February/March 2020 Winter's Last Chance Thread

[Holston_River_Rambler]

Happy hour doesn't give us much, but the GFS likes the idea of a mega EPO ridge late.

[Holston_River_Rambler]

Looks like it also goes for the SPV split again around 260 hr, but reconsolidates. 

[Carvers Gap]

1 hour ago, Holston_River_Rambler said:

Looks like it also goes for the SPV split again around 260 hr, but reconsolidates. 

With it being late in the season and it taking a beating...that  PV is going to be ragged. Will be tough for it to reconsolidate.  Holston, we want to be under the warm anomalies, right?  I know that sounds counterintuitive, but I "think"(???) that it is colder under those warmer strat areas....

[Carvers Gap]

1 hour ago, Holston_River_Rambler said:

Happy hour doesn't give us much, but the GFS likes the idea of a mega EPO ridge late.

GEFS just reaffirms that modeling is really struggling with the LR.   Beats down the SER like the EPS did.  Man, it is cold at the surface.  I can't possibly understand why it is said to have a cold bias.  J/K.  Man that is a lot of blue and purple on Tropical Tidbits. 

[Holston_River_Rambler]

42 minutes ago, Carvers Gap said:

 Holston, we want to be under the warm anomalies, right?

 I think it's a case by case basis. Because it has been so well coupled I think when it recently rolled back to Siberia, I think that helped promote the Hudson Bay Ridging, but could be wrong there. 

I'm also not sure exactly what mechanisms transport the displaced the cold air if there is a split. 

I do know we want something like what the GFS showed in the dynamic tropopause. Lots of poleward disruptions to kick swipes of energy of the pole and toward the mid latitudes. 

[Holston_River_Rambler]

That shakes up the areas where the SPV dips down toward the troposphere 

[Mr. Kevin]

I believe if we have a true -qbo mainly at 30 and 50mb, we should see a period of colder weather that has some stability imo.

[John1122]

Euro Trend. 

Mon D10

 

Tues D9

 

Wed D8

What looked to be a 3-4 day cool shot looks more like a 12-18 hour one at this point, as we warm back to AN after spending 2-7 mostly BN and there's not a lot of BN 2m in the lower 48 or Southern Canada at D 10. BN 850s are more widespread, but sadly we don't live at 850 unless you're in Western NC or the caretaker at LeConte.

[John1122]

Ugly GFS trend this am as well.

Mon 6z D12.5

Tues 6z D11.5

Wed 6z D10.5

[John1122]

1 minute ago, weathertree4u said:

 

Are you implying I am cherry picking model runs? 

[Holston_River_Rambler]

Euro is back to its triplet idea with the SPV while the GFS is still wavering. I think something is definitely going to happen to disrupt the SPV in abut 6 - 7 days, but how that plays out afterwards, hard to say. Most likely outcome would be reconsolidating, based on persistence, but not guaranteed. 

 

[Holston_River_Rambler]

Here's how the "triplets" idea translates from 10 mb to 50 mb, to 100 mb, to 500 mb:

[Holston_River_Rambler]

Interesting to me to see how it all kind offsets as you get lower in the atmosphere. 

[weathertree4u]

Just now, Holston_River_Rambler said:

Here's how the "triplets" idea translates from 10 mb to 50 mb, to 100 mb, to 500 mb:

One thing I can say for sure is that this Winter has had lots to track, not necessarily with storms but with overall model changes. 

[Holston_River_Rambler]

Indian Ocean is purt near lit this AM too

[Carvers Gap]

28 minutes ago, Holston_River_Rambler said:

Euro is back to its triplet idea with the SPV while the GFS is still wavering. I think something is definitely going to happen to disrupt the SPV in abut 6 - 7 days, but how that plays out afterwards, hard to say. Most likely outcome would be reconsolidating, based on persistence, but not guaranteed. 

 

Which means modeling is going to be all over the place if that occurs.  Can you tell, Holston, if that is a "top down" split?  Sometimes we can get immediate reactions from those and sometimes not.  I know in the spring of 2018, it took about 2-3 weeks to really impact the troposphere if I remember correctly...Basically, what I am getting at is if the TPV is affected and when?

[Carvers Gap]

2 minutes ago, Holston_River_Rambler said:

Indian Ocean is purt near lit this AM too

Looks like 2-3 are firing pretty well.  I kind of agree with you that the phase four area is firing.  You are likely going to be right on that.

[weathertree4u]

1 hour ago, John1122 said:

 

Are you implying I am cherry picking model runs? 

I apologize - upon further review - I see how my post was not contributing to the overall knowledge base of the discussion so I removed them - though, seriously, fruit is going to start developing if we do not get some cold!

[Holston_River_Rambler]

1 minute ago, Carvers Gap said:

Can you tell, Holston, if that is a "top down" split?

