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Superbloom of Flowers in the California Desert After Wet Winter

5 Apr 2017, 1:58 pm

[Credit: Kyle Magnuson, via NOAA and Creative Commons license]

After five years of exceptional drought, desert landscapes across southern California exploded with “superblooms” of wildflowers this March following ample winter precipitation. According to local news reports, it’s the most spectacular display some locations have seen in more than two decades.

[Credit: Rob Bertholf via NOAA and CC license]
Wrapped up snugly in a thick, waxy coat, the seeds of desert wildflowers may lie dormant on the seemingly barren ground for years.  Washed and softened by unusually heavy or frequent fall and winter rains, the waiting seeds finally crack open and push their roots into the rocky soil. Provided that spring brings sunshine, warmth, and only gentle winds, the plants will take advantage of the narrow window of favorable conditions to complete their life cycle.

The superbloom has migrated north to California's Central Valley, and the show is simply indescribable at the Carrizo…

Posted by U.S. Department of the Interior on Monday, April 3, 2017

At least some desert wildflowers bloom in most years, but in “superbloom” years, they put on a spectacular show—a carpet of greenery and thousands of blooms stretching across acres and acres of the landscape. Like “leaf peepers” are drawn to New England in the autumn, visitors flock to desert parks to witness the phenomenon. Among the locations where seasonal climate conditions in winter 2016-17 were favorable for a spring superbloom is Anza-Borrego Desert State Park, in southeastern California.
South of Palm Springs, the park is in California’s Climate Division 7—the Southeast Desert Basins—where the average winter precipitation is just shy of 3 inches (less than half of Los Angeles’ normal winter precipitation of 7 inches). While the 2016-17 winter precipitation in the division was not record-shattering, it was more than twice the normal amount, and—perhaps importantly—it followed the worst extended dry spell in the division’s historical record.
Since 1896, the division has only experienced two other periods where precipitation during the winter wet season was below average for five years or more in a row: the five winters from 1952-53 through 1956-57, and the six winters from 1985-86 through 1990-91. While those periods might seem equal to the one that just ended, when we place these dry spells into an annual context, it becomes clear that the dry spell that began in the winter of 2011-12 was exceptional.
During the other long-running dry spells, rainfall outside of the winter months brought the annual total near or even above average in at least one year. The six consecutively dry winters of the late 1980s and early 1990s don’t even show up as an extended dry spell in the annual tallies. By comparison, the drought that started in 2011 brought six relentlessly dry and extremely hot years (four of the five hottest years on record for Southeast California occurred during the recent dry spell).
[Credit: slworking2 via NOAA and CC license]

The 6.11 inches of precipitation that fell across California’s Southeast Desert Basins during the winter of 2016-17 was more than 200% of the division’s normal 2.97 inches. In addition, the Anza-Borrego desert basin received a “bonus” soaking rain event in early fall: a station in the park recorded just over 0.5 inches of rain on September 20. The rainfall may not have been record-breaking, but the patient seeds of the desert basins’ wildflowers had been waiting for that moisture for an unusually long time. As the warm, sunny days of March unfolded, the well-watered desert exploded in spectacular bloom.

[NOAA Article credit: Rebecca Lindsey]

For WeatherNation: Meteorologist Mace Michaels

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