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| A depiction of the strong heat ridge in the 'eastern United States now is causing near record temperatures. |
It was an incredible 95 degrees - so hot for southeastern South Dakota, with winds gusting to 38 mph.
It's cooler behind a cold front in Yankton today, but the heat stays on from Iowa and Minnesota all the way to the East Coast.
And it's going to stay summer like in parts of the Northeast and southeastern Canada for the next several days.
Blame it all on another one of those huge mega ridges. What I mean by mega ridge is an immense northward bulge in the jet stream that brings lots of very warm air north and lets it sit there.
These ridges don't usually last long, but sometimes, they stall, and the heat builds to very high, unseasonable levels and lasts a long time.
These things happen from time to time, but there is evidence in recent years, that these stalled mega ridges are happening more often and lasting longer. Could be a sign of global warming. More on that in a minute.
In this case, the ridge started forming over southeastern Canada around September 10 or so. That created the start of a spell of remarkable warm weather for this time of year across southern Quebec and Ontario, and northern New England, including Vermont.
This big blob of warm air has expanded westward into the Great Lakes and upper Mississippi Valley, eastward into the northwestern Atlantic, and now southward down the United States East Coast.
The strength of the ridge is peaking, too. That explains the tempeatures in the mid-90s in Yankton and places like Chicago on Friday.
In northern New England, temperatures will really get into record territory today through about Tuesday.
Burlington even has a slight chance of reaching it's latest 90 degree reading on record. As of today, the latest in September it has reached 90 in Burlington since they started keeping track of such things was on September 16, 1939. There is a chance temperatures could reach 90 degrees Sunday or Monday.
Record highs are sure to fall. The records highs for Sunday and Monday are 84 and 85 degrees, respectively. The official National Weather Service forecast highs for both days is 88 degrees.
This odd as this heat ridge feels for this time of year, it has protected us Vermonters from some potential trouble. First, it deflected the remnants of Hurricane Irma eastward, so we barely got a few showers out of that, instead of torrential downpours.
Then, the ridge blocked the northward progress of Hurricane Jose, which ended up stalling southeast of New England and giving Cape Cod and the islands a few days of gusty winds, rain and coastal erosion. Now the ridge seems like it also wants to block the northward progress of Hurricane Maria, which appears as it it will stay off the East Coast, and then head northeastward out into the North Atlantic.
These huge mega-heat ridges can cause real damage and even death if they hit at the wrong time of year, however. The notorious one in eastern North America in March, 2012 brought temperatures into the 80s for a week as far north as Quebec.
When the inevitable normal late winter/early spring weather came back in late March and early April, the frost killed billions of dollars worth of fruit crops on trees that bloomed to soon.
In the summer of 2003, a summer long heat ridge in western and central Europe brought temperatures to unprecedented levels for weeks on end, resulting in the heat-related deaths of possibly 35,000 people.
A heat ridge in 2010 caused an unprecedented heat wave that lasted nearly a month in Russia. About 10,000 people died of heat related illnesses and from pollution caused by an outbreak of wildfires caused by the hot, dry weather.
So as you can see, mega heat ridges don't always smile down on us benignly, like the current one is in Vermont and elsewhere in North America.
Some of these heat ridges are just natural variability - the weather has always gone off the rails from time to time.
However, there seems to be growing scientific evidence that climate change might be slowing down and bending the jet stream more and more. That makes these mega ridges more likely, and more likely to stick around for awhile longer than usual.
It seems like a decreasing temperature contrast between the Arctic and the tropics might be to blame. (The Arctic is warming up much faster than the tropics, which explains the declining contrast.)
So, enjoy the gorgeous, long stretch of weather Vermont and other areas have had are are having lately, but as aways, there's always a black lining around the silver cloud, to screw up a cliche.
Meanwhile, our current mega heat ridge will break down toward the end of the week, and we will return to our regularly scheduled cool autumn weather.
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