NOAA is reporting that summer temperatures across the
contiguous United States, June through August of this year, were the fifth
highest on record, and a forecast for a La Nina weather pattern emerging has
been downgraded to a “neutral” forecast that could mean continued
warmer-than-average temperatures in the Pacific Northwest through the fall and
Climate and weather experts recapped summer weather on
Thursday, showing that the Northwest states of Oregon, Washington, Idaho and
Montana all experienced warmer-than-average temperatures over the summer. But
temperatures were well below record highs in California and most East Coast states.
Meanwhile, below-average or near-average precipitation was
recorded in Columbia Basin states, with the exception of much-below average
rainfall in Idaho for the summer.
A U.S. Drought Monitor report issued Sept. 13 shows that
“abnormally dry” conditions persist in Oregon, Washington, Idaho and Montana,
with scattered pockets of “moderate” or “severe” drought conditions.
NOAA’s Climate Prediction Center issued an updated El
Nino/La Nino forecast on Sept. 8, scaling back earlier predictions for a La
Nina forecast for the fall and winter to instead a “neutral” forecast.
Overall, “neutral conditions are slightly favored (between
50 to 60 percent) during the upcoming Northern Hemisphere fall and winter
2016-2017,” the forecast states.
“La Nina would normally lead to cooler temperatures across
the Northwest,” said Peter Rosencrans, head of forecast operations with the
Climate Prediction Center. “We have changed our forecast to go with slightly
higher-than-average temperatures in the Pacific Northwest.”
Complicating the forecast picture for the Pacific Northwest
is “The Blob” — a large pocket of warm water that has persisted in the northern
Pacific Ocean since 2013.
Asked how The Blob may influence El-Nino/La Nina
forecasting, Rosencrans said it has an influence, but the primary drivers
behind El Nino or La Nina weather patterns are very powerful influences of
water temperatures that are monitored by zones in the rest of the Pacific,
including the tropics.
Rosencrans said it’s somewhat of a chicken-or-egg situation.
The Blob is known to mostly be caused by persistent high-pressure weather that
curbs churning currents in the ocean, causing warm water to settle in.
“The problem is the blob is caused by a decrease in Pacific
wind speeds … But if you get a couple of good storms go through it can really
churn,” Rosencrans said. “We could go back to La Nina and the conditions that
go with it. We go with the data and where that takes us.”
Just over the last week or so, it became apparent the warm
water mass known as The Blob has been re-established in the Pacific off the
Northwest coast, as noted by Cliff Mass, a professor of atmospheric sciences at
the University of Washington.
Water temperatures off the Pacific Northwest were “slightly
above normal. Nothing exceptional” since early July, Mass stated on his blog,
showing corresponding graphics from NOAA. “But fast forward to a few days ago
(Sept. 8) and you will notice MUCH warmer temperatures over the Northeast
Pacific. The Blob is back.”
The potential for warmer-than-average fall and winter over
Columbia Basin states, as noted in the latest Climate Prediction Center report
— raises concerns of water supply for fisheries managers. Generally, it can
cause below-average snowpacks, earlier runoff periods and warmer water
temperatures in rivers that support salmonids.
In addition, recent research by NOAA Fisheries and
University of California, Santa Cruz, scientists assessed marine ecology
effects of the 2015-2016 El Nino pattern and The Blob for the first time.
“Last year there was a lot of speculation about the
consequences of ‘The Blob’ and El Nino battling it out off the West Coast of
the United States,” said Michael Jacox, lead author of the research. “We found
that off California El Nino turned out to be much weaker than expected. The
Blob continued to be a dominant force, and the two of them together had
strongly negative impacts on marine productivity.”
The combination of El Nino and The Blob were shown to slow
the flow of nutrients from the deep ocean, reducing the productivity of coastal
Water temperatures at or near five degrees above average are
also believed to be responsible for sightings of warm-water marine life far to
the north of their typical ranges, and the temperatures likely contributed to
the West Coast’s largest harmful algal bloom ever recorded in 2015.
The current forecast for El Nino/La Nino neutral conditions
can make forecasting at the regional level challenging, said Laurel McCoy, a
meteorologist with the National Weather Service in Portland.
Neutral conditions can pave the way for powerful storm
systems that can cause widely varying weather, McCoy said.
“The Climate Prediction Center is thinking we’ll probably
have temperatures slightly above normal but precipitation could go either way,”
The last La Nina pattern recorded was in 2013-2014, before
it gave way to the El Nino pattern that influenced the region in 2015-2016.
More information on El Nino/La Nina and The Blob can be
-- CBB, July 15, 2016, “Study: The Warm-Water ‘Blob,’
Combined With El Nino, Depressed Marine Productivity Off West Coast” http://www.cbbulletin.com/437129.aspx
-- CBB, April 10, 2015, “‘Warm Blob’ Of Water Off West Coast
Linked To Warmer Temps, Disruption Of Marine Food Web” http://www.cbbulletin.com/433648.aspx
-- CBB, Dec. 18, 2015, “Study: In Warmer Ocean Years
Juvenile Salmon Consume More Food, But End Up Smaller, Skinnier” http://www.cbbulletin.com/435732.aspx