15): GOOD
East Central (AS 16, 17): GOOD
Southeast (AS 18, 19, 20): GOOD
Southwest (AS 21, 22, 23, 24): GOOD
Prepared by Steven Ippoliti, NRCC Predictive Services Meteorologist