THERE IS AN EQUAL AND OPPOSITE REACTION (Trough)
Isaac Newton's third law of motion can in a sense describe what has been going in this winter, in Alaska, and downstream, over the western U.S.
This winter so far in south-central Alaska has been quite turbulent: heavy snow and colder than normal temperatures in November, then 5 strong (of which 2 were especially) damaging windstorms with very warm temperatures bringing heavy rain and snow over the area, including Anchorage from 04-20 December, and finally back to colder temperatures and very heavy snowfall until just two days previous. It's safe to say that many people here are really wondering about what is going on, and there is some apprehension.
Meanwhile, downstream, in California, there was this from 10 Jan. :
".DISCUSSION...SUNNY SKIES AND MILD TEMPERATURES PREVAIL ACROSS THE CENTRAL CA INTERIOR THIS AFTERNOON. THE WEATHER DOES NOT GET MUCH BETTER THAN THIS IN JANUARY...UNLESS YOU LIKE RAIN AND MOUNTAIN SNOW. LITTLE IF ANY PRECIPITATION HAS FALLEN IN THE CENTRAL CA INTERIOR SINCE THE 20TH OF NOVEMBER. SADLY...THE WEATHER LOOKS AS THOUGH IT WILL REMAIN DRY AS A BONE FOR AT LEAST ANOTHER 7 DAYS. AN UPPER LEVEL RIDGE OF HIGH PRESSURE SITUATED ALONG THE WEST COAST IS TO BLAME...AND IT WILL DOMINATE OUR PATTERN THROUGH SATURDAY. DURING THIS TIME...A WEAK TO MODERATE OFFSHORE FLOW WILL PREVAIL ACROSS CENTRAL CA AND SKIES WILL BE MOSTLY CLEAR.
AFTERNOON TEMPERATURES THE NEXT COUPLE OF DAYS WILL BE MORE LIKE
THE MIDDLE OF MARCH THAN THE MIDDLE OF JANUARY. THE RECORD HIGHS FOR TOMORROW AND SATURDAY IN FRESNO AND BAKERSFIELD WILL BE WITHIN REACH…
…AFTER NEXT THURSDAY...THE MODELS FORECAST A GRADUAL SHIFT SOUTHWARD OF THE STORM TRACK AND THE POTENTIAL FOR WET WEATHER...PERHAPS AS EARLY AS NEXT FRIDAY NORTH OF FRESNO COUNTY THEN POSSIBLY SOUTHWARD INTO KERN COUNTY NEXT WEEKEND. ALTHOUGH THE PAST FEW RUNS OF THE MODELS HAVE SIGNALLED A SIGNIFICANT CHANGE TO A WET PATTERN...EACH RUN SEEMS TO BACK OFF A LITTLE BIT THIS FAR SOUTH. HENCE...FORECAST CONFIDENCE IS TOO LOW AT THIS TIME TO MAKE ANY GUARANTEES. THE FACT IS...IF FRESNO DOES NOT RECEIVE MEASURABLE RAIN BEFORE THE 25TH OF JANUARY...IT WILL BE THE LONGEST STRETCH OF DRY WEATHER EVER RECORDED BETWEEN THE MONTHS OF NOVEMBER AND MAY SINCE THE LATE 1800S [when records there began, eds]. TODAY IS DAY 53 IN THAT STRING AND WE ARE STILL COUNTING."
This was what is called the Area Forecast Discussion from the NOAA/National Weather Service office in Hanford, CA, which covers the San Joaquin Valley, Central Coast, and central Sierra Nevada mountains. Twice daily, the meteorologists on duty describe the weather pattern(s) of the day, how the different numerical weather prediction models are handling them, and what the prognosis is for the next several days. A great way to get a thorough picture of the weather, in whatever area you may find yourself in. http://www.nws.noaa.gov/organization.php
".DISCUSSION...SUNNY SKIES AND MILD TEMPERATURES PREVAIL ACROSS THE CENTRAL CA INTERIOR THIS AFTERNOON. THE WEATHER DOES NOT GET MUCH BETTER THAN THIS IN JANUARY...UNLESS YOU LIKE RAIN AND MOUNTAIN SNOW. LITTLE IF ANY PRECIPITATION HAS FALLEN IN THE CENTRAL CA INTERIOR SINCE THE 20TH OF NOVEMBER. SADLY...THE WEATHER LOOKS AS THOUGH IT WILL REMAIN DRY AS A BONE FOR AT LEAST ANOTHER 7 DAYS. AN UPPER LEVEL RIDGE OF HIGH PRESSURE SITUATED ALONG THE WEST COAST IS TO BLAME...AND IT WILL DOMINATE OUR PATTERN THROUGH SATURDAY. DURING THIS TIME...A WEAK TO MODERATE OFFSHORE FLOW WILL PREVAIL ACROSS CENTRAL CA AND SKIES WILL BE MOSTLY CLEAR.
