Climate Change CAN Worsen Winter Storms. But It's Complicated

Upper level forecast shows how cold weather
in eastern U.S will last into early Februarty.
Green lines depict the jet stream. Note how
wavy it is and how it heads southeastward
into the United States. Those red dotted
areas indicate areas of high pressure and warm
air for the region. That so much of the red
dots mean there's an Arctic amplification,
which means cold air is being squashed 
southward toward us. Scientists are 
studying whether climate change is making
weather patterns like this more likely. 

I suppose I can't blame President Trump for wondering where global warming went. 

There's massive amounts of ice and snow from New Mexico to southeast Canada. The South is locked in ice after a bunch of freezing rain. People are shivering in their homes without electricity. 

Dozens of daily record low high temperatures and record low overnight temperatures have already been set this weekend, mostly in Kansas, Oklahoma and Texas.  More records will fall in the next few days, mostly across the South and southeastern parts of the U.S.  

Whether this storm, or any other extreme winter event in recent years can be tied to climate change is iffy. But there are some picky scientific details that suggest the warming world can paradoxically helping create these epic winter storms and cold snaps. 

As Meteorologist Jeff Berardelli explains, climate change can during relatively brief periods enhance the cold in places like the United States.

Sometimes - and this is occurring now - blocking high pressure settles over the Arctic, especially near or over Greenland - making them warm. At least warm compared to the insane cold you should expect up there. 

This setup shoves the cold air down into places like the United States and western Europe. 

Meanwhile, the Arctic overall is warming at a pace up to four times greater than most of the rest of the world.  That's called Arctic amplification. In fact, right now it's super warm for the season in parts of Greenland. In Nuuk, on the relatively mild southwest coast of Greenland, normal highs this time of year are around 20 degrees with a low of about 12.

The Weather Channel says Nuuk will have a high temperature of 42 degrees today, and it probably won't go below freezing tonight. 

Berardelli notes that the extra warming from climate change amplifies the blocking high pressure over the Arctic or Greenland.  That, in turn even more firmly pushes the cold air toward the United States and other mid-latitude places .

The air coming down from the Arctic because of this pattern isn't any colder than it used to be. In fact it's somewhat warmer. Punches of frigid air that have always blasted into the Upper Midwest are generally a bit milder than the were a generation or two ago. 

For instance, one study by Climate Central noted that the lowest temperature of the year has increased by 12 degrees since 1970. 

But when these Arctic air masses get pulled all the way down into the southern half of the United States, big trouble ensues. Like the winter storm we're having this weekend. 

There's at least circumstantial evidence that a wavier jet stream has started to occasionally send at times unprecedented blasts of Arctic air far south, all the way to the Gulf of Mexico.

We had the big Texas freeze and utility collapse in 2021, the one that killed nearly 250 people. Last January, an unprecedented snowstorm swept the Gulf Coast, burying places from New Orleans to Pensacola, Florida in more than six inches of snow. New Orleans was actually under a blizzard warning in that event. 

Just last week, it snowed again in northwest Florida. Now this storm. 

The Arctic and Greenland blocking helps make the jet stream wavier, which helps explain why there's such a harsh cold spell going on now.  When jet stream plunges south from northern Canada, it's going to be horribly, miserable cold.

There's still a lot of debate in the scientific community on whether climate change itself is making the jet stream much wavier, especially in the winter. 

When that happens, we could see bigger southward dips in the jet stream, like we're seeing now. 

There's at least circumstantial evidence that a wavier jet stream occasional has started  sending at times unprecedented blasts of Arctic air far south, all the way to the Gulf of Mexico.

Per Grist:

"'The problem is that it's really hard to show whether or not that's happening,' said Jacob Chalif, who studies the phenomenon at Dartmouth College. 'Arctic amplification started really kicking off in the '90s, and we only have really solid record of the jet stream going back to 1979.'"

That leaves about a decade of records to help determine whether what's going on now is something new. 

Dartmouth researchers are now using machine learning to get a picture of jet stream patterns during the  the entire 20th century. There's evidence there were even wilder swings in the jet stream between 1900 and 1979. 

So, the jury is still out as to whether a warmer Arctic is increasing the chances that the U.S. will have terrible winter storms due to whacked-out jet streams. 

Another factor is the polar vortex. It's that big whirl of absolutely ridiculous frigid air that roams the high latitudes. When it's in Canada, closer to the United States, chances are at least part of the nation will be on the cold side.

