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AMZ8990

February 2019 Winter Speculation

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2 minutes ago, Carvers Gap said:

We had discussed this before, but TyphoonTip had said that because most of the Pacific basin was warmer than average that the gradient between the warm SSTs and the rest of the basin was not strong.  Gradients in air and water are what cause currents to move in the oceans and the atmosphere.  Temperature gradients cause pressure gradients which can cause wind which moves the atmosphere.  Weaken those gradients...and weather patterns change.  I still strongly contend that until the AMO flips, we are in for a stretch of bad winters.  There is a very strong correlation in E TN to the AMO.  As for La Nina, I wonder if the gradient might be stronger since the basin is AN for SSTs.  BN SSTs would create a stronger gradient in a basing that is AN.  As for next winter...so many things will be in play.  The QBO should be nearing the end of its positive cycle by the end of next winter(maybe we can get it to flip early or to decline...).  If the Nino is strong...that is trouble.  However, predicting the ENSO state at 12 months out is iffy at best.  We also have to consider the PDO.  That said, sometimes scenarios that look like certainties never materialize.  Who is to say that we don't get a favorable MJO setup next winter despite the ENSO.  Maybe we are entering a time frame where the ENSO is not coupling with the atmosphere in expected ways.  I think each winter is its own animal so to speak.  We won't know(Captain Obvious here) what next winter is like until probably December 1.  What I would like presently is a stretch of 2-3 weeks of dry weather.   Cause right now, all of this ocean water is making a mess of my yard and jogging routes.

It might be like this year and we might not know what next winter is going to be like until it's almost over.  lol

I am with you on the needing dry weather front.  We definitely need to catch a break from all the juice!  Unfortunately, that part looks a given the next 10-14.

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Too add further insult I just saw a video of heavy snow falling in Vegas for the first time in several years. The pacific runs things here. Always hope for a big -EPO that couples with a +PNA. That's what crushed the super nino year one a few years ago.

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JB posted this today.  And trust me, I hate to "rain" on a good "post mortem" - just kidding of course.  However, the EMON MJO updated.  Now IMHO, the MJO notably loses a bit of its "umph" in terms of being a driver late in the season.  But since the MJO has been driving the bus this winter, this might deserve consideration. I am going to place this here for so that we can look back and see if it verifies...and if it does verify, will the trough take up shop similarly to the 12z GEFS?  All I will say...that is a slow, slow tour of the cold phases.  To me, that is a nice, late season EC storm signal in conjunction w the tanking SOI.  I will also attach the CPC NAO outlook(talk about an index that has not verified negative most of the winter!).   FTR, I usually keep tracking storms until the last flakes fly.  And I really like to make note of this as well...as much as I did not like the 90s in terms of winter, there were some memorable snowstorms in the Smokies during spring - yardstick stuff.

1807827502_ScreenShot2019-02-12at4_41_45PM.png.17b32c7a88ef3ddfd03f02c096237bf4.png

1125407625_ScreenShot2019-02-12at4_50_34PM.png.bed082999e8a1a8037e41322dcd49c53.png

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I don't think it is totally over yet, but we are on life support and to make a clean diagnosis, we have to evaluate the wounds.

That EMON looks about like the Carl Schreck RMM plot I used a while back when I made my March 10th storm give or take prediction. That and the Crankyweather prediction of big flip to spring around that time were basically my two indices for that prediction. I really think the 2 - 3 transition is a good one for us. 

If we can stagger to that line. 

Here it is today. Been pretty consistent. 

giphy.gif 

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Of note on the MJO, we have either rushed through the cold phases or completely missed them this winter.  It has spent plenty of time in 3-6 this winter.  If the EMON is correct(there are other models that are not as bullish...but it does look like the MJO will got into the colder phases), we have not seen our last cold shot.  As Holston noted with the recent Tweet, phase 8 might favor a SER according to new research in conjunction w maybe a weak Nino.  Here is the JFM temperature correlation map for the MJO.  We are in phase 7 which lines up nicely.  The 12z GEFS flips to an eastern trough around 300 and would line-up nicely with phases 1-3.

