Labor Day vacationers escaping the heat of the Valley for the cooler Arizona locales should be on watch for potentially dangerous wet weather this weekend.
Forecasts are calling for the possibility of strong thunderstorms with heavy rain in some areas statewide, with the frequency and intensity potentially picking up Saturday morning. A hurricane in the Pacific Ocean may add to the chance of storms.
It isn’t known whether this predicted rain could lead to flash flooding. But the National Weather Service already is urging caution for people who will be in floodprone areas, such as canyons, dry washes and low spots on roadways.
Flash floods can sweep through these areas even if the weather is dry and the rain is falling miles away.
“You can add lightning to the mix with these storms, as well,” weather service meteorologist Valerie Meyers said Thursday.
Moisture typical of the monsoon is flowing back into Arizona following a warm, dry week.
Temperatures in Phoenix have been up to four degrees above average, and rain hasn’t come near the heart of the Valley since the morning downpour of Aug. 24.
Possibly making matters wetter is Hurricane John, which is forecast to approach the tip of Baja California today then move into the eastern Pacific.
With south-to-north wind patterns, the monsoonal flow might tap into this tropical moisture and bring it into Arizona by Saturday.
Once John’s moisture is in place, the atmosphere would need 12 to 16 hours to percolate.
If all the meteorological conditions come together, “then we could have pretty explosive development,” Meyers said.
But if John sends up too much moisture, or at the wrong time, cloudy skies could inhibit the development of thunderstorms.
The upside to the forecast is temperatures are predicted to stay below average beginning Sunday and into the first few days of next week.
Because of the monsoon’s rainfall, fire restrictions only affect public lands in western Arizona. But past wildfires have forced the closure of some forest lands.
• In northeast Maricopa County, the Tonto National Forest is closed near the Bart, Cave Creek Complex and Edge fires of 2005. Also off-limits is the Coconino National Forest northwest of Sedona near this summer’s Brins fire.
• On the Bill Williams River, Cibola, Havasu and Imperial national wildlife refuges, open fires of any type are prohibited at all times.
• Less stringent restrictions are in effect on Bureau of Land Management property near Lake Havasu City and Yuma. There, open fires are prohibited but propane stoves, lanterns and tiki torches are allowed provided they are placed at least 10 feet from any surrounding vegetation.
• Smoking is prohibited on the refuges and BLM areas, except within an enclosed vehicle or building, in a developed recreation site or while in an area at least 10 feet in diameter that is barren or cleared of all flammable material. Also forbidden are the use of fireworks, flares or other incendiary devices.
• The restrictions on BLM sites are scheduled to be lifted on Oct. 31. At the refuges, the smoking ban will end in October, but the prohibitions on fires and incendiary devices are year-round.
Heading to the lakes?
The road to popular Bartlett Lake is open again, just in time for Labor Day weekend. Flash flooding last month closed the only passage to the Verde River reservoir. But Maricopa County transportation officials said Thursday that repairs were finished on Bartlett Dam Road. And according to the Arizona Department of Transportation, there should be few if any construction delays on the major highways used by vacationers.