Some of the worst flooding that the Verde Valley has experienced has come when warm tropical rainfall melts snow above the rim. The resulting runoff drains into the Oak Creek, West Clear Creek, Beaver Creek and eventually the Verde River.
Conditions are developing for a repeat performance Sunday night. Sunday night. Nothing is guaranteed at this writing, but the forecasting models show the Oak Creek will surpass flood stage in Sedona and Cornville. Flooding is also possible.
The worst case was Feb. 20, 1993 when flows in the Oak Creek and Verde River and surrounding tributaries set records. In 2005, snowmelt after a warm winter storm again caused flooding in low-lying areas along the Verde River, Oak Creek and near Bridgeport, and Cornville and other areas. Ranchers moved cattle, residents moved low-lying mobile homes and emergency shelters were opened for displaced homeowners.
Jerry Doerksen, chief of the Verde Valley Fire District says, "If you experienced flooding during 2005, it would be good to prepare for the same thing again."
The Yavapai County Emergency Management Coordinator Nick Angiolillo was alerted Friday by the Flagstaff Weather Service of the prediction for floodwaters by NOAA, the parent agency of the weather service. In addition to the Verde Valley, Mayer and Black Canyon city agencies also got warning calls.
The prediction models may change for the flooding potential before Sunday night, but two days out, emergency crews were already making plans.
The National Weather Service has alerted emergency service providers in Yavapai County and the Verde Valley to the possibility of substantial flooding during the overnight period beginning Sunday evening and ending Monday morning.
Mike Staudenmaier, Science Officer for the National Weather Service in Flagstaff says, "We are looking for one to three inches of rainfall up to 7500 feet that is a lot of rain on snow and can cause a lot of run off. Rain on snow in the winter is a recipe for increased flow. It is not unusual, but it is above average. The rim currently has 10" of snowfall in the Flagstaff area and up to 18" above 7500 feet."
But he cautions that there are a lot of factors at play. Rainfall at 38 to 40-degrees doesn't fully melt the snow on the ground. It creates an "icy mixture." The amount of run off into Verde Valley tributaries also depends on the depth of snow in the Verde as well.
The river forecasts are the "best thoughts" on impacts from a couple days out. Those conditions are likely to change somewhat and are cautionary predictions. As the storm approaches, those graphs will change depending upon local conditions.
If the prediction for high water remains in the models, then the area will first be alerted of a Flash Flood Watch and a Flash Flood Warning when flooding is imminent.
Residents are advised to pay attention to warnings about potential flooding and take precautions if necessary.
Doerksen says remember the Three-Ps, pets, prescriptions and papers. Take credit cards and money and have a plan.
Fire departments are always prepared with sand and sandbags for those who need protection from rising water.