1717678049_ScreenShot2019-02-12at5_01_24PM.png.0b9c8244a3da2d0e3b9383d20631edd1.png

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5 minutes ago, Holston_River_Rambler said:

I don't think it is totally over yet, but we are on life support and to make a clean diagnosis, we have to evaluate the wounds.

That EMON looks about like the Carl Schreck RMM plot I used a while back when I made my March 10th storm give or take prediction. That and the Crankyweather prediction of big flip to spring around that time were basically my two indices for that prediction. I really think the 2 - 3 transition is a good one for us. 

If we can stagger to that line. 

Here it is today. Been pretty consistent. 

giphy.gif 

What would really stink is if the MJO finally died and went into the COD only to come out in phase 8 for a double dip through the cold phases.  LOL.  I do agree w Jeff that the hangover from the strat split should wear off around mid-March...."should"...been saying that all winter and the weather doesn't want to cooperate.

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Even worse for me would be if it indeed stuck below the equator as it toured the colder phases to provide more forcing in the S. Hemisphere and then did what you say above. How the tears would flow, but until he mentioned it this AM, never thought it could have more of an impact in the S. hemisphere. 

 

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Normally I would be more optimistic, I used to get at least one 3-6 inch snow in March almost every year, probably 4 out of 5, and I got one last year. But it was on the first day of spring after a terrible winter. I love any snow when it's falling but seeing thick snow on apple and cherry buds didn't overjoy me like snow does in true winter months.

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Like the next guy I too am not a fan of mild temperatures and rain... soo much rain. But hey, at the very least we have an active pattern. Here's to hoping we get a broad trough in late february with a -EPO and -NAO with an MJO that doesn't give us the middle finger by entirely skipping the desired phases.

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41 minutes ago, Holston_River_Rambler said:

Here is raindancwx's March outlook. Wasn't too shabby a forecast. 

so far 

 

At least he seems to acknowledge one of the two bigger risks being big interior SE snows.  That part definitely sounds like a late winter season El Niño thing.....

 

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2 minutes ago, tnweathernut said:

At least he seems to acknowledge one of the two bigger risks being big interior SE snows.  That part definitely sounds like a late winter season El Niño thing.....

Yeah, hopefully whatever method he used will still bear some fruit for someone in our forum. 

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1 hour ago, tnweathernut said:

At least he seems to acknowledge one of the two bigger risks being big interior SE snows.  That part definitely sounds like a late winter season El Niño thing.....

The cold centered in the middle of the country is pretty much Nino climatology for that time of year...I think.  Now, normally it would be in the East and retrograde back into the middle of the country.  In this case, it would have to progress out of the Rockies.  LOL.  So, the placement of the cold looks right...but the progression to get it there will be exactly opposite.  It would be pretty funny to see plenty of warm March forecasts...and then see winter return for that entire month.  This weather pattern is not playing nice...I keep saying it.  I think all analog bets are off right now.  I do think one constant is the continuation of ample amounts of rainfall.

BTW, for those looking at seasonal forecasts....Roger Smith has a pretty good winter forecast on the main discussion forum.  He straight called for an early end to winter.  

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"Around late December, I expect that the western ridge will swell up over Alaska and Yukon and allow cut-off low pressure to form in the southwest states. This will lead to an interval of very mild weather in most of the south, southeast and eastern U.S. The storm track will then run from about New Mexico to Michigan to southern Quebec. Much above normal temperatures will accompany this phase of the winter.

Then this mild regime will collapse as the western ridge subsides slightly and moves inland a bit further. That will lead to a weakening if not the end of the cut-off low and allow the storm track to drop back into the mid-south and east-central states. A period around Dec 21 will be one early opportunity for heavy snowfalls in the east. A second window of opportunity will occur some time in late January or the first week of February. After that, I think winter will quickly come to an end and spring-like warmth will prevail."

Push all that forward by a month to account for the SSW not mentioned in his forecast and give him a slight break for being within 10 days of the Dec storm and mmmmmmmmhmmmmhmmmm.

Looks good.

So far. 