Not sure I know enough about the terminology to know the difference, lol. The talking wxtwitter heads are calling it a "wave two" disruption and using jet maps and dynamic tropopause images, so I'm guessing its a bottom up kind of thing with storms slinging energy poleward and upward.

But this is a good mission for me today and would like to try and figure it out. 

[Carvers Gap]

2 minutes ago, Holston_River_Rambler said:

Not sure I know enough about the terminology to know the difference, lol. The talking wxtwitter heads are calling it a "wave two" disruption and using jet maps and dynamic tropopause images, so I'm guessing its a bottom up kind of thing with storms slinging energy poleward and upward.

But this is a good mission for me today and would like to try and figure it out. 

Well, sometimes the tropical polar vortex at the surface will split first and work its way into the stratosphere.  And at other times, the stratosphere polar vortex will split first and work its way down which is top down.  Both work, but the first one has a more immediate reaction.  The top down changes can take 2-3 weeks(sometimes immediate thought) sometimes to impact the troposphere and sometimes an SPV doesn't affect the TPV at all.  That is why I like that animation that you post.   You can see where the split is occurring.

[Holston_River_Rambler]

As I understand it right now (subject to change ad I learn more) the dynamic tropopause shows places where the stratospheric polar vortex dips down into the troposphere. So in this example, you can see a bit of subtropical something or other being deflected poleward and disrupting what I see as the main TPV. 

Heres how that would translate to a potential -AO at 500 mb. 

(sorry for the backwards and forward, but wanted to make sure I captured the interaction in the gif)

Just using the GFS for an example and  because I don't have the Euro's dynamic tropopause content. 

[Holston_River_Rambler]

We kind of saw something like this earlier in the winter:

Sorry for the arrows (they were originally for when I used this early in the season) but you can see a similar dance at the pole in the first few frames. This is from when there was talk about a flip at the end of December, but the attack just pushed it back to Greenland and we got the  +NAO

 

[Carvers Gap]

I actually still like the February 5-10 window.  Here is the side-by-side comparison of the past two runs at 500.  0z was actually colder with the initial front on the 5th.  And again, without a -NAO it is going to try to lift out.  This is at 18z on February 5th.  One positive is the trough and initial front sped up a bit and deepened quite a lot compared to the previous run.  The run-to-run change at 2m was actually net colder on the Euro OP for d5-8 when compared to 0z.  I would post the R2R maps of those days, but I think you can get the picture by looking at the comparison at 500 at 186.  New run is on the left.  For once, the overnight run during this time frame actually improved.

 

[Carvers Gap]

One thing to keep an eye on is the EPS trend weakening the area of BN heights that slides into the West after d10.  For three straight runs it has displaced the stronger heights northeastward towards eastern Canada. That gives modeling a couple of options.  It could be that modeling will bring back an eastern trough periodically or it could pull the cold up to the Hudson Bay.  If it pulls up to the Hudson Bay, heights will likley build under the area of BN heights w periodic shots of cold pinwheeling into the SE and East.  

@Holston_River_Rambler, another thing to watch is if the TPV splits...modeling could flip on a dime if modeling thinks that is going to hold.  Sometimes that flip is good(see 2018) and sometimes it is bad(see Jan 2019).  In both cases modeling had pretty consistent looks and then bang...everything was upended within about two suites.  If the SPV occurs in early Feb, not sure it can help us as the lag of effects into the troposphere would possibly not get here until mid-late Feb.  That said, seems like the strat and troposphere are coupled right now.  If it stays that way, the effects could be immediate.  And then sometimes SPV splits don’t translate to the troposphere at all.  I suspect an SPV split this time does translate down.  A TPV split can work like an electrical breaker.  Flip that switch and things on modeling often switch dramatically.  So circling back, having the BN heights on the EPS building over the HB might be a hint at where one of those PVs ends up.  Speculation on my part, but something I have noticed.

[BNAwx]

I was wondering the other day how models generally perform in “la nada” years and if the lack of a strong signal from that region is the reason modeling has waffles around so much this year...more so than normal it seems.  I think we would’ve had more stability in modeling and perhaps a better outcome this winter if we would’ve had a true El Niño.  I haven’t looked a SST forecasts but hopefully next winter we’ll actually have a weak or moderate El Niño to work with.

I’m not saying winter’s over just yet.  I usually give it until March 15th then after that, I’m ready for Spring...

