December 2019 Med/Long Range Disco

[WinterWxLuvr]

The GFS op is cool. Blows about 3 big storms right off the se coast. Not sure I’ve ever seen that

[Bob Chill]

5 minutes ago, WxUSAF said:

Bob, I agree that I think we'll get there eventually.  Whether it's on Dec 29 like the GEFS thinks, some compromise of Jan 3rd-ish, or probably Jan 7 or after as EPS might suggest (via extrapolation), I don't know.  I'd probably chicken out and lean toward a compromise of the first few days of January if I had to pick.  

One thing I came across in reading this morning is that there's a pretty huge snow cover deficit in Eastern Europe and western Russia.  Always a bit of chicken-and-the-egg situation, but that might help bolster the Scandanavian ridging that keeps reloading the east -NAO and occasionally west -NAO and can be seen clearly on your CFS map above.  

@griteater linked me up to the full member suite. Check out all 20 GEFS members. 17 are either a winter pattern overhead or very close to one... Either the GEFS is off on a wild tangent or it's going to score the coup on this. 

[frd]

Just now, WinterWxLuvr said:

The GFS op is cool. Blows about 3 big storms right off the se coast. Not sure I’ve ever seen that

Can't deny the STJ so far this season...........  eventually you have to think they time up correctly for us.  

[WxUSAF]

Just now, frd said:

Can't deny the STJ so far this season...........  eventually you have to think they time up correctly for us.  

Trend for strong southern stream shortwaves rolling across the country the last 2 months is clear. Have to think odds of a widespread big dog storm is higher than normal when you add in the trend of HL blocking. Still maybe less than 50-50 odds, but still above normal.

[Yeoman]

5 hours ago, Weather Will said:

Sure.  Looks like mid 40s for Christmas at this time.  View it as perfect weather to see family and friends.

I prefer low 50's for family and friends

[tombo82685]

58 minutes ago, WxUSAF said:

GEFS and Eps diverge significantly after D10 as has been said, but they’re very similar at D10. One subtle difference between them at D10 is the one that loads a good pattern for us on the GEFS and bad on the Eps. On the Eps at D10, the TPV is stronger and slightly more NW (poleward) relative to the GEFS. GEFS has the TPV a bit weaker and then moves it southward over Hudson Bay after D10. Eps keeps it at high latitudes and leaning toward Alaska. The tropical forcing and the wave 2 hit on the strat vortex peaking around Xmas suggest an evolution like to GEFS should happen eventually, but wouldn’t be surprised if it’s after the new year and not a few days before like the GEFS has.

The thing that has me skeptical on the GEFS faster return is how it's handling the tropical forcing. It seems to me it's rushing the convection to fast into WPAC. If you look at roundy's OLR diagram it doesn't get tropical forcing into the WPAC till after first week of January. By New Year's the forcing is only in phase 5 or so. Granted this isn't super strong, so it's not like it's overwhelming everything, but it still tips the scale towards warmer. 

The current cold shot is actually a by product of the strong wave 1/displacement we had back in early Dec. You can see the slow ooze from the stratosphere into troposphere on the NAM. We do have the strong wave 2 hit you would think that would influence the pattern. The euro has the same wave 2 hit so it's not like one is seeing it and the other is not. My guess is one model sees it coupling with the trop, while the other doesn't?

 

I think best approach is to see if the gefs can kick it or hold steady. If they start can kicking, then we have our answer, but my money is it's fast

 

[WxUSAF]

@tombo82685, yeah will be interesting to see how things look in 48-72 hours.  GEFS starts moving the TPV south on the 28th, and not coincidently, that's when the EPO ridge goes up. That's the mark on the wall.  6z GEFS actually accelerated things a bit relative to the last few runs previously.  

[WxUSAF]

HMs take on this discussion 

 

[frd]

8 minutes ago, tombo82685 said:

the euro has the same wave 2 hit so it's not like one is seeing it and the other is not. My guess is one model sees it coupling with the trop, while the other doesn't?

Agree here,  good point.

This may be setting up the two different outcomes.  

[frd]

Back to the West Pac and the Nino 

 

[psuhoffman]

1 hour ago, frd said:

Back to the West Pac and the Nino 

 

Umm that’s weak but a classic modoki representation with the core of warmth near the dateline. 

[Bob Chill]

Just now, psuhoffman said:

Umm that’s weak but a classic modoki representation with the core of warmth near the dateline. 

I don't disagree with the numerical data but visually it's anything but a notable Nino. PDO keeps improving though...

[psuhoffman]

2 minutes ago, Bob Chill said:

I don't disagree with the numerical data but visually it's anything but a notable Nino. PDO keeps improving though...

