Moving ahead, Figure 37 (below) depicts recent temperatures at the 1-millibar level of the atmosphere, right at the top of the stratosphere. At the 1-millibar level, it isn’t just the level of oxygen that’s remarkably low. The point of examining recent trends isn’t to try and anticipate how the stratosphere will act during the winter – that’s dependent on the number of stratospheric warming events during the season (a number that can be zero). That’s not to say we should completely disregard the QBO, however: as I said earlier, wasting time is not something I go out of my way to do. 0.30. The majority of the country exhibits a slight positive correlation of temperatures with the QBO, save for slight negative correlations in southern Florida and the Pacific Northwest. Given this admittedly-rough description, it is no surprise then that Figure 34 shows a negative correlation between geopotential heights at the 50-millibar level and the QBO.

This means that a positive QBO should cause geopotential heights over the Arctic Circle to be deeper (a.k.a. It’s worth briefly explaining what the Arctic Oscillation is before delving into the correlation graphic. The Arctic Oscillation is tracked by observing 1000-millibar geopotential height anomalies over the far upper latitudes of the Northern Hemisphere, above 20 degrees North to be specific. When the AO is said to be negative (-AO), geopotential height anomalies over the upper latitudes are higher than normal. The AO has two phases: a positive phase, and a negative phase. QBO) while negative zonal winds (-QBO) are in white. But let’s suppose the QBO weakens faster than we expect, and we arrive in the winter season with a QBO stuck at nearly zero. In spite of that, in my point of view the best way of saving money and time is to use all season tires when it is hot or wet. Cancun is also susceptible to hurricanes, so if you are visiting during hurricane season you will likely have more rain as well.

As hoped, the QBO does have correlation values exceeding 0.30 (in absolute terms), seen over the upper latitudes of the Northern Hemisphere at somewhere between -0.30 and -0.40. Now, think about what happens if the winds in the stratosphere over the Equator strengthen, as happens in a positive QBO. Given that we expect a positive AMO this winter, the implication here is that geopotential height anomalies should also lean higher as a result, indicating a weaker stratospheric polar vortex. Indeed, barring any unexpected event that impacts temperatures, recently-observed temperatures in the lower stratosphere don’t suggest a particularly stronger or weaker polar vortex to begin the winter months. AO), geopotential height anomalies over the upper latitudes are lower than normal. Going by that premise, it doesn’t seem immediately apparent that the stratosphere will be substantially colder than normal to begin winter, which would be a boon to the strength of the polar vortex. This appears likely to strengthen the stratospheric polar vortex, increasing the chances for a broadly warmer than normal winter across the country. The Quasi-Biennial Oscillation is currently in its positive phase, and is expected to remain in its positive phase – albeit to a weaker magnitude – moving into the winter.

As the graphic also shows, however, this did not condemn the upper stratosphere to far-below-normal temperatures throughout the winter. This means the tropospheric polar vortex is stronger than normal, and this stronger vortex “locks up” the colder air at the upper latitudes, keeping it from flowing south. Taking the graphic as seen, a positive QBO would appear to most strongly encourage above-normal precipitation near the Front Range of the Rockies, in the Upper Midwest, and in western New York. While the correlations between precipitation and the QBO are more diverse across the country, they are only diverse in the sign of the correlation, and not the magnitude. Much like the temperature correlations, however, this would only be the case if those correlations were stronger. The idea of this analysis is to see if the AMO, despite being based out of ocean temperature anomalies, also affects conditions in the stratosphere. Indeed, in the figure, we see a wide swath of gray has propagated down through the stratosphere as of late, signaling strengthened westerlies and therefore a positive QBO.

The next relationship I’d like to examine involves another correlation, but also with a twist like we used in the QBO portion. While viewing the chart, it quickly becomes evident that the QBO does not impose as strong an effect on conditions at the surface as oscillations like ENSO and the PDO do. We can confirm this by viewing Figure 31 below, which shows a historical time series of zonal winds. It is then time for a general refresh! A question you might be posing is ‘How can some strong winds at the Equator make the stratospheric polar vortex stronger? The fact that it is virtually bereft of fresh water resources and rain fall make it so; there is only an average of 150 mm of snowfall, which makes it a cold desert. Also make sure that the fluid mixture is not filled too much with water and is instead more of a 50-50 mixture between water and antifreeze.