 

[Carvers Gap]

The EPO on the EPS yesterday was positive.  Overnight, it flipped negative as evidenced by the pic below.  To give you an idea at how much modeling is bouncing around.  In the medium and LR, the EPO has reversed large portions of the EPO with reach run going back to Jan 26.  Overnight it looked like this.  Will it stay?  No idea.  This started occurring about the time we started talking about the PV splitting.   The AO is strongly positive which I wonder if that will reverse given the nature and structure of the upcoming trough.  One index we have not spoken about enough is the AO.  It has been quite positive this winter and is forecast to remain strongly so.  That said, observed AO readings are currently of of sync(below) what predicted values on the CPC site.  Regarding the pattern after the 10th, let's keep an eye on the EPO trend as that seems to be the only thing available that can help us at times.

 

[Carvers Gap]

38 minutes ago, BNAwx said:

I was wondering the other day how models generally perform in “la nada” years and if the lack of a strong signal from that region is the reason modeling has waffles around so much this year...more so than normal it seems.  I think we would’ve had more stability in modeling and perhaps a better outcome this winter if we would’ve had a true El Niño.  I haven’t looked a SST forecasts but hopefully next winter we’ll actually have a weak or moderate El Niño to work with.

I’m not saying winter’s over just yet.  I usually give it until March 15th then after that, I’m ready for Spring...

 

Great question.  I will start the discussion, but am certainly not the final say.  I am no fan of La Nada.  "Meh" is my word for those years.  Some call this year a Modoki El Nino, but I think it will be classified officially as a La Nada.  The problem this year is the Modoki is centered right over the top of the phase 6 MJO!  LOL.  Not good.  I think that ENSO 4 region has caused havoc along with a record IOD.  It(the phase 6 MJO region) is/has been a near constant area of convection and rain.  I think what has caused modeling problems is the rest of the MJO has propagated normally while phase 6 just sits there and stews.  It has trumped all other phases that have fired.  Now, I do think modeling does much better when Nina or Nino locks in as the pattern is fairly consistent, especially during either winter or summer.  Shoulder seasons are always a crapshoot.    If you haven't already, search for TyphoonTip's discussion about the SST gradient in the Pacific.  We really have not had a moderate Nina since January of 2012 though January of 2018 was close.  Our last strong La Nina was January 2011.  Interestingly some of those great winters around the 2010 timeframe occurred in between some moderate to strong La Ninas.  I am a big fan of weak La Nina ENSO patterns.  Like anything they don't always work out but they can be very cold at times.  That said, I think the Super Nino of 15-16 really warmed the Pacific and has screwed up the temp gradient there.  It is above normal.  We really need a strong Nina to wipe that out.  We haven't had one in nearly nine years.  IMHO, until that temp gradient gets cooled...we get what we have had the past two winters which are analogs(based on ENSO) that don't work.  Jeff talked about analog problems recently.  To paraphrase Typhoon, he basically said that a weak Nino needs a stronger gradient/transition to cooler water.  Right now most of the Pacific is warm, and the gradient between the warmer SST area and a cooler one is non-existent as much of it is AN.  I think much of the reason for that is because we have not had a strong La Nina to cool the Pacific and reset the gradient.  Now, strong La Ninas are usually warm winters here, but we might need to suffer through one of those winters in order to get a better gradient.  

Next winter's ENSO? Probably a good question for @jaxjagman.  I have seen commentary for both a Nina and Nino. I have read some information that when we exit the solar min and get closer to the max that Super Ninos are possible - hopefully several years from that.  I have also read that the winters just after a solar min have more blocking.  I won't hold my breath, but we will see.  Next winter's ENSO is a question mark for me.  Looks like ENSO neutral is forecast through summer and into fall with slightly negative SSTs.  If forced to make a summer forecast based on that alone - As the summer progresses we might have increasingly dry and increasingly AN temps.  Might be a normal start and a hot August and September.  

https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

https://ggweather.com/enso/oni.htm

[Carvers Gap]

Way out there...the setup on the 12z GFS at 200 is not terrible.  It is the third of three waves that pass progressively more eastward between February 4th and 8th(5th through 8th in MBY).  That system would likely not be fighting to overcome crazy warm temps.  Looks like waves 2 and 3 are something I will watch for MBY.  Areas in west TN and Arkansas would need to watch the first wave per the GFS.  Right now, it cuts right over west TN.  But if the trough speeds up, that could change.  It sped up just a hair after several runs of slowing down.

[Carvers Gap]

And then beginning at 240, the GFS digs a system at 500 from Idaho to off the coast of Southern California.  West Coast version of a Miller B?   I think there will a trough digging, at least initially out there, but that looks like a feedback issue.

[Carvers Gap]

That ridge in the GOA is impressive impressive though d10+.  Again, just an odd run at that point.  Probably will stick a trough back in the East late in the run, but its progression is unlikely after 240 - which is not surprising given that we are talking about an operational at range.   Sure enough big ice storm late in western areas of the forum.  Again, not really buying much after d10, but interesting.  That was probably five sentences too much, but there you go.