December 2019 Med/Long Range Disco

[midatlanticweather]

4 minutes ago, psuhoffman said:

GEFS goes ape with the epo ridge in early December and floods the whole conus with cold. Enough SE ridge though to suggest the boundary would be close enough for some threats.  That kind of a pattern is when some SE ridge isn’t a bad thing. Otherwise it would just be cold and dry. 

hmmmmm.. 2013 - 2014 redux??? 

Hope so!

 

[yoda]

wonder if its the usual EURO bias... but thats a slow moving cut off low in the SW on the 12z EURO at h5 Days 8 and 9... actually migrates southward down the West Coast from Day 6 to Day 9

ETA:  Finally being kicked out on Day 10

[psuhoffman]

14 minutes ago, midatlanticweather said:

hmmmmm.. 2013 - 2014 redux??? 

Hope so!

 

Actually you couldnt get a better H5 match to the long range GEFS look than early December 2013.  DC south didn't do so well (frankly their climo early December is a BIG problem) but everywhere NW of there had a pretty good run with several snow/ice events during that period.  Of course everyone won when that look repeated again and again during prime climo.  

 

[frd]

@psuhoffman  very interesting thread here if you read all the replies  from HM. 

Over at 33 Isotherm and others talk about the atmosphere's , AAM, momentum budget , GLAMM, etc. and why they foresee a warm up in December while reading between the lines here it appears Anthony has other ideas. This stuff is awesome to read about. 

     

 

[jaydreb]

EPS breaking down the -NAO by the end of the first week of December but in the process this seems like a pretty good look to my untrained eye.  

 

[WxUSAF]

^I’d take that look in a second. Eps D10 looks very nice and that D15 looks good too. Notice how the NAO breakdown keeps happening at D13+ in each ensemble mean. It’s not getting any closer. Yet at least. And the return of the -EPO for early December is becoming more likely. I also like how the Eps has the EPO ridge axis closer to the west coast. Sign me up.

[psuhoffman]

34 minutes ago, WxUSAF said:

^I’d take that look in a second. Eps D10 looks very nice and that D15 looks good too. Notice how the NAO breakdown keeps happening at D13+ in each ensemble mean. It’s not getting any closer. Yet at least. And the return of the -EPO for early December is becoming more likely. I also like how the Eps has the EPO ridge axis closer to the west coast. Sign me up.

 

If this becomes an epo dominant pattern something to keep in mind was how ( Ithink it was 2013/14) the guidance kept muting the epo ridge in the long range and absent NAO help torching us. That of course never happened. 

[psuhoffman]

One other thing wrt an epo pattern, there isn’t much correlation between the epo and snow. But that’s because a west based or shallow epo ridge doesn’t help at all.  But when the epo ridge is east based or builds over the top into Canada it does seem to correlate with snow here better. 

[WxUSAF]

6 minutes ago, psuhoffman said:

One other thing wrt an epo pattern, there isn’t much correlation between the epo and snow. But that’s because a west based or shallow epo ridge doesn’t help at all.  But when the epo ridge is east based or builds over the top into Canada it does seem to correlate with snow here better. 

Yeah, that’s the key. Have that ridge onshore and we’re in a decent spot. Throw in a tendency for -NAO and a 50-50 and oh boy...

[showmethesnow]

1 hour ago, psuhoffman said:

One other thing wrt an epo pattern, there isn’t much correlation between the epo and snow. But that’s because a west based or shallow epo ridge doesn’t help at all.  But when the epo ridge is east based or builds over the top into Canada it does seem to correlate with snow here better. 

You are pretty much talking a EPO/PNA combo with the ridging running up at least the northern west coast. Sort of what is being advertised in the longer range at this time.  

[frd]

 

I hope some of this is white.

 

[CAPE]

For anyone interested in today's edition of the weeklies - here are the 7 day height and temp anomalies a week or so beyond the end of the 0z EPS. Takes us out to mid Dec. Usual disclaimer..not a big fan of this tool in general, but that being said, I don't hate this look.

[CAPE]

^Totally a gradient pattern look. Given climo, I would love that if I were in NE.

[Eduardo]

1 hour ago, psuhoffman said:

 

If this becomes an epo dominant pattern something to keep in mind was how ( Ithink it was 2013/14) the guidance kept muting the epo ridge in the long range and absent NAO help torching us. That of course never happened. 

LR models constantly pushed back the breakdown of that rocking -EPO pattern in 2013-14 just as they constantly pushed back the breakdown of last year’s mess.  

Hoping this year follows in 13-14’s footsteps and a “deep winter” like that sets in.  Keep that icy arctic cold nearby and good things will happen for everyone!  

[psuhoffman]

44 minutes ago, showmethesnow said:

You are pretty much talking a EPO/PNA combo with the ridging running up at least the northern west coast. Sort of what is being advertised in the longer range at this time.  

We can survive a -pdo if the epo ridge builds over the top into NW Canada which suppresses the flow across the conus some. Problem last year was even when we had an epo ridge it was centered too far west which allowed the se ridge to pump. 

[frd]

Weeklies are trash,  but I find this look very ironic for the period, especially in view of the regular post 12/20 warm ups recently,  right in time to mess up my eternal hopes of a White Christmas! 

 

[Bob Chill]

44 minutes ago, psuhoffman said:

We can survive a -pdo if the epo ridge builds over the top into NW Canada which suppresses the flow across the conus some. Problem last year was even when we had an epo ridge it was centered too far west which allowed the se ridge to pump. 

My biggest question is whether or not the models are rushing or flat wrong about the ao/nao going positive in 2 weeks or less. The nao block coming up was totally missed from long range.

