December Medium/ Long Range

[cbmclean]

6 minutes ago, CAPE said:

The GEFS has backed off on the idea of digging a trough out west the past few runs.

The extended products imply a trough could be back in the east the last week of December.

Weren't the euro weeklies you posted last night looking pretty good the week leading up to xmas?  Yeah yeah, I'm impatient.

[CAPE]

3 minutes ago, cbmclean said:

Weren't the euro weeklies you posted last night looking pretty good the week leading up to xmas?  Yeah yeah, I'm impatient.

Yes. The 0z EPS has more of a trough out west at the end of the run so the updated weeklies might look a bit different.

[jayyy]

Quick nostalgia… My greatest memory of a snowstorm run up was the march 4-6 2001 debacle. Yeah it was a bust but those model runs and you and Nor’easter posting about it were what weenie dreams were made of.

I remember texting you on AIM the morning of the December 30 2000 bust

Feels like it’s been ages since we had an event get better from day 7-9 inward. I guess because it has been


.

Didn’t we get two snowstorms last year, both of which trended in our direction in the last 48 hours? The ole create a new thread storm


.

[dailylurker]

1 hour ago, Eskimo Joe said:

Wonder if the long range stuff is models reverting back to climo state? We saw that last year where beyond D10 guidance kept trying to advertise a solid pattern that never materialized.

This is not a deb comment. It's just I've always wondered why models always show these super rare senerios beyond day 10. You think they would show more of a climo look. Not some rare blizzard at Cape Hatteras. We get modeled 200" a year from day 10+. You'd think models would show cutters and warmth as a default. Not 30" of snow on OC lol

[Eskimo Joe]

13 minutes ago, dailylurker said:

This is not a deb comment. It's just I've always wondered why models always show these super rare senerios beyond day 10. You think they would show more of a climo look. Not some rare blizzard at Cape Hatteras. We get modeled 200" a year from day 10+. You'd think models would show cutters and warmth as a default. Not 30" of snow on OC lol

Agreed. I wish operational guidance would stop at Day 7. Too much extrapolation beyond that. Let the ensembles take over after that.

[TSG]

46 minutes ago, dailylurker said:

This is not a deb comment. It's just I've always wondered why models always show these super rare senerios beyond day 10. You think they would show more of a climo look. Not some rare blizza7rd at Cape Hatteras. We get modeled 200" a year from day 10+. You'd think models would show cutters and warmth as a default. Not 30" of snow on OC lol

Speaking from a high level here as I only casually understand the inner workings of NWP models, but the main reason is it's a physical model rolling forward based on it's own predictions. A small error made in the first few days could easily lead to downstream effects that blow up to "super rare scenarios" by day 10+. "A goat fart is incorrectly modeled in Mongolia and that causes the PV to drop into NY 12 days later" as an over the top example. You can design the system with "bumpers" to try to keep it in reality, but too much limitation and you remove its usefulness as a forecasting tool if it essentially only ever shows "climo". 

[Weather Will]

Watch the MJO as we go through December.  Quicker it passes through warm phase 6 the better....

[Terpeast]

10 minutes ago, Weather Will said:

Watch the MJO as we go through December.  Quicker it passes through warm phase 6 the better....

it may be speeding up just a little… IIRC previous runs showed it still in 5 until the 11th or so

[MillvilleWx]

1 hour ago, WxUSAF said:

Webb posted this elsewhere, I think it’s Roundy’s low frequency forcing prog. It’s not always perfect, but this is a solid look by Xmas week. Maybe it’s rushing it a bit, but this pattern probably recycles throughout the winter and with a predominant -EPO, our source region will stay cold. 
 

Actually really like this look a lot. We can work with something like this. I just hope people here realize that this will end up being a N/S dominated regime and we'll need energy to dig in order to really get anything substantial. One thing I do think we have in our favor is colder temps will be around more often than not. Then it just comes down to timing something. If we get ANY blocking whatsoever, I would be really excited on the prospects. Fingers crossed!

[SnowenOutThere]

Latest GFS with yet another completely different evolution for the potential 8th storm. NS is completely absent while the southern energy looks mildly better than its 0z run

[midatlanticweather]

3 minutes ago, SnowenOutThere said:

Latest GFS with yet another completely different evolution for the potential 8th storm. NS is completely absent while the southern energy looks mildly better than its 0z run

The only consistency with these model runs is that they are consistently inconsistent! This run has quite a different look compared to the last!  

 

[WxUSAF]

 

[yoda]

12z GFS looks... weird?  At day 9

[Terpeast]

7 minutes ago, midatlanticweather said:

The only consistency with these model runs is that they are consistently inconsistent! This run has quite a different look compared to the last!  

