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Central PA - Early/Mid December 2016


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Definitely was a raw day here in the low 40s with off and on rain. In a show of an actual normal progression towards winter, parts of Upstate NY and even some of the New England gang seeing their first accumulating snowfall today (second one for some of the Adirondacks). Also some freezing rain in far NE PA and northern NJ. Could've been us if the low were to have tracked below PA with that high to the north but it is late October after all.

Suppose I could make a few remarks about the upcoming pattern and also the upcoming winter. First the upcoming pattern, as we look to start into November next week with an above average temp regime enveloping most of the US. A look at the NAO/AO/PNA forecast would make you think otherwise on this end of the country, with +PNA and - NAO developing and continued -AO. However, the EPO is forecast to go solidly positive (and WPO remaining positive)..which would imply low pressure in the Gulf of Alaska and a stormy west coast pattern. That alignment in turn floods the US with Pacific air and keeps the colder air up in Canada (though it would appear most of the really cold air departure wise resides on the other side of the pole for the time-being anyways). Don't have access to the Euro weeklies but from what I've read they're pretty cold in the second half of November. I am of the opinion that we get winter action right out of the gate this winter, perhaps as early as late November...but we'll need to see that particular feature break down or retrograde. So we'll see how things go the next couple weeks. 

As far as the winter itself, I personally think our region will see temps much closer to normal averaged over the whole winter than last year.. which I guess really isn't a stretch to say given the abomination of + temp departures we had last winter. I also anticipate at least near average snowfall for most of our region, with the best chance of above average snowfall in the N and NW part of our subform. We all know that kind of prediction can get thrown out the window in one storm (See: Jan 23, 2016), of course. But yea, I'm taking that boring, middle of the road approach this winter. When talking about the upcoming winter last year around this time, I labeled it as a high risk, high reward kind of winter... where we could have a really big snowstorm(s) or it could simply just be too warm due to the very strong El nino and no blocking. Turns out we ended up with both in the Sus Valley and southern tier.

The status of the ENSO coming into this winter is quite different indeed, with an ONI departure of -0.5ºC in the latest three month average (JAS) and a weekly average of -0.6ºC as of last week. An official La Nina would be noted if there is 5 consecutive three month averages at or below -0.5ºC.. and JAS was only the first one that hit that threshold so far. Forecast plumes currently suggest these values don't deviate much for the winter.. with most staying clustered near the current values. So it's looking like we will have a weak La-Nina or even a negative side ENSO neutral winter. So with a Nina that probably won't have any particularly dominant influence, it becomes more of a toss-up of what kind of sensible weather we might see. Even so the temp anomalies in the Pacific are definitely a lot different, obviously in the ENSO regions of course.. but also in the East Pacific as a whole. Gone are the + departures up and down the west coast (see comparison below). I think most of our weather events this winter will be predominantly northern stream ones vs southern stream. That doesn't mean we can't get a good split flow or a phaser at some point during the winter.. but a more northern stream dominated winter is one la-nina influence I expect to see. I don't necessarily mean that in a bad way either, as an active northern stream can still deliver plenty of winter weather as long as the pattern's lined up okay. However, I think our chances for a top end storm (say a high end NESIS Cat 3 or higher) are considerably lower this winter and we have more typical systems of the 4-10" variety with some clippers mixed in and perhaps a shot at a bigger nor'easter or two. Well that ended up being a book.. but those are some of my initial thoughts on the upcoming winter. 

ENSO status as of October 24th

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

 

SST anomalies October 27th, 2016:

anomnight.10.27.2016.gif

SST anomalies October 26th, 2015:

anomnight.10.26.2015.gif

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Nice post MAG. I was going to say something in November, but you basically covered everything lol. One additional note I'll make is I think there will be an increased risk of icing events across the entire subforum with the usual suspects along 81 and the Susquehanna Valley being highest risk. My take on that is the added persistent blocking we may see this year and the greater chance of cross polar flow regime during peak cold for the winter. All we would need is a sloppy phase running into a blocking high to make life a living hell for everyone in here. We haven't had a true major/crippling ice event in a long time. This winter shows slightly greater potential than previous years given the colder outlook with northern stream dominance delivering better sustained cold for the subforum. 