Sometimes, the polar vortex stretches, and becomes more oblong. if it stretches toward the U.S., we get frigid and fast.

Some science suggests that the polar vortex is stretching more frequently than it used to

Per CNN

"Judah Cohen, a research scientist at MIT, said the stretching of the vortex is tied in part to sea ice loss in parts of the Arctic from human-caused climate change. He also said above average snowfall in parts of Siberia raises the likelihood of such stretching events, and this too is influenced by a paucity of sea ice in the Barents and Kara Seas in the Atlantic Ocean."

'"On the southern flanks of the polar vortex, over the U.S. and Asia, an under that where that stretching is happening, there's been an increase in severe winter weather,' Cohen said. 'I'm not saying any one weather event is attributed to climate change,' he said. 'But I do think it loaded the dice here.'"

Even if you ignore the polar vortex and the Greenland Block and the wonky jet stream, the fact of the matter is it's winter. Sure, the climate is warmer, hut that doesn't mean winter is canceled. It can still get brutal out there.

We're living that out right now.  

 

"Greenland Block" Causes Remarkable Heat Wave Up There; But Kinda Boring Vermont Weather

Upper air pattern featured intense, record warm (for them)
temperatures over Greenland, chilly low pressure off the
east coast of Canada and the Pacific Northwest, and
boring weather for us here in Vermont. 

We're in a weather pattern known as a "Greenland Block."

When this happens, weather systems tend to get gummed up. The Greenland Block is an intense area of high pressure that parks itself over or near the island. 

This situation has low pressure spinning aimlessly off the east coast of Canada, massive high pressure in central Canada, and a diverted storm track that's sending rain and snow storms well to the south of New England, pretty much missing us here in Vermont. 

MAKES VERMONT BORING

The whole set up causes pretty boring weather here in Vermont, as you might have noticed. Temperatures have been sort of near normal if the first eight days of this month. Aside from last Saturday, we've gotten some valley snowflakes and some light accumulations in the mountains.

Temperatures night to day and day to day have varied remarkably little, too. This time of year, on any given day, there's usually an 18 degree difference between the morning low temperature and the afternoon high. 

Early March usually features wildly variable weather, with deep freezes and big thaws and back to deep freezes. But this year, in the entire eight day span of the month so far, there's only been a range of 18 degrees between the highest and lowest temperatures,  at least as measured in Burlington. 

By contrast, last year, the first eight days of March had a huge 67 degree range in Burlington, ranging from minus 3 to 64 above.

So yes, comparatively speaking, this month's weather in Vermont has been something of a yawner so far. 

MAKES GREENLAND HOT 

There's one place, though, that has had some extreme temperatures in this Greenland Block set up. And that is right in Greenland. 

As the Washington Post tells us, temperatures up there in Greenland were as much as 50 degrees above normal.

Greenland's capitol, Nuuk, on the southwestern coast of the island reached 59 degrees on Sunday. That set a record for the entire month of March. More remarkably, it was warmer than any day ever record in Nuuk during April. 

Climatologists and climate scientists always get nervous when there's a big heat wave in Greenland. In the summer, of course, this leads to big melts on the island's ice sheets. 

In this case, it's so early in the season that, even though it was incredibly warm for this time of year, most of the island was still too chilly to get the vast ice sheet melting in any significant way. 

However, every winter, bright white snow falls on the huge ice sheets. The snow is whiter than the underlying ice, and acts to reflect the early summer sun's heat.  That, in turn, can shorten the ice melt season in Greenland. 

This week's Greenland heat wave melted a lot of that bright white snow, the Washington Post reports.   That means there will probably be a lot less snow from the winter of 2022-23 on the ice sheet in late spring than there usually is. That's true even though more snow is inevitable in Greenland before summer. '

Also, the temperature of this snow will be warmer than it usually is, so it won't take as long as normal to get it to melt.

If big summer heat waves hit Greenland in the summer, as they did in 2012, 2018 and 2019, comparatively large amounts of ice will melt and flow into the oceans.  

What goes on in Greenland doesn't stay in Greenland. If too much ice up there keeps melting summer after summer, it will contribute to global sea level rise. 

Greenland has an incredible amount of ice.  But even if just 3 percent of its massively thick ice sheet melts, global sea levels would rise by almost a foot, WaPo reports. 

Scientist say that even if the world stopped releasing greenhouse gases from fossil fuels this very second, we would lose at least 3 percent of Greenland's ice cap.  

