January 2023 Mid-Long Range Disco

[psuhoffman]

@WesternFringe I replied in the "snowfall futility" thread.  Lets move our discussion there so as to not further clutter up this thread.  Others have been discussing this general topic there also so I agree with terp that this belongs there.  

[psuhoffman]

8 minutes ago, pazzo83 said:

Don S was showing similar data regarding NYC.

past results do not always predict future outcomes... but lets be honest its not how we want the season to start.  

[pazzo83]

1 hour ago, WesternFringe said:

@psuhoffman

When we grade students (you are in education like me, right?), do we use the median or the mean?  Why?  Do we use GPA (Grade Point Average) or GMA (Grade Median Average)?  Why?  We use the mean because it better represents all of a student's scores, not just the one grade in the middle.  Now, I am fully aware that outliers can skew the mean, but with an n of 136, that isn't an issue.  We worry about outliers skewing the mean when we have a low n (< 18), not with an n over 100.  This is why educators are usually required to have a certain minimum threshold for number of grades in determining a student's final grade.  I know no statistician that would be worried about skewing the mean with an n of 136, especially when none of the numbers in the data set are more than 4 times the mean.  If we had outliers of 200" of snow in a year when the mean is 15", then maybe.  Don't we wish.  But these annual snowfall outliers count, and should be represented in the data.  By using the median, one essentially takes all of the best years out of the data and reduces the n precipitously. This is a bad idea, especially with snow! lol

I am not saying that snowfall isn't decreasing for DC, but I am saying it has not been a drastic decrease (especially in our lifetimes).  This is the data set I used:

https://www.weather.gov/media/lwx/climate/dcasnow.pdf

I ran another linear regression starting with 1942, as you did.  The slope of that line is -0.058" and the standard error is -0.054".  The R squared is .01, which means 99% of the variability from year to year is random and not do to the independent variable, which in this case is time (presumably the climate changing over time).  

So, yes, DC is seeing .058" inches less of snow per year since 1942.  Most people wouldn't be able to notice the difference of .058" of snow per year.  If you can, you have superhuman perception.  99% (R squared) of the change in annual snowfall from 1942 is explained by randomness, and not due to the passage of time.  

The slope of the line goes down and up depending on the starting point, of course.  When I choose different starting points closer to present (to match the ages of folks in here and thus their winter memories), the slope of the line can be literally almost 0, or can actually be positive.  

In summary, I concede that the slope of the line is negative, and always have in my posts.  However, I also have learned that the human brain constantly looks for patterns and trends, even when they are non-existent or super small.  That is why I like stats and means and cold hard numbers.  Hats off to you sir if you can notice a decline of hundredths of an inch per year where 99% of the change is due to randomness, or statistical noise. 

No one can tell the future, but if I had to guess we have some monster years coming up in the El Nino years which will make the slope flatter and closer to zero. The sky isn't falling, we can still do snow, and good years lie ahead.  When 99% of the variability is random statistical noise, this tells me we are not in some inevitable downward spiral regarding snowfall.

Again, I stick by my conclusion that although annual DC snowfall is falling (no pun intended), the change is very small, not cataclysmic, and 99% due to randomness.    

you can't just run a simple linear regression on this time series because the observations aren't IID (independent and identically distributed), so your raw R-squared value isn't really useful.  We know that snowfall here is cyclical.

[ravensrule]

3 hours ago, BristowWx said:

Agreed.  I will be happy to score with something sloppy for sure.

My sweet spot. I'll take a few sloppy inches all day. 

[BristowWx]

20 minutes ago, ravensrule said:

My sweet spot. I'll take a few sloppy inches all day. 

If you are ever incarcerated that’s the right attitude to have.  Godspeed good sir!  

[Amped]

18z gfs would be a historic freezing rain event for the M/D line but the gfs can't forecast freezing rain.

[Ralph Wiggum]

This is a rapid turn of events if true:

[DE2PA]

18z GFS 7+ days out..

[CAPE]

Euro Weeklies for the mid- late month period. Looks Okay. Certainly could be a lot worse.

[Maestrobjwa]

11 minutes ago, DE2PA said:

18z GFS 7+ days out..

I'm using the 5 day rule from now on...if it's still there on Monday then let the reeling in begin, lol

[Solution Man]

5 minutes ago, Maestrobjwa said:

I'm using the 5 day rule from now on...if it's still there on Monday then let the reeling in begin, lol

[Ralph Wiggum]

The look of that banana high up top is getting more stout each run. Wonder if we can reverse the curse and instead of morphing away from threading a needle we can morph this somehow into a legit event. There is a path to victory but it isn't clean nor easy. That WAR may feed a ridge over top of the wave and end up being a blessing in disguise. It's a fast mover with not a whole lot to slow it down but who knows....if we time things right could be a modest little event. Still think this is a tight window with not enough going in its favor...yet. Something under 9 days to track and seeing the backside of the warmth? Thats a win in my book attm.  

[Weather Will]

1/35 chance inside 9 days….18Z GEFS (1 also to the east, west and north).

[Ralph Wiggum]

Looking forward to the gefs to see if the op has any support. I mean, the gefs has been heading this way past 2 or 3 runs so I don't think it's absurd to think we transition sooner than later during prime climo. Biggest things I've noticed past several runs in the LR out past the 8th are the retraction of the pac jet, poleward momentum, and the rebuilding of HL neg height anomalies across the EPO, AO, and NAO. PNA moving away from negative isn't hurting either. Don't want to rush the changes we know so.etimes these are delayed but these are all encouraging signs. No head fakes please.

