The weather this spring has been an anomaly. Rain and snow in California this June, historic floods along the Mississippi River, blistering heat waves and monster tornado outbreaks east of the Rockies have made this season one for the record books.
On Tuesday, the temperature reached 103 degrees at Minneapolis-St. Paul International Airport. This shattered the old record of 95 degrees set in 2004. Flooding on the Mississippi River reached levels not seen since 1927, with thousands of acres of farmland still underwater. Tornadoes have killed hundreds this spring, with Missouri and North Carolina especially hard hit.
Last weekend, 1.05 inches of rain fell at Cal Poly, where official records for San Luis Obispo are kept. That breaks the previous rainfall record total of .80, set in June of 1991. Rocky Butte near San Simeon recorded nearly 4 inches of rain last weekend!
At the same time, significant snowfall accumulations were recorded in the higher elevations of the Sierra. This year’s snowpack was one of the deepest on record.
“In my past 40 years as a hydrologist for Pacific Gas and Electric Company, this snowpack is the largest for this late spring date that I can recall,” Gary Freeman said. “It wasn’t the largest snowpack in terms of water content on record. Eight years, including 1995, 1983, 1969, 1958, 1952, 1938, 1916, and 1914, were all larger in the Central Sierra as measured at the Donner Summit snowcourse during the past 100 years. But it is the largest on record for this time of year.”
In a normal winter, most of the snowpack melts in May.
The Stouts Meadow automated snow sensor site at 5,400 feet, above McCloud Reservoir, has exceeded the 1998 mark, a record snowpack with a late melt.
“The snow is thick in the higher elevations,” Freeman said.
Should the temperatures suddenly warm up — and, at this time of the year, temperatures can turn on a dime — melting snow in the Sierra could flow down from the mountains all at once, causing flooding.
The largest concern statewide focuses on the San Joaquin River. Reservoirs such as Exchequer and Millerton continue to be managed with space left to help accommodate the expected deluge of spring runoff.
Many readers have asked me what is causing this wacky weather. Is the recent weather an anomaly or a sign of things to come with a warming climate?
Perhaps it’s the residual effects of La Niña and the negative phase of the Pacific Decadal Oscillation, a long-lived El Niño-like pattern. Add a touch of Maiden Julian Oscillation, and a lot of remaining unknowns, and we have this year’s delayed snowmelt.
This year’s La Niña was one of the strongest in the past half-century, and seawater temperatures along our coastline seem to support this, averaging nearly two degrees Fahrenheit below average at the Diablo Canyon power plant, for instance.
However, we still don’t understand what causes the areas of high pressure to switch from one part of equatorial Pacific to the other, producing the El Niño/Southern Oscillation, or ENSO, cycle.
A warming climate could also be contributing to this wild weather. Over the long term, California’s Sierra snowpack is melting two to three weeks earlier than the pre-1970s. Even lilac and honeysuckle are blooming earlier, and birds have been arriving earlier in the spring to lay eggs.
Freeman told me, “These occasional outlier years from the current warming trend are part of year-to-year variance that makes our current California climate what it is. With climate change, we are told to expect larger year-to-year variation and extremes.”
I personally believe that climate change is probably contributing to this wild weather in ways we don’t fully understand.
Since no one really knows what’s causing these unusual weather patterns, I’d rather be safe than sorry and try to reduce the amount of carbon going into the atmosphere.
This week’s forecast
A 1,030-millibar Eastern Pacific High will remain nearly stationary, about 600 miles to the west of San Luis Obispo, over the next 72 hours while a thermal low remains over the Great Central Valley of California.
Fresh to strong (19- to 31-mph) northwesterly (onshore) winds along the coastline will enhance the marine layer during the late night and early morning hours, producing areas of drizzle along the northwesterly (Los Osos, Morro Bay and Montaña De Oro) facing beaches.
However, these winds will help mix out the temperature inversion layer during the late morning and afternoon hours producing a greater amount of sunshine, especially along the southwesterly facing beaches of Avila Beach and Cayucos as these winds to descend from the Irish Hills and Santa Lucia Range.
Additionally, with some moisture aloft, there are slight chances for some afternoon showers/thundershowers to develop along the Sierras.
Temperatures today will range from the high 50s along the northwesterly (Los Osos, Morro Bay and Montaña De Oro) facing beaches to the high 60s along the southwesterly facing (Avila Beach and Cayucos) beaches and coastal valleys.
The North County will warm to the high 70s to the low 80s.
As a high pressure ridge begins to build in from the west, the low coastal clouds are expected to burn off much earlier in the morning Monday, with warmer temperatures expected for all locations.
At this time, there are no changes to the extended forecast, as gradual warming is expected through Wednesday, with slightly cooler temperatures forecast Thursday through next weekend.
Surf and sea report
Fresh to strong (19- to 31-mph) northwesterly winds along the coastline will generate 3- to 5-foot northwesterly (310-degree deep-water) sea and swell (with a 5- to 8-second period) today through Tuesday.
The wind fields will shift northward and increase off the Northern California coastline Wednesday through Friday.
Fresh gale to strong gale force (39- to 54-mph) northwesterly winds off Cape Mendocino will generate a 7- to 9-foot northwesterly (290-degree deep-water) swell (with an 8- to 12-second period) along our coastline Wednesday through Saturday.
Arriving from the Southern Hemisphere, a persistent 1- to 2-foot Southern Hemisphere (220-degree deep-water) swell (with a 14- to 16-second period) will continue along the Central Coast through Monday.
A 1-foot Southern Hemisphere (190-degree deep-water) swell (with a 20- to 22-second period) is forecast along our coastline Tuesday, increasing to 1 to 3 feet (with an 18- to 20-second period) on Wednesday. This swell is expected to peak on Thursday at 2 to 4 feet (with a 16- to 18-second period).
The Diablo Canyon waverider buoy is reporting a sea surface temperature of 53.1 degrees.
Seawater temperatures will range between 51 to 54 degrees through Tuesday, increasing to 52 to 55 degrees Wednesday through Friday.
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John Lindsey is a media relations representative for PG&E and local weather expert. To subscribe to his daily weather forecast, email him at pgeweather@ pge.com.