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32 minutes ago, Holston_River_Rambler said:

"Around late December, I expect that the western ridge will swell up over Alaska and Yukon and allow cut-off low pressure to form in the southwest states. This will lead to an interval of very mild weather in most of the south, southeast and eastern U.S. The storm track will then run from about New Mexico to Michigan to southern Quebec. Much above normal temperatures will accompany this phase of the winter.

Then this mild regime will collapse as the western ridge subsides slightly and moves inland a bit further. That will lead to a weakening if not the end of the cut-off low and allow the storm track to drop back into the mid-south and east-central states. A period around Dec 21 will be one early opportunity for heavy snowfalls in the east. A second window of opportunity will occur some time in late January or the first week of February. After that, I think winter will quickly come to an end and spring-like warmth will prevail."

Push all that back by a month to account for the SSW not mentioend in his forecast and mmmmmmmmhmmmmhmmmm.

Looks good.

So far. 

He is one of the gurus on the forum.  He has forgotten more than I will ever know.  I have great respect for him.  He does some incredible research.  When I saw that seasonal forecast...I was like, "Uh, oh."  When RS is not on board, it is akin to losing support from the Euro.  That forecast is about as money as one can get.  The most difficult month to hit in a seasonal forecast is the last of the three months.  Chaos just gets the better of most forecasts no matter how well thought out those are.  I think the anomalous strength and frequency of the Maritime Continent and Indian Ocean equatorial convection in relation to the ENSO state was not foreseen....The abnormally high SOI during December was the warning shot along with the flip of the QBO during late fall.  As the QBO rose, our chances of sustained, Atlantic blocking went caput.  For me though, I can't call this winter a dud.  As for many El Nino years, there are locally decent snow amounts.  IMBY, we saw nearly a foot with one storm.  That is the most that I have seen with one storm in almost twenty years I think(that 09-10 storm was close...I could be missing another).  My guess is that we have received around 14" of snow this winter w all of the other nickel and dime events.  That is about normal for my neck of the woods.  That said, I like long bouts of cold.  We haven't had that so far and that is not unexpected with El Nino winters.  If we were to get another big(out of the blue) snowstorm later this month, we would be much above normal.  NE TN tends to find a way to get decent snow during El Ninos...but I never would have guessed it would have been on the front end of the season....again, this winter has not played nice.  

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Unbelievable how the Euro just keeps bringing it for almost a whole week:

giphy.gif 

If that pattern verifies it really wouldn't take much for somebody in the high country or eastern valley to hit 10 inches, just depending on exactly where the firehose sets up.

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I feel a little awkward doing this (since it is a wholesale copy and paste), but it fits with some of the conversation we were having yesterday and seems helpful for understanding how we got where we are and where we might be going. I've seen a person or 2 in the MA forum do this, so here is a take from a meteorologist from the UK named "Singularity" on 33 and rain weather board:

"There was evidence in favour of the E to W transitional QBO stage supporting SSWs occurring, but not necessarily propagating all the way downward. 

 

I believe for that we needed a predominantly wave-2 driven vortex split event, instead of the mainly wave-1 driven displacement-then-split event that we saw. Reason being that the former drives a much faster response that would likely have outpaced the descending W QBO and established major easterly flow anomalies in the troposphere. The much slower 'drip-down' nature of the event we've seen instead has allowed the W QBO to become a blockade that's kept most of the negative zonal wind anomalies in the stratosphere. I have a feeling that the manifestation for a time of a very unusual three-way vortex split right after the reversal initiation may further have impeded the downwelling by distributing the negative zonal anomalies more widely, essentially making them more diffuse.

 

At the time of the SSW, part of the response was a cooling of the upper troposphere above the tropics, enhancing convection even where the base state doesn't support it. Alongside the negative zonal anomalies, the SSW-driven positive temperature anomalies have also been held in the lower stratosphere, keeping the upper tropical troposphere cooler than usual and allowing the convection to continue to behave in ways that don't tie in with the Nino base state (interference with the patterns the Nino base state otherwise drive being the scrambling of the tropical-extratropical processes that Tamara refers to). Climate change may have taken this even further than it would otherwise have gone via increased overall oceanic heat content, but that's a matter of debate - to me the stratospheric mishaps seem more important for this particular winter's turnout.

