Good morning Weather2020 fans,
Spring is just two weeks away, and yet the pattern continues to be a cold one. Warmer days are around the corner right? Well, yes in some respects, but don’t expect a warm beginning to spring. In fact, Weather2020 is forecasting a cold first half of spring as the same pattern cycles into April. There is even a good chance of a late March and even an April outbreak of Arctic air. By December we updated this map saying that this would be the dominant pattern for the winter:
Arctic Oscillation (AO) & The North Atlantic Oscillation (NAO)
When the AO and NAO index go higher into positive territory, like it did during the 2011-2012 warm winter, Arctic air is likely going to be held north across Canada with a farther north jet stream across North America. There was a strongly positive AO two years ago and the United States ended up having a very mild winter. Three of the previous four winters had strongly negative AO indexes, and, those three winters (2009-2010, 2010-2011, and 2012-2013) were cold and very snowy across the United States even though the weather patterns were quite different.
If the AO and NAO go negative, then Arctic air is much more likely to plunge south into the United States. The jet stream would be forced farther south and become energized. This stronger jet stream can lead to major winter storm systems. Again, if the AO and NAO do go deeply into the negative, the jet stream would likely shift farther south and lead to a more southern track of winter storm systems during this phase.
When Weather 2020 first issued the winter forecast, the indexes were trending into the positive and it was one of the factors we were paying attention to, but at the same time the weather pattern was setting up into a very cold one for this winter, and now it is continuing as we move into spring. We have come up with a hypothesis that it is actually the LRC that is helping create the positive phases of the AO and NAO this season. The dominant storm track in this cycling pattern has helped force the jet stream to dive into the upper midwest and Great Lakes. The Polar Vortex has been carved out several times and there has been a mean trough that then exits into the north Atlantic which has prevented any Greenland blocking upper high, and as a result we the AO and NAO have not been able to go strongly into negative territory. This same pattern has allowed the conditions for the cold, and not just cold, but record breaking, record shattering cold at times. Just this week many cities had their coldest March high temperature ever recorded. This same pattern has produced ridging in the eastern Pacific allowing for the generation of Arctic air masses and the higher surface pressures over western Canada. The LRC, the cycling weather pattern, is actually creating these unique conditions, is what we hypothesize. We introduced this pattern in December when we updated the winter forecast. It was still in the it’s early stages, and now three months later the pattern will not suddenly change. The weather pattern is cycling according to the LRC and we are now about to experience the spring version.
The AO has dipped into the negative during the past few months, but the NAO has been forced positive in response to the cycling weather pattern and the jet stream energy shooting across the North Atlantic Ocean.
The Climate Prediction Center keeps track of these indexes. If you would have made the winter forecast just based on what you see above in these indexes, then it would have been very difficult to predict the cold winter that was just experienced. The evidence was there in what we know about the LRC and the cycling weather pattern and it is something to consider in next winter’s forecast and in the winters to come.
So, where do we go from here? Weather 2020 has been making accurate long range forecasts that we have been documenting and we are posting a few on the business tab on this site, which is just now being updated. The Super Bowl weather forecast was spot on and made about a month before the Super Bowl. The part of the weather pattern that produced that one big warm-up timed perfectly for the Super Bowl will be returning later this month into April. That same part of the weather pattern also produced another major Arctic outbreak and this will also likely be happening even as we move into late March and April. This will likely have significant weather impacts on many cities as the Major League Baseball season gets under way. expect a stormy and cold first two weeks of baseball season at many locations.
There will be ups and downs as the ride into spring has started. Spring and winter will be battling it out with winter winning many of the early battles, and spring winning most of the later battles. For now, let’s enjoy the ride and Weather2020 will keep you updated as we move through the transitioning seasons.
You can download the Weather2020 app for iOS7 devices and get the 12 weeks of weather forecasts. We will be working on a droid version of the app sometime this year and we will keep you updated.