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February Medium/Long Range Discussion Thread


North Balti Zen

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Cohen is very bullish! http://www.aer.com/science-research/climate-weather/arctic-oscillation

"The near term response of the tropospheric atmospheric circulation is the easier part and anticipating the long term impacts if any on the tropospheric circulation are more difficult.  The Global Forecast System (GFS) has been predicting for the most part a relatively quick recovery of the polar vortex.  However I believe that the PV weakening could persist for longer than currently predicted by the GFS.   That belief is based on the more disruptive nature of the PV weakening above 10 hPa and our own PV forecast model.  But even if the GFS is correct, I consider the PV weakening to be significant that could influence the atmospheric circulation for multiple weeks.   It typically takes about two weeks from the peak for the impacts from the stratospheric PV weakening to reach the surface so it could still be a while before a pattern forced by the PV weakening to be fully established. 

Therefore longer term, I anticipate that the SSW/weak PV event does favor colder weather in the Eastern United States (US).  My thinking for why the Eastern US will turn more persistently colder in the coming weeks is based on the strong ridging/positive geopotential height anomalies predicted centered near Alaska in the stratosphere.  That feature looks to be relatively persistent and in my opinion should favor downstream troughing over the Eastern US.  Some model forecasts continue to predict the Eastern US trough to be transitory with the pattern transitioning to a trough in the Western US with ridging in the Eastern US.  This has been the dominant pattern this winter resulting in relatively cold temperatures for western North America and mild temperatures for eastern North America.  It is certainly plausible that this pattern continues to dominate for the remainder of the winter, especially with the cold sea surface temperatures persisting across the mid-latitudes of the North Pacific.  But I expect that even if this pattern does return, it will not be persistent but rather transitory with the pattern returning once more to one that favors cold temperatures in the Eastern US."

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5 minutes ago, Thanatos_I_Am said:

Alright this is a question for th experts on here and before the model nazis get all over me, I know, it's 9 days out. What is preventing that low from coming up the coast more, towards our sweet spot? It seems like the HP is in the classic banana position. So what gives?

chaos. look it up

eta: on a side note, chaos is a good met class thread topic!

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11 minutes ago, Maestrobjwa said:

And overall...is it true that the most likely winter pattern for us to get snow is a weak-moderate El Niño? (I've heard that a few times)

Others more expert on those climatological signals can chime in...but yes, in general (emphasis on general!) a weak-moderate Nino tends to result in our better winters here.  Especially a moderate west-based Nino.

 

6 minutes ago, WinterWxLuvr said:

Might want check enso stats for 13-14 and 14-15.

There has to be bigger players.

I'd have to check, because I honestly can't remember the precise ENSO state those two winters, but I thought we were in some level of a Nina (we had a prolonged period of -ENSO through that time, I recall?).  Yes, there do have to be bigger players beyond ENSO unless that's the true driver in a particular year.  We lucked out big time in 2013-14 and to a lesser but still significant extent in 2014-15, with a persistent -EPO with ridging along the western U.S.  Neither winter gave us a HECS-level event (though Feb. 2014 was close), but we scored multiple moderate events, especially in 2013-14.  Maybe the QBO played a role, too, I don't know; I'm not as familiar with how well (or not) the QBO phase can influence the flow in the troposphere though I've read there is some correlation.

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18 minutes ago, Always in Zugzwang said:

Others more expert on those climatological signals can chime in...but yes, in general (emphasis on general!) a weak-moderate Nino tends to result in our better winters here.  Especially a moderate west-based Nino.

 

I'd have to check, because I honestly can't remember the precise ENSO state those two winters, but I thought we were in some level of a Nina (we had a prolonged period of -ENSO through that time, I recall?).  Yes, there do have to be bigger players beyond ENSO unless that's the true driver in a particular year.  We lucked out big time in 2013-14 and to a lesser but still significant extent in 2014-15, with a persistent -EPO with ridging along the western U.S.  Neither winter gave us a HECS-level event (though Feb. 2014 was close), but we scored multiple moderate events, especially in 2013-14.  Maybe the QBO played a role, too, I don't know; I'm not as familiar with how well (or not) the QBO phase can influence the flow in the troposphere though I've read there is some correlation.