Sorry I should clarify. We’re in a warm neutral enso state. But the representation of sst anomalies is in a modoki like phase with the warmest anomalies still centered near the dateline. There are pockets of both warm and cool anomalies along the enso domain further east. Webb seemed to imply it was moving towards a canonical nino representation.  Maybe I was misreading it. 

[psuhoffman]

@frd @Bob Chill @WxUSAF

I’m in general agreement wrt pattern evolution. Makes sense the gfs is too fast and the eps might be too slow in weakening and displacing the TPV.  Oddly the gefs bailed on its mjo projection into 7 and now goes into 6 like the eps yet still (for now) accelerates the pattern flip. 

[frd]

23 minutes ago, psuhoffman said:

Umm that’s weak but a classic modoki representation with the core of warmth near the dateline. 

 

Will be interesting to see how things continue to progress this month and next.  

Two things :

Granted the visual look is still warm neutral enso state. 

However, I believe the takeaway is more favorably placed  tropical forcing is ahead , combined with a weakening + IOD and slow warming spreading East in time, along the lines of what Webb stated, hence an improving pattern .

 

 

 

 

[frd]

4 minutes ago, psuhoffman said:

Oddly the gefs bailed on its mjo projection into 7 and now goes into 6 like the eps yet still (for now) accelerates the pattern flip. 

I can only guess this might be related to what @tombo82685 posted earlier that the GEFS might have this outcome because of implied coupling from the previous event in early December. 

Funny thing is that the GEFS is biased,  I believe,  in being too aggressive at times with things such as HL warming events, etc. So, maybe it is wrong in its outcome, however, as you posted psu it still accelerates the pattern flip.   

There is always too the possibility the GEFS has the right idea this time. IMO the environment for coupling may have merit, even if for a short duration. However,  caveats apply , as stated earlier by HM with the NWP.

 

 

 

[jaydreb]

We can work with this.  

 

[frd]

Stir the pot in Jan possible.   - AO is all I ask for. 

Looking at that depiction seems different from recent years, I believe.

Ventrice states the ECM depiction below matches up to his precursor SSWE composite. Looks fairly close to me. 

Just another thing to monitor in fantasy land. 

 

 

[Bob Chill]

One unfortunate thing both the EPS and GEFS agree on right now is there is little if any chance for snowfall through the end of the month. Not surprising given where we are going over the next 10 days. 

[psuhoffman]

I’m willing to wait quite a bit if this is where we are heading (and there is evidence from analogs and tropical forcing not just blind hope to suggest it is).  

[tombo82685]

14 minutes ago, frd said:

I can only guess this might be related to what @tombo82685 posted earlier that the GEFS might have this outcome because of implied coupling from the previous event in early December. 

Funny thing is that the GEFS is biased,  I believe,  in being too aggressive at times with things such as HL warming events, etc. So, maybe it is wrong in its outcome, however, as you posted psu it still accelerates the pattern flip.   

There is always too the possibility the GEFS has the right idea this time. IMO the environment for coupling may have merit, even if for a short duration. However,  caveats apply , as stated earlier by HM with the NWP.

 

 

 

It has to be strat related the cold. The rmm plots, which are not the best tool to look at for the mjo continue to back up towards the warm phases. Newest one has a little pass into phase 5 before gaining amplitude into 6. This matches closer to the OLR plots I posted this morning and closer to the euro. So it's in warm phases of mjo, yet still gets to that h5 look post day 10? Either it's picking up on strat related or you will continue to see can kick that never makes it past day 10 till we get WPAC forcing. 

[Eduardo]

2 minutes ago, psuhoffman said:

I’m willing to wait quite a bit if this is where we are heading (and there is evidence from analogs and tropical forcing not just blind hope to suggest it is).  

 

How does this evolution compare with that of 2013-14?  IIRC, we flipped cold right around New Years, (at least up here) cashed in with a storm right in the beginning of January, and remained in the freezer for at least a month and a half.

[psuhoffman]

4 minutes ago, tombo82685 said:

It has to be strat related the cold. The rmm plots, which are not the best tool to look at for the mjo continue to back up towards the warm phases. Newest one has a little pass into phase 5 before gaining amplitude into 6. This matches closer to the OLR plots I posted this morning and closer to the euro. So it's in warm phases of mjo, yet still gets to that h5 look post day 10? Either it's picking up on strat related or you will continue to see can kick that never makes it past day 10 till we get WPAC forcing. 

There are multiple conflicting waves though. The gefs is definitely picking up on convection towards the dateline towards day 15. There are also areas of convection in unfavorable locations near the maritime continent. The gefs could be keying on the wave in the western Pac. There are multiple permutations that could be why the gefs and eps are divergent.

 

[tombo82685]

5 minutes ago, psuhoffman said:

There are multiple conflicting waves though. The gefs is definitely picking up on convection towards the dateline towards day 15. There are also areas of convection in unfavorable locations near the maritime continent. The gefs could be keying on the wave in the western Pac. There are multiple permutations that could be why the gefs and eps are divergent.

