Jet Stream Meanderings Responsible For Weird Weather, Areas Of Record Heat

A quick morning downpour today precluded breakfast out
on the deck, but gave the plants a nice watering. 

The weird weather pattern since yesterday has pretty much worked out as forecast.  Which is an accomplishment.   When the weather is odd, the chances that a forecast will be dead wrong go way up. Not on this case, so far. 

Batches of showers and thunderstorms have been heading due south from Canada, mostly moving through New York and Pennsylvania, and for the most part bypassing Vermont.

One patch of showers did wander into Vermont this morning, dropping a quick quarter to third of an inch of rain to some areas, just to water the gardens a bit. w 

The conga line of storms and showers will renew themselves later today and tonight, again proceeding south through New York and Pennsylvania.  These repeated rounds of heavy rains could lead to local flooding in both states.  Vermont looks safe from that, anyway, but it does remain cool for the season. It will stay on the cool side until Friday. 

Meanwhile, western and central Europe is recovering from the opposite problem - a record breaking heatwave. Some cities reported all-time record highs, and others set records for the entire month of June. 

Examples cited by the Washington Post include:

The French cities of Biarritz (109.2 degrees), Rochefort Saint-Aignan (105.1 degrees) and Tarbes (102.6 degrees) set all time record highs over the weekend. Roughly 200 cities in France established new record highs for the month of June.

In Spains's Basque area, San Sebastian reached 111 degrees, breaking its all time record high by a wide margin.  

The Czech Republic established a new record high for the month of June with a Sunday temperature of 102.2 degrees in Husinec.  

Poland set a new June record with a high of 100.9 degrees in Slubice. Switzerland also established a new June record high of 98.4 degrees in Beznau.  

Meanwhile, the record heat also grinds on in the Midwest and South in the United States. Minneapolis hit 101 degrees on Monday, a record high and their first 100 degree temperature since 2018. record highs of near 100 degrees are in the forecast for southern cities like Atlanta.

The heat in Europe and the middle of the United States, and the cool, weird weather here are all related. 

The jet stream, which guides weather systems generally west to east across the Northern Hemisphere  normally has lots of bumps to the north and dips to the south. It's usually hot under the northward bulges and cooler under the dips. 

In the summer, the dips and bulges in the jet stream aren't as pronounced and big as they are in the winter. So, more often than not, the hot areas are only kind of hot and the cool areas are just kind of cool.

But the jet stream in the past few days has featured huge northward bulges and big plunges to the south, which is odd for this time of year. So, the extremes have been pretty extreme. On top of that, the bulges and dips haven't been moving around much so everybody gets stuck under roughly the same weather day to day. 

That's why there's a flood threat in New York and Pennsylvania. Those storms from Canada keep going over the same spots. 

Climate change is a factor, too.  The heat under those northward bulges in the jet stream in central North America and Europe is given an added boost by global temperatures that have risen in the past several decades.  Temperatures that would have just missed hitting a record high, say, in the 1970s are now smashing records.

These bigger than normal summertime bulges and dips in the jet stream might also be related to climate change. The science is still uncertain with this. But some experts think that because the Arctic is warming faster than the mid-latitudes, there's less of a north to south temperature contrast.

The jet stream thrives on a big contrast and in those conditions behaves itself. The theory goes that the relative lack of a contrast between the North Pole and down where we live is making the jet stream meander more than it would otherwise. 

That meandering jet stream gives us those big bulges northward where they had the heat waves, and those big plunges south, one of which has given us the past week's worth of cool, odd and unsettled weather. 

The jet stream looks like it will untangle itself a bit in the coming days,  hopefully resulting in more or less average summer weather for most of us. 

"Omega Block" To Create Some Big U.S. Weather Contrasts By The Weekend

The weather pattern expected to shape up this 
weekend and early next week over the U.S. A big
ridge of high pressure in the middle of the nation
will keep that area very hot, while the Northwest and
Northeast will be unusually cool. 

 The heat wave grinds on today in the South and parts of the Midwest, with temperatures today up to 100 degrees expected as far north as Yankton, South Dakota and as far north as Chicago tomorrow and Wednesday.  

The heat will grind on in the South especially this week, but we'll remain protected from the scorching weather by a northwest wind flow.  

Over the weekend, the weather pattern over the United States will take on a symmetrical form, with two strong upper level low pressure areas over the northwest and northeast corners of the nation, and a strong, wicket hot dome of high pressure smack dab in the middle. 

It's called an Omega block since the jet stream pattern resembles that of Omega. 

This all means that the Pacific Northwest and northern Rockies, and New England will be unseasonably cool while temperatures rocket past 100 degrees in the Plains again late this weekend and early next week.

As this weather pattern gradually takes shape, it's already pretty chilly in the northwest. We even see a winter storm warning of all things in effect for high elevations in and  near Glacier National Park in Montana.

Several inches of snow are forecast above 5,000 feet in elevation, and up to two feet above 7,000 feet. Not a great time to hike through that national park!

I think some highest elevations in the Pacific Northwest and northern Rockies might have some snow issues well into the weekend. 

Eventually, hiking will become no picnic here in Vermont, either. The upcoming weekend cool spell won't feature snow, except perhaps atop Mount Washington. But after some pleasant days through Wednesday and a rain and storm risk Thursday and Friday, things do get chilly, especially in the mountains. 

The weather pattern, with the jet stream 
configuration as described in image above
is called an Omega block because it 
resembles the symbol from the
Greek alphabet 

The weekend if five days away, so the forecast will need to be fine-tuned. But at this point, expect some very nippy weather, and some cold showers, especially on the Green Mountain summits. I picture temperatures near 40, gusty winds causing sub-freezing wind chills and those light, but cold showers by Sunday up there.

Down here in the valleys were most of us live, it won't be that dramatic, but I expect we'll have a fairly long spell of not beach weather. We'll revert back to what is normal May weather, with highs in the 60s and lows in the 40s to around 50 during that spell of chill.

Omega blocks are usually slow to break down, so once the cooler air hits us by Saturday, it could last quite awhile, maybe even a week or more. For what it's worth, NOAA's Climate Prediction Center keeps us cooler than normal pretty much to the end of the month. 

That doesn't mean every day from this weekend onward to the end of the month will be cool.  It just means that chances are that most days will be on the cool side.