Tag Archives: NOAA’s Climate Prediction Center

Dry weather started early this year amid cloudy conditions

UPDATE:
July 5. Greg Johnson, who lives in Hansville and manages the Skunk Bay Weather station there, said the unusually high rainfall in June for Hansville, compared to the rest of the peninsula, was the result of the Puget Sound convergence zone settling over the area on several occasions. Weather conditions brought localized squalls during the month, he said, adding, “This is very unusual for us.”

The reading at Greg’s weather station, 1.98 inches for the month of June, was somewhat lower than the 2.26 inches recorded at Kitsap PUD’s weather station in Hansville.
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Cool, often cloudy conditions have helped obscure the fact that very little rain has fallen on the Kitsap Peninsula over the past two months.

Precipitation in Holly (click to enlarge)

Now that we are in the fourth quarter of the water year, we can see that rainfall levels for this year will be close to average for most areas on the peninsula. What might not be recognized, however, is that April was well above average, while May and June were well below average.

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Rainfall pattern returns to normal across the Kitsap Peninsula

After two years of near-record rainfall across the Kitsap Peninsula, precipitation has returned to a more normal pattern.

Halfway through the water year, which begins in October, rainfall in Hansville, Silverdale and Holly are all within 10 percent of the average for this time of year, according to weather instruments managed by Kitsap Public Utility District.

This near-average total for the first half of the year comes about despite a very wet November, when Hansville broke the all-time record for precipitation for that month. Since then, the monthly rainfall numbers have been mostly below average, except for a wet January when Holly nearly broke the record for that month.

As we’ve seen time and again, the amount of rainfall decreases dramatically as one travels from south to north on the Kitsap Peninsula. That’s the general pattern for all times of the year, although the amount of precipitation can vary wildly.

Hansville received 25.5 inches for the six months ending April 1, compared to a 28-year average of 23.1 inches for that period. Last year, the six-month figure was 7 inches higher at 32.5 inches, and the first half of 2016 went down in the record books with a total of 37.0 inches.

Silverdale posted 35.1 inches of rain by April 1, compared to a 28-year average of 38.1 inches for this time of year. Last year, this Central Kitsap area received 51.7 inches by April, and in 2016 the number was 52.3 inches, second only to 1999 with 69.8 inches.

In rainswept Holly, residents experienced 68.7 inches by April 1, compared to a 27-year average of 65.0 inches. By April 1 last year, Holly was practically swimming with 95.9 inches, driven by 24.0 inches during the month of October 2016 and 21.8 inches the next month. But nothing compares to the first half of water year 1999, when Holly received 120 inches for the first half of the year. Following a fairly dry summer, water year 1999 in Holly ended with 127.5 inches of precipitation.

NOAA’s Climate Prediction Center has projected somewhat higher-than-average rainfall through the end of this month in the Pacific Northwest, followed by fairly average conditions going into summer. Forecasters rely heavily on observations about temperatures in the Pacific Ocean, which influence a natural cycle known as the El Niño Southern Oscillation, or ENSO. See video this page.

A very strong El Niño during 2015 and 2016 (associated with the much-discussed “blob”) shifted into a weak La Niña in 2017. Conditions have now reversed course again and seem to be headed toward neutral. La Niñas are generally associated with cooler and wetter weather for our region of the country, while El Niños suggest warmer and dryer conditions — although it does not always turn out that way.

Neutral conditions are expected to arrive by summer, and some forecasters predict that the warmer El Niño could arrive toward the end of the water year in September, according to information released today by the Climate Prediction Center.

“Some of the computer models are forecasting development of El Niño by next fall,” noted research scientist Emily Becker in a new post on the ENSO Blog, “but there are a number of reasons why we’re not completely taking the bait right now.

“First, forecasts made this time of year tend to be less successful,” she continued. “Another reason is that, while elevated subsurface heat content in the spring sometimes precedes the development of El Niño in the fall, some recent studies have found that this relationship has not been very reliable over the past two decades.”

Researchers observed a warming trend in March among subsurface waters in the Eastern Pacific. Those waters are expected to rise to the surface over the next few months to potentially neutralize any cool surface waters that remain. The outcome is likely to be the end of the current La Niña and possibly the beginning of a new El Niño, featuring warmer ocean conditions.

Rainfall and aquifers keep drought away from the Kitsap Peninsula

UPDATE: April 24, 2015
Cliff Mass, professor of atmospheric sciences at the University of Washington, says in his blog that it is too early to be predicting severe drought in Western Washington this summer because of possible late-spring rains:

“I believe the media and some local politicians have gotten a bit too worried about our ‘drought.’ We have NOT had a precipitation drought at all….we are in a snow drought due to warm temperatures. The situation is unique and I suspect we will weather this summer far better than expected.”

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The word seems to be getting around about the record-low snowpack in the mountains, which could create a shortage of drinking water and even lead to problems for salmon swimming upstream. Read about Gov. Jay Inslee’s expanded drought emergency, issued today, as well as the last update from the U.S. Department of Agriculture.

CK

Kitsap Peninsula and the islands of Puget Sound are in their own worlds, fairly insulated from what is happening in the higher elevations. In these lower elevations, the key to water supplies is rainfall, not snow, and the outlook for the year is normal so far.

As you can see from the charts on this page (click to enlarge), this year’s rainfall has been tracking closely the long-term average. If the rains are light and steady, much of the water will soak into the ground and recharge the aquifers where most area residents get their water. The aquifer levels tend to rise and fall over multiple years, depending on the rainfall.

Hansville

Casad Dam on the Union River, which supplies a majority of Bremerton’s water, filled in January, well ahead of schedule, said Kathleen Cahall, water resources manager for the city. The dam is scheduled for a normal drawdown, and Kathleen said she does not expect any water shortage.

“We filled the reservoir fairly early this year,” she said. “We are looking pretty good for the summer.”

Holly

October, the first month of the water year, was unusually wet, Kathleen said. December precipitation also was high. The other months were fairly normal for precipitation.

Precipitation in the Puget Sound region is expected to be below average for June, July and August, according to models by the NOAA’s Climate Prediction Center. Interestingly, large portions of the Central and Southwest U.S., Alaska and Florida can expect above-average precipitation. See U.S. map.

precip

Streams on the Kitsap Peninsula are fed by surface water flows and shallow aquifers. At the moment, most of the streamflows are near their historical average. That’s not the case for the larger rivers in the Northwest, which rush out of the mountains. Most are well below their normal flows, as shown by the map with the dots.

Low streamflows usually mean higher temperatures and stress for salmon. Low flows also can affect fish passage in some stretches of the rivers while also reducing spawning areas.

Streamflows

While things look fairly good on the Kitsap Peninsula now, things can change quickly. We have different vulnerabilities than elsewhere. Climate-change models predict that rains will grow more intense in the future without changing annual precipitation very much. That means more of the water will run off the land and less will soak in, potentially reducing aquifer levels over time. Managing those underground water supplies will become more and more critical.