AFTERNOON TEMPERATURES THE NEXT COUPLE OF DAYS WILL BE MORE LIKE
THE MIDDLE OF MARCH THAN THE MIDDLE OF JANUARY. THE RECORD HIGHS FOR TOMORROW AND SATURDAY IN FRESNO AND BAKERSFIELD WILL BE WITHIN REACH…
…AFTER NEXT THURSDAY...THE MODELS FORECAST A GRADUAL SHIFT SOUTHWARD OF THE STORM TRACK AND THE POTENTIAL FOR WET WEATHER...PERHAPS AS EARLY AS NEXT FRIDAY NORTH OF FRESNO COUNTY THEN POSSIBLY SOUTHWARD INTO KERN COUNTY NEXT WEEKEND. ALTHOUGH THE PAST FEW RUNS OF THE MODELS HAVE SIGNALLED A SIGNIFICANT CHANGE TO A WET PATTERN...EACH RUN SEEMS TO BACK OFF A LITTLE BIT THIS FAR SOUTH. HENCE...FORECAST CONFIDENCE IS TOO LOW AT THIS TIME TO MAKE ANY GUARANTEES. THE FACT IS...IF FRESNO DOES NOT RECEIVE MEASURABLE RAIN BEFORE THE 25TH OF JANUARY...IT WILL BE THE LONGEST STRETCH OF DRY WEATHER EVER RECORDED BETWEEN THE MONTHS OF NOVEMBER AND MAY SINCE THE LATE 1800S [when records there began, eds]. TODAY IS DAY 53 IN THAT STRING AND WE ARE STILL COUNTING."
This was what is called the Area Forecast Discussion from the NOAA/National Weather Service office in Hanford, CA, which covers the San Joaquin Valley, Central Coast, and central Sierra Nevada mountains. Twice daily, the meteorologists on duty describe the weather pattern(s) of the day, how the different numerical weather prediction models are handling them, and what the prognosis is for the next several days. A great way to get a thorough picture of the weather, in whatever area you may find yourself in. http://www.nws.noaa.gov/organization.php
The Sierra Nevada snowpack, which almost all the population of California relies upon for it's domestic, industrial, and agricultural irrigation water, as of two weeks ago (and it's been dry since), was only at 19 % of average. Which does not bode well for the coming year, if it doesn't start building up soon.
The most recent graphic of snowdepths there, shows the story. It's actually bare around Lake Tahoe! And snowdepths which should be in the multiple metres over the higher elevations, are not even reaching 50 cm across most of the region!
The snow drought situation is a little better further north, in the Cascades of Oregon and Washington.
"Despite the presence of La Niña, which favors wetter and snowier than normal winter conditions, December was unusually dry and calm across Washington. Low clouds and poor air quality were the most notable weather concerns of the month.
"Normally, December is one of the more active weather months of the year,” said Washington State University AgWeatherNet meteorologist Nic Loyd. "However, a strong ridge of high pressure blocked the storms that might have otherwise reached the Northwest.
"The high-pressure system persisted over the region from the end of November through Christmas,” he said. "As a result, Washington experienced very little interesting winter weather until the final week of the year.”
Mountain snowfall was very low in December, and the Cascade snowpack remains below normal at the beginning of 2012. Northwest Avalanche Center data indicate that mountain snow depths ranged from 55 to 103 percent of normal on Jan. 1. Paradise and White Pass snow depths were at record low levels for a La Niña winter.
