Last Thursday, the National Oceanographic Atmospheric Administration came out with its latest El Niño/La Niña-Southern Oscillation Advisory, predicting that the current La Niña will peak in the strong category and will persist until next spring.
Historically, this condition has produced below-average rainfall for the Central Coast.
Another strong category La Niña occurred during the 1989 rain season (July 1988 through June 1989) and lingered into the1990 rain season (July 1989 through June 1990).
The 1990 rain season was the driest on record, with only about 8 inches recorded in San Luis Obispo. Hope for a wetter 1991 season faded as San Luis Obispo County moved into February as the driest rain season in its history.
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After five years of below-normal rainfall throughout our state, California’s lakes and massive reservoirs were nearly empty. Both Santa Margarita and Nacimiento lakes were at 6 percent of capacity; Lopez Lake had fallen to 39 percent of capacity.
Communities throughout San Luis Obispo County instituted water rationing. The Atascadero Mutual Water Co. was about to limit households to 400 gallons of water a day.
Santa Margarita was going to ban all outside watering. Morro Bay stopped approving new water hookups along with at least half-dozen other communities in the state. Many coastal communities contemplated seawater desalination.
Drought-driven rationing programs ordered customers to cut water consumption by 20 percent in San Francisco, San Jose, Ventura, Santa Barbara and Monterey.
The coastal mountains turned from the normal golden browns and red hues of summer to more of an ash gray color. Many of our streams and creeks stopped flowing and the local ranchers and farmers were at their wits’ end.
A strong La Niña was probably the culprit. A typical winter pattern associated with La Niña is a persistent ridge of high pressure over California that often forces the storm track towards the Pacific Northwest, leaving the Central Coast without any significant rain.
In January 1991, the seawater temperatures in the equatorial and eastern Pacific Ocean warmed, reaching a strong El Niño classification later in the year.
The low pressure block over the Hudson Bay in northeastern Canada dissolved and the high pressure ridge over California shifted, allowing the storm track to move over our state.
The skies opened in March and a pair of storms dropped more than 4 inches of rain in San Luis Obispo during the first week of March, more rain than almost anyone could hope for.
Creeks that were bone-dry at the end of February started flowing again. The storms kept marching through the county and by mid-March the hills finally turned green and California poppies began to bloom.
On March 18 and 19, a series of storms swooped down from Alaska and produced up to 10 inches of snow on the Cuesta Grade and 2 to 4 inches of rain in the coastal valleys. Parts of the North County turned into a “winter wonderland.”
Paul Deis, a chief engineer with the D&P Mountain Railroad, told me that a Southern Pacific freight train derailed at 4:35 a.m. March 19 because the tracks had washed out near Vandenberg Air Force Base.
Remarkably, no one was injured as the lead locomotive made it across the washout section of track with its crew, but the other two locomotives did not.
In a remarkable twist of fate, the Amtrak Coast Starlight passenger train was heading north from Santa Barbara.
If the freight train had not derailed, the passenger train may have hit the washed-out section of track with great loss of life.
The nearly 13 inches of rain that fell that March in San Luis Obispo was more rain than fell during the rain seasons of 1989 and 1990 and ended the five-year drought.
According to an article by Larry Mauter in what was then the Telegram-Tribune, Rachel Parker, who lived near Morro Creek, was probably the one who coined the phrase “miracle rains” as she watched her steer munch grass produced by the late season rains. Her bovine had been subsisting on a flake of hay a day.
This week’s forecast
A classic Central Coast fall weather pattern is upon us. A 1,033-millibar area of high pressure at the surface is over the Great Basin — the area between the Sierra Nevada range to the west and the Rocky Mountains to the east — and will dominate our coastal weather.
This system will produce night and morning northeasterly (offshore) winds. In other words, the winds flow from the land out to the Pacific.
These winds bring the relatively dry and warm air to our shoreline, pushing the marine layer far out to sea with sparkling clear visibilities.
This condition may bring warmer temperatures to the coastal valleys than those in the interior.
Today’s temperatures will reach the high 70s and maybe the low 80s along the northwesterly facing beaches (Los Osos, Morro Bay and Cambria) before the afternoon northwesterly winds cool things off. The southwesterly facing beaches (Avila Beach and Cayucos) will warm to the mid- to high 80s, while the coastal valleys (San Luis Obispo) and the interior (Paso Robles) will range between the high 80s and low 90s.
Temperatures will be unseasonably warm over the next several days, but not excessive. Afternoon northwesterly winds along the coastline will reach strong to gale force levels (25 and 38 mph) this afternoon, decreasing on Monday as a trough of low pressure approaches the coastline.
A spectacular fall will continue this week with gentle north to northeasterly (offshore) winds on Tuesday and Wednesday allowing temperatures to climb into the 80s across most locations.
A gradual cooling trend will occur later in the week, especially at locations closer to the coast with the redevelopment of the marine layer. Today’s upper-level charts indicate the storm track will remain to the far north for an extended period.
Surf and sea report
This morning’s 3- to 5-foot northwesterly (305-degree deep-water) sea and swell (with a 5- to 11-second period) will increase to 5 to 7 feet this afternoon and will remain at this height and period through Monday morning.
A 6- to 8-foot northwesterly (305-degree deep-water) swell (with an 8- to 12-second period) is forecast Monday afternoon through Tuesday, decreasing to 4 to 6 feet Wednesday.
This northwesterly swell will further lower to 3 to 4 feet (with an 11- to 13-second period) Thursday through Friday.
A 1- to 2-foot Southern Hemisphere (200-degree deep-water) swell (with an 18- to 20-second period) will arrive Monday, increasing to 1 to 3 feet (with a 16- to 18-second period) Tuesday.
This swell with further build to 2 to 3 feet (with a 15- to 17-second period) Wednesday through Thursday.
Seawater temperatures will range between 53 and 55 through Monday, increasing to 55 and 57 degrees Tuesday through Friday.
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John Lindsey is a media relations representative for PG&E. He is also a local weather expert and has lived along the Central Coast for more than 23 years. To subscribe to his daily weather forecast or ask a question, e-mail him at firstname.lastname@example.org.