OUTLOOK

The Greenland Block is getting ready to break down slightly, at least. Temperatures will return to much closer to normal frigid weather in Greenland in the coming days. Average high temperatures in Nuuk this time of year, for example, are in the low to mid 20s. Highs are forecast to be in the low 30s there in the coming days. 

This will make the weather in Nuuk similar to that in Vermont over the next several days. The Green Mountain State's weather is forecast to remain boring for the next several days. For the next week, we'll continue to have daily highs in the 30s and lows around 20. We will continue to see little day to day variation. 

It's possible Vermont could see a decent snow, rain or mixed storm around Tuesday, but that's extremely iffy. Forecast models disagree hugely on this at the moment.  So as usual, stay tuned. 

This December's Weather Will Be A Real Wild Card. Here's Why

NOAA on November 30 issued this long range
forecast covering December 8 to 14. It featured
enhanced chances of colder than normal weather
over most of the United States. 

 I've noticed some very conflicting longer range weather forecasts for December, at least for everything after the middle of the upcoming week. 

That's because there are at least two big forces battling it out. Whichever one wins will greatly affect whether its warm, or cold, or snowy or rainy or dry.

The big chatter in social media circles among weather geeks is the Greenland Block gradually setting up. I mentioned this one the other day in a previous post. 

A Greenland block is when massive high pressure sets up over and near Greenland.  When this happens, the jet stream over North America gets squashed further south than it usually is. 

When the jet stream is south like that, it tends to get colder in much of the United States. The jet stream, suppressed to the south, opens the door to frigid Canadian air that can flow southward. Sometimes, the cold air interacts with storm systems passing through, and you can - but not always - get big snowstorms in the eastern United States.

Here in Vermont, it often, but again not always gets cold when there's a Greenland block.  Big snowstorms usually go too far to our east to affect us much, but not always. 

However, with all this in mind, there's another factor in play here big time, at least for now. 

Fighting the Greenland block is a ridge of warm high pressure setting up over and near the southeastern United States. Depending upon how strong this ridge gets, it can make it on the warm side in Vermont. 

Nobody is quite sure if the Greenland block or the southeastern ridge will dominate. For either, it could be win, lose or draw.  Or one can dominate, then the other. 

You see the problem. Long range forecasts are always dicey. With this battle going on, any forecast beyond a few days is very suspect. Take those predictions with a grain of salt. 

To illustrate the forecast iffiness, the first image in this post is the long range 8 to 14 day forecast for the United States that was issued on November 30.  It covers the period from December 8 to 14.  It kind of shows the Greenland block winning, with cold air favored over most of the nation. You can see hints of the southeastern ridge with warm air forecast near the Gulf of Mexico and Florida.

This forecast also anticipated below normal precipitation over New England, as the Greenland block would smush storms too far to our south to affect us that much. 

NOAA yesterday issued this 6 to 10 day forecast that
covers pretty much the same period as the forecast
map above. Now it features mostly warmer than
average temperatures over the eastern half of the nation.
Forecasts this month beyond a few days will be
especially iffy due to questions about how two
large weather systems play with each other. 

Yesterday, the six to 10 outlook was issued, which will cover the period from December 9 to 13.  That's almost the same time period from the earlier, longer range forecast I just mentioned above.

Instead of cold weather dominating the nation, the chill is relegated to the western third of the nation. Warm air would bathe most of the eastern United States. The southeastern warm ridge for the win!  

This updated forecast issued yesterday also favors wetter than normal weather over New England. Because we'd be close to the battle line between cold and warm, so that's where storms would go.

The other big questions are how long will the Greenland block last and how strong will it remain while it's there?  Same issues for the warm southeastern ridge.  Does it move away? Weaken over time? Strengthen? Who knows?

Between the two forecasts I described above, I'd give the edge to the one that was issued yesterday.  Only because it's more recent and covers a time period not as far off in the future as the prediction issued on November 30.

Even so, don't count on either forecast being correct.  I always tell people don't count on forecasts for more than four or five days beyond the current date. That's really, especially true for the rest of this month.  

Whatever happens, we'll probably see an active weather pattern through most of December. That suggests fairly frequent storms, but we don't know whether they will be strong or weak.  We don't know if they will be snow, rain or a mix.  And we don't know how many of these storms will come close enough to Vermont to make a big difference in our weather. 

In the short term, the pattern favors warmth.  A couple of modest storms will come through midweek. They'll produce mostly rain, with maybe just a little ice in the coldest pockets. 

If you want to know what will happen after about Thursday, you're on your own.  I'll let you know later in the week.