Originally Published: August 5, 2018 6:33 p.m.
In a matter of a month, the Prescott area received enough rainfall to go from one of the driest years it has ever had to a wetter than usual one.
Before monsoon moisture came swinging through in early July, Prescott was in the midst of an unprecedented dry streak. Between Jan. 1 and July 4, the National Weather Service’s official precipitation gauge at the Prescott Municipal Airport had only measured 1.87 inches of precipitation – the lowest total amount ever recorded for those months. The normal value for that period of time is 5.14 inches.
The winter leading up to 2018 was no better. Between September and January, it was both the driest and warmest winter in recorded weather history in Prescott with only 0.53 inches of precipitation.
The effects of so little moisture for such a stretch of time were clear. Wild animals were reportedly entering residential areas in desperate search of food and water; cattle herders were having to liquidate their herds due to lack of available forage; and the water levels of Prescott’s two creek-fed lakes (Willow and Watson) were the lowest they had been since 2007.
Much of that began to take a turn for the better when measurable precipitation started on July 5, and then continued to visit the area almost every day since.
LOTS OF RAIN
In July alone, the Prescott Municipal Airport received 4.49 inches of rain. Add the extra 1.05 inches of rain it received between Aug. 1 and 4, and the total amount since Jan. 1 is 7.41 inches. That’s just above the average amount (7.38 inches) for this time of year.
Precipitation recorded at Prescott’s Sundog weather station has been even more impressive. Since Jan. 1, the station has seen 11.23 inches of precipitation as of Aug. 4. The normal for that timeframe is 9.92 inches.
Jim Rhodes, a Lab Technician/Relief Operator at the Sundog Wastewater Treatment Plant in Prescott, is the primary volunteer to take the precipitation readings at the Sundog weather station. In his experience from taking the readings since 2012, he can’t recall Arizona monsoon weather moisture this consistent and heavy in such a short period of time.
July 19 especially stood out. That day alone, the plant received 3.12 inches.
“That might be a record for one of the highest rainfalls here,” Rhodes said.
According to the National Weather Service, Rhodes is correct. The last daily record for rainfall in the Prescott area was 1.31 inches in 1930.
When rain falls in copious amounts in a short period of time, reservoirs certainly benefit, but an area’s vegetation only gets so much of it.
“A lot of it runs off, so it’s not so beneficial when it comes to soaking into the ground like we might hope for,” said Megan Taylor, a meteorologist with the National Weather Service.
Jeff Schalau, Interim Regional Director for the University of Arizona Cooperative Extension in Prescott, agrees.
“As far as soaking in and going in deep, we’re basically still in a drought, and the soil is probably moist down to a couple of feet right now, but there’s a lot of dry times that had impacts that we’re not seeing,” Schalau said.
Heavy downpours when topsoil is already saturated also leads to flooding, which Northern Arizona has seen a good share of so far this summer.
On a rosier note, the monsoon season doesn’t officially end until Sept. 30, so more precipitation is expected for at least the near future.
“We usually see the thunderstorm activity at least through the first part of September,” Taylor said.
Additionally, climate scientists are saying that we’re going back into an El Niño weather pattern, “which could mean that we will get above average — or at least average — winter moisture this next winter,” Schalau said.