Weather Watch

March is wet, but March ’95 was really wet

Recently, a reader asked about the March 1995 storm that produced more than 11 inches of rain in Santa Margarita within 24 hours.

Historically, March in San Luis Obispo County can be wet — averaging more than 3.5 inches of rain.

But in March 1995, a storm developed about 900 miles off the Central Coast and caused an intense cold front to stall over our area.

The rain began to fall early March 9, and continued through the next day, producing amazing 24-hour rainfall totals.

They ranged from a low of 3.4 inches recorded in Pismo Beach, to 11.6 inches in Santa Margarita.

The stalled cold front was accompanied by gale-to-storm-force (55 to 73 mph) southeasterly winds in the Diablo Canyon area.

San Simeon reported sustained wind speeds of 70 mph with gusts reaching 88 mph, while the Diablo Canyon meteorological tower reported peak sustained winds of 58 mph, with gusts reaching more than 65 mph.

These winds produced a great amount of orographic enhancement — as the air mass is lifted up over our coastal mountains (upwind), it cools and eventually reaches its dew point temperature.

When this occurs, rain will develop on the windward side of the mountain. Like squeezing a wet sponge, moisture from this air mass is released in the form of precipitation.

Some locations in the hills above Cambria and along the Cuesta Grade reported rainfall amounts exceeding 12 inches over 24 hours.

Areas throughout San Luis Obispo County experienced flooding, with Cambria being one of the hardest hit. In fact, Cambria’s Fire Department used a boat to rescue people along Main Street.

A review of this event indicated that an El Niño condition was present in the eastern Pacific Ocean, a weather pattern similar to the one we’re experiencing so far this year.

Only time will tell if the Ides of March will bring more wet weather, keeping our totals above normal for the season.

This week’s forecast

An upper-level low moved into Southern California late last night, but not before producing widely scattered rain showers, at times moderate, and a few thunderstorms throughout San Luis Obispo County on Saturday.

Rainfall totals ranged from a few hundredths of an inch at Diablo Canyon, a quarter-inch in Los Osos to nearly a half-inch at SLOWeather.com’s tracking station in southwestern San Luis Obispo.

A change in the weather pattern will develop today as a 1,034-millibar high takes a position off the Northern California coastline.

This condition will produce a steep pressure gradient along the Central Coast, which in turn will give fresh to strong (19 to 31 mph) northwesterly winds this afternoon.

A mostly dry cold front will pass the Central Coast on Monday morning, followed by strong to gale force (25 to 38 mph) northwesterly winds Monday afternoon through Tuesday.

This condition will set up a spring type of weather pattern, with coastal low clouds developing along the northwesterly facing beaches and a few of our coastal valleys during the late afternoon and evening.

This pattern will also signal the transition to warmer weather in the North County, versus the coastal valleys and beaches.

Surf and sea report

A 956-millibar storm with hurricane-force winds developed Friday and tracked along the Aleutian Islands toward Anchorage.

This system will produce a 7- to 9-foot northwesterly (300-degree deep-water) swell (with a 20- to 22-second period) along our coastline this afternoon through tonight.

Increasing northwesterly winds along the California coastline will produce an 8- to 10-foot northwesterly (310-degree deep-water) sea and swell (with a 5- to 15-second period) along the Central Coast on Monday through Tuesday.

This northwesterly (310-degree deep-water) sea/swell will decrease to 6 to 8 feet Wednesday, but will build back to 8 to 10 feet (with an 11- to 14-second period) Thursday and Friday.

Preliminary analysis long-range forecast:

An intense eastern Pacific storm is expected to develop later in the week and produce a high-energy west-northwesterly swell along the coastline March 16.

Conservation tip

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John Lindsey is a media relations representative for Pacific Gas and Electric Co. He is also a local weather expert and has lived along the Central Coast for more than 23 years.

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