Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
Nice graphic here. And the answer is NO. Wish people would stop trying to find reasons or blames for something!! It's a puzzle people. A 100 or 1000 piece puzzle. One thing is not a cause for another. It can be a factor, but I hate when only 1 or 2 is mentioned.
"The color shadings in the purples to pinks show the extremely cold air mass up near the North Pole. At times, these chunks of cold air will get pulled south into the US when the jet stream buckles".
The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles. It ALWAYS exists near the poles, but weakens in summer and strengthens in winter. The term "vortex" refers to the counter-clockwise flow of air that helps keep the colder air near the Poles. Many times during winter in the northern hemisphere, the polar vortex will expand, sending cold air southward with the jet stream (see graphic above). This occurs fairly regularly during wintertime and is often associated with large outbreaks of Arctic air in the United States. The one that occurred January 2014 is similar to many other cold outbreaks that have occurred in the past, including several notable colder outbreaks in 1977, 1982, 1985 and 1989.
There are several things the polar vortex is NOT. Polar vortexes are not something new. The term “polar vortex” has only recently been popularized, bringing attention to a weather feature that has always been present. It is also not a feature that exists at the Earth’s surface. Weather forecasters examine the polar vortex by looking at conditions tens of thousands of feet up in the atmosphere; however, when we feel extremely cold air from the Arctic regions at Earth’s surface, it is sometimes associated with the polar vortex. This is not confined to the United States. Portions of Europe and Asia also experience cold surges connected to the polar vortex. By itself, the only danger to humans is the magnitude of how cold temperatures will get when the polar vortex expands, sending Arctic air southward into areas that are not typically that cold.
In short, there is no cause to be alarmed when you hear about the polar vortex, but you should be prepared for colder temperatures. Check the forecast for your area on weather.gov to ensure you are dressed appropriately. It is also a good idea to check the items in your home and car emergency kits at the beginning of each winter season to ensure you are prepared for any type of hazardous winter weather.
Many mets have been expecting this especially when you consider solar considerations and pattern mechanisms. This is going to get very interesting!!!
I haven't read this whole article yet but a SSW (Sudden Stratospheric Warming) event "SPLITS" the Polar Vortex and brings cold and snowier times to Mid Latitudes.
Also, what you wont hear a lot about is something I been noticing. When a PV "strengthens" to become a strong PV in the Fall, then splits off, that's when you get crazy times. If a PV was weak, then split off, then you get weak pieces. Make sense?
Leaving the introduction here in case link gets broken in future.
Quote:
Sudden stratospheric warmings (SSWs) are the most prominent phenomena taking place in the wintertime polar stratosphere, representing the dynamical linkage between troposphere and stratosphere. During a major SSW event the zonal-mean zonal winds at 10 hPa and 60∘ N reverse from westerlies to easterlies, and the stratospheric temperature rises by several tens of kelvin over the course of a few days (Butler et al., 2015). SSWs have been shown to be related to the enhancement of tropospheric forced planetary wave packets that propagate upward into the stratosphere and interact with the mean flow (Charney and Drazin, 1961; Matsuno, 1971; McIntyre, 1982; Limpasuvan et al., 2004). These upward-propagating planetary waves amplify with height, approaching the critical level where they irreversibly break and deposit westward angular momentum (quantified as a convergence of the Eliassen–Palm flux), which leads to the deceleration and breaking down of the polar night jet (Polvani and Saravanan, 2000). Stratospheric circulation anomalies, in turn, can influence the troposphere (Kuroda and Kodera, 1999; Baldwin and Dunkerton, 1999). In particular, they can lead to the development of a negative phase of the Northern Annular Mode (NAM), shifting tropospheric storm tracks southward and making northern and central Europe prone to cold Arctic air masses (Thompson et al., 2002). SSWs occur approximately once every second winter; however, there is no regularity: during the 1990s SSWs occurred only twice, while in the 2000s they took place almost every winter. During the last decade the events occurred in 2013, 2018 and 2019. The 2013 and 2018 events were followed by cold and snowy weather in Europe (Nath et al., 2016; Karpechko et al., 2018). Since the stratosphere tends to be more predictable than the troposphere, SSWs are considered to be a potential source of extended-range predictability (Christiansen, 2005; Sigmond et al., 2013; Scaife et al., 2016; Karpechko, 2015; Domeisen et al., 2019; Kautz et al., 2019). It is therefore important to understand factors controlling the variability of the polar vortex and SSW generation
For those that want simple English.... (I think we mentioned it in this thread already)
Basically when the Stratosphere warms rapidly it can disrupt the polar vortex with Arctic air masses becoming dislodged and affecting parts of the Northern Hemisphere. A weak / split Polar Vortex is better at bringing cold/snowy patterns into the US or Europe than a Polar Vortex that stays strong and does not split.
