Storms in June could increase risk of wildfire

The June outlook from the Climate Prediction Center calls for at least a 33 percent chance of above-normal rainfall for much of Arizona.

That means our dry spell is just about over, with drought-busting storms just around the corner. Right?

Not quite. In fact, if a few storms were to pop up in June, it might even make things worse when it comes to an already active wildfire season.

First of all, June typically is the driest month for much of Arizona, according to the Arizona State Climate Office. Average rainfall in Flagstaff is 0.36 inches, while it’s 0.2 inches for Tucson. In Phoenix, any rain in June is

considered a blessing, as the normal figure is just 0.02 inches.

So above-average precipitation for the month isn’t saying much.

University of Arizona climate scientist Mike Crimmins offers some context to that outlook.

“It’s a slight change in background probability of whether or not you might get precipitation over that time period that is above average,” Crimmins said. “It’s kind of a long way of saying if you get raindrops that occur at any point before the end of that period, that forecast will be correct.”

Crimmins said the outlook seems somewhat indicative of a seasonal transition.

“It’s a pattern we will sometimes see as we’re moving into the monsoon, but we’ll often see it as we’re skating out of it,” Crimmins said. “It’s that kind of southerly, southwesterly flow. It’s really contingent on whether or not there is moisture south of us.”

In order for that transition to bring us any rain in the next few weeks, the monsoon would have to get active in Mexico first.

“Then we could possibly see some of the moisture outflows marching north, which is what some of the (computer) models are suggesting,” Crimmins said.

But, he added, the limit for any real reliability from the computer models starts to drop after about a week.

However, if that outlook does prove true and storms develop, they could do more harm than good.

“This is a very dicey pattern for dry lightning,” Crimmins said. “We could be in the middle of June and have clouds and thunderstorms popping at high elevations, and all they could really do is put down wind and lightning.”

He said it would almost be better if we stayed dry until the heart of the monsoon, when heavier rainstorms are more likely.

The latest map released by the U.S. Drought Monitor shows increasing areas of extreme and exceptional drought overtaking much of the state.

Since May 1, the percentage of extreme drought covering the state has increased from 60.35 to 73.61 percent. The percentage of exceptional drought (the most severe condition) has increased from 9.62 to 15.71 percent.

Throughout the state, officials are taking precautions such as imposing fire restrictions and even closing portions of the national forests and other public lands. Those measures could help prevent humancaused fires but wouldn’t do much to stop lightningcaused fires.

“You can’t close a thunderstorm out of the forest,” Crimmins said. “So hopefully, if we do get (storms) next week or the following weeks, it’s accompanied by a lot of rain. But right now (the forecast) doesn’t look super, super juicy.”

May was a little warmer and much drier than normal for Phoenix, according to National Weather Service numbers.

The average high temperature for the month was 96.5 degrees, which was 1.7 degrees above normal. The average temperature (combining the average high and low and dividing by two) was 83.5 degrees, which was 1.4 degrees above normal. The average low was 70.5 degrees, which was 1.1 degrees above normal.

There was one high-temperature record set in Phoenix in May. The high of 106 degrees on May 6 was a record for that date.

There was no measurable rain at Phoenix Sky Harbor International Airport for the month. The normal figure for May is 0.11 inches.

Phoenix has not seen measurable rain at the airport (the official reporting station for the city) since March 11, when 0.04 inches fell. And that was the only measurable rain for the meteorological spring (the months of March, April and May).

That makes this the fifth-driest spring on record. The city is also 2.74 inches behind normal rainfall totals for the year. Through May 31, only 0.77 inches of rain had been recorded at the airport.