‘Reverse’ spring good for trivia but doesn’t improve dry conditions

It was a kind of spring that Los Angeles last experienced almost 100 years ago.

For the first time in nearly a century, March was the warmest month in downtown L.A. and May was the coolest. Weather scientists have a name for it: a “reverse” meteorological spring.

But besides serving as a bit of trivia, did it actually mean anything on the ground?

That is where experts say rare does not clearly equal significant.

For one thing, though the months encroaching into summer actually got cooler after a record-warm March -- the opposite of what usually happens -- they won’t necessarily spell a lessened fire danger after years of drought.

Any moisture brought on by cooler temperatures and gray skies this spring was quickly nullified by gusty, drying winds, state and federal fire officials said. Trees and brush-like chaparral remain dry and often brittle.

“We would need two to three years of significantly wet winters to see a difference,” said Capt. Scott McLean of the California Department of Forestry and Fire Protection.

The National Weather Service said L.A.’s “reverse” meteorological spring is the first since 1921. There have been three since record-keeping began in 1877.

Whether such a pattern would help vegetation is hard to say given the broader context of a drought that has surpassed three years.

Frank McDonough, a botanist at the Los Angeles County Arboretum & Botanic Garden, said it’s unclear whether the weather irregularity had an effect on plants because they are already under so much stress from other environmental events.

The increasingly cooler temperatures did offer relief from warm temperatures, and even heat spells, that have invaded even Southern California’s winter in recent years.

But that’s one of the only things that can definitely be concluded about the “reverse” spring.

“One single occurrence in almost 100 years of this oddity does not signify anything specific,” said Joe Sirard, a meteorologist with the National Weather Service. “It is just one of those rare occurrences and really nothing more. It will likely not happen again for another 100 years.”

This year, March was spring’s high point for warm weather due to a persistent area of high pressure over the northeast Pacific Ocean. The drought and warmer waters off the coast also could have played a role. It was the warmest March on record for L.A. After that, the temperatures just went down after the system moved away.

In downtown L.A, the average monthly temperature for March was 68.2 degrees. In April, it was 65.8 and in May it was 64.1.

Average monthly temperatures from 1981 to 2010 for March, April and May in downtown Los Angeles were 60.6 degrees, 63.1 and 65.8, respectively.

“Even though this phenomenon is unusual, it is not unprecedented,” said Jake Crouch, a climate scientist with the National Oceanic and Atmospheric Administration’s National Climatic Data Center. “We saw a similar situation in 2012 in the eastern U.S., where March was warmer than April and May in several cities.”

Climate experts say the strengthening El Niño event — which is raising hopes for a wet winter — did not contribute to the reversed spring.

Although “the promised El Niño may have added to warm waters and a record warm winter and early spring, it would not account for the cool May and the reversal,” said Steve LaDochy, a professor of climatology at Cal State L.A.

And the backward spring is not necessarily a sign of things to come, said LaDochy, pointing out that such a pattern almost happened in L.A. in 1955, 1959 and 1994.

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