Lately research shows the placement of the nino is a big factor in our winters.  Some people have also speculated the possibility also being the same for the placement of nina conditions.  The classic enso pattern favors sea surface tremperatre anomalies along the east Pacific coastlines near the equator.  What more recent research has shown is that our winters are favored more when the warmest sea surface temperature anomalies are centered closer to the central tropical Pacific Ocean instead of the east tropical Pacific.  This somewhat atypical signal has been classified as the the modoki enso signal.  Some have argued that the nina winters we score on are also modoki, but I haven't seen enough data to give a say.  Notice that we are currently experiencing a modoki nina, so maybe that will help in the end!

 

sst.daily.anom Jan 30_2017.gif

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8 minutes ago, mitchnick said:

The extended range charts are available too though with long seasonal lags.  Last November DJF outlook showed modoki nino. lol  http://www.ecmwf.int/en/forecasts/charts/seasonal/mean-sea-level-pressure-public-charts-long-range-forecast?time=2017010100,2856,2017043000&area=Tropics&forecast_type_and_skill_measures=tercile summary

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17 minutes ago, Always in Zugzwang said:

I hear you...and overall for the most part agree with you about the March 2009 event.  There's nothing memorable for me from 2008-09 other than that one storm.  And I "only" got about 5-6" from that, saved mostly by some good bands that went through in the morning after even that looked like it might fail!  But still, impressive for early March and it was something; it was below freezing for two days.  I don't look at that year as a complete fail like 2001-02 or 2011-12, which had under 5" for me each of those years.  2007-08 is up there too though not quite as bad.  2005-06 had that one good event in mid-February, but that was much better farther north and west of the immediate DC area.  I still got on the order of 8-10" where I was at on Capitol Hill.  But the winter sucked otherwise (God-awful warm January!), and it was 60+ degrees the week after the storm.  Again, I look at that as a "meh" winter, saved (sort of) by one event, but not at the level of complete failure or near shut-out like the other years I mentioned.

I suppose I'm trying to say that I'm just hoping for something to make this a "meh", semi-forgettable winter rather than a "wow, that's a record-breaking fail!" one.

Ooh, a tour of below average winters. I actually don't mind thinking through most below average snowfall winters because most of them had at least one or two decent snowstorms. 

05/06 was nowhere near the bottom of the heap, as you said. But it was more than the February event because late November through early December 2006 was a wintry period for us. Matt made a remiscing thread on that period: 

I appreciated the two moderate snows (the 12/9 event switched to pouring sleet) within a week in early December and an inch at the start of Thanksgiving break. 

January was horrible, making for a long wait, but that winter actually ended up *above* seasonal average for parts of Montgomery County. 

As for the below average seasons, I'm with you in that one decent storm (>6") can make that season not be terrible in memories. But that's only if the 6"+ storm covered the streets. I see 08/09 in the same way as you...especially since we had the disruptive late January snow to freezing rain storm. 94/95 was in that category but even better because while 2/95 was the 6"+ storm, we had a 4" snowfall a week earlier.

Or two moderate (3-5") snowstorms can do it too, like 91/92. A terrible winter had us lucking out with one decent January and one decent February snow. It's a bad winter but not nearly the worst. 96/97 counts in the same category for me because the 6"+ February didn't cover any streets around me for almost the entire event. 90/91 was ok too with the against all odds 12/28/90 5" storm and the multiple snows to freezing rain events in that early January week.

06/07 counts in a special category with the two moderate events of 2/13-14/07 and 2/25/07, but of course the whole month of February was memorable with the severe cold and other minor snows. 07/08 met my two moderate event criteria with the 12/07 overperforming clipper and the 4.5" 1/17/18 "mini-1/22/87" event. 

 

 

 

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20 minutes ago, BTRWx said:

I haven't looked at other models than the cfs2 and the euro and both are very similar.  But we don't have to have a real Niño,  a warm la nada will work too.

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2 minutes ago, psuhoffman said:

You know it's bad when the long range thread for this winter becomes a discussion about what we want for next year before feb 1. lol 

That certainly was not my intention.  I like what we have on the horizon in coming weeks!

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