"If the mountain snowpack remains below normal, it could have a negative impact on available water for irrigation during the summer,” said AgWeatherNet Director Gerrit Hoogenboom. Even so, there is still a chance to recover from the snow deficit if heavy snows materialize during the later part of winter.
At year’s end, increasingly unsettled weather brought heavy rain to the coast and strong wind and unseasonable warmth to eastern Washington. Prosser experienced its warmest December day on record on the 28th, and the daily low temperature of 52 degrees smashed the old December record by four degrees. Long Beach recorded 2 1/2 inches of rain Dec. 28-29, winds at St. John gusted to more than 50 mph and, in the Walla Walla area, temperatures jumped to around 60 degrees."
As the latest graphic of Cascade snowpack depth shows, there is quite a bit more here than in the Sierra, as you might expect, since they are further north, but, still well below average.
Meanwhile, to the north, here in Alaska:
Meanwhile, to the north, here in Alaska:
Valdez digs out from under a world class snowfall
By CASEY GROVE
Anchorage Daily News
Published: January 15th, 2012 05:21 PM
"VALDEZ -- This city feels like a hamster maze.
"VALDEZ -- This city feels like a hamster maze.
WINTER WALLOP
The 322 inches of snow in Valdez as of Saturday was:
• 44.3 inches more than the same date in 1990, the year Valdez set its seasonal snowfall record
The 322 inches of snow in Valdez as of Saturday was:
• 44.3 inches more than the same date in 1990, the year Valdez set its seasonal snowfall record
• An average depth of 78 inches, or 61/2 feet
• Weighing an average of 112 pounds per square feet
• 168.1 inches more than the seasonal average for the same date
• About even with the average total snowfall for an entire winter
Eight-foot-tall walls of snow border icy, scraped-clean streets. Around every corner, a piece of heavy equipment is pushing, carrying or blowing snow. An army of workers on rooftops wields shovels against the thick blanket of white, tearing off one massive chunk at a time.
The word "snow" has become just another four-letter expletive uttered in this Prince William Sound hub.
Valdez is known as the snowiest place in Alaska and one of the snowiest in the world, a longtime source of local pride and a basis for well-earned bragging rights.
But with half a winter still to come and history-making accumulation already for this point in the season -- 322.1 inches as of Saturday -- the snow has begun to take a toll on the mental and physical well-being of the hardy residents here.
"Many of us can't see out of our windows," said Sheri Pierce, the city clerk. "My house, when you look at it from the street, it's completely covered. It's a little like living in a cave. It's dark inside."
"This kind of snow season puts stress on people," said Mayor Dave Cobb. "It's easy to get cabin fever."
After 31 straight days of snowfall, the dumping stopped Wednesday. By Friday, the sky was clear and windy, and the nearby mountains shone with sun. The break in the weather is expected to last about another week, allowing the city to catch up.
Some weary residents reported 18- and 20-hour-long days between work and shoveling snow. A local massage therapist says his calendar is filled with appointments due to back and muscle pain -- and because he's had to take time off for the snow at his own home. Local stores are sold out of shovels and snow scoops, so people brought stacks of them from Anchorage and Fairbanks...
...Day-to-day life has been more difficult lately in Valdez, to be sure. The stories are often downright wacky. But then there are the frightening tales that residents tell, some of them bordering on near-death experiences.
There's the one about the electrician who ran to escape a warehouse on the edge of town when the roof collapsed and the corrugated walls folded in on him. Or the man partially buried in snow that sloughed off his neighbor's roof, crashed through a door and inundated his bedroom while he slept. And his other neighbor, across the street, who just a few minutes later was knocked off her feet when her own roof avalanched.
"It's been crazy, and from what I understand, it's the next two months we have to worry about," said Doug Mason while taking a short break from shoveling a church roof.
The overload forced what is likely the first-ever school closure in Valdez from snow buildup, said Cobb, the mayor, who's lived here for about 40 years. Technicians were measuring the weight on local buildings, and a structural engineer from Anchorage was looking for damage Saturday.