As for snow, I like your call a lot. I think a general focus will be normal to above normal across NW PA with areas Clearfield on west being prime targets due an active northern stream and persistent upslope and LES off Erie. Pending the depth of the cold early in the season, Erie could see a solid freeze by January which would effectively cut down on LES potential into latter half of winter. However, something that could be overlooked is of that we're to occur, these cold shots from NW trajectory could maintain their overall magnitude across the lakes, from Canada, due to little moderation from a frozen lake. This would give the area better chances at seeing quite cold anomalies in a perfect setup, as well as deeper surface layer cold to be worked with in the event of a southern tracker. Should be a fun winter if you ask me. The best part I believe will be a slighter better than average chance of snow on holidays, so we should be able to keep the mowers in the garage/shed this time around. 

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Thanks for the early thoughts guys.  Seems in line to what I've been reading.  It would be nice to see "typical" climo in true Central/Northern latitudes.  also the thought of persistent NW flow/lake effect would be nice.

NO mowers this year for Christmas Eve.  Yeah that's a big plus.  That was a major shot to the chicklets last year.

Looking forward to first tracking (which sounds like its a couple weeks out).  Good archery hunting weather in the interim.

 

Nut

 

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On October 28, 2016 at 8:54 AM, MillvilleWx said:

Nice post MAG. I was going to say something in November, but you basically covered everything lol. One additional note I'll make is I think there will be an increased risk of icing events across the entire subforum with the usual suspects along 81 and the Susquehanna Valley being highest risk. My take on that is the added persistent blocking we may see this year and the greater chance of cross polar flow regime during peak cold for the winter. All we would need is a sloppy phase running into a blocking high to make life a living hell for everyone in here. We haven't had a true major/crippling ice event in a long time. This winter shows slightly greater potential than previous years given the colder outlook with northern stream dominance delivering better sustained cold for the subforum. 

As for snow, I like your call a lot. I think a general focus will be normal to above normal across NW PA with areas Clearfield on west being prime targets due an active northern stream and persistent upslope and LES off Erie. Pending the depth of the cold early in the season, Erie could see a solid freeze by January which would effectively cut down on LES potential into latter half of winter. However, something that could be overlooked is of that we're to occur, these cold shots from NW trajectory could maintain their overall magnitude across the lakes, from Canada, due to little moderation from a frozen lake. This would give the area better chances at seeing quite cold anomalies in a perfect setup, as well as deeper surface layer cold to be worked with in the event of a southern tracker. Should be a fun winter if you ask me. The best part I believe will be a slighter better than average chance of snow on holidays, so we should be able to keep the mowers in the garage/shed this time around. 

I pondered mentioning the potential for more ice storms this year but I'm not so sure the Nina is going to be a strong enough influence to have confidence in an icier C-PA winter than usual. And of course I say that with the expectation that I'm sure we'll have the usual couple of sleet/zr setups. It certainly is something to consider if the Nina deepens more than is currently forecast as that can be a Nina trademark around here. The last bout of consistent Nina in the late 2000s (specifically the 07-08 and 08-09 winters) certainly had their share of ice events in them, and I can think of a couple notable ice events back in the late 90s/early 2000s Nina. On that point..that period also featured drier winters, esp 99-00 where State College was on par with 01-02 and 11-12 snowfall wise despite that winter having its cold stretches. The CPC composite on La Nina snowfall certainly shows a weakness on snowfall in PA (but not necessarily overall precip). Pretty much why I'm reserved on my thinking of near average snowfall overall. I'd have no problem laying out the prospects of having a drier and/or heightened ice threat kind of a winter with a stronger or more established La-Nina, but with it looking closer to ENSO neutral to perhaps weak La-Nina.. it makes for more of a toss up. When looking at the snowfall data around here (Harrisburg, State College, Williamsport) you'll find most ninas in fact aren't all that noteworthy snow-wise, generally below average. Obviously the glaring exception is 95-96, one of the weaker episodes. 

