The Pattern Change After the Pattern Change

If you were to look at the 7 day forecast you’d probably fall asleep due to boredom. For weather lovers it doesn’t get much more dreadful than this.

WVIT Forecast 7 Day 2012

Even though this is about as dull as it gets for January there are tons of changes going on across the globe. In fact, the jet stream is about to undergo a really monstrous change between now and 10 days from now. This is an (overly) simplistic way of looking at it.

WVIT_Jet Stream

There’s a whole lot that will go into this pattern change and virtually every signal is banging the drum for a wholesale change of the pattern by January 15th. The odds of a significant Arctic outbreak over a portion of the country are good and the odds of a significant snowstorm in Connecticut during the last 2 weeks of January are better than normal.

- Meteorological Discussion Below -

If you had a box of Crayolas and had to draw medium range weather porn – this is what you’d draw.

18z GEFS Day 11-15 500mb Height Anomalies

18z GEFS Day 11-15 500mb Height Anomalies / Courtesy: Alan Huffman

I mean… does it get more beautiful??? A gorgeous -EPO ridge dislodging the already split PV (see yesterday’s post) and a phenomenal looking ridge bridge from the -NAO region straight across the North Pole over into Canada.

Not surprisingly, the D11-D15 850mb temperature anomalies are approaching -10C over Saskatchewan and Manitoba! The GEFS today aren’t alone. By D15 the Euro Ensembles are equally impressive with a beautiful +EPO/-AO/-NAO combo. This is a FRIGID COLD setup for portions of the lower 48 with some impressive cold not too far from southern New England.

m500z_f360_bg

While it’s too early to get into specifics regarding where the core of the coldest weather will setup I’m excited. Cross-Polar flow will deliver the goods to this side of the globe and the signal for strong ridging over Greenland (-NAO) starts raising the specter of a decent snow pattern for the northeast.

While the stratosphere is doing some good things upstairs near the Arctic Circle, tropical forcing from the MJO is also working its magic. There’s renewed vigor to the somewhat sleepy MJO thanks to a burst in MJO-driven convection near Indonesia.

ECMF_phase_51m_small

The ECMWF Ensemble MJO forecast shows the tropical convection rounding the equatorial Pacific after leaving Indonesia and winding up toward phase 7 by 1/20. Many of the dynamical and statistical MJO forecasts are similar.

These plots, courtesy of Alan Huffman, show the 500mb anomalies that correspond to each MJO phase in January.

Phase 5 / Phase 6 / Phase 7

Notice how mild phases 5 and 6 are for the northeast – and how cold (and stormy) phase 7 can be. While the initial Arctic dump may be to our west in the D11-D15 time range as long as the MJO keeps trucking toward the dateline we shouldn’t have much problem getting into the fun stuff. The change is coming – we just may need to be a bit patient!

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