NWS still expecting long flood season, followed by warm summer

Posted at 4:12 PM, May 22, 2018
and last updated 2018-05-22 18:12:40-04

MISSOULA – Rivers may be running lower, but the National Weather Service is still predicting several more weeks of runoff.

Right behind that is a long-term outlook for a fire season full of warmer and drier-than-normal conditions.

While Western Montana rivers are still running high, the strong runoff we saw earlier this month has moderated. But National Weather Service hydrologists and forecasters remain confident that flood season, which would usually just be starting now, will continue well into June. And it’s all because of massive high country snows that still have to melt out.

“The thing that we’re going to see this spring is prolonged river heights. So we’re going to see the water flowing at a height that it normally wouldn’t be for a long period of time," said NWS hydrologist Ray Nickless. "And that’s typical of a snowmelt regime that, like I said, you can only get so much out of the snowpack at once. And when you’ve still got 50-inches of water, well you can figure one inch per day you’ve got another 50-days of high water.”

Appearing on “Face the State” this week, Nickless and NWS meteorologist Marty Whitmore said they’re also watching the approaching fire season, which could start soon after flooding subsides. With last winter’s La Nina ocean conditions being replaced by a “neutral” pattern, forecasters lose a key weather indicator. But it’s still looking hot and dry.

“Which means we start to lose a little bit of our signature on long-term forecasting ability because of that neutral scenario. Nevertheless, the trend is certainly into fire season being warmer than normal and drier than normal for a portion of the state," Whitmore said. "That signature becomes less prominent as you go toward the east. So it’s really kind of from the Rockies to the West Coast is where we see a fairly strong likelihood of warmer-than-normal, and drier-than-normal is really across the Pacific Northwest and into Western Montana.”

However, that may or may not indicate a bad fire season. It depends on caution and lightning.

“This year we’ve got a big snowpack. We realize that it might be a later start, but we’ll see. But boy, July was so extreme last year and if we have that again, and that’s tough to predict. Fire season is really one of the most tough, most difficult things to predict because it’s not just weather. It’s also the amount of starts, both human and lightning-caused. But right now above normal. I’m not necessarily saying another 2017. But above-normal.”

The good news is that for the first time in three summers, much of Montana should be drought-free, which should be good for the season’s water supply.

“But that still doesn’t mean you can’t get into a fire season like we’ve talked about," Nickless said. "You get into the dry period, and especially in the low elevations it can dry out real quick.” 

Whitmore advises people to stay abreast of changing summer conditions, whether it’s floods, fire or thunderstorms, by staying up on breaking weather reports.

And, of course, one good way to do that is by downloading the KPAX Stormtracker Weather app and following our Facebook and Twitter posts.