Heavy rainfall and resultant flooding on Saturday left 40 to 50 hikers stranded in Bear Canyon near the Catalina Mountains.
The hikers that were rescued said the river swelled within minutes, according to Associated Press.
The stranded hikers were rescued by helicopter and a technique of roping that bound them together with flotation devices to cross the raging water.
On Saturday, the rainfall for the Bear Canyon region was believed by AccuWeather Expert Meteorologist Jim Andrews to be around an inch with temperatures in the middle to upper 50s.
Phoenix broke their 24-hour record rainfall amount with 1.18 inches. Some local rainfall amounts in southern Arizona broke 2 inches. Tucson International Airport observed 0.46 of an inch within a one-hour period on Saturday.
Andrews said that the rainfall came down relatively fast.
"Within an hour, it went from raining not very hard to very hard," he said.
Runoff from the mountain could have caused the local creek to swell very quickly and without warning, according to Andrews. This could have taken the hikers by surprise.
Andrews also said, the Catalina Mountains are capable of making their own weather, because of "upslope," which is when winds blow up the mountain.
"The added lift wrings out more water than normal," he said.
Andrews also offered some "words of desert wisdom."
"Bodies of water should be off limits. A desert wall of water can come downstream with no warning because of heavy amounts of rainfall in a short period of time," Andrews said.
Tropical Storm Hermine will turn toward Florida with heavy rain, gusty winds and the risk of flooding late this week.
Another strong tropical disturbance has moved off the coast of Africa and bears watching for strengthening and impact on the Caribbean and the United States during September.
A swarm of tropical systems cruising the Atlantic Ocean will raise surf and risks to beachgoers along the East coast of the United States into Labor Day weekend.
Two tropical systems, Madeline and Lester, could pose hazards to Hawaii into Labor Day weekend.
Though the summer season is winding down, forecasters are predicting a warm start to fall across the Northeast — a weather pattern that could spell bad news for fall foliage lovers.
While warmth will dominate much of Asia this autumn, drought relief is on the way for southeastern areas, but tropical cyclones could threaten lives and property surrounding the Bay of Bengal.
Houston, TX (1990)
A total of 0.31 inches of rain today. This was the first measurable rain in Houston since July 30th with 0.16 inches. This is the longest dry spell ever in Houston in August.
Philadelphia, PA (1991)
Mercury reached 90 degrees or better for the 49th day this year, as the high was 92. This tied the all-time record for the most 90 plus days in a year, set in 1988. The record would be broken in September. The total for 1991 was 53 days.
West Chester, PA (1922)
So much hail fell that fields were covered with up to two feet drifted hail--the next day!!