December 2019 Med/Long Range Disco

[WinterWxLuvr]

We had snow the day after Christmas in 2012. We had snow on the night of the 29th in 2017. Those two I remember clearly. There may be others.

[JakkelWx]

[BristowWx]

8 minutes ago, JakkelWx said:

Is there an 850 temp for that?  I can’t see one on TT. Just curious

[JakkelWx]

19 minutes ago, BristowWx said:

Is there an 850 temp for that?  I can’t see one on TT. Just curious

There isn't one on TT, but there is one on Pivotal. https://www.pivotalweather.com/model.php?m=gefs&p=850th&rh=2019121318&fh=loop&r=conus&dpdt=&mc=

Edit: Wrong image

[psuhoffman]

2 hours ago, C.A.P.E. said:

It wont matter. That's a rainstorm. And that is not blocking- it is a fairly transient upper ridge. In order to overcome a hostile Pac, a legit block that actually extends into the NA for multiple days, with a quasi-stationary 50-50 low stuck underneath, would give us a fighting chance.  Bootleg stuff- an h5 ridge near GL with a blue ball racing northeastward through the 50-50 region, is a thread the needle deal, and indicative of a lack of  true blocking. Outside of perfect timing/a lot of luck, that likely wont work out well for the majority of our region, esp when the EPAC is hostile.

I agree with the rainstorm diagnostic but I do think we are seeing legitimate blocking. We never saw anything like this last year when any negative NAO was purely a transient ridge just passing though. This is a legit block. 

And the only reason it’s isnt more long lived is the tpv splits and it gets absorbed into the full latitude ridge. But ridging over the top persists and if the jet cuts under it would be a legit block again. We had one other nice block a couple weeks ago and it lead to a perfect track upper low but the antecedent airmass was crap.  Blocks won’t just sit stationary over GL for long stretches. The best though wax and wane and oscillate around reforming and persist for weeks or months.  If there isn’t a hostile factor to destructively interfere they can create a feedback loop where storms are forced under through the 50/50 domain and the wave breaking there feeds the NAO ridge.  50/50s don’t usually sit forever either. They have to move out or storms would get suppressed and nothing would ever turn up the coast. But with good blocking the next system takes its place and on the means there is a net negative there throughout.   The pac is running major interference. If we repeat the blocking later we should be ok.  

[Maestrobjwa]

21 minutes ago, WinterWxLuvr said:

We had snow the day after Christmas in 2012. We had snow on the night of the 29th in 2017. Those two I remember clearly. There may be others.

We did? What was it, a few flurries or a dusting? Lol

[BristowWx]

15 minutes ago, JakkelWx said:

There isn't one on TT, but there is one on Pivotal. https://www.pivotalweather.com/model.php?m=gefs&p=850th&rh=2019121318&fh=loop&r=conus&dpdt=&mc=

Edit: Wrong image

Thanks man.   If I clicked the right button it looks below 0C...but I am plow housed so who knows. 

[yoda]

1 minute ago, BristowWx said:

Thanks man.   If I clicked the right button it looks below 0C...but I am plow housed so who knows. 

Just look for the blue and green combo... thats the 0C line

[Ralph Wiggum]

33 minutes ago, BristowWx said:

Is there an 850 temp for that?  I can’t see one on TT. Just curious

Surface temps. As you already know pretty much useless at this range irt r/s stuff but useful for showing there is cold air around and available on the GEFS.

[WinterWxLuvr]

4 minutes ago, Maestrobjwa said:

We did? What was it, a few flurries or a dusting? Lol

No. The 2012 was about 6” and the 2017 was about 1.5”. 2012 also had about 3” on Christmas Eve.

This is in Winchester

[Maestrobjwa]

8 minutes ago, WinterWxLuvr said:

No. The 2012 was about 6” and the 2017 was about 1.5”. 2012 also had about 3” on Christmas Eve.

This is in Winchester

Ah that explains it (sorry I can't see people's location tags on the mobile version, lol) Was about to say...6 inches doesn't happen on the last week of December in the cities! Haha

[Ralph Wiggum]

Nobody mentioned the GEFS 5-day 2m temp avgs thru the entire run are BN aside from 1 AN panel at the start and a N panel. Really believing the moderation is going to be muted and transient. Alas, it is the GEFS but verification hasn't been shoddy lately.

[psuhoffman]

Almost a total cave to the euro on the Dec 22 storm. Gfs went from the idea of sliding the upper low across the south to cutting it through Minnesota in one run. It still holds onto some stj wave but mostly it was a cave to the euro. 

[yoda]

00z GFS has a large cutoff h5 low Day 9 into Day 11 off the coast of CA lol

ETA: still there Day 12

[cbmclean]

9 minutes ago, psuhoffman said:

Almost a total cave to the euro on the Dec 22 storm. Gfs went from the idea of sliding the upper low across the south to cutting it through Minnesota in one run. It still holds onto some stj wave but mostly it was a cave to the euro. 

Eh, only took it until D8/9 to cave.  The more painful ones are when it is insistent at like D4/5 and then caves.

[BristowWx]

I might be hallucinating but it looks like at hour 240 on the Euro a tropical storm is forming off the EC of FL on Xmas Eve.  

[showmethesnow]

I know the two maps below are ominous looking as we see a full latitude trough entering the western US. But take note with what we are seeing within the red circle as the EPS and the GEFS move forward in time. 

 

 

 

 

Note that we are seeing the trough hold strong from the pv down to just off the SW coast (even through the red circle) as evidenced by the height lines and stronger pressure anomalies. Also notice were the ridging has set up in the Pacific.