lanina.jfm.snow.gif

I agree with you on the LES and upslope potentials, and that is why I consider the N and NW having the best chances for above average snowfall. The dominant northern stream and more downstream blocking this winter should allow for more of a NW flow regime into PA. The Laurels and even some of the NW quarter of PA to a degree really have not seen major events the last couple winters. Last winter of course because it was a heat wave but even the frigid 14-15 winter... where until last winter Laurel Summit reported it's lowest total since that station started in 02-03 (around 120" where the average was over 160"). We did that winter without NAO blocking but a dominating western ridge/-EPO. With the mean trough axis and ensuing frigid air being centered near or just to the west a lot of the winter.. we had more of a westerly or WSW component to the lake effect, attributing big time to Buffalo and WNY's crazy snows but taking away from the Laurels and northwestern PA outside of the immediate NW PA snowbelts. 

 

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On 10/28/2016 at 8:54 AM, MillvilleWx said:

Nice post MAG. I was going to say something in November, but you basically covered everything lol. One additional note I'll make is I think there will be an increased risk of icing events across the entire subforum with the usual suspects along 81 and the Susquehanna Valley being highest risk. My take on that is the added persistent blocking we may see this year and the greater chance of cross polar flow regime during peak cold for the winter. All we would need is a sloppy phase running into a blocking high to make life a living hell for everyone in here. We haven't had a true major/crippling ice event in a long time. This winter shows slightly greater potential than previous years given the colder outlook with northern stream dominance delivering better sustained cold for the subforum. 

As for snow, I like your call a lot. I think a general focus will be normal to above normal across NW PA with areas Clearfield on west being prime targets due an active northern stream and persistent upslope and LES off Erie. Pending the depth of the cold early in the season, Erie could see a solid freeze by January which would effectively cut down on LES potential into latter half of winter. However, something that could be overlooked is of that we're to occur, these cold shots from NW trajectory could maintain their overall magnitude across the lakes, from Canada, due to little moderation from a frozen lake. This would give the area better chances at seeing quite cold anomalies in a perfect setup, as well as deeper surface layer cold to be worked with in the event of a southern tracker. Should be a fun winter if you ask me. The best part I believe will be a slighter better than average chance of snow on holidays, so we should be able to keep the mowers in the garage/shed this time around. 

Dont tease now ;)

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10 hours ago, Blizzard of 93 said:

It's great to see the excitement building for this winter. MAG & Millville had great posts with their winter thoughts.

The Euro, Canadian & GFS are indicating a pattern change around November 15th that with a trough Setting up in the east. 

Let the games begin !

good to see you back Kemosabbie 

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Eric's winter outlook mirrors most other mets that I've read. Temps near normal (+/-2) with near normal snowfall for most in our region. NW areas like Clearfield probably above normal while areas along and east of I95 slightly below. He expects spells of both cold and milder weather and says that we have a below normal chance of a snowstorm greater than 1'. 

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Deterministic guidance is starting to zero in on what appears to be our first significant cold shot and likely LES outbreak of the late fall/early winter season as a highly amplified pattern drops a major trough into the eastern US next weekend. It would appear we get a bit of a retrograde in the anomalously low heights/pressures progged in the Gulf of Alaska enough to center the major downstream ridge in the central part of the country. Euro progs 850 temps getting to -10ºC in most of PA on Saturday. Certainly a major change from what he have been seeing but perhaps not necessarily number busting cold. Our side of the globe still doesn't have the truly cold air yet.  Even so, alignment appears favorable for the NW PA and Laurels snowbelts and that setup would probably send snow showers/squalls into central PA and perhaps even some of eastern PA. 

 

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1 hour ago, Voyager said:

Dipped down into the low 20's (23 to be exact) this morning here in Tamaqua. Over in Carbon County it "supposedly" got down to 19 in Lehighton.

but you get your endless summer request later this week....

when I find that Voodoo doll of yours...........so help me.

Sounding like next week may be looking more like a late fall pattern w/ chances at random flakage...

 

Nut

 

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