[Ralph Wiggum]

2 minutes ago, Weather Will said:

1/35 chance inside 9 days….18Z GEFS (1 also to the east, west and north).

Well damn, I knew it didn't have a ton going for this window but wasn't expecting that tbh. Thanks for posting.

[Weather Will]

3 minutes ago, Ralph Wiggum said:

Well damn, I knew it didn't have a ton going for this window but wasn't expecting that tbh. Thanks for posting.

Hopefully we will have a discreet threat to track by the end of NEXT week….

[Scraff]

Only opened the blinds for a minute, but I’ll be back…with the blinds open and a stocked beer fridge to boot. 

[CAPE]

17 minutes ago, Ralph Wiggum said:

Well damn, I knew it didn't have a ton going for this window but wasn't expecting that tbh. Thanks for posting.

It was zero on the 12z run. So an improvement lol. Not overly enthused about this window esp for the coastal plain. A few days later, maybe.

[Ralph Wiggum]

4 minutes ago, CAPE said:

It was zero on the 12z run. So an improvement lol. Not overly enthused about this window esp for the coastal plain. A few days later, maybe.

Yep. Sticking with original thinking as well. The 6th- 7th is thread the needle. And op rushing the change. Like you, I'm still thinking a little later. This system is the transition and we get there a little later. Progression still looks to be on track as per original thinking. 

[DE2PA]

55 minutes ago, Maestrobjwa said:

I'm using the 5 day rule from now on...if it's still there on Monday then let the reeling in begin, lol

 

[DarkSharkWX]

Euro extended/weeklies, GEFS, and GEFSX has MJO going through Phase 8. An -EAMT event would retract the jet back and since its overextended rn, form a +PNA. Along with the NPJR, MJO p8 would further enforce +PNA and blocking(along with +SCAND). While I'm still skeptical about it, this is an encouraging signal to see, and changes in the modeling will probably occur sooner or later if this signal continues to stay

 

[jayyy]

Just to add, these 'workable' looks are far from epic, unicorn, textbook etc. I will take workable over epic perfection tbh. Unicorns are make believe.

Most of the events we see come from workable looks and not epic looks, tbh. Epic setups at 500 (PNA NAO AO EPO, etc) leaves NYC buried more often than us. Our area seems to like setups that produce sneaky events - overperforming on WAA, clippers that slow down and bomb out, etc. Give me a sneaky low riding along a cold front that just passed south of us a day or two earlier over trying to thread the needle on a Miller B or having to bank on enough ridging out west to allow a storm to bomb out in the right spot. Idk why, but we seem to do best when we least expect it. Our latitude likes simple.

Give me some help in the pacific and a high up north and I’ll gladly roll the dice.

[DarkSharkWX]

40 minutes ago, jayyy said:

Most of the events we see come from workable looks and not epic looks, tbh. Epic setups at 500 (PNA NAO AO EPO, etc) leaves NYC buried more often than us. Our area seems to like setups that produce sneaky events - overperforming on WAA, clippers that slow down and bomb out, etc. Give me a sneaky low riding along a cold front that just passed south of us a day or two earlier over trying to thread the needle on a Miller B or having to bank on enough ridging out west to allow a storm to bomb out in the right spot. Idk why, but we seem to do best when we least expect it. Our latitude likes simple.

Give me some help in the pacific and a high up north and I’ll gladly roll the dice.

Here is all of the 500h pattern for the major snowfalls our area has had since 2009-10 winter(excluding the major KU storms, and storms that only gave major snowfall to far far northern areas and/or high elevations). Just goes to show that we dont need a perfect pattern to score good snowfall in our area, some help from atlantic/pacific can be used well(as you said)
edit: oops accidently added december 13th instead of jan 13th

 

 

[DE2PA]

 

Back again with the 06z fantasy runs. 

[BristowWx]

21 minutes ago, DE2PA said:

 

Back again with the 06z fantasy runs. 

That would improve morale. I’m in until 12z..or the GEFS say no

[Solution Man]

1 minute ago, BristowWx said:

That would improve morale. I’m in until 12z..or the GEFS say no

Show me the next 4 days in a row, then maybe

[CAPE]

The GFS is pretty persistent with the wave on the 7th producing frozen somewhere in the MA. Not seeing that on other guidance, and the GEFS has not been very supportive of the idea to this point. The stronger signal across the ensembles is for around 11-12th, and at that point if the pattern progresses (favorably), we should have more cold available.

[DE2PA]

1 minute ago, CAPE said:

The GFS is pretty persistent with the wave on the 7th producing frozen somewhere in the MA. Not seeing that on other guidance, and the GEFS has not been very supportive of the idea to this point. The stronger signal across the ensembles is for around 11-12th, and at that point if that pattern progresses (favorably), we should have more cold available.

60 degrees to 16” in ~48hrs. What could go wrong?

[CAPE]

Speaking of the 12th, 6z GFS goes boom. A bit discombobulated and late developing the coastal low for our area but close to something big lol.

 

 

[CAPE]

Stronger signal on the 6z GEFS for a winter storm on the 6-7th, but mostly for PA northeastward into central/northern NE.