December Medium/Long Range Discussion

[WinterWxLuvr]

8 minutes ago, JakkelWx said:

 

 

Those are money. Take that one to the bank

[Maestrobjwa]

9 minutes ago, Eskimo Joe said:

A nice 2" - 4" regionwide Christmas eve would be stellar.

It would be almost magical...and again, if there was ever a year we needed it, it's this year!

[Maestrobjwa]

Just now, WinterWxLuvr said:

Those are money. Take that one to the bank

Why does the modeled precip look all smeared in the LR graphics anyway? Is that just what the computers do?

[WinterWxLuvr]

1 minute ago, Maestrobjwa said:

Why does the modeled precip look all smeared in the LR graphics anyway? Is that just what the computers do?

I have no idea.

[NorthArlington101]

eh... maybe I am slightly interested in Sunday. A little snow TV with a low-stakes upside of 1.5" or so.

[Eskimo Joe]

13 minutes ago, NorthArlington101 said:

eh... maybe I am slightly interested in Sunday. A little snow TV with a low-stakes upside of 1.5" or so.

Any snow is good snow. Snow on snow that reinforces cold for more snow is even better. Snow during the holidays is the best. Snow during the holidays that reinforces cold for more snow is the bestest. It's a simple four step pyramid that leads the way to success.

[Eskimo Joe]

2 minutes ago, JakkelWx said:

Snow on snow that reinforces cold for more snow on top of snow that reinforces even more cold air for even more snow on snow?

[howrdcounty snow]

new member

[Heisy]

46 minutes ago, Maestrobjwa said:

Why does the modeled precip look all smeared in the LR graphics anyway? Is that just what the computers do?

I mean the gfs is basically a cold front near Christmas. Not saying that’s what it’ll be but that’s why it looks like that

[Heisy]

43 minutes ago, NorthArlington101 said:

eh... maybe I am slightly interested in Sunday. A little snow TV with a low-stakes upside of 1.5" or so.

How’s it look through 115 hours or so. Curious if any ensembles developed a low off the coast

[NorthArlington101]

6 minutes ago, Wentzadelphia said:

How’s it look through 115 hours or so. Curious if any ensembles developed a low off the coast

Most interesting/busy panel.

[Rhino16]

35 minutes ago, Eskimo Joe said:

Any snow is good snow. Snow on snow that reinforces cold for more snow is even better. Snow during the holidays is the best. Snow during the holidays that reinforces cold for more snow is the bestest. It's a simple four step pyramid that leads the way to success.

The reaper should start a Snow MLM scheme...

[Weather Will]

28 minutes ago, howrdcounty snow said:

new member

Welcome!

[Roger Smith]

The 40" event around BGM and 30" generally from there to central NH could pay some dividends for your region eventually. That snow pack is going to be there until there's two weeks of thaw (maybe late Feb to Mar) so any time good synoptics show up, any arctic highs ahead of snowfalls should be beefed up over the inland northeast.

From this GFS run, would tag the period Jan 3-5 as promising, there's deep winter cold showing up for several days before that and a strong low diving southeast into the plains states at end of the run (Jan 2). Would have to suspect that might recurve around the Carolinas into a powerful nor'easter. 

The Christmas Day event looks at this point like a flash freeze, near 60 on the 24th, near 20 on the 25th. Probably a region wide dusting from that, 1-3" max potential. Will be more interesting for the temperature drop. 

[psuhoffman]

1 hour ago, PivotPoint said:

Honestly, if we can ditch any Aleutian low and get ridging up around AK, continue a -AO regime with even a neutral to slightly negative NAO... that’s a good look for us. The southern jet is active. I’m not quite sure why that is. My understanding is La Niña doesn’t feature the southern stream but I feel like this weak Nina to neutral ENSO state has kept the juice flowing. I like the period after the big (potential) cold period right after Xmas. Dive that AO down and have the NAO switch directions heading up. Good signal for a Miller b that can toe the line as NAO relaxes a bit.