As I always say though.... Weather & Climate is one big 1000 piece puzzle. So many pieces involved to get the big picture.
10hpa = 100,000 feet. Typically in summer time we see Easterly Winds up there.
A reversal of wind = a quick breakdown of the Polar Vortex.
When the reversal of winds happens in late winter or spring it means a nail in the coffin for winter weather at the mid latitudes. When it happens in Mid Winter it could mean interesting snow and cold at Mid Latitudes.
The reversal and sudden warming in the Stratosphere means the Polar Vortex splits apart. That's what you want if you want deep cold and snow at the mid latitudes at the surface. It depends where that split goes though. Could be Europe, Asia, NA, ect.
A Polar Vortex split may sound weak but each piece carries super cold air. Problem with a split Vortex is the pieces can total dissolve and disappear.
A strong Polar Vortex means its hard to get a severe winter at mid latitudes since that Vortex is bottled up in the Northern Lats
Look what the forecast is next month..... (Red Line). I think winter makes a comeback after Mid January. We'll see. As I always say, the weather and climate is a big puzzle, so many pieces involved.
There have been a number of recent studies looking at the surface temperature following large PV disruptions. In Figure iii, I show the NH surface temperature anomalies for the period following an MMW from four different analysis....
Figure iii. Composite of surface temperature analysis follwoing a major mid winter warming from four different anlyses. The different analyses are explained in the text.
All the analysis are fairly consistent with each other and can broadly be described as the surface temperature anomaly pattern in the weeks following an MMW is consistent with a canonical negative AO/NAO surface temperature anomaly pattern with relatively cold temperatures across Northern Asia, Northern Europe and the Eastern US with relatively warm temperatures across Southern Asia, the Middle East, North Africa and Northeastern Canada.
This pattern is sometimes called the quadrupole pattern. The three most robust regions of temperature anomalies are the cold temperatures in Siberia and the warm temperatures in Northeastern Canada and the Middle East.
Across the US the exact region of cold temperatures does vary across the different analyses and can be in the Eastern US, Western US and even sometimes include Western and Central Canada.
I show in Figure iv, a plot that I have shown before in the blog. It is the weekly surface temperature anomaly plot following a significant PV disruption using cluster analysis in Kretschmer et al. (2018a). During the week of the PV disruption the most robust negative temperature departures are across Northern Asia and Northern Europe. There are also negative temperature departures in the Western US in weeks one and two but by week three, the largest negative temperature departures stretch from Central Canada and into the Eastern US. Throughout the three weeks the North American Arctic is warm. Based on this analysis, even if it is not cold initially in the Eastern US following an SSW/MMW, the odds for cold weather do increase with time.
In addition, there are two upcoming synoptic events that I believe are consistent with an impending PV disruption. A warm, wet and windy storm here in the Eastern US. This event reminds me of December 2003 and January 2006, both ahead of an MMW. The second is an anomalous cold surge in East Asia. One of the most famous was in January 2008 and more recently there was one in January 2018.
Quote:
One question is - will the upcoming PV disruption be a displacement (one PV center that is displaced from the North Pole) or a split (two distinct daughter vortices). The GFS can’t seem to make up its mind while the ECMWF seems to be more solidly in the split camp. Every significant PV disruption since 2009 has been a split and that for me “the trend is your fiend” is a compelling reason to expect the same in January.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
