Figured I'd keep general weather/pattern stuff in this thread, so here goes.
Hope y'all like winter, because the medium/long range models are showing development of a pattern for at least the first 3 weeks of January which should be colder than normal and is conducive to east coast snowstorms, although as usual for these things, predicting the cold well in advance is easier than predicting snow well in advance (so many things have to go just right for snow in this area, as we just saw on Friday). There are several quotes/links below from 3 well-respected meteorologists on this, none of whom would ever be called snow hypesters,, with the level of excitement being pretty high.
The pattern features an anomalously strong -NAO (North Atlantic Oscillation) often called a Greenland block with high pressure in that area "blocking" the cold air from the polar vortex from circulating towards Greenland, which shunts the polar vortex down into the eastern 1/3 of the US as part of a large trough, bringing cold air with it.
The second ingredient needed is moisture and the subtropical jet looks to be active during this period, bringing moisture along the base of the trough and possibly up the coast if the timing works out, which can bring wintry weather to our area and in this kind of pattern, historically, we've often (but not always) seen major snowstorms.
There could also be clipper type systems that come from Canada and the midwest towards our area that deliver smaller amounts of precip (maybe snow); we have a couple of these chances from 12/31 through 1/6 with the bigger chances looking like they could occur after that. Note that the ensemble means for the major long range models (when those models are run dozens of times with perturbations to gauge sensitivity) also show more snow than "normal" for the next 15+ days. We'll see, of course.
From John Homenuk: "Day 10 Composite 500hPa Height Anomalies from todays 12z ECMWF EPS are astonishing both in regard to the intensity of high latitude blocking and the individual analogs - many of which are centered around memorable periods of winter weather in the Eastern US." This is a 4 sigma (4 std deviations, meaning it occurs <1% of the time) anomaly; the first image below shows what this looks like on the Euro model and also shows the closest analogs to this model depiction, several of which featured major east coast snowstorms in that pattern.
From Jeff Berardelli: "If you like cold and snow in the East, the pattern the next 2 weeks is text book! For the layman, (relative) warm blocking in the Arctic “displaces” the tropospheric Polar Vortex, forcing cold southward into the US. For the weather nerds out there, the high latitude block reaches 4.5 Standard Deviations / Sigma from the mean next weekend on the European model. Easily a record. It may not verify, but if it’s even in the ballpark, it’s on like Donkey Kong! Buckle up!!" He includes a nice video showing what the pattern formation looks like (it's in the link below in case it doesn't show up in this post).
From Tomer Burg (who is calling for 20-29" of snow in NYC during January): "What does this mean for snowstorm prospects in the East Coast? Initially, not much. Notice how we start with the same cold and dry NW flow regime we've been in before. The key is to monitor the upstream evolution, as the Bering Sea block erodes and is likely replaced by a Pacific trough, increasing the chances of western US ridge amplification.
The kind of pattern increases the probability of a moderate to major snowstorm vs. climatology in the Mid Atlantic, and potentially southern New England, which would necessitate a well-timed upstream ridge amplification coinciding with downstream confluent flow and a sufficiently cold airmass in the northeast US. While a major snowstorm is never a guarantee, chances of at least one or two in the January 8-25 time frame are higher than average."
After Friday's debacle. . . .