NAO hanging around neutral isn’t a horrible look for us as long as AO goes negative and PNA isn’t a rager. One thing I’ve learned in the mid-Atlantic... a -AO is almost better then a -NAO because when the NAO goes real negative we get suppression. And NC wins. And that sucks

Yes this. Wes did an amazing correlation chart and DC snow correlates to the AO more then any other single factor. Adding to this...if you want a HECS then you need a -NAO. Only one of our region wide 18”+ storms in the last 50 years didn’t have a killer block and that one PD2 featured a perfectly timed Arctic high. We got kinda lucky. But that still changed to a LOT of sleet...so had timing been any less perfect...you get it. But oddly the really big ones that feature a great block also usually feature what under a non blocking regime would be a bad pacific. I talked about this some in the snow climo thread. Our HECS look is a weird combo that doesn’t work under normal circumstances. That kind of block would often suppress an event...but a trough near AK that amplified the ridge/trough downstream or a trough crashing the west that tries to ridge in the east actually helps get something to force its way up into what is likely locked in cold and a high pressure due to the confluence. It’s a weird combo that leads to those crazy anomaly storms. But if we just want snow...a good old fashioned warning event snowstorm, a -AO and a PNA or EPO ridge are the way to go. 

[JakkelWx]

7 minutes ago, psuhoffman said:

But if we just want snow...a good old fashioned warning event snowstorm, a -AO and a PNA or EPO ridge are the way to go

Good thing a moderate to strong -AO like the one we have right now usually correlates to a -NAO. But sometimes even with a -NAO and 50/50, it can still fail if the block is too far north and the 50/50 low moved out too fast like this storm we just had.

Or am I wrong about the -AO/-NAO correlation?

[psuhoffman]

49 minutes ago, JakkelWx said:

Good thing a moderate to strong -AO like the one we have right now usually correlates to a -NAO. But sometimes even with a -NAO and 50/50, it can still fail if the block is too far north and the 50/50 low moved out too fast like this storm we just had.

Or am I wrong about the -AO/-NAO correlation?

There is some overlap of the domains so usually yes. This pattern we had was good enough imo.  This is kind of a perspective thing. CAPE isn’t wrong that had the block been centered further south it could have shifted the confluence south and limited the ridging and warm surge ahead of the low. But then if the system hasn’t dug so far west it also could have suppressed the whole thing!  Had we got a better mid level pass and close we would have been ok. Plus we are still suffering the effects of the November continent wide torch in that the cold was shallow. Not true arctic air. So no it wasn’t the best most perfect pattern ever but we’ve had tons of snow in worse looking patterns. I would be happy this this look keeps repeating. Especially mid winter we can do just fine with the block centered in the AO domain with some ridging extending into Greenland.  But December isn’t forgiving around here. Like I said yesterday it’s easier to snow before Xmas with a progressive wave that doesn’t pull in the warmth from the Atlantic. Amplified coastals are a really tough sell this early. 

[CAPE]

1 hour ago, psuhoffman said:

Yes this. Wes did an amazing correlation chart and DC snow correlates to the AO more then any other single factor. Adding to this...if you want a HECS then you need a -NAO. Only one of our region wide 18”+ storms in the last 50 years didn’t have a killer block and that one PD2 featured a perfectly timed Arctic high. We got kinda lucky. But that still changed to a LOT of sleet...so had timing been any less perfect...you get it. But oddly the really big ones that feature a great block also usually feature what under a non blocking regime would be a bad pacific. I talked about this some in the snow climo thread. Our HECS look is a weird combo that doesn’t work under normal circumstances. That kind of block would often suppress an event...but a trough near AK that amplified the ridge/trough downstream or a trough crashing the west that tries to ridge in the east actually helps get something to force its way up into what is likely locked in cold and a high pressure due to the confluence. It’s a weird combo that leads to those crazy anomaly storms. But if we just want snow...a good old fashioned warning event snowstorm, a -AO and a PNA or EPO ridge are the way to go. 

The primary reason a -AO is number one when it comes to DC snow is it means the PV isn't a super wound up ball of doom, with all the cold locked up in the high latitudes. When there is a real deal -AO it reverses the "natural order", and allows anomalous cold to move into the midlatitudes with relative ease. As you said, we still want some NA blocking as it greatly increases chances for a favorable storm track underneath, and it is pretty much a requirement for an HECS as it inhibits a coastal storm from flying up the coast. Ofc 2009-2010 was the classic example of  a negative AO/NAO working the magic.

