Friday, January 30, 2015

Weather Pattern Locked: California Drought, Northeast Winter Worsens

Let's look at the big picture for a minute.
The percent of California in severe drought
dropped from over half the state to a third of the state by
the first of this year. But now, the area
of severe drought (dark red) is increasing again.
All of California is in at least slight drought (yellow) 

For the past few weeks, it's been cold and wintry in the northeastern United States.

After some welcome rains in California in December, it's been bone dry again out there all this month.

It's been quite warm in the western United States for the past few weeks, too.

Reminds me a lot of last winter.

And it should. After breaking down a bit toward the end of 2014, the persistent weather pattern that locked itself over North America most of the time since 2013 is back in place and shows no signs of leaving anytime soon.

That's really bad, really grim news for drought-stricken California, and not as bad but still annoying news for the eastern United States, at least for those who don't like winter and are not fans of burning extra fuel and paying more to heat their homes.

Some scientists suggest that these "locked" weather patterns, ones that last much, much longer than normal, are in part a child of global warming. The jet stream usually forms a fairly tight circle around the places well north of the United States.

But as the contrast between a rapidly warming Arctic and not so rapidly warming tropics decreases, the strength of the jet stream weakens, say a lot of scientists. That gives room for unusually big bulges and dips in the jet stream to form and sometimes lock themselves into place.

Scientists pretty much all agree that global warming is taking place, but there is still some disagreement as to whether the warming screws around with the jet stream like I described. But the evidence so far is intriguing, and I know a bunch of climatologists are studying the matter pretty damn closely.  
The news media photographs Frank Gehrke who this week
was not finding much snow, or potential water in the
California mountain snows as he took measurements
for the California Department of Water Resources. 

As I noted, what became colloquially known as the Ridiculously Resilient Ridge is back along the West Coast. The RRR, as I'll call it, is a big bulge northward in the jet stream, poking way, way north toward western Canada, and at times Alaska.

Storms in the winter usually want to cross the Pacific Ocean then blow through California.

That's what gives the Golden State its annual winter rainy season, when reservoirs fill up. Feet and feet of snow piles up in the Sierra Nevada. That snow gradually melts in the spring and summer, adding more to needed water supplies.

The RRR sitting along the West Coast acts as a roadblock for those Pacific storms, steering them north toward British Columbia. (or sometimes Washington State, which explains why that area had such nasty floods and landslides earlier this winter.)

When the RRR weakened in December, some storms did blow through California, bringing needed rain and snow and raising hopes the drought would ease some.

In January, the RRR came back in force. Really bad. Normally San Francisco gets about four and a half inches of rain in January.

In January, 2015 the rainfall total for San Francisco is going to come to Zero. Zip. Nada. That will make this January the driest on record in the Bay Area. It will also make last January, 2014, the second driest January on record, with a whopping 0.01 inches of rain.

Let's take a journey up to the Sierra Nevada mountains to see how things are going on up there. Maybe we can play in the snow while we're at it.

Um, no.

People with the California Department of Water Resources regularly tromp around the Sierra Nevada mountains, measuring the snow and figuring out how many inches of rain you'd get if that snow was melted.

They just came back with an update yesterday and nobody was happy with it. Overall, water in the California Sierra snowpack is just 25 percent of what it should be this time of year. At Echo Lake in the mountains east of Sacramento, there was just 2.3 inches of "rain" in the snowpack, just 12 percent of normal.

It didn't help that it was also unusually warm in California during January. Some of the scant snow cover in the Sierras melted already.

You can see why all this California dryness is a problem. The California drought has been going on since 2012. The longer things go on like this, the worse things get. They've got to get water from somewhere, and if it doesn't rain or snow, what do you do?

This will affect all of us in the form of higher food prices. Lots of farms in California give us a much of our dairy, meat, fruits and vegetables. No rain, and these things don't happen. That will tighten supplies.

Basic economics comes into play. The tighter the supply, the higher prices go.

January is normally the wettest month of the year in California. The rainy season usually extends through February and March, petering out in April.

