Northern California is experiencing one of the wettest starts to a water year in the history of record keeping, dating back to the turn of the 20th century, weather officials said.
The California Department of Water Resources maintains an eight-station index, where it measures rainfall at eight locations throughout the mountainous region of Northern California, ranging from Mount Shasta City down to the American River Basin.
It compiles the rainfall at each station to arrive at a number that indicates the amount of precipitation Northern California is receiving. Thus far in the 2012-13 water year, which begins Oct. 1 and ends Sept. 30, 24.1 inches of rain have fallen in the Northern Sierra and Southern Cascade areas.
This is 196 percent of the average for this point in the year.
The wettest year in the history of Northern California came during the 1982-83 water year, when a total of 88.5 inches drenched the region.
At this date in December 1982, about 23 inches of rain had fallen, so the region is currently on pace to exceed the wettest year in the region’s history.
Another very wet year occurred two years ago in the 2010-11 water year, when a total of 72.7 inches accumulated. At the same point in 2010, about 22.5 inches of precipitation fell.
Average precipitation for the region for an entire year is 50 inches, and the region is currently halfway there with nine and a half months left in the water year.
The driest year on record occurred in 1923-24 when only 17.1 inches of rain fell on the parched region.
If it does not rain again until Oct. 1, 2013, it will still have exceeded the dry record by 7 inches.
Last year, in the middle of December, about six inches of rain had fallen on the region, but precipitation rates increased in February and March, and the water year finished slightly below average with 41.6 inches of accumulation in the region.
During the recent weather system that passed through western Nevada County Tuesday night into Wednesday morning, about a quarter-inch of rain fell, said Eric Kurth, National Weather Service meteorologist.
The precipitation-laden weather gives no sign of ceasing soon, Kurth said, with another cold and relatively dry system slated to hit during the day Friday.
After another break in the wet weather from Friday night through Saturday afternoon, another small storm is forecasted for the foothills that evening, Kurth said. Snow is possible but not likely in the upper elevations of the foothills, but most areas of western Nevada County will see rain as a result of the system.
The previous storm systems that dumped copious amounts of water on the region, were warmer and originated in the tropical regions of the Pacific Ocean. The storm systems currently projected were born in the Gulf of Alaska or northern Canada.
Their path to Northern California was paved by a high pressure ridge that has settled in the atmosphere just west of the California coast, Kurth said.
The sporadic arrival of storms represents a “typical unsettled pattern,” which is a normal pattern for the cold winter months, Kurth said.
When this pattern meets up with the “atmospheric rivers” that originate around Hawaii, the type of storms the region witnessed in 2010-2011 is produced — the type truck drivers dread and skiers go to bed dreaming of, Kurth said.
The systems scheduled to intermittently hit the region over the next week will not be
the kind that produce large
powder days up the hill but will contribute to snowpack construction.
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