Wednesday, March 12, 2014

March 15-19 Potentially Significant Storm System

I'm eyeing the March 15-19 period for what could be a significant storm system.

The image above shows ECMWF 500mb height anomalies from a previous forecast, valid on March 9th, which was two days ago. While this forecast is not current, and the forecast image above is not current either, we did see a big storm move through Japan on March 9th. There is a rule, well explained by Joe Renken, that states a weather phenomenon in East Asia will be reciprocated in the United States 6-10 days later. This means that if there is a storm system in Japan on a certain day, we can expect a storm in the US 6-10 days after that. The same goes for high pressure and warm weather. Using the image above, we can expect a storm in the US 6-10 days after March 9th, which would bring us to a March 15-19 storm. Not only that, but this forecast indicates the storm in Japan will be/was strong when it passed through, and this means that the storm we experience March 15-19 could very well be strong, too.

Shown above is the latest ECMWF ensemble mean forecast for 500mb height anomalies on the evening of March 15th. Interestingly enough, we see the ECMWF ensembles already have this storm in the Plains, meaning the idea of a big winter storm for this timeframe is becoming popular. The ensembles have a positive PNA pattern in place, meaning we see high pressure shooting north along the West Coast, with consequential storminess in the Plains. We also see ever-so-slight ridging in the Southeast, but this is suppressed by the piece of the polar vortex displaced over southern Canada. It looks like the ensembles want to develop a split jet stream pattern, which could open the door for phasing of storm systems. Despite this potential, I feel that any storm in this timeframe would either move east and possibly up the coast, though I'm a bit hesitant about that potential due to the polar vortex pushing down on the jet stream as well as the storminess over Greenland (which typically does not favor East Coast snowstorms). The other idea would be the storm moving north and hitting the Midwest/Great Lakes, but I'm also skeptical on this idea due to the polar vortex piece trying to suppress the storm (which could very well happen), as well as the lack of high pressure in the Southeast to force the storm north. We'll get a much better handle on this in coming days, but be warned that the March 15-19 period could see a potentially significant storm hit the US.

It is also worth noting that we could see some severe weather, though to which degree is to be determined.



Anonymous said...

Nope, I'm not having it. I'm putting my foot down,no more snow storms this year! Right Bree?

Anonymous said...

That is 100% correct, I'm not having it! I'm done!
What is with this weather? For pete sakes, how much longer can we take this? Seriously?
I do Thank you Andrew for keeping us in the know, you are priceless!
But for the love of God bring on some spring!