A mostly average start to Arizona monsoon season
Climate Prediction Center forecasts above-normal precipitation totals still
Some parts of Arizona have gotten rain nearly every day since monsoon storms began to fire up in early July. Summer storms tend to be localized; some areas have received more rain than others. Tucson is a bit above its average for the early monsoon.
As we approach the midpoint of the 2018 Arizona monsoon season, the question is: How’s it going?
Mostly, the answer is: Meh, about average.
But that depends on where you live. Some parts of Arizona have gotten rain just about every day since monsoon storms began to fire up in early July. However, as anyone who follows the weather here is aware, our summer storms tend to be very localized. Some areas have received more rain than others.
In Phoenix, the rainfall total so far for this monsoon (June 15-Sept. 30) is 0.69 inch, with 0.56 of that falling on July 9. The average total for June and July is 1.07 inches.
Tucson is a bit above its average for the early monsoon. That city has received 3.11 inches, while normal is 2.4 inches. Flagstaff is also overperforming at 3.35 inches (2.82 is normal).
Yuma joins Phoenix on the underwhelming side. Yuma has gotten just 0.22 inch, which is 0.02 inch below normal.
Mike Crimmins, a University of Arizona climate scientist who also works with the U.S. Drought Monitor, said that pattern holds true throughout the state.
“The precipitation pattern across the state isn’t that impressively wet ... with much of the state approaching near-average precipitation amounts for the (June 15-July 31) period,” Crimmins said via email. “There are some really wet spots in Yavapai and Coconino counties, which we will probably start looking at soon, but those are pretty localized. (There are) also some dry spots so far, too, where the precipitation hasn’t measured up so far.”
The good news is that there is still hope for wetter days ahead.
The Climate Prediction Center’s forecast for Arizona is still calling for abovenormal precipitation totals.
CPC’s August outlook has a 40 percent probability of above-normal rainfall for most of the state. When that outlook is pushed out for three months, that probability drops to 33 percent.
Meteorologists expect temperatures to remain above normal for that same period.
Climate Prediction Center scientists also are forecasting El Niño conditions to develop this fall and winter. That often means more rain and snow than normal for the southern United States, even in the event of a weak El Niño.
El Niño is more of a winter phenomenon, but it could affect the tail end of the monsoon. El Niño conditions are defined by warmer-than-normal waters in the eastern Pacific Ocean. Waters that warm up in late summer and early fall could help fuel the development of storms. Some of the moisture from those storms could make its way into Arizona.
“I would expect the east Pacific tropical activity and maybe even Gulf of Mexico come into play as we move into August,” Crimmins said.
❚ The average high temperature of 107.5 degrees tied for ninth-highest on
record and was 1.4 degrees above normal. The record for the month is 109.8 degrees in 1989.
❚ The average temperature (taking the average high and low and dividing by 2) of 96.5 degrees tied for seventh on the all-time list and was 1.7 degrees above normal. The record average is 98.3 degrees in 2009.
❚ The average low temperature of 85.5 degrees stands eighth on the alltime list, 2 degrees above normal. The record is 87.1 degrees in 2009.
❚ Eight temperature records were set in July, including five for warmest overnight lows.
❚ Phoenix is close to tying the all-time record for number of days with low temperatures of at least 90 degrees, according to the National Weather Service. As of Thursday, there have been 10 such days. The record is 15 (in 2013 and 2003). The average number is four.
❚ There also was a record for highest rainfall total for July 9 when 0.56 inch was recorded at Phoenix Sky Harbor International Airport. Overall, however, June was drier than normal, with .07 inch total.
❚ Normal rainfall for July is 1.05 inches.