Monsoon season in the Flagstaff area has been minimal this year, bringing little precipitation during an important weather period.
According to the National Weather Service (NWS), rain gauges at the Flagstaff Pulliam Airport have recorded an average of nearly 10 inches of rain during monsoon season over the past decade. Although monsoon season officially runs until Sept. 30, Pulliam Airport has recorded just over 1 inch of rainfall during the 2019 monsoon season.
Emily Thornton, a meteorologist for the NWS, explained that monsoon season is caused by a shift in wind direction. Around late June, winds become more southerly in the Four Corners region, which brings moisture from the Gulf of California into northern Arizona. This trend usually continues into the fall, which could allow this year’s monsoon season to strengthen.
“We still have time to go,” Thornton said. “Outlooks from the Climate Prediction Center over the next month have equal chances for above or below normal precipitation. There is no clear signal either way.”
Looking forward, monsoons have little influence on the upcoming winter season. Thornton said a weak monsoon season does not guarantee either a dry or wet winter and previous years have shown no correlation between these seasons. Furthermore, she said there are only theories and estimations regarding these weather patterns.
“The Climate Prediction Center three month outlooks favor around a 33% chance of above normal precipitation,” Thornton said. “Not the best odds, but it is promising. We will just have to wait and see.”
There is speculation that the weak monsoon season and its ensuing dryness allowed incidents such as the Museum Fire to occur. Furthermore, there is also a general concern that this summer’s dryness could pose additional risk for fires in the future.
Paul Summerfelt, wildland fire management officer for the Flagstaff Fire Department, explained that wildfires are nearly impossible to predict. Summerfelt said forecasting weather conditions in advance is especially difficult.
“It’s really hard to project wildfires,” Summerfelt said. “When I’m asked about what fire activity will be like going forward, I say to ask again in October. We’re going to get prepared, but we’re not going to project the season that we’re going to have.”
According to both Thornton and Summerfelt, this winter will be a critical component in evaluating future fire risk. A wet and snowy winter could eliminate any dryness inflicted by this year’s monsoon season, which would decrease the likelihood of wildfires. However if weather conditions remain this dry, it is probable that there will be additional fire risk heading into the spring and summer.
In northern Arizona, fire season is commonly defined as the period from May to June. This time frame represents the period during high wildfire risk due to prolonged drought and high temperatures. However, Summerfelt said the concept of a fire season has become obsolete in recent years.
“The idea of a fire season used to be correct, but fire professionals across the country, especially across the west, understand that we’re not dealing with a fire season anymore. We’re dealing with a fire year,” Summerfelt said. “There’s more fire activity in the May, June and July window, but we have fires year-round.”
Summerfelt also said that this summer’s fire activity has been limited and fortunate. Given the hot temperatures and lack of precipitation, more wildfires were anticipated throughout Arizona. Summerfelt said that even the Museum Fire could have been more problematic.
“Fire season has been exceptionally slow this year, even though it’s been dry,” Summerfelt said. “We would have expected a fire like [the Museum Fire], if not worse. But in terms of Arizona, we didn’t have a lot of large fires this summer.”
Both Thornton and Summerfelt said they believe that the weather is truly a variable issue. Temperatures and precipitation, along with their ramifications, are challenging to predict. In turn, long-term weather trends are nearly impossible to forecast, despite any current occurrences. Summer monsoons, winter storms and year-round wildfires are all related, but both weather professionals displayed their uncertainty regarding these phenomena. The most reliable method is simply to wait and see.