Sunday’s forecast for a major pounding of the Northern San Joaquin Valley with heavy rain and high winds comes almost 20 years to the day on Jan. 8, 1997 when floodwaters reached a dry levee just south of Woodward Avenue that provided southwest Manteca’s last line of defense.
The upcoming storm is the same type of system known as a “Pineapple Express” that triggered the 1997 flood south of Manteca that covered 60 square miles, forced the evacuation of 2,000 people and caused $100 million in damage.
The conditions surrounding the Pineapple Express — also called an atmospheric river that horizontally transports moisture out of the tropics — are somewhat different this time.
Back in 1996 there had been unusual snowfall in early December. Then a Pineapple Express arrived during the last few days of the year bringing heavy rain to as high as 8,000 feet — the same as predicted this weekend. That heavy rain triggered a significant early snowmelt.
Reservoirs such as New Melones on the Stanislaus River had higher than average storage out of concern California could enter drought conditions.
The Bureau of Reclamation and State Department of Water Resources were slow to react to the unseasonable snowmelt. By the time releases were kicked up there was a serious concern by state emergency officials that New Melones that holds 2.4 million acre feet could be breached. Water rushed down river reaching the confluence with the San Joaquin River at the same time stepped up released from other rivers did.
This time around New Melones was holding only 632,000 acre feet of water putting it at 26 percent capacity before the first storm hit this week.
And while the rains could diminish the snowpack that is critical for a huge chunk of California’s water needs in the non-winter months there is capacity in reservoirs to capture some of the runoff.
Sand bags available
for local flooding
City of Manteca officials — concerned that the intensity of the downpour forecast for Sunday could temporarily overwhelm part of the municipal storm runoff system — have made free sandbags available.
Manteca residents may receive up to 10 sandbags per resident with proof of Manteca residency from G & L Irrigation and Farm Supply, 1990 E. Yosemite Ave., Manteca, (209) 825-5959. They are open Monday through Friday from 7 a.m. to 5 p.m., Saturday from 8 a.m. to 4 p.m., and are closed Sunday.
Park could close
The forecast of heavy rain this weekend is expected to send the Merced River well above flood stage prompting warnings that Yosemite National Park could be closed.
The park flooded in January 1997, which caused extensive damage to park roads, campgrounds, lodging, and utilities. The park was closed for two months due to extensive damage to the park’s infrastructure.