 

 

Yea that could be very true. Just seems like roundy's OLR plot is focusing on building a wave in phase 5 that travels through 6 and 7 to start january off. The stratobserve site just updated but you could make a case here the cold it's showing to start new year is strat related. We had a strong wave 2 hit in nov that brought about a period of -NAM to troposphere. Then we had wave 1 displacement hit that was slower to propagate downward, that brought us this cold shot. Now we have another wave 2 hit starting now and you can see the building -NAM right around new years

[psuhoffman]

37 minutes ago, Eduardo said:

How does this evolution compare with that of 2013-14?  IIRC, we flipped cold right around New Years, (at least up here) cashed in with a storm right in the beginning of January, and remained in the freezer for at least a month and a half.

It’s almost opposite. This time in 2013 the pacific was mediocre but the Atlantic was a hot mess on wheels. 

The early Jan snowstorm and arctic blast was thanks to a brief west based -NAO combined with the “ok” pac. 

the NAO blocking forced a storm under us that started out in the upper Midwest. Very rare for Chicago and our area to get significant snow from the same system. 

There was a brief moderation after that.

The arctic blast and snow later in January was courtesy of a perfect pac, full latitude pna epo ridge with a mediocre Atlantic. 

There are always lots of moving parts. And some patterns work better in one part of winter than another.  We generally need Atlantic AND pacific help early in Winter. Dec 2009 was a perfect NAO and PNA. Later in winter an NAO Block and PNA EPO ridge is often too much of a good thing and just cold dry. In late Jan and Feb we want a west based -NAO and a mediocre pacific. Ideally a split flow which often shows up as a -epo -Pna numerically. 

Some winters that share some similarity to right now wrt pattern progression early that went on to good things in january were 59-60, 65-66, 86-87, 93-94. 3/4 went in to have good blocking the rest of winter. 94 was all epo and that’s we we got a lot of ice and mix events not snow. There were some duds that shared commonality too though. 97-98 had a similar pattern around Xmas. 98 did have blocking but the raging nino torched the whole continent all winter.  I doubt that outcome again though. 

[peribonca]

Euro with low off cape Hatteras at 144h but only have access to tropical tidbits maps

[BristowWx]

Just now, peribonca said:

Euro with low off cape Hatteras at 144h but only have access to tropical tidbits maps

I saw that.  120h was in quite a different location over inland SC

[yoda]

2 minutes ago, peribonca said:

Euro with low off cape Hatteras at 144h but only have access to tropical tidbits maps

Nothing up here... closest it gets is S VA with precip and its all rain

[BristowWx]

2 minutes ago, yoda said:

Nothing up here... closest it gets is S VA with precip and its all rain

right.  just thought it was notable compared to 0z with the placement of the low.  

[HighStakes]

24 minutes ago, psuhoffman said:

It’s almost opposite. This time in 2013 the pacific was mediocre but the Atlantic was a hot mess on wheels. 

The early Jan snowstorm and arctic blast was thanks to a brief west based -NAO combined with the “ok” pac. 

the NAO blocking forced a storm under us that started out in the upper Midwest. Very rare for Chicago and our area to get significant snow from the same system. 

There was a brief moderation after that.

The arctic blast and snow later in January was courtesy of a perfect pac, full latitude pna epo ridge with a mediocre Atlantic. 

There are always lots of moving parts. And some patterns work better in one part of winter than another.  We generally need Atlantic AND pacific help early in Winter. Dec 2009 was a perfect NAO and PNA. Later in winter an NAO Block and PNA EPO ridge is often too much of a good thing and just cold dry. In late Jan and Feb we want a west based -NAO and a mediocre pacific. Ideally a split flow which often shows up as a -epo -Pna numerically. 

Some winters that share some similarity to right now wrt pattern progression early that went on to good things in january were 59-60, 65-66, 86-87, 93-94. 3/4 went in to have good blocking the rest of winter. 94 was all epo and that’s we we got a lot of ice and mix events not snow. There were some duds that shared commonality too though. 97-98 had a similar pattern around Xmas. 98 did have blocking but the raging nino torched the whole continent all winter.  I doubt that outcome again though. 

Interesting because the first 3 winters 59/60, 65/66 and 86/87  in the grouping saw the bulk of snow and cold come in an epic 2-3 week period. 59/60 came in march with a ridiculous sustained cold first 2 weeks for that time of the year. That's something I'm not opposed to at all. There's nothing like deep winter for a solid period. I would be willing to sacrifice the rest of winter for a memorable short stretch. I suspect 93/94 had more longevity because it was -epo driven much like 2013/2014 which was probably as close to wall to wall winter that we can achieve.