Monday, December 5, 2016

Monday Morning Weather Discussion: Cold, Active, and Challenging Peroid Ahead

Good morning everyone. Most of us woke up to a coating of snow this morning which reminds us all that winter is here. At the very least, very cold air is coming from the end of this week through the foreseeable future and there will be a lot of energy on the field to play with during that time period. Rounds of snow are likely up in New England during this time period and now the question is will the white stuff make it down to the big cities. Time will tell but I will share with you my updated thoughts.

Here is a Summary:

  • Chilly air maintains itself through mid week before a shot of arctic air plunges temperatures by the end of this week
    • Expect highs in the mid to high 40's this week with temps droping to the low to mid 30's for highs this weekend as an arctic front moves through
  • On Tuesday afternoon a storm system approaches from our south west
    • Snow will break out in interior areas including extreme NW NJ and northern PA into NY.
      • Several inches possible in the interior with this system
  • As the arctic cold front moves in later this week, we need to keep our eye on some snow to break out  Thursday and Friday
    • Snow squalls are possible 
  • Following the big chill later this week, we then need to keep our eyes on a storm system to develop early next week on the back of the arctic air mass
    • Storm would likely be more wintry in nature

So lets take a look at models...

The storm system tomorrow afternoon...


I like this projection of where it shows the rain vs snow. We really need to keep a close on on NW NJ at the higher elevations as there could be a surprise in store there. Other areas to the south a cold rain will fall.

The arctic plunge then comes in end of this week. These are temperature departure from averages in C...


Very very impressive. This is cold air guys. Expect highs 15 degrees below normal with is low 30's to high 20's for spots in the interior. Wind chills will be in the low 20's for many areas this weekend. 

As this arctic front moves in, we need to watch for snow showers or squalls (intense short bursts of snow) Thursday and Friday..


We will watch this closely to see if any low pressure system want to spin up along this front. At this time I think its just snow showers.

Following this weekend, we then turn to early next week as a storm could form on the back of this arctic front..


Do not pay attention to rain/snow nature of this image or even the position of the low. This will be very shaky and shift after every model run. I show this because storm love to form on the back of arctic outbreaks, so this is something we need to watch closely for early next week. As I said over the weekend, the 12-18th time period is the target zone for first snows in the big cities.

If anything, there has been a trend for troughs to correct a little more east as a long range forecast period approaches. For example, here is the projected upper air pattern for Thursday with the arctic front approaching..


This was the old model projection from last week....


The trough is more east on the new image (top) and as a result we have arctic air on tap. 

Looking ahead to early next week, it will be interesting to see if this corrects at all to bring a storm system through with cold air ahead of it..

Just speculation for now. In any event regardless of the outcome, the cold air is here to stay for the most part, and naturally I believe snow will follow. If it doesn't then that will be a bad sign for the rest of the winter. The DNA of this season lies in the next 2-3 weeks!

Fun times ahead!

2 comments:

  1. Hey Willy, I was looking at Judah Cohen's AER site, and if I'm reading him right, his Siberian snow model for this year indicates that the big-winter pattern should start locking-in over North America by mid-December, about a month earlier than usual. And yet he seemed a little bit ambivalent as to whether that really seems to be happening. FWIW, my morning review of the weather situation gives me the rough sense (very very rough) that there could theoretically be significant blocking in the northwestern Atlantic (big high south of Greenland, negative NAO, big trough over the east coast, the kinked jet stream flooding it with Arctic air turned loose by a negative AO) . . . plenty of warm water in the northwestern Atlantic, the adjacent Atlantic cold pool is diminished -- BUT -- the required forcing from the Pacific side that sets all of this up just ain't happening yet (PNA negative or close to neutral, EPO neutral or +, MJO not doing anything, weak La Nina at the equator but cold water to the north, which diminishes the GofAlaska blob). So the pattern into the 3rd week of December seems to stay fairly zonal. There's plenty of cold air, but it mostly seems bottled up over Siberia and central Asia. The Arctic and Hudson Bay sea air and even northern Greenland air is up to 10C above what it should be, due to the low sea ice. So even a significant SSW and a loose polar vortex might be a little less chilling than in the past (although still darn cold, cold enough for snow down here). Also the westerly QBO might modulate the SSW's somewhat. NOT that we're gonna have another Nino winter here in NJ and the northeast, but perhaps it ain't gonna deviate too much from an average winter, at least in the opening rounds. Cold and snow coming for sure, but nothing historical (with the usual "I could be wrong" warning, since weather systems are inherently chaotic). By mid-January, though, the whole picture could obviously change. That's what makes it so interesting, and that's why we keep on reading your blog! Jim G

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    1. Hey Jim,

      AER has a bold winter prediction. With the exception of last winter there track record is impressive. This WPO pattern is dominating right now. That ridge in the western north pacific is driving down the arctic hammer next two weeks. I really believe these next two cold shots are for real. So far the analog method is beating models on the seasonal prediction but its still too early to claim any victories. A colder than normal December however is increasingly likely every day. IF we see snow its usually on the front or back of these arctic outbreaks. Monday will be interesting but a lot needs to fall into place without major blocking.

      Now in terms of the teleconnections. We got no +PNA and very little blocking currently. The WPO aided by a -AO (will relax as well) is enough to bring these arctic fronts through. If we do not have that PNA or major blocking however getting the "big storm" close to the cities is not likely. Instead we will get many clippers and some may pack a punch if they run into a little blocking and can amplify. Still, this will favor the northern mid atlantic and new england. I won't be complaining if we get a few light to moderate events that build up a decent snow pack by the end of DEC.

      The jury is still out on late December into Jan. The models are all over the place and shift from one extreme to the other. I would like to see more of a -NAO develop and the PNA spike up at times. The analogs suggest it will but time will tell. We have very interesting times ahead and this year is going to be more difficult than most to forecast!

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