The city put out a call last week for temporary shovelers to first clear the school roofs, then other city buildings, and raised the standard pay from about $16 to a little more than $20 an hour. About 160 laborers, some from Interior and Southcentral communities, had signed up by Saturday.
"People take pride in being able to say they live in 'the snow capital of the world,' and bucking up and doing what they need to do to deal with something like this," said John Hozey, the city manager. "Just the thought of considering asking for help from outside didn't sit well with a lot of people."..."
In Anchorage, while only 89 inches of snow has fallen since the season began, this is more than double the average for the season up to mid-January, and several inches greater than the entire winter average amount.
In Anchorage, while only 89 inches of snow has fallen since the season began, this is more than double the average for the season up to mid-January, and several inches greater than the entire winter average amount.
This has left our back-streets clogged as well, as large piles from people's driveways kept growing and growing, then bulging out into the road, as this view near the Chugach Front Research Centre attests.
Even our intrepid assistant editor Mattie is wearying of the deep snow. Here she is swimming in deep powder yesterday as I broke open our favourite running trail on snowshoes, heading up to 1424 metre (4670') Konoya Point.
Even our intrepid assistant editor Mattie is wearying of the deep snow. Here she is swimming in deep powder yesterday as I broke open our favourite running trail on snowshoes, heading up to 1424 metre (4670') Konoya Point.
She got quite tired plowing/swimming her way through a metre of thick, deep powder, ascending 600 metres uphill, in temperatures ranging from -25 to -30C (-11 to -22F). Although it was just a 16 km trip, it took us 4 1/2 hours. Last winter we were able to run on this trail all through the winter season, but since heavier snowfalls began during this one in Mid-November, no one has been in on it.
This graphic tells the story of our winter here, and in the western Lower 48 quite succinctly. This is the "Composite Mean" for the month of December, 2011, of the 500 millibar height field. Remember, these values, in metres, are the height at which atmospheric pressure equals 500 millibars, which is about half of sea level pressure. The lower these heights are, the colder the airmass, and higher values, those bulging northward, just off the lower 48 coastline, represent an "upper level ridge", whilst the very low values over the Bering Sea, an "upper-level trough". Warm, dry weather is to be found adjacent to, and under these ridges, generally speaking. This chart then is a mean of all 31 days of the month of Decembers' 500 millibar heights and shows that strong ridging was generally present there all month, keeping California warm and dry, and preventing any snowpack development in the Sierra Nevada.
Needless to say, with this "blocking ridge" in place more strongly than average, the mean pattern for Alaska then, was for low pressure systems moving in the colder onshore flow ahead of the very deep, cold Bering Sea trough to move into the Gulf of Alaska and move ashore there between Kodiak and Yakutat, bringing strong winds and rain initially, then heavy snow in their wakes. In fact, when this ridging pattern off of California was at it's most amplified, the flow onto the Gulf Coast and South-Central Alaska was more southerly, and warmer. And this is what occurred during that memorable 04-20 December period, when Anchorage was subjected to the five consecutive low pressure systems/frontal passages, which brought strong winds (up to 200 kph in one case!), and heavy/rain snow.
The pattern finally began to change with the last heavy snowfall event, on the 11th-12th of this month.
Needless to say, with this "blocking ridge" in place more strongly than average, the mean pattern for Alaska then, was for low pressure systems moving in the colder onshore flow ahead of the very deep, cold Bering Sea trough to move into the Gulf of Alaska and move ashore there between Kodiak and Yakutat, bringing strong winds and rain initially, then heavy snow in their wakes. In fact, when this ridging pattern off of California was at it's most amplified, the flow onto the Gulf Coast and South-Central Alaska was more southerly, and warmer. And this is what occurred during that memorable 04-20 December period, when Anchorage was subjected to the five consecutive low pressure systems/frontal passages, which brought strong winds (up to 200 kph in one case!), and heavy/rain snow.
The pattern finally began to change with the last heavy snowfall event, on the 11th-12th of this month.
