Stormy Pattern Continues into March

Posted: February 20, 2013, 5:29 pm by ntroiano

Winter has been pretty much unrelenting since the middle of January, with what seems like a parade of never-ending storms threatening much of the Northeast and New England every few days or so. If you’re hoping that Punxsutawney Phil was right and winter will quickly fade into the background later this month, you may want to think again. Just as the WeatherWorks Winter Forecast predicted back in late October, it is becoming increasingly clear that conditions will remain cold and stormy through the first two weeks of March…with several chances for a significant coastal storm to impact the entire forecast region. Want details? Well, you’ve come to the right place! Take a glimpse below to see just how much snow you should expect before you hang up those winter coats and snow shovels for good.

As we head into the last week of February and the early part of March, it looks as though atmospheric teleconnection indices will be favorable for a colder and stormier than average pattern. The attached graphic shows a model comparison of forecast mid-level heights (temperatures) for the ECMWF (European Model, left) and the GFS (American Model, right) valid during the first week of March. Note that both models indicate cooler anomalies (represented by the blue shading) are likely in association with a broad trough of low pressure across the eastern third of the nation. Additionally, each forecast shows above normal heights (represented by the red shading) just to the south of Greenland. Both these features are characteristic of a negative Arctic / North Atlantic Oscillation pattern (- AO/NAO). These teleconnections are historically tied to stormy and colder than average conditions for our neck of the woods and signal multiple chances for significant snow will be possible before winter gradually comes to an end.

It is also worth pointing out that the ECMWF forecast (left) shows above normal heights and a ridge of high pressure in place across the Western US. This feature is associated with a positive Pacific North American Pattern (+ PNA) and when combined with a – AO/NAO is exceptionally favorable for cold and snowy conditions for the Northeast and New England. Although this is currently not as well depicted by the GFS, chances are that this setup will ultimately pan out…as the ECMWF is notoriously more skilled at predicting mid-level height patterns at this range, especially when the atmosphere is expected to feature a “blocking” regimen.

As would be expected, several deterministic models have started picking up on these features as we head into this timeframe. Because of this, most of the medium and long range guidance is showing a particularly active pattern, with at least two or three coastal storms predicted between now and the middle of March (see attached graphic below). Snow lovers shouldn't cheer just yet though, as there have been several times in recent memory when favorable patterns such as these have failed to work out in the end.

This go around the availability of cold air will be a key in determining which areas get snow, and which locations just see a cold rain. Believe it or not, conditions actually look to favor more snow as we head later in the season and towards the first week of March. That being said, the first couple of systems expected to impact the area in late February (including this weekend’s Northeaster, not shown) may be more wet than white for areas other than interior New England. Of course, specifics at this point are nearly impossible to give…so your best bet is to check back from time to time as the most up-to-date information becomes available.

Lead Long Range Meteorologist
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