Rain, hail, snow and wind — last week had it all before the traditional kick-off to the summer months — Memorial Day weekend.
Those cold temperatures could keep thermometers chill through the next week as the Climate Prediction Center forecasts unseasonably cold temperatures, driven in part by the ongoing El Niño sea-surface warming in the Eastern Pacific.
El Niño affects weather across the globe, including a tendency to steer storms into Arizona.
A cold trough, or dip in the jet stream, out on the Bering Sea and Pacific has caused the colder and wetter than normal weather.
“The jet stream has been dipping farther south than typical this time of year,” said Ken Daniel from the Flagstaff office of the National Weather Service.
Temperatures dipped so low in the Tucson area that the NWS issued a freeze warning on May 20.
The Snowbowl Ski Resort reported its longest season in history, which wound up just last weekend. However, as yet another storm rolled into Arizona this week, the snow cameras atop the mountain at 9,500 feet showed a frigid winter landscape.
The low temperatures caused snow in the White Mountains and Flagstaff, hail in Payson and Pine and a tornado in the Cameron area.
Hail pelted Rim Country off and on May 20.
The late rain comes on the heels of the wettest year on record for the 48 continuous United States, according to the National Weather Service. As a result, the U.S. Drought Monitor only has 2 percent of the country in drought.
Only the Navajo Reservation in the northeast corner of the state and a big chunk of New Mexico remain in the grip of “moderate drought.”
This time last year most of Arizona suffered from “exceptional drought,” which had continued off and on for most of the past decade.
The wet weather could continue into next year. The National Oceanic and Atmospheric Administration (NOAA) predicts El Niño will hang around for another year.
Many climate models have predicted that the gradual rise in average temperatures globally would pump far more energy into El Niño events, making them increasingly extreme. So the extreme swings from drought to flooding may prove progressively more common as temperatures rise, according to some climate models.
The NOAA reported that the nation’s winter precipitation total was 36.2 inches, a full 2.22 inches above the 20th century average. The total came in .02 of an inch above the previous winter record set in 1997-98.
Much of the rainfall was concentrated in the Plains, Great Lakes, Southern Appalachians, Mississippi and Ohio.
Places like Nebraska reported the snowiest winter ever — 46 inches. All but five of the lower 48 states reported above-average precipitation — with Arizona, Oregon, Idaho, Montana and Utah the only states reporting below average winter rain and snow.
Generally, Rim Country and much of northern Arizona reported rainfall well above normal, especially at the higher elevations. Southern Arizona received much less rain.
The runoff swelled reservoirs long stressed by the drought.
Roosevelt Lake went from about 38 percent full to 78 percent full, with all the downstream Salt River lakes brimming.
The C.C. Cragin Reservoir also filled to the brim and spilled thousands of acre-feet of water over the spillway down into West Clear Creek.
This week’s storms once again recharged the region’s streams. Early this week, the Salt River swelled to 800 cubic feet per second, 50 percent above normal. The Verde River and Tonto Creek were both flowing at about their normal rates, 150 cfs and 95 cfs respectively.
Runoff from the Rocky Mountains has put off the threat of water rationing throughout the West by at least a year, due to falling water levels in Lake Mead. The massive reservoir is about five feet higher than at this same time last year, according to the U.S. Bureau of Reclamation. That’s still about 240 feet below full pool and about 37 feet above a level that shut down the hydro-electric generators and triggered sweeping water restrictions.