Weather Watch

High temperature records melting

PG&E volunteers recently partnered with Greenspace — The Cambria Land Trust to transplant native Monterey Pine tree seedlings in Cambria.
PG&E volunteers recently partnered with Greenspace — The Cambria Land Trust to transplant native Monterey Pine tree seedlings in Cambria.

So far, 2014 has seen nine maximum temperature records broken at the Paso Robles Municipal Airport and 12 at the San Luis Obispo County Regional Airport. Even more telling, there weren’t any low temperature records reported. At the current pace, 2014 will produce the most daily high temperature records ever seen in San Luis Obispo County in one year.

As the state heads into summer, the latest guidance from the U.S. Climate Prediction Center is calling for “above-normal temperatures” for all of California through August. The drought monitor map, issued by the National Drought Mitigation Center, indicates the state of California has moved into a severe drought category or worse for the first time since tracking began.

In fact, the worst category, “exceptional drought,” now stretches from the Golden Gate southward toward Ventura County, encompassing Monterey, San Luis Obispo and Santa Barbara counties.

National Weather Service meteorologist Curt Kaplan, who was raised in the San Fernando Valley, said, “I do worry, I do remember as a kid growing up we had plenty of rain. I don’t see that any longer. There’s always going to be those conditions when we break cold or hot temperature records. With that being said, I see it getting worse. I see less rain. I see hotter conditions when it should not be as hot.”

Kaplan makes an interesting observation. What made the heat waves at the end of April and last week so severe was the double-punch of strong high pressure in the upper levels of the atmosphere and the surface high over the Great Basin.

Let me explain. Meteorologists determine the thickness of the atmosphere by analyzing 500-millibar upper-level charts. In other words, this chart will tell you how high the pressure is three or four miles above the Earth’s surface. The higher the 500-millibar line, the thicker the atmosphere, and the warmer it will be.

Last week, the 500-mb line was at 589 decameters (dm) above the Earth and centered over the Central Coast.

Anything above 580 dm will usually give hot temperatures.

To make matters worse, the surface high over the Great Basin produced Santa Lucia (offshore) winds that compressed and heated the air mass as it flowed down the Santa Lucia Mountains, causing even warmer temperatures and lower relative humidity levels.

Over the last few years, the Santa Lucia winds have become more common during the late spring and summer months, resulting in less “May gray” or “June gloom” along the coast. This lack of fog has added insult to injury, because there is less moisture for plants in the coastal regions of our county.

Rick Hawley, the executive director of Greenspace — The Cambria Land Trust, told me, “I’ve noticed a marked decrease over the years in the amount of fog along the coastline. It’s astounding how much water this provides to plants as the fog condenses on these trees and drips to the ground.”

This dearth of moisture has further stressed native Monterey pine trees in the Cambria area. The Monterey pine is native to just five areas: the Año Nuevo State Park area, Monterey, Cambria and two islands off Baja California.

This past week, a group of PG&E volunteers helped Hawley transplant Monterey pine seedlings to larger pots at their greenhouse facility. These trees will be strategically planted to re-invigorate this forest.

When the weather heats up, something special can occur. The Monterey pine is a “California closed-cone pine,” which means it needs a fire or very hot weather to open and drop its seeds. When the temperature gets very hot, the trees emit an eerie cracking sound, like bacon frying in a pan, as the pine cones open and their seeds rotate like small helicopters to the ground. This past Wednesday, I heard the snap, crackle and pop of these pine cones opening up as the temperature reached 103 degrees at Baywood Park.

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