So you need a lot of storms to make up for the lack of water they're currently facing. In the immediate future, say, the next week or two, there's no signs of any big storms coming to California.

The RRR is holding firm, and time is running out for rain.

On the east side of the RRR, the upper level winds sweep southeastward along the east face of that ridge, down from near the North Pole to the northeastern United States.  
Plenty of snow here, unlike the Sierra Mountains.
Paul Baxter digs out blizzard-buried cars
this week in Marlborough, Mass.
Photo by Bill Sikes/AP  

That explains the repeated nasty cold snaps that have been sweeping through lately, and will continue to do so through much of February.

There might be some brief intervals of relative warmth between cold snaps, but they'll keep coming for much of the month. Especially up toward New England.

The winds coming southeastward from Canada get to their southernmost point somewhere along the United States East Coast, then start to swing northward again along or just off the coast.

That's where you get storms, where the jet stream swings north again after diving south from Canada over the eastern United States.

The position of that swing north wiggles a little, so some of the storms go out to sea and don't bother anyone on the East Coast. Or they come closer to the coast, and you get what we got in New England on Monday and Tuesday--a blizzard.

Worse, ocean temperatures are warmer than normal off the East Coast. Warmer water tends to create more evaporation and more moisture for storms to work with. The warm water tends to also make nor'easter storms stronger. That's a large part of the reason why the blizzard this past week in New England was so intense.

This could be another consequence of global warming. Ocean temperatures warm up, helping create bigger, wetter storms. Even though global warming are making  winters in general milder, it'll still often cold enough to snow. Global warming doesn't repeal winter. It just changes it.

Although droughts are happening, unusually intense precipitation events like this week's blizzard are also increasing in most of the country, especially the Northeast, says National Geographic magazine, citing various scientific sources.

There will be a continued spray of storms forming along or off the East Coast for much of the rest of the month. It's hard to tell more than two or three days in advance of each one whether they will come close enough to the coast to cause snowstorms or other rough weather, or whether they head out to sea, just leaving the East Coast "basking" in the frigid, dry air from Canada.

One such East Coast storm, borne from a weak system that came across the Great Lakes and was crossing New England this morning, will blow up off the coast and give Maine another humdinger of a snowstorm later today into Saturday. (The rest of northern New England is generally getting three to seven inches of snow from this.)

That storm will propel strong winds and frigid air into New England tonight and tomorrow, prompting lots of wind chill alerts.

Another in the series of storms could affect the East Coast around Monday. The computer forecasting models as of Friday morning were still disagreeing on this one.  It looks like the storm will probably cause a snowstorm somewhere in the eastern United States.

But how big a snowstorm? And precisely where?  Nobody is sure yet. It could hug the coast and give southern New England another unwanted heavy snow. Or it could blow out to sea, just leaving some light snow flurries as a calling card.

If I had to guess, the Monday storm might affect Philadelphia and New York and Long Island the most, but don't hold me to that. The situation is still fluid.

The picky details are hard to sort out. But the big picture - the RRR on the West Coast, and the eastern cold, are here to stay for awhile.


  1. Hi,I live in New Mexico, I used to live in Vt,and read your blog a lot. I have a question,we are getting snowstorm after snowstorm.Where are these storms coming from,I thought they were coming from California.

  2. I am obviously not Matt but I think those storms are dropping straight from the north. Part of that weird jet stream pattern. Seems like Texas has had a lot of snow too, relatively speaking.
    The jet stream is so far north in California that weird tropical systems have come up twice into the southwest and far southern california, sadly mostly missing the sierras and also pretty warm. Perhaps that moisture is combining with cold air to bring you snow.

    1. We sometimes get storms from the north,like the thunderstorm/snow squall that smoked us,a couple months ago. However as Matt said,it seems the storms develop over us,and "jump" over California.As a side note,to see more New Mexico weather, and have some interesting reading,check out John Farleys weather web site.

    2. We sometimes get storms from the north,like the thunderstorm/snow squall that smoked us,a couple months ago. However as Matt said,it seems the storms develop over us,and "jump" over California.As a side note,to see more New Mexico weather, and have some interesting reading,check out John Farleys weather web site.