Historic Early Season Snowstorm

Snowfall forecast for Saturday - click to enlarge!

Sometimes, you just need to call it what it is. This is straight up a bonafide snowstorm, the likes of which not many people have ever seen or probably will ever see again…because of when it’s occurring. If you showed me these maps, I probably would have guessed mid to late November…still early, but more reasonable. If this storm occurred in December, we’d be talking about a blizzard for the Northeast Corridor. It’s remarkable by every stretch of the imagination.

The snow map is above, and here are a few things to note…especially the 3rd one…

1.) Wind: It will be strong, with our models today suggesting we see some 20-30 mph winds in the interior, with perhaps some 40-50 mph gusts on the coast. This will cause havoc inland, as any sort of wind > 10 mph with heavy, wet snow on trees that still have some leaves will lead to trees coming down and likely widespread power outages in the red area, numerous power outages in the purple area, and scattered outages in the dark blue area.

2.) The Northwest Connecticut into Western/Central Massachusetts corridor looks to be absolutely crushed by this storm. It will likely be an extremely severe hit there and could be one of the worst snowstorms in terms of problems and inconvenience for them in recent memory.

3.) Elevation will play a MAJOR role in this storm. While I have opted to unfilter things a bit regarding snow amounts, I can’t help but feel that there may be a wide and sometimes unbelievable disparity in snow totals in some areas…especially in and around Hartford, CT, Morris County, NJ, the area between Reading and Pottstown in PA, north and west of Baltimore…all places where terrain tends to transition from the more flat Coastal Plain to the Appalachian foothills…this may occur elsewhere as well, especially in valleys, like the Lehigh, Susquehanna, and Connecticut Valleys. You may see some areas with 2-3″ of wet snow…travel 5 miles north to slightly higher terrain and see 6-10″ of snow. It will be that kind of storm…the kind where a truly accurate snowfall forecast map is next to impossible.

4.) The Big Cities will likely see flakes…especially Philly-Boston, but mostly at the tail end of the storm and any accumulation should be minor and mostly on grassy surfaces….though Saturday evening could be comical in some places.

So go load up on supplies for Sunday’s football games, enjoy game 7 tonight, and enjoy the snow while you have it, because warmer air will start melting this stuff as fast as Sunday afternoon.

Facebook Us…Oh, And Snow.

It’s been a disruptive month for State of Occlusion! Transitioning my life offline from the West Coast to the East Coast, so haven’t had time to blog. I’ve discovered Facebook to be an extremely useful tool to communicate short bursts of information and post maps quickly. I will occasionally use this blog to elaborate on various significant events, but in the meantime, for the latest thoughts and information from me, like the Facebook page and tell your friends. We’ve already got 100 fans…let’s go for 200!

Follow State of Occlusion on Facebook for the latest!

In the meantime, while many in the Northeast enjoyed record warmth this Friday, winter is around the corner ready to take its season back. It will be cooler and extremely windy Saturday, followed by a leveling off of temps Sun and Mon. One storm will swing through Monday, potentially dropping heavy snow on Upstate NY, far N PA, into Connecticut and Southern/Central New England. Round two will affect areas south of I-80, somewhere between DC and New York, bringing the potential for very heavy snow on Tuesday as colder, Arctic air pours in. Right now the best odds for this appear to me to be between Baltimore and Allentown, back west across all of PA into Ohio and east into NJ. Potential does exist for 6″ or more with this storm, so this may cause significant travel issues in the Mid-Atlantic on Tuesday. Cold Wednesday followed by another semi-thaw (though not to the extent you saw this week).

I will post updates on Facebook through the holiday weekend.

Here We Snow Again!

Snowfall Forecast for Tues/Wed.

There’s the snow map at the left. Here’s some ideas by region.

– Boston area could see some very high snow amounts of 16-20″, depending on the exact track of the storm. If the storm tracks just right, they could get slammed, as some models suggest. Interior Southern New England right now would appear to be the jackpot, but I wanted to emphasize the risk to the Boston area. Parts of CT and MA may see some 20″+ amounts, with generic 8-16″ amounts as you approach the coast (some coastal areas and the CT River Valley may see lesser amounts). Cape Cod will likely be close enough to the storm to mix or change to rain. This will cut down on snow amounts a bit there. Additionally, wind will crank on Wednesday, leading to blizzard conditions in parts of New England.

– Metro NYC area/NE NJ won’t be the jackpot this time around. However, this still appears to be a respectable, business hampering snow. Think of the last system that went through, think of post-Christmas, and expect this storm to end up somewhere in between the two. There will yet again be a very sharp cutoff to significant snows, somewhere within the I-287 corridor. Blowing and drifting snow will occur in this region Tuesday night and Wednesday.