[Buddy1987]

Do I really want to invest in Sun/Mon? There was a lot of exertion from last storm. Guess that’s why we all enjoy being on here. 

[BristowWx]

2 minutes ago, Buddy1987 said:

Do I really want to invest in Sun/Mon? There was a lot of exertion from last storm. Guess that’s why we all enjoy being on here. 

I would t...I see bad things happening.  Very bad things. 

[JakkelWx]

23 minutes ago, BristowWx said:

I would t...I see bad things happening.  Very bad things. 

We do bad very goodly here.

[JakkelWx]

[cbmclean]

33 minutes ago, JakkelWx said:

I am unsure how to interpret this chart.  Can you help?

[JakkelWx]

3 minutes ago, cbmclean said:

I am unsure how to interpret this chart.  Can you help?

It looks like the SPV is going to soon downwell into the tpv. 

Its game time.

[cbmclean]

Just now, JakkelWx said:

It looks like the SPV is going to soon downwell into the tpv.

I understand what the SPV and TPV are and that they are usually distinct entities.  What happens when the SPV downwells into the TPV?

[psuhoffman]

1 minute ago, cbmclean said:

I understand what the SPV and TPV are and that they are usually distinct entities.  What happens when the SPV downwells into the TPV?

The bottom line is there are indications the PV might be a weakling this winter. That is opposite what we’ve had recently. 

[cbmclean]

2 minutes ago, psuhoffman said:

The bottom line is there are indications the PV might be a weakling this winter. That is opposite what we’ve had recently. 

Last year especially the strength of the PV was truly sickening to behold.  Perhaps the most demoralizing part was the fact that modeling picked it up so early and it advanced forward in time so remorselessly.  I am still scarred by your infamous post from December 30th of last year highlighting the historical results from past analogs to the pattern then forecast, absent extensive NA help. 

[North Balti Zen]

44 minutes ago, cbmclean said:

What happens when the SPV downwells into the TPV?

Dr. Peter Venkman: This forum is headed for a disaster of biblical proportions.
Moderator: What do you mean, "biblical"?
Dr. Raymond Stantz: What he means is Old Testament, Mr. Moderator, real wrath-of-God type stuff. Cold you can see and icebergs coming down from the sky! Rivers and the Chesapeake freezing solid!
Dr. Egon Spengler: Forty years of darkness! Ji saying it is too much snow, EJ calling "uncle"...
Winston Zeddmore: The dead rising from the grave! The panic room abandoned!
Dr. Peter Venkman: Human sacrifice, Phineas and Amped no longer trolling  - MASS HYSTERIA!

[psuhoffman]

27 minutes ago, cbmclean said:

Last year especially the strength of the PV was truly sickening to behold.  Perhaps the most demoralizing part was the fact that modeling picked it up so early and it advanced forward in time so remorselessly.  I am still scarred by your infamous post from December 30th of last year highlighting the historical results from past analogs to the pattern then forecast, absent extensive NA help. 

By mid December I knew we were in trouble...and by Xmas I knew we were completely screwed and likely headed for a total dud winter.  We were looking at a combination of the worst possible pacific pattern and NAM state possible...and judging by the onset of those two patterns combined with the typical duration of both when they present at that level of anomaly...history said both were likely to continue through the majority of our snow climo.  The history of such years with that pacific and high latitude look was really ugly. 

Right now everything up top looks more favorable.  The pacific is more murky.  The Euro weeklies resume the central pac ridge look week 3 and keep it locked in straight through...there is a -AO most of the time but mostly ruined by the awful pac.  However...the models were doing that by Xmas not long ago and then backed off.  It seems they "think" we should be going to that out in time...but like it past years when they thought things would get better, keep pushing that look out.  What has ended up the reality is a mediocre but not completely hostile pacific.  If that continues and the AO remains negative we should have a decent winter.  So far things look better then I expected.  

[Snowchaser]

Hmmm this looks very interesting for early next week.