[frd]

Does the nature of the EPO block wreck havoc on the previous NAO block? .

I read the Pac block will aide in the destruction of the NAO. You can not have both that extreme for such a long duration. 

Any thoughts on that. 

I know Isotherm had mentioned the NAO block would be transient . I mention these things understanding I am referencing a Day 11 to 16 forecast.   However, pretty sure last winter might have touched on this topic. 

If am interpreting HM's postings correctly than I am guessing he is anticipating possibly more -NAO this winter.  

And,  he did say recently the weeklies are "useless " ! 

[Bob Chill]

If we lose the -ao/nao and get a massive epo ridge going like we're seeing it changes the way we can get snow. It's a tradeoff because we basically need sig temp help in early Dec. Especially I95 eastward. The big epo can def deliver big cold and it's looking more likely as we move towards Dec. 

The bad part of the pattern is cold highs will be on the move and luck/timing becomes more important. Rain, flawed, and mixed events are the most common during -epo/+nao patterns and they can be very frustrating with cold running away before precip. 

I'll only get worried if a shutout pattern shows up. Right now all signs point to early Dec not being hostile. Can't ask for much more than that. 

[Mr. Kevin]

3 hours ago, Bob Chill said:

If we lose the -ao/nao and get a massive epo ridge going like we're seeing it changes the way we can get snow. It's a tradeoff because we basically need sig temp help in early Dec. Especially I95 eastward. The big epo can def deliver big cold and it's looking more likely as we move towards Dec. 

The bad part of the pattern is cold highs will be on the move and luck/timing becomes more important. Rain, flawed, and mixed events are the most common during -epo/+nao patterns and they can be very frustrating with cold running away before precip. 

I'll only get worried if a shutout pattern shows up. Right now all signs point to early Dec not being hostile. Can't ask for much more than that. 

Bob, do you think we have a ways to go since the -pna looks to last for a while? Troughing on west coast isnt what you want to see imo for sustained cold. I guess the main reason for the -pna is perhaps the unfavorable mjo?

[WEATHER53]

We’ve got solid to extreme high pressure from Alaska to Mongolia and it’s not breaking down 

[OSUmetstud]

11 hours ago, frd said:

 

I hope some of this is white.

 

The king of weenie maps

[Wonderdog]

Cutter after cutter on 6z GFS until maybe hour 384. I think I've seen this before. Of course, winter is still a month away.

[CAPE]

30 minutes ago, Wonderdog said:

Cutter after cutter on 6z GFS until maybe hour 384. I think I've seen this before. Of course, winter is still a month away.

Cutters wont stop happening because its winter. 

Met winter starts Dec 1.

6z GFS op run probably doesn't have the next 15 days nailed.

[Wonderdog]

12 minutes ago, C.A.P.E. said:

Cutters wont stop happening because its winter. 

Met winter starts Dec 1.

6z GFS op run probably doesn't have the next 15 days nailed.

Of course you're right. Although I've always wondered why DEC. 1st is the beginning of Met winter especially in the MA.

[Ralph Wiggum]

Seems that since the HH run a few evenings ago when this thread was brimming with confidence irt the LR -EPO/-AO/-NAO trifecta looks things have become more muted in the LR especially in the AO/NAO regions  on some guidance as the PAC is taking on the dominant player look and is trying to show signs of running the show as early as day 8. As usual, grain of salt past 240. But we can see the NAO goes negative as early as Sunday but around the same the time or soon after, the EPO ridge is beginning to try and flex which is the new player on the field emerging. With that said, where we were once seeing the NAO establish and bleed into the AO the pulsing EPO appears to dampen out any HP over the pole while the NAO slowly fades. You can also see on the ens how the EPO starts a bit west and in turn pumps a SE and even an argument for a S Central ridge before migrating towards the west coast (hopefully but again that is post 240). Like someone said, it is refreshing to see a 50/50 pop now and then so with an EPO ridge and no NAO it has that transient quick-hitter kind of look thump to you know what sorta flow if that pattern held during early climo. So not a total fail nor a total victory sort of pattern coming up. Just one where caution is still urged and I'm not sure anyone knows where this is going to head in Dec right now. Thanksgiving week as stated is going to be a transitional week....it is either a reload as the pattern relaxes and resets or a complete reshuffle of the deck where we start seeing the PaC play bully and push the Atl around as has been so common in recent years.

(Attached are the EpS and GEFS day 10....big diffs at HL. FWIW the GEPS is more like the EPS in keeping the NAO neutral/neg.)

[CAPE]

18 minutes ago, Wonderdog said:

Of course you're right. Although I've always wondered why DEC. 1st is the beginning of Met winter especially in the MA.

In meteorology, every season is 3 full months. Makes much more sense than the sun angle deal.

[Weather Will]

Quick look at the 6z and not sure why there is so much negativity.  It is not going to be  much above normal the next two weeks, there is a lot if cold air lurking to the North, and most importantly to me an active storm track.  Any snow In December is bonus snow...let it play out!

[WinterWxLuvr]

30 minutes ago, C.A.P.E. said:

In meteorology, every season is 3 full months. Makes much more sense than the sun angle deal.

Yeah but the reality is that most of March is a winter month. More so most years than early December. So I would actually think our winter lined up more with the solstice to equinox than to the calendar.

[pasnownut]

53 minutes ago, C.A.P.E. said:

Cutters wont stop happening because its winter. 

Met winter starts Dec 1.

6z GFS op run probably doesn't have the next 15 days nailed.

if one looks a the 500's wrt Op and Ens....they are notably different.  Ens looks just fine for now, and for whatever one believes in LR guidance, I'll roll with the ENS (also because I like that look much more.)