 

 

I think we can see a good example of the interference this coming week; the neutral ENSO MJO composites (top row) fit the ECM 00z much more than the Nino ones, despite AAM and GWO observations indicating that it would usually fit more to the positive ENSO composites;

 

nada_6_feb_mid.pngnada_7_feb_ok.png
nino_6_feb_mid.pngnino_7_feb_ok.png

 

GFS fits mostly the neutral P6 composite before seemingly jumping straight to something akin to the P8 neutral composite (see below, left) with little P7 response - probably due to how it stalls the MJO in P7 for a while; continued eastward propagation is needed to bring about the typical response to activity within a given phase of the RMM plots.

 

The negative NAO-related UK cold potential for late this month and into March depends on how well we can break free of the Nina-like interference and so bring about an MJO P8 response more typical of the Nino base state.

 

So more toward the right-hand composite than the left-hand one. Note how I'm saying 'more toward' here; the composites should never be taken too literally (ideally we'd have different ones for each possible combination of MJO phase, GWO phase and AAM tendency, but there simply aren't enough historical years of obs data to do this meaningfully!).

 

nada_8_feb_mid.pngnino_8_feb_mid.png

 

As you can see - the temperature regime across the UK will be extremely sensitive to how much the interference gives way."

Original link:https://www.33andrain.com/topic/868-teleconnections-a-technical-discussion/?page=35&tab=comments#comment-133636 

 

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1 hour ago, Holston_River_Rambler said:

I feel a little awkward doing this (since it is a wholesale copy and paste), but it fits with some of the conversation we were having yesterday and seems helpful for understanding how we got where we are and where we might be going. I've seen a person or 2 in the MA forum do this, so here is a take from a meteorologist from the UK named "Singularity" on 33 and rain weather board:

"There was evidence in favour of the E to W transitional QBO stage supporting SSWs occurring, but not necessarily propagating all the way downward. 

 

I believe for that we needed a predominantly wave-2 driven vortex split event, instead of the mainly wave-1 driven displacement-then-split event that we saw. Reason being that the former drives a much faster response that would likely have outpaced the descending W QBO and established major easterly flow anomalies in the troposphere. The much slower 'drip-down' nature of the event we've seen instead has allowed the W QBO to become a blockade that's kept most of the negative zonal wind anomalies in the stratosphere. I have a feeling that the manifestation for a time of a very unusual three-way vortex split right after the reversal initiation may further have impeded the downwelling by distributing the negative zonal anomalies more widely, essentially making them more diffuse.

 

At the time of the SSW, part of the response was a cooling of the upper troposphere above the tropics, enhancing convection even where the base state doesn't support it. Alongside the negative zonal anomalies, the SSW-driven positive temperature anomalies have also been held in the lower stratosphere, keeping the upper tropical troposphere cooler than usual and allowing the convection to continue to behave in ways that don't tie in with the Nino base state (interference with the patterns the Nino base state otherwise drive being the scrambling of the tropical-extratropical processes that Tamara refers to). Climate change may have taken this even further than it would otherwise have gone via increased overall oceanic heat content, but that's a matter of debate - to me the stratospheric mishaps seem more important for this particular winter's turnout.

 

 

I think we can see a good example of the interference this coming week; the neutral ENSO MJO composites (top row) fit the ECM 00z much more than the Nino ones, despite AAM and GWO observations indicating that it would usually fit more to the positive ENSO composites;

 

nada_6_feb_mid.pngnada_7_feb_ok.png
nino_6_feb_mid.pngnino_7_feb_ok.png

 

GFS fits mostly the neutral P6 composite before seemingly jumping straight to something akin to the P8 neutral composite (see below, left) with little P7 response - probably due to how it stalls the MJO in P7 for a while; continued eastward propagation is needed to bring about the typical response to activity within a given phase of the RMM plots.

 

The negative NAO-related UK cold potential for late this month and into March depends on how well we can break free of the Nina-like interference and so bring about an MJO P8 response more typical of the Nino base state.

 

So more toward the right-hand composite than the left-hand one. Note how I'm saying 'more toward' here; the composites should never be taken too literally (ideally we'd have different ones for each possible combination of MJO phase, GWO phase and AAM tendency, but there simply aren't enough historical years of obs data to do this meaningfully!).

