Tuesday, January 8, 2013

Where Could The Polar Vortex End Up?

The latest ECMWF model forecast from Europe is showing the polar vortex (what makes the Arctic as cold as it is, not including the presence of a tundra landscape) sitting over Nova Scotia, Canada and the Canadian Maritimes. This solution would bring incredible cold and wind to the Maritimes, while a negative NAO rages, high pressure builds over the Arctic and a sliver of energy still remaining in Canada tries to build the vortex back up. What an incredible solution this would be if it verified.

But the truth is, models are horrible at handling pattern changes, so it's best we turn to ensemble forecasts.

The top image shows the ECMWF Ensemble prediction system, commonly called the ECMWF EPS (or just EPS for short) forecast at 10 days, and the GFS Ensembles (GEFS) are shown on the bottom, also valid 10 days out. These forecasts are showing 500 millibar height anomalies, where low pressure is shown in cool colors and high pressure in warm colors. Both ensemble sets agree on the polar vortex dropping down into Canada enough to bring the North US some serious cold, but nothing historic (nothing historic has been expected thus far- just serious, harsh cold). I feel like this will be a long-lasting event, with the sudden stratospheric warming's effects lasting for a couple weeks. This means, rather than one big cold shock, it appears possible that waves of cold will penetrate the nation, each wave spreading more and more cold around.

This is still a while away and the models remain without a consensus, so I will be updating you on the possibilities as this forecast time comes closer.



Anonymous said...

We keep hearing about the cold coming in the next few days, but what about any snow for eastern iowa?

Simon said...

Thanks Andrew, and congrats if this scenario keeps unfolding as you've been suggesting the past few days. I sure hope so.

One question. Given your previous post talked of the 'incredible' SSW with 'off-the-charts' readings, why are you relatively circumspect in the expected effects in USA (cold..but nothing historic)? Is it because the major effects will hit Europe & Asia, or is there little relationship between the intensity of the SSW and the eventual effect down here?

Cheers, and keep up the sterling work!

Eldon Lopes said...

Really great analysis! I have 2 questions, what do you think is causing that stratospheric heating? and so you think we could be experiencing an Arctic dipole anomaly?

Anonymous said...

a lot of us keep asking about the snow........IS THERE GOING TO BE ANY ???????
I realize this pv is hot subject or maybe the cold subject but please do a post on the snow

Louey7 said...

Hi. Accuweather for Louisville has warm weather through the rest of January and beginning of February. And mostly no snow...

Is that reliable? ( I trust accuweather more than weatherchannel )

AccuWeather Forecast for Louisville, KY