Martin Kidston

(Missoula Current) While cooling rain heading into September isn't terribly unusual for western Montana, it is considered unique when it comes from a hurricane.

Forecasters across the West are keeping close watch on Hurricane Hilary, which formed into a Category 2 storm on Thursday afternoon and will likely become a major hurricane as it inches toward southern California.

While Missoula has baked in triple-digit heat for the last three days, the remnants of a tropical storm may be just what the doctor ordered.

“At this point in time, the heaviest rain will fall over the Missoula and Bitterroot valleys, or generally west-central Montana, and heavier stuff over in north-central Idaho,” said Leanne Allegretto with the National Weather Service in Missoula. “We're looking at light to moderate steady rainfall Sunday onward. The heaviest period will be Sunday night into Monday afternoon.”

While residents in west-central Montana don't need to batten down the hatches or run to the lumber yard to board up windows, the weather system could deliver one inch of rain over the greater Missoula region.

However, it's more likely that rainfall totals will measure around .50 inches to .75 inches.

“If that track shifts, obviously that could go up or down,” said Allegretto. “We're looking at a pretty steady rain, cooler temperatures and higher humidity. All the things we'd want to see to help with the forest fires.”

Current rainfall forecast from remnants of Hurricane Hilary. (NOAA)
Current rainfall forecast from remnants of Hurricane Hilary. (NOAA)

The timing of the storm is ideal given recent hot temperatures and scant rainfall. July delivered little moisture and August hasn't exactly been generous. But in the days to come, that will change.

“We could see rain this time of year, but we certainly don't see it from tropical systems,” said Allegretto. “The extraordinary part is that it's the remnants from a hurricane at this point. The real troubles are going to be down in the desert Southwest. By the time it gets up here, we'll get the tail end of whatever it has left.”

As of Thursday afternoon, the National Hurricane Center said Hilary was south of Cabo San Lucas heading northwest at around 14 miles per hour. It was carrying maximum sustained winds of 105 miles per hour across a wide region and is expected to intensify.

The storm is forecast to deliver 8 to 10 inches of rain across portions of California and Nevada, with decreasing amounts as it slides north into Montana and Idaho.

As it stands, Allegretto said it won't likely include any wind or lightning when it arrives in Montana on Sunday.

“If it does, it'll be further west,” she said. “None of the other stuff we'd worry about. If it turned convective, we could deal with flash flooding around the burn scars, but we're not predicting that yet.”