Last week I issued a blog looking at storm potentials this week that could bring disruptive snow to the area. Revisiting those threats again this morning, it looks like we will be in the clear of a big storm to effect the region. However, there could still be a period of light snowfall that brings minor accumulations to parts of the Tri-State.
The two dates of interest I mentioned in my last blog was 1/15 and 1/18 since both dates will feature a trough dropping into the eastern CONUS. Above is the 500 mb vort map for the 1/15 threat. There is still a good amount of energy ejecting out of Canada and into the trough that should still spark some light snowfall to develop from the Apps and points east to the coast. But due to the lack of spacing between both pieces of energy, it does not allow the initial trough to amplify along the coast and organize a pinched off surface low.
The next threat is on 1/18. Since the "kicker" feature behind this trough is not as pronounced (as you can see from the above 500 mb map), there could be a more widespread area of light snowfall on Friday. The s/w energy with this trough is not as impressive as the 1/15 event, but the trough takes on a bit more of a negative tilt. So, this threat still bares watching and there could be an area of 1-3 / 2-4 inch type of snowfall somewhere in the northeast region (possibly more in New England). It's dependent on exactly where the energy transfer occurs associated with the clipper system in the Great Lakes during this time period.
Therefore, I would pay more attention to potential snowfall for Friday and pretty much write off Wednesday from anything of importance happening other then a nuisance snow or rain shower.
Looking ahead, there is still a strong signal from the current observations of SST's in the northern Pacific of another -EPO regime developing by the end of this month. I think we are going to look at a few possibilities:
1. A -EPO/-PNA pattern develops again similar to what we saw in December / early January.
2. A -EPO/+PNA Pacific set-up develops.
3. A +EPO/+PNA Pacific set-up develops.
Given the look of current observations and some long term guidance, I am liking a combination of options number 2 & 3 to come together. The -EPO will enter a relaxation period, but I think it reforms in conjunction with a western U.S. ridge. If this combination of incredible western northern hemisphere blocking comes to fruition, it will call for arctic air and a persistent trough to reign over the eastern U.S. once again.
The MJO forecasts from the GEFS (top) and EURO (bottom) are showing signs of life with members taking the MJO out of the circle of death and into phases 6 / 7. The MJO phase 6 does not shock me since early next week we will experience a temporary 1 or 2-day warm-up as the western ridge collapses eastward. But once we get by early next week, that is when our weather pattern becomes interesting and the colder than normal weather settles back in.
Above are the proposed GFS 2-M Temp Anomalies after the temporary warmup early next week. As you can see, even if this is slightly overdone, it is still an impressive cold air mass coming down due to the western blocking developing like I talked about earlier.
The question then becomes, will there be a storm to accompany the cold that could turn things white?
That is something that remains to be seen, and it would be unfortunate to see cold / dry conditions develop the end of this month. Most people like to see snow come with the cold. There's no point in posting long range surface maps, but some of them do show storm threats down the road. The problem is our NAO. Can we get a sustained -NAO to get some blocking to work with which would (4 "w's" in a row, wow) really turn this into a Godzilla-type of pattern? There are signs of a potential sudden stratospheric warming (SSW) event taking place and there is usually a 2-4 week lag time before it reflects on our pattern here in the eastern CONUS. If that comes to light, then a -NAO pattern could be in store for us once we get into February. However, I do not expect a sustained -NAO to come in January, other then transient episodes that could be our window of opportunity to capitalize on come the end of this month.
We will see what happens. There could be a lot of fun in store for us by week 4 into February!
-Francesco Paparatto
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