Monday, March 3, 2014

March 16-20 Potentially Significant Storm System

I'm watching for a potentially strong storm system in the March 16-20 timeframe.

The image above shows 500mb height anomalies over the North Pacific, valid on the morning of March 10. If we look at Japan, we see deep purples over the island nation, indicating the presence of anomalously low heights. This tells us there is a storm system afoot; the purples indicate the storm is of the stronger variety when compared to other systems. How can weather in Japan relate to weather here in the US? If we use the 6-10 day correlation, explained by Joe Renken, which states that a storm system in Japan can affect the United States 6-10 days later, we find that this storm system would be expected to create a storm in the United States during a March 16-20 time period. Even more interesting is how models bring two strong storm systems through Japan during this March 10 time period, meaning we could be in for a significantly stormier and cooler than normal mid to late March.

We can actually figure out the projected track for this storm as well, by using a tool titled the Lezak Recurring Cycle. The Lezak Recurring Cycle, or LRC, is a tool developed by meteorologist Gary Lezak that, in essence, can enable forecasters to predict the overall weather pattern months in advance. The gist of the LRC involves a cycling weather pattern that develops in October and November of each year; no pattern is the same from year to year. Around mid November, the LRC begins to repeat, meaning we start to see a similar weather pattern in mid November that we saw in early October. This means that the cycling pattern has begun, and it will continue to cycle on a regular, unchanging 40-60 day interval for the next ~10 months before it dissipates over the following summer. Since this season's cycle has been holding at around 57 days, we can go back from the March 12-17 period and arrive around the  January 16-20 time period. The image above shows observed 500mb height anomalies from the January 16-20 timeframe, where North America is located on the upper right portion of the image. If we look at what the atmosphere was like in that mid-January period, we find a defined northwest flow scenario, with strong ridging over the West Coast leading to deep negative height anomalies across the East Coast. The jet stream below for the same January 16-20 period reflects this northwest flow.

If you're a weather buff, you probably know where I'm going with this. If not, pay close attention. The northwest flow scenario involves the jet stream shooting north into Alaska due to that massive ridge of high pressure, before plummeting south into the Southeast and then north again across the East Coast. In the January 16-20 period, we also saw support from the subtropical jet stream, which helped to enhance wind speeds and phase the two jet streams. If a storm were to come along during this northwest flow scenario, it would most likely become enveloped in the jet stream, and become a coastal storm. To sum up, if the LRC cycles again to be even somewhat close to what we saw in mid-January, it's possible this ends up being an East Coast storm. However, because we're so far out, we don't even know if this storm will even happen. This is just a heads-up for a part of what could be a very stormy mid-March.

Also see: March 12-16 Potentially Significant Storm System