Posted: May 24, 2011 6:58 AM by Russ Thomas (KPAX/KAJ StormTracker Weather)
Updated: May 25, 2011 8:14 AM
MISSOULA- It's one of the hot topics every year right about now- just how bad will Montana's fire season be? Meteorologist Russ Thomas takes a look at the science behind the wildfire forecast.
It truly is a science in every sense of the word, from hypotheses to formulas, to equations, to hopefully nailing the final result. It affects the livelihood of all who call western Montana their home during the summer months...wildfire season.
What you may not know is that the process begins on the heels of the previous season.
"Have we had a good Fall? Do we have a lot of moisture before the snow comes, before the ground is frozen? If so, we know that the vegetation is not as stressed as a result. Are we in a long term drought?" are some of the questions that Northern Rockies Coordination Center Predictive Services Meteorologist Bryan Henry tries to answer each year.
Winter snowpack along with springtime temperatures and precipitation are important components when looking to make a forecast.
While what happens in the Fall, Winter and Spring is certainly part of the equation, the biggest impact might just be what happens in the early to middle part of Summer, where we get hot and dry and the underbrush dries. That can be the biggest game changer of all according to Henry.
"The heat in late June and early July can trump just about anything else," he explained. "If we were to flip that switch to very hot or very dry for a number of weeks, then we could have quite a problem should we have a big wind event."
Our unusually cool and wet Spring, coupled with near record snowpack levels in 2011 has helped with short term forecasting, but even then the bigger picture can be tough to forecast.
"Knowing that we're going to have a compressed season makes it easier for us to determine exactly what kind of acreage we're going to burn in this season, knowing that it's been half as long as it would typically be. Now gauging how active the second season is going to be, that's another question," Henry told us. "That's when it becomes complex and that's when the positioning of that high pressure ridge is going to mean everything."
That brings us to the last piece of the wildfire forecast equation...the placement of that ridge. Henry explained why hot and dry might be the better bet to avoid large fire outbreaks.
"The first scenario being the ridge being right on top of us meaning very hot and dry, and the second scenario being the high pressure just off to the east and leaving the door open for monsoonal thunderstorm activity. I'd be much more concerned about monsoonal thunderstorm activity."
That's especially true when you consider that in a thunderstorm, lightning can strike up to 10 miles away from the core of the storm.
The forecast for the high pressure to be on top of or slightly west of the Northern Rockies will hopefully help us avoid any late season wildfire surprises.
The initial forecast for the season calls for a mild fire season, but the NRCC will update its forecast in late June.