A spring for the his­tory books

Los Angeles Times - - CALIFORNIA - By Veron­ica Rocha veron­ica.rocha @la­times.com Twit­ter: @Veron­i­caRochaLA

For the first time in nearly 100 years, L.A. went from warm to cool.

It’s been the kind of spring that Los An­ge­les last ex­pe­ri­enced al­most 100 years ago. 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, does that fact have any real mean­ing?

Ac­cord­ing to ex­perts, rare in this case does not clearly equal sig­nif­i­cant.

For one thing, although the months lead­ing to­ward sum­mer were cool com­pared to a record-warm March — the op­po­site of what usu­ally hap­pens — it 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 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 record­keep­ing be­gan in 1877.

Whether such a pat­tern helps veg­e­ta­tion is hard to say, given the broader con­text of a drought that is in its fourth year.

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

The in­creas­ingly cooler tem­per­a­tures did of­fer re­lief from the warm tem­per­a­tures that have in­vaded South­ern Cal­i­for­nia’s win­ters in re­cent years. And that’s one of the only things that def­i­nitely can 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.

Tem­per­a­tures 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 phe- nomenon 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.

Bob Chamberlin

ON A DRIZ­ZLY MAY MORN­ING, a man walks past the win­dows on the Grand Park kiosk on Spring Street, which ref lect L.A. City Hall twice. For the first time in 94 years, the city had a “re­verse” me­te­o­ro­log­i­cal spring.

Robert Gau­thier

BILL MIERS of Belling­ham, Wash., pho­to­graphs Dis­ney Hall Thurs­day. Temps are down from March.

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