I've been watching for weeks now as the jet stream breaks down, that "river of wind" that divides the cold air to the north from the warm air to the south (in the northern hemisphere anyway). If you don't know what a jet stream is, see the Wikipedia for some help before reading further.
Several weeks ago, I started noticing some really significant troughs developing in the jet stream. I mean, it's normal, especially this time of year, to see significant troughs suddenly develop along the eastern slopes of the Rocky Mountains chain, but these were sudden and explosive. Being in Albuquerque, I had a front seat to the ensuing high winds and frigid temperatures associated with major troughs. Perhaps that's why I noticed the pattern emerging early on.
When a trough is developing in one part of the stream, to both the east and west of it the stream will curve opposite, forming ridges. Technically, the curvature of the jet stream, the troughs and ridges, are caused by Rossby Waves. That's, I'm sure, the case here, but something truly significant was occurring. The troughs were developing so deep and so rapidly that it seemed the ridge to the east wasn't able to develop fast enough and the whole system would appear to collapse. The jet stream would completely disconnect, as a ridge would move northward, heading for northern Canada, leaving the main jet stream behind. The trough would also appear to get cut-off and drift eastward as the jet stream flattened and reconnected in a simple west to east flow.
Odd enough on its own to see this happen multiple times over a couple weeks, but then a new pattern began to emerge. The troughs began digging even deeper as they developed, digging down as far as northern Mexico in a very narrow slice that seemed to defy logic. The troughs appeared to become more stable, also, as they held together long enough to travel all the way to the east coast, bringing 30s and 40s into central Florida. The major disconnect still occurred, but now off the east coast of the US and Canada. The ridge that developed would move backwards, westerly, into northern Canada and toward Hudson Bay as a new southern branch of the jet stream would form in the tropical Atlantic. At first, this southern branch would cut northward toward Britain, before regaining a semblance of normalcy over continental Europe.
About 3 weeks ago, strange storms began appearing in the GFS model forecast just off the east coast of the US, over the Gulf Stream. These storms would appear to develop before an advancing cold front as a trough made its way toward the east coast. The storm would begin as a small area of thunderstorms with a central low pressure area, much like you'd expect a subtropical cyclone to begin, but suddenly "bomb out" over 12-18 hours, becoming what appeared to be major baroclinic lows with high winds and heavy rainfall, on the *south side* of the jet stream.
The GFS would forecast the jet stream to detach, with a ridge moving northward over Greenland and drifting east toward Norway and a trough developing in the middle of the Atlantic digging southward to the coast of Africa.
These strange storms never materialized the way forecasted, but the jet stream pattern that emerged was right on the money. What followed was extreme cold for Europe as the jet stream dug through northern Africa and into the western Mediterranean. An article today on the effects of this extreme divergence of the normal jet stream pattern details temps dipping to 5*F in Poland, -4*F in Scotland and -11* in Moscow.
In the past week, another change to this pattern has emerged as the jet stream is now digging south past Hawaii, ridging over the western US, then digging a subtle trough toward Florida before B-lining straight across the Atlantic to western Africa. Check out these screenshots (24 hour intervals) from the GFS 250mb wind speed forecast from Stormsurf.
You'll note that the 00 "hindsight" shows the jet stream trough just east of Hawaii digging south toward the equator. A ridge cuts through northern California and east to the Great Lakes before another trough digs south in two branches, one reaching toward the Yucatan. The jet stream then follows a basically straight line heading through the Florida Straights to western Africa. You'll also notice the anomalous circle of high winds over Greenland - the weird cut-off ridge that keeps developing and drifts northward, then eastward toward Norway.
In the 24 hour forecast, you'll note a ridge beginning to migrate east into northern Canada as well as a sudden dig develop in the jet stream over the northern Caribbean, just north of Cuba and Haiti. There's also a shift of the pattern over Europe, with a ridge becoming defined from western Africa into Spain and a well-defined trough around Italy.
For the 48 hour forecast, the ridge developing toward northern Canada appears to cut-off from the main jet stream as a new "southern branch" appears to be developing over the Pacific, flowing west to east well south of Hawaii. In fact, you can almost make out a VERY southern branch of the jet stream developing and dipping south of the equator, off the coast of South America and cutting through Central America before reconnecting with the main jet stream in the Caribbean. By 72 hours, this pattern is more pronounced. A very zonal flow has developed across the southern US and the ridge in Canada has been completely cut off. You'll note that the cut-off ridge over Greenland reconnects with the main jet stream, as well, while a developing ridge over Europe becomes more pronounced.
By the 96 hour and 120 hour forecasts, however, a very pronounced trough is seen over the east coast of the US, the strange southern branch crossing the Pacific is bridging just north of Hawaii, and the now reconnected ridge over Greenland is migrating toward northern Europe. An area of high winds appears "stuck" off the coast of Florida as this massive ridge fully reconnects with the main jet stream, and by hour 144, the forecast shows that ridge beginning to disconnect again while a central branch of the jet stream forms a trough just off the coast of Africa and a southern branch develops digging south toward the equator over the Atlantic. The wind velocities off the east coast of Florida are at a peak, and at hour 168, the forecast shows the jet stream completely breaking down again with a major trough moving into western Africa.
Now, I know that's fairly boring to many, but what I'm seeing is a major issue developing as the winter season sets in for the northern hemisphere. Could this be caused by a Gulf Stream problem? It would sound good if we weren't seeing such a strange breakdown of normal jet stream patterns over the Pacific as well. Could this be caused by the strong La Nina in the Pacific? That would sound good if we saw a return to normal as the jet stream approached Europe. This appears to be a breakdown of the atmospheric dynamics themselves, as if something actually "broke" in the upper atmosphere and the traditional, rather stable division of hot and cold air along a zonal boundary is becoming more chaotic as a result.
This article from The Times in the UK details the recently confirmed discovery that the Gulf Stream and North Atlantic Drift are truly in danger of shutting down due to increases in melt water in the North Atlantic. Over the last 12 years, a 30% decrease in the cold water return flow has been measured. This, of course, could lead to a total breakdown of the thermohaline circulation. Remember "The Day After Tomorrow"? Yeah, that's what we're talking about here.
Earlier this fall, an article from the Russian Times warned about the coldest winter in 1,000 years for Europe. The article did claim the speed of the Gulf Stream has halved in the last couple of years, which isn't *entirely* true. From what I've gleaned from reading countless articles over the past months, it's being debated within scientific communities as to how much "slow down" has actually occurred in the Gulf Stream itself and, this even more hotly debated, how much of an effect it might have on the climate.
Needless to say, it's starting off as though they were right on the money with their prediction about it being the coldest in 1,000 years.
The problem is that it's not just the Atlantic, not just Europe, that's being affected here. As I said, the strange breakdown of the jet stream over the Pacific can't be explained by the Gulf Stream weakening on its own. What else is happening here? What are we missing?
And for a quick laugh, this article from The Telegraph actually blames "global warming" for a mysterious "blocking high" that has caused the jet stream to tweak out. I have to call BS as, not only is the same pattern developing over the Pacific but this "blocking high" the professor refers to in the article does not explain the troughs in the southern branch of the jet stream reaching nearly to the equator at times. That article is nothing but a puff-piece meant to put the minds of the masses at ease.