A spring for the history books
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.