This low, which initially looked as though it might behave similarly to the December ones, ended up tracking inland a little further east, and spared Anchorage from receiving any rain, and kept the strongest winds higher up on the Chugach hillsides, instead of descending into the city. Temperatures did warm up for several hours above freezing in some parts of the Anchorage "Bowl", but this was not accompanied by any rain. Then, on the back-side of this low, as it tracked inland, 20-32 additional cm of snow (8-12") fell. This was the last heavy-snowfall producing system for the beleaguered communities of Cordova and Valdez as well, fortunately. The pattern has since changed in the last few days. The ridging along the west coast has weakened, and an upper-level low is now centred just off the OR/WA coast, bringing them cool, showery weather with light snow, even at the lower elevations. Leaving Alaska on its back side, under a cold, dry, northerly flow. The prognosis for this pattern by the long range numerical weather prediction models is for it to persist at least another week, possibly longer. Let's hope so, so that at least the Cascades, and northern Rockies, if not the Sierra Nevada, can begin to build their much-needed snowpacks again.
So to sum up then, during a La Nina winter, http://www.publicaffairs.noaa.gov/lanina.html, cooler and wetter than normal conditions tend to occur over the Pacific Northwest, and colder conditions, overall in Alaska.
In spite of this, strong and persistent upper-ridging along the west coast of the U.S., brought just the opposite, and forced the majority of low pressure systems to move into Alaska, with just the weaker remnants affecting British Columbia and Washington/Oregon. Whilst California remained high and dry.
We've been warning you for some time, here at the Alaska Progressive Review, that strong, persistent upper-ridging weather patterns have been increasing and amplifying, over the past ten years especially. Because high pressure ridging, when the jet stream expands further northward, carrying heat from the tropics and subtropics northward into the mid-latitudes and sub-arctic, is how the atmospheric circulation maintains a global energy balance. So that the Tropics don't overheat, and the poles chill to levels that would allow semi-persistent snow/ice cover in place to expand (at least in the Northern Hemisphere, Antarctica remains frozen because it is a high-elevation land/ice mass). Since more heat is now available, and increasing, this pattern is amplifying.
Now that global heating is accelerating, these are the kind of patterns we will continue to see amplify, over the coming decades. Remember, the Earth overall has warmed about 0.8C (1.44F) over the past 100 years, as atmospheric CO2 concentrations from fossil fuel combustion and deforestation increased from about 300 ppm to 392 ppm. Since it is now expected that CO2 levels will reach 550-600 ppm in the next 40 years, and along with that, global average temperatures to rise a minimum of 2C, think about what that will mean for the weather patterns that will be occurring here in Alaska, and in the Western US. To say nothing of the rest of the World. Cheers.
So to sum up then, during a La Nina winter, http://www.publicaffairs.noaa.gov/lanina.html, cooler and wetter than normal conditions tend to occur over the Pacific Northwest, and colder conditions, overall in Alaska.
In spite of this, strong and persistent upper-ridging along the west coast of the U.S., brought just the opposite, and forced the majority of low pressure systems to move into Alaska, with just the weaker remnants affecting British Columbia and Washington/Oregon. Whilst California remained high and dry.
We've been warning you for some time, here at the Alaska Progressive Review, that strong, persistent upper-ridging weather patterns have been increasing and amplifying, over the past ten years especially. Because high pressure ridging, when the jet stream expands further northward, carrying heat from the tropics and subtropics northward into the mid-latitudes and sub-arctic, is how the atmospheric circulation maintains a global energy balance. So that the Tropics don't overheat, and the poles chill to levels that would allow semi-persistent snow/ice cover in place to expand (at least in the Northern Hemisphere, Antarctica remains frozen because it is a high-elevation land/ice mass). Since more heat is now available, and increasing, this pattern is amplifying.
Now that global heating is accelerating, these are the kind of patterns we will continue to see amplify, over the coming decades. Remember, the Earth overall has warmed about 0.8C (1.44F) over the past 100 years, as atmospheric CO2 concentrations from fossil fuel combustion and deforestation increased from about 300 ppm to 392 ppm. Since it is now expected that CO2 levels will reach 550-600 ppm in the next 40 years, and along with that, global average temperatures to rise a minimum of 2C, think about what that will mean for the weather patterns that will be occurring here in Alaska, and in the Western US. To say nothing of the rest of the World. Cheers.
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