Jan 2, 2016

Memories of a Warm November and December

Memories of our prior two warm months is what we will have after an arctic cold front blasts through the area during Sunday 3 Jan 2016. In my previous blog post, New Year Ringing in Winter , I illustrated how the weather pattern was beginning to show signs of taking on a much more "typical" winter look .

In this blog post I'll be more detailed about the arctic frontal passage and following chill down that will occur Sunday through Tuesday (3 Jan-5 Jan).

A cold front plunging from north to south across the region during Sunday afternoon (Fig.1) means business!
Fig.1 Forecast map for 6 PM Sunday 1/3/16

Fig.2 Timeline and impacts for the arctic blast

This arctic cold front will be preceded and accompanied by scattered snow showers and brief heavy snow squalls. The squalls will have gusty winds, heavy snow (perhaps some brief thunder/lightning, too) and could result in near whiteout conditions, as well. There will be some local accumulations too any where from a dusting to as much as 2 inches. Combine the squalls and possible local accumulations and you have the possibility for some major impacts on road travel. (Fig. 2)
In addition temperatures will plummet with the frontal passage and this could lead to a "flash-freeze" of untreated road surfaces and sidewalks. I expect temps to drop from the 30s rapidly through the 20s by early Sunday night and down into the teens (single digits north) by Monday morning.

Jan 1, 2016

New Year Ringing in Winter

After a record warm December 2015 across the Upstate of New York, where the warmest ever average monthly temperatures were set in Glens Falls, Poughkeepsie and Albany, we can expect colder weather to head our way.

The arctic blast will move in on Sunday the 3rd day of the New Year. The leading edge of it, the cold front, will be accompanied by some scattered snow showers and squalls. Once the front passes your location expect gusty NW-N winds and falling temperatures to develop . On Monday highs will be near 20° with Tuesday's high in the low 20s, but wind chills will make it feel like it is in the teens. Needless to say these daytime temperatures are below normal.

As for Sunday, Monday and Tuesday nights we'll be in the brrrrr zone. Monday night will be the coldest one with single digit minimums, even subzero readings for the colder locations especially north of Albany (Hello Glens Falls and the Adirondacks!) while the other two nights will feature teens.

The reason for the turn to much colder weather: Refer to figure 1 (below). The jet stream forecast for Monday (Jan 4th) indicates a trough ( dashed yellow line) and the polar jet (blue colored area west of the trough) amplifying across eastern Canada and the Northeast corner of the U.S.. The jet stream winds ares blowing from the polar regions of North America down toward the Northeast. (One could even say the flow is cross-polar, blowing from Siberia to arctic Canada then down towards us.) This jet stream pattern is near perfect for delivering cold air our way.
Fig.1 Jet stream forecast for Mon 4 Jan 2016
By midweek moderation ensues as the cold high pressure cell moves to the East Coast on Wednesday (Fig.2) then slides offshore thereafter. Look for readings to warm back into the 35° to 40° range Wednesday through next Friday.

Fig.2 Surface forecast for Wed AM 6 Jan 2016

But by late next Friday (Fig.3) cold air will begin to press south out of eastern Canada. At  the same time a split flow jet stream pattern develops. We'll have two jet stream across North America, one from central Canada to the Great Lakes and Northeast - the polar jet (PJ) and a southern the jet or subtropical jet (STJ) blowing across the southern US to the Southeast Coast. The jets will be amplifying or getting stronger, especially the STJ.

WPC Surface forecast for Fri AM 8 Jan 2016

This sort of a split and amplifying jet stream pattern can lead to an active  pattern of unsettled weather developing, i.e., potential winter storms, especially with low pressure systems developing beneath the STJ (Fig.4). 
Fig.4 WPC surface forecast for Sat 9 Jan 2016

Now I am not saying we will see a winter storm here but  I am saying that there will be potential threats to watch.  So for snow lovers your hopes can be raised,and  for those who wish otherwise, come  its winter and you live in the Northeast!