Lack of rain puts signs of drought back on California map

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Little rain has fallen in California since the water year began on October 1, putting signs of drought back on the map.

The Federal Drought Watch Map, a drought measurement mechanism primarily used in agriculture, shows that 81% of the state is abnormally dry. A small portion (4%) of the map near the Arizona border is designated as “moderate drought.”

“While reservoirs remain elevated, many indicators are supporting the drought, including 60-day rainfall deficits, high evaporation demand and healthy vegetation,” reads a statement from the report, released weekly. with drought conditions across the country.

The National Weather Service shared a two-week comparison, showing this week’s map and the November 5 map, when very little in the state indicated drought. The difference is dramatic. (See image above.)

The Drought Monitor is a joint effort of the National Oceanic and Atmospheric Administration, the US Department of Agriculture, and the National Drought Mitigation Center at the University of Nebraska-Lincoln. A map is released each week with drought conditions across the country, indexing everything from groundwater storage to river level. The factors that water managers monitor most closely are total precipitation and reservoir and snowpack levels.

Precipitation has been virtually non-existent since the start of the rainy season. For the eight-station index compiling data from eight gauges in the Sierra, total precipitation since October 1 is 0.26 inches of rain, well below average. And although parts of northern California saw showers on Thursday, a major storm is unlikely to hit the state until Thanksgiving week or the last week of November.

“A strong high pressure ridge between Hawaii and California is pushing everything [storms] north of us, ”state climatologist Mike Anderson said. ” Some [long-term] models indicate it could move westward, which could allow storms to fall along the east side. We might have a little rain burst at the end of the month which could increase the totals a bit. “


But reservoirs around the state are in relatively good condition after last year’s winter, which was marked by wet storms and a heavy snowpack. The state’s largest reservoir, Shasta Lake, is currently 120% full. Lake Oroville represents 92%, Lake Folsom 113% and Lake Oroville 92%.

“One thing to always keep in mind is what last year looked like,” Anderson said. “Last year we came out of a rainy season and our snowpack was the fifth largest. This year’s slow start to the season doesn’t have the same worry as if you were in the fourth year of a drought.”

ALSO: Winter weather outlook: “The odds tilt slightly towards warmer and drier than normal”

The overflowing reservoirs are a good thing because the state of the snowpack this winter is a big unknown. The National Oceanic and Atmospheric Administration’s winter forecast slightly favors the likelihood of a warmer, drier winter over a wetter, cooler winter, but Anderson takes that prediction with a grain of salt and said we don’t will not really know until we deepen the season. .

Anderson pointed out that weather conditions from previous seasons reveal this winter could go all over the place with end-water precipitation totals eight below or above average. In 1960, the eight-station index recorded just 0.12 inches of rain in October and November, the lowest precipitation total on record for those two months with records dating back to 1921. a precipitation total that was 80% of average, which isn’t bad considering the slow start.

“The book is yet to be written, we just need to be careful and see how things go and hope that we can continue to improve in our seasonal forecast,” Anderson said.

Regardless of what happens, Anderson said it is wise for all Californians to conserve water. “We live in such a variable climate and you have to approach it with the mindset of being conservation oriented,” he said. “What really touches me is what former Governor Brown once said: ‘You have to make conservation a way of life in California.'”

Amy Graff is a digital editor for SFGATE. Email him at agraff@sfgate.com.

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