– Southern NJ will be close to the center of the storm, so I do expect the possibility of a mix. It also appears the storm will really explode a little too far away from this area this time. I still expect a respectable 4-8″, with the potential for higher amounts in mainland Cape May, Atlantic, Burlington, and Ocean Counties (6-10 perhaps?). Coastal sections may even see less, primarily in Cape May County. If mixing for some reason does not occur, tack on an additional 2-4″ to these forecast amounts. Blowing snow will cause a few problems Wednesday.

– Philly/Trenton will be solidly in the 4-8″ range, with potential for higher amounts (8-12) as you get closer to Trenton/New Brunswick and slightly lesser amounts as you slide south and west of Philly. Blowing snow will be a problem on Wednesday.

– DC/Baltimore appear to be in the 1-4″ range, with again potential for higher amounts in the northeast corner of the map. Much of the interior back through OH/MI will average 1-4″ as well, with potential for a few 4-6″ amounts in spots, depending on how things shake out.

And that’s that! After this storm, it appears we’ll head into a relative period of calm in the Northeast. So enjoy this if you like big storms and snow. Winter is certainly not over though, so stay tuned.

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Just a reminder… State of Occlusion is on Facebook. I’ve posted some additional cool links, quick model updates, and snow maps early on that page. “Like” the blog by clicking here!

Norlun Troughs?

Going to get a little technical briefly. Going to put this pretty plainly: What’s coming Friday will more than likely not be forecasted very well. Why? We’re dealing with a phenomenon that’s pretty common in the Northeast in winter…it usually rears its ugly head at least once. We call this an inverted trough…Norlun trough…or instability trough. What is it? Well, typically, when you think of an atmospheric trough, you think of a “U” or “V” shaped pattern. In an inverted trough, this, well, inverts. It looks more like an upside down U. The lower pressure, or lower heights end up on the north side, rather than the south side. These sorts of setups can produce some nasty weather, heavy precipitation, and thunder.

Here’s more info on Norlun troughs (recognized in the 90s and named for the meteorologists who discovered it).
A technical paper on Norlun trough events.
And here’s more on inverted troughs.

So what’s it to you? Well, the models are beginning to hone in on how this storm on Friday and Saturday is going to behave. And they are indicating that an inverted/Norlun trough type setup may occur. The bottom line is that there will be snow. The question is twofold: Will the Norlun event occur, and if so, where will it setup? This morning’s models pegged it right over North Jersey and NYC. This evening it looks to be shifted a little further north. This is important, because outside of the Norlun trough there will be a generic sort of snowfall. But under the narrow Norlun trough, there should be significant snow, with the possibility of thundersnow and more.

Right now, the NAM model (a mesoscale, small scale, higher resolution model) is showing extremely heavy snow (and has on three straight runs today) for areas immediately north of NYC, Long Island, the Catskills, and the Western Mohawk Valley. The GFS model is suggesting this will be further north and east into New England and the Adirondacks.

Latest Snowfall Risk Assessment for Friday and Saturday

So my snow “assessment” has a broad area of potentially significant snow showing in red. I right now have this from about the Bronx, east-southeast into Long Island (yes, that places the division of snow vs. heavy snow within NYC). It stretches up into the western Hudson Valley, Catskills, western Mohawk Valley and southwestern Adirondacks. I also include much of southwest Connecticut as well, including Bridgeport and New Haven. The problem is that it’s next to impossible to pinpoint exactly where within this idealized zone the prolific snow will be. The yellow territory indicates the basic “cone of error” of sorts. I don’t foresee the risk of heavy snow shifting south of NYC much, if at all. The risk to me is clearly on the northern and eastern sides. This could shift further north, so the axis of the heavy snow stretches from Syracuse/Utica through Albany, the Berkshires, and Central Connecticut to the coast. And it could even shift further north too.

The heavy snow band will be awesome though, with extremely heavy rates of snow, likely some thunder, lightning, and whiteout conditions. I could see max amounts of 10-15″ in this band. You will only need to go a few miles from that core of heavy snow however to find amounts of 6″ or less…that’s the type of storm we’re looking at: Very narrow gradient, very sharp gradient, with extremely variable snowfall totals. Thus, this makes forecasting this system extremely difficult, if not impossible at this point. So if you live from NYC into Central New York and all of Southern New England, stay tuned. As I said, the forecasts for this will more than likely be challenging, vague, and possibly even wrong initially. But that’s the story.

Outside of the heavy snows, expect a brief period of maybe some heavy snow, with a coating or so, up to about 3″ in spots across much of NJ, PA and central New England. Closer to the heavy snow axis, there may be some 3-6″ amounts. But those will be isolated.

New model data indicating the possibility still of a major snowstorm Tuesday of next week. There are still a multitude of questions as to whether it will track in the sweet spot for a DC-Boston hit, as tonight’s GFS is showing, or if it will pass further south. More on that after this first event passes.

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Don’t forget, State of Occlusion is on Facebook! I’ll post some additional cool links and snow maps before they’re published here on that page. “Like” the blog by clicking here!