The months of December, January and February, historically our wettest months of the year, have only produced a combined total of 3.5 inches of rain this season. Normally, the rainfall total for that period should be about 13.9 inches at Cal Poly, home of climatology for San Luis Obispo.
As of today, this season’s three-month total is the driest since 1963, even drier than 1976-77 or 1990-91.
As we move into March, recovery from this rain deficit will be more difficult. The longer-range models still indicate a normal amount of monthly rainfall in March and April, but barring a March of ’91 miracle rain event, it may be too little, too late to produce even near-normal amounts of rainfall this season. If we don’t get any more rain, this could be the driest winter on record.
Todd Morris of the National Weather Service in Oxnard told me that the probability of precipitation peaks Feb. 22 in San Luis Obispo, with rain occurring 35 percent of the time. After that, the probability of rain decreases through summer, reaching a low around Aug. 20, with rain only occurring in 6 percent of the days.
This year’s La Niña (colder than normal surface seawater in the central and eastern equatorial Pacific), combined with the cold seawater phase of the Pacific Decadal Oscillation (a much longer-lived El Niño-like seawater temperature pattern) and the Arctic oscillation (the degree to which Arctic air penetrates southward) have all combined to produce one of the driest years on record. The storm track has remained far to the north.
Fortunately, after back-to-back La Niña cycles, we frequently go into an El Niño phase, which means we could have normal to above-normal rainfall next year.
Because of the lack of storms and persistent night and morning northeasterly (offshore) winds, this February has experienced more clear skies than normal. Usually, this month is the third cloudiest of the year, with mostly cloudy conditions 36 percent of the time. Only July and August, which endure the gray of the marine layer about 41 percent of the time, are cloudier. This February, skies were mostly cloudy just 12 percent of the time. By the way, November is typically the clearest month of the year, with mostly cloudy days occurring just 10 percent of the time.
As most surfers will tell you, not only has it been clearer this February, but seawater temperatures have been chilly. Indeed, this February saw the average seawater temperatures reach about 52 degrees at Diablo Canyon nuclear power plant. These were some of the coldest February seawater temperatures since record-keeping began in 1976. Normally, seawater in February averages 55 degrees. Earlier last week, daily average seawater temperatures sank below 50 degrees.
A 1,029-millibar surface high over the Great Basin will produce gentle to moderate (8- to 18-mph) northeasterly (offshore) winds this morning. These offshore winds may be especially gusty in the coastal canyons and passes and areas near Morro Bay High School and eastern San Luis Obispo.This offshore flow will produce clear and sunny conditions this morning. Today’s high temperatures will reach the mid-60s throughout the county.
The winds will shift out of the northwest and increase to fresh to strong (25- to 31-mph) levels this afternoon as an upper-level low-pressure system over Northern California moves southward through the Central Valley. This system will also produce increasing clouds later today into Monday.
This very cold upper-level low and moisture- starved system will produce a few scattered showers throughout the county Monday. Many locations will probably not receive measurable precipitation. However, moderate gale to fresh gale force (32- to 46-mph) northwesterly winds accompanying this system along the coastline may produce up to a quarter of an inch of rainfall along the northwesterly facing slopes of the coastal mountains. High temperatures Monday will reach only in the mid-50s, with snow levels dropping to about 2,500 feet. In other words, Monday will certainly feel like a winter day.
Cold air will filter in behind this low and produce below-freezing temperatures in the North County and near-freezing temperatures in the coastal valleys early Tuesday morning.
A cold front is forecast to pass over the Central Coast on Wednesday with gentle to moderate (8- to 18-mph) southerly winds and showers throughout the county. Most of the rain is expected to remain north of the Monterey County line. Nevertheless, this system is expected to produce around a quarter of an inch of rain in the coastal valleys and more than half an inch of rain in the mountains.
Dry weather with warmer conditions will develop Thursday and will continue through Friday. The longer-range models are still indicating increasing chances for rain by the second week of March.
Today’s surf report
Increasing northwesterly winds will generate a 7- to 9-foot northwesterly (300-degree deep-water) sea and swell (with a 7- to 14-second period) today.
Moderate gale to fresh gale force (32- to 46-mph) northwesterly winds Monday will generate a 10- to 12-foot northwesterly (320-degree deep-water) sea and swell (with an 8- to 12-second period). The offshore NOAA marine buoys will probably reach over 16 feet on Monday.
A 6- to 8-foot northwesterly (290-degree deep-water) swell (with a 7- to 18-second period) will arrive along the Pecho Coast on Tuesday. This northwesterly sea and swell will decrease to 5 to 7 feet (with an 8- to 17-second period) by Wednesday.
Increasing northwesterly winds will produce an 8- to 10-foot northwesterly (300-degree deep-water) sea and swell (with a 7- to 15-second period) Thursday through Friday.
Seawater temperatures will range between 51 and 53 degrees through today. Seawater temperatures will decrease to 49 to 51 degrees Monday and will remain at this level through Tuesday.
Hike the spectacular Pecho Coast Trail to the Point San Luis Lighthouse.
The trail to the Point San Luis Lighthouse is open to 20 hikers on Wednesday and 40 hikers on Saturdays, with a departure time of 9 a.m. and a return time of 1 p.m. The hike to the Point San Luis Lighthouse is 3.75 miles and moderately strenuous.
Reservations are strongly encouraged to avoid being turned away at the trailhead. Reservations must be made two weeks in advance.
At the Light Station, an admission fee of $5 per adult will be required of those accessing the Lighthouse Headkeeper’s quarters tour. This fee supports the work of the Point San Luis Lighthouse Keepers’ restoring, maintaining, and operating visitor services at this Historic Site. To make your reservation, go to: www.pge.modwest.com/pgereservations/.
John Lindsey is a media relations representative for PG&E. He is a local weather expert and has lived along the Central Coast for more than 25 years.
If you would like to subscribe to his daily weather forecast or ask him a question, send him an email at firstname.lastname@example.org.