 

Yep. It seems the models, esp the GFS, are completely lost as to handling the dec 8-11 system (we can’t even nail it down to a calendar day). Until we see multiple models converging onto a similar solution, nothing is off the table. 

[Maestrobjwa]

12 minutes ago, SnowenOutThere said:

Latest GFS with yet another completely different evolution for the potential 8th storm. NS is completely absent while the southern energy looks mildly better than its 0z run

Gotta wonder if this is an early clue of how tracking will be this year...chaos waves anyone? 

[SnowenOutThere]

Just now, yoda said:

12z GFS looks... weird?  At day 9

I think that is the only word to really describe its whole evolution. Has the southern energy finally eject but NS stuff keeps trying to phase or push it around?

[winter_warlock]

4 minutes ago, yoda said:

12z GFS looks... weird?  At day 9

Well its day 9. So... lol

[SnowenOutThere]

2 minutes ago, SnowenOutThere said:

I think that is the only word to really describe its whole evolution. Has the southern energy finally eject but NS stuff keeps trying to phase or push it around?

Ends with a messy sleet/ice storm thanks to a well placed high in Canada to give cold air damming while the 850s get toasted. 

[yoda]

5 minutes ago, SnowenOutThere said:

Ends with a messy sleet/ice storm thanks to a well placed high in Canada to give cold air damming while the 850s get toasted. 

Heavy ice storm FWIW lol

Close to half inch of ice into DC metro 

[Chris78]

That would be a heck of an ice storm with temps from the low 20's in the west to upper 20s closer in to the cities.

on top of a few inches of snow to start.

[Chris78]

Last 5 runs of thr Gfs.

It likes a storm in this time frame but who knows where at this point lol

As to be expected this far out. 

[Ralph Wiggum]

GFS et all have thrown everything and the kitchen sink at us for next weekend. Goes to show how many pieces are involved in trying to figure things out. I'm still hoping to eek out some flakes with the fropa on the 5th. Verbatim tho, that's a crippling ice storm for alot of folks in the interior this run.

[high risk]

1 hour ago, dailylurker said:

This is not a deb comment. It's just I've always wondered why models always show these super rare senerios beyond day 10. You think they would show more of a climo look. Not some rare blizzard at Cape Hatteras. We get modeled 200" a year from day 10+. You'd think models would show cutters and warmth as a default. Not 30" of snow on OC lol

        The reason is that, despite what one unnamed poster thinks, models are not driven by analogs and don't have climatological factors.    You start with an initial state and integrate the equations forward, and they take the solution wherever they take it.   

[high risk]

1 hour ago, TSG said:

Speaking from a high level here as I only casually understand the inner workings of NWP models, but the main reason is it's a physical model rolling forward based on it's own predictions. A small error made in the first few days could easily lead to downstream effects that blow up to "super rare scenarios" by day 10+. "A goat fart is incorrectly modeled in Mongolia and that causes the PV to drop into NY 12 days later" as an over the top example. You can design the system with "bumpers" to try to keep it in reality, but too much limitation and you remove its usefulness as a forecasting tool if it essentially only ever shows "climo". 

       I appreciate what you're trying to say here, and you were very much on the right track in saying that a small error at the start can lead to a massive error downstream 10 days later.     But you can't design a model like the GFS with "bumpers".     You can absolutely mitigate extreme solutions with bias-corrected, calibrated products, but the actual model solutions are what the model integration leads to.

[WEATHER53]

2 hours ago, Eskimo Joe said:

Agreed. I wish operational guidance would stop at Day 7. Too much extrapolation beyond that. Let the ensembles take over after that.

There is much wrong 

[WinstonSalemArlington]

39 minutes ago, yoda said:

Heavy ice storm FWIW lol

Close to half inch of ice into DC metro 

When was the last time a true ice storm verified inside the Beltway?

[Ji]

When was the last time a true ice storm verified inside the Beltway?

2007 or 1993

[Ji]

I’ve never seen Bamm weather so into a winter

[RedSky]

39 minutes ago, Ralph Wiggum said:

GFS et all have thrown everything and the kitchen sink at us for next weekend. Goes to show how many pieces are involved in trying to figure things out. I'm still hoping to eek out some flakes with the fropa on the 5th. Verbatim tho, that's a crippling ice storm for alot of folks in the interior this run.

How much kitchen sink for Philly?

 

[aldie 22]

12 hours ago, Ji said:

This winter is cooked. It’s played its cards already and we lose again

Yeah probably