 

 

Now let's see what the GEFS has to offer. That ridging that we see far off the coast on the EPS is much farther east on the GEFS and driving through the red circle. What this is doing is breaking down the full latitude trough and its connection to the pv to the north. So what we are seeing is essentially the beginnings of a split flow setting up as we have a building northern based PNA/-EPO over cutting the SW weakness/low. Once this sets up it effectively begins to shut off the PAC flow into the central and eastern US as we now have a mechanism for delivering cold into those regions.

 

You can see the differences with temps between these two solutions through the torch period. EPS has almost CONUS wide warm anomalies whereas the GEFS is much more muted with even seasonal to slightly below in the east. 

 

 

 

Now the question is, which is right? Considering the key feature, the PAC ridging, starts diverging around roughly day 7 we probably won't have too long to wait. Though the GEFS may be rushing it somewhat at this time I myself favor the GEFS solution as it plays into the general look the pattern has favored into the NW and Alaska so far this season. The EPS makes a weak attempt to achieve this look and yet never gets there as it once again plants lower heights into that region at the end of the run. I just don't buy its evolution.

When all is said and told I believe the impacts we will see in the East from the PAC flood will be minimal at best with maybe a day or two of a mild warmup. We may not even see that depending on whether the N Atlantic (blocking, 50/50s) can cooperate and keep some form of troughing in the east and along with that seasonal temps.

[CAPE]

@showmethesnow

Nice write-up. I am inclined to agree. Probably the warmest periods we see will be when we get into the warm sector of storms taking unfavorable tracks, which will be brief. At this point I doubt we see a period with multiple sunny days and temps in the 50s and 60s.  The NA should be favorable enough to keep the immediate east coast on the cool side. That being said, chances of seeing a region wide legit frozen event going forward towards Christmas looks pretty low at this point. If the pattern evolves ideally, the days thereafter might get more interesting.

[showmethesnow]

IF.....the GEFS is somewhat right with its evolution/timing of the PAC ridging this potentially sets us up a very sweet look for us. Now it takes more then just a sweet look to score, as there are many other factors involved. But give me this look in real time and not in model fantasy land and I would be salivating.

(***Just a followup to my previous post. Look at what we are seeing in the west. PV extension west of Alaska, -EPO/+ NPNA, SW weakness/low. It should look familiar to you as we have seen it quite often so far this year. One of the reasons I favor the GEFS over the EPS at this time***)

 

EPS is just a short step away from having a very similar look to what we see with the GEFS above. We see that ridging extending up into Alaska and we end up with that same sweet look.

 

[frd]

 

I have been harping on this for over a year, and it continues, another record as well.  The Pac hyper jet. 

And, this is in a backdrop where we have been rather lucky in this region as most of the country has been above normal temp-wise through the 12 th.  

I would bet if  improvements in the Pac evolve, including some +PNA support,   a moderate snow event is soon in the cards for us. 

The Pac jet is too difficult to be modeled correctly at times, add to this the MJO progression and other associated variables, plus standing wave and it is a complex mess. 

from a met , purduewx80 on the NYC forum:

<<

Speaking of the raging Pacific jet - Boise, ID set a new 250mb wind speed record today - 173KT at 12Z vs. the previous record of 169KT. Records there go back to 1948.

 

 

 

[Mr. Kevin]

My money is on the eps 9/10 times. HM said the standing wave is weakening and the warm pattern advertised is a product of the +IOD decreases with the lag effect. Alot of unknowns imo. HM is brilliant, but people sometimes over exaggerate things. 

I wanted to add that there are varying opinions out there, but the main thing is why are we even seeing this warmer pattern advertised on the eps and why is the Pacific not favorable for cold moving forward? 

[psuhoffman]

@showmethesnow I feel like the eps and gefs are nearly identical long range if we account for their tendencies this year. A compromise is likely, and frankly wouldn’t be a bad look. The eps wasn’t far from a good look past day 10. 

[LurkerBoy]

I mean, Tuesday of next week is a torch. We won’t be avoiding any torch because it’s already on the way.

[showmethesnow]

1 minute ago, LurkerBoy said:

I mean, Tuesday of next week is a torch. We won’t be avoiding any torch because it’s already on the way.

I don't know if I would call one day worth of warmth a torch. And that is more so for down in your local (NC) vs up in our region where the northern sections may not even get out of the 30's. Even the southern and eastern portions of the region see only a brief half day warm up at best. 

And this brief warm up isn't even associated with the EPS advertised PAC flood it is just a natural response of a trough moving into our region.

[stormtracker]

So the GFS...looks..kinda interesting at 156?

[showmethesnow]

14 minutes ago, psuhoffman said:

@showmethesnow I feel like the eps and gefs are nearly identical long range if we account for their tendencies this year. A compromise is likely, and frankly wouldn’t be a bad look. The eps wasn’t far from a good look past day 10. 

I agree. I am actually liking what we are starting to see through this period (EPS advertised PAC flood) as it nears in time. But it is a fine line between the solutions given by the EPS and the GEFS for our sensible weather in the extended. And as you said a compromise is more then likely but I just happen to weight the GEFS more then I do the EPS which if true would probably put us in a pretty good place.

[BristowWx]

Just now, stormtracker said:

So the GFS...looks..kinda interesting at 156?

Back to 1040+ high in better location.  Interesting development 

[WinterWxLuvr]

1 minute ago, stormtracker said:

So the GFS...looks..kinda interesting at 156?

Very. Look up in Quebec

[showmethesnow]

1 minute ago, stormtracker said:

So the GFS...looks..kinda interesting at 156?

Get that confluence in the NE to hold a little longer and it would be interesting very quickly.

[stormtracker]

Just now, BristowWx said:

Back to 1040+ high in better location.  Interesting development 

Check the H5 map.   It's a wholly different solution