BILLINGS — Monday's highs will be near 80°F along the Montana/Dakotas border, with mid 80s to around 90 elsewhere. Billings and Roundup have a 20-40% chance of exceeding 90°.
Smoke from Canadian fires is affecting Montana and northern Wyoming Monday, especially west of Rosebud (Forsyth) County including Yellowstone (Billings) County. Air quality is expected to improve Monday night through Tuesday with a pattern change in the winds.
A southwesterly flow over the north-central U.S. may lead to persistent thunderstorms and varying temperatures throughout the week. An increase in the humidity is expected, adding fuel and lift to create thunderstorms.
There is a "Marginal" risk of severe thunderstorms (1 on 1-5 scale) mainly from Billings to the west Tuesday due to this increasing moisture and instability. By Wednesday, a stronger wave may lead to more favorable conditions for severe storms with the possibility of heavy rain and thunderstorms throughout Wednesday night into Thursday.
For Thursday, the risk is reduced for severe storms, but heavy rain may still develop based on moisture levels.
As far as temperatures go, Tuesday looks to be the overall warmest day with highs in the 80s to lower 90s. A cooling trend mid-week will slip us to near-normal temperatures int eh 70s to mid-80s Wednesday and Thursday.
A warming trend can be anticipated Friday into the weekend, with a lot of the lower elevations reaching the mid-to-lower 80s. River and stream levels remain stable, but there is potential flash flooding in burn scar areas, especially with expected heavy rains.