 

nada_8_feb_mid.pngnino_8_feb_mid.png

 

As you can see - the temperature regime across the UK will be extremely sensitive to how much the interference gives way."

Original link:https://www.33andrain.com/topic/868-teleconnections-a-technical-discussion/?page=35&tab=comments#comment-133636 

 

What does AAM tendency mean?  Or singularly what does AAM stand for?

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The SOI(see the image below from the Long Paddock) is going in the tank right now.  It is at -25.22 currently.  Now, the 0z EPS looks terrible in the LR.  The 6z GEFS is now showing a trough in the LR, but it is not moving forward(per JB...and I agree).  However, the AO is forecast to go positive and stay positive.  IMHO, at some point something is going to have to give.  Again, I think the constant is ample precip.  I think that part of the equation is there.  The question is whether the EPS is missing yet another trough amplification in the East.  If we can somehow score a cold front w even minimal staying power...with the precip pattern loaded for bear, I still think that potential is there for a decent storm.  Please notice that I am not calling for a prolonged period of winter weather at this time.  Just hunting for a window in which a winter storm could occur.  

As for non-winter stuff, as Holston noted above, it is impressive how much precip is being shown on modeling.  If anything, MBY should be really green this spring if my lawn furniture doesn't float or blow away first.  Also, for gardeners out there, looks like spring and into early summer looks like a good water year.  I hesitate to say the mid and late summer will have great water.  Why?  One winter we were pounded by storm after storm like now...by summer the pattern had flipped to hot/dry and my garden dried out.  I do think w the El Nino tendency right now that summer should feature decent water all of the way through.

Screen Shot 2019-02-13 at 10.00.31 AM.png

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Some really good stuff in this winter re-analysis by @Isotherm.  It contains in-depth discussion on the QBO, AAM, tropical forcing, SSW, etc.  Normally I would grab a quote or two in order to preface the write-up, but I think the entire piece is worth a read.  Great information on this winter's drivers.

 

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Several people have mentioned their concern for flooding, and I definitely share that concern. Here’s the latest 12z Euro precip map. Still raining at 240 hours.

 

 

Euro Accumulated Precip.png

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43 minutes ago, Math/Met said:

Several people have mentioned their concern for flooding, and I definitely share that concern. Here’s the latest 12z Euro precip map. Still raining at 240 hours.

Euro Accumulated Precip.png

You know that is trouble when the rainfall map (in inches) would also make a great snowfall map without being adjusted for ratios.  Whew.

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So, are we part of the MJO forcing now?

giphy.gif 

That Velocity potential and irrotational wind map (I guess that's what it is?) map makes it look like our area may be getting close.

Perceptible waters are just amazing. Wave after wave of 250 - 300% abv. normal on the GFS and Euro. 

If forced to make a forecast now I'd say 4" - 6" over the next 15 days with some localized areas approaching 10" depending on where/ how long everything sets up. 

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So, are we part of the MJO forcing now?
giphy.gif&key=8a4f4421d6f1cfe151dbecd8d1c8b79a25b4e6276c77fabd3043de64b76b93c2 
That Velocity potential and irrotational wind map (I guess that's what it is?) map makes it look like our area may be getting close.
Perceptible waters are just amazing. Wave after wave of 250 - 300% abv. normal on the GFS and Euro. 
If forced to make a forecast now I'd say 4" - 6" over the next 15 days with some localized areas approaching 10" depending on where/ how long everything sets up. 


At first I thought you were talking snow accumulations.....only to realize you mean more rain. Dadgumit!!!


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10 minutes ago, Greyhound said:

only to realize you mean more rain. Dadgumit!!!

It's pitiful right now. Maybe we can set up a "Splash Country" car pool in Knoxvegas. The positive I take from this pattern is that in my experience as an E. Tennessean this sort of epically anomalous pattern usually has epic changes in store as time goes on and it changes. Snow and cold?  Warm and dry? I'll wager I'm ready for either around March 1st.   

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37 minutes ago, Holston_River_Rambler said:

So, are we part of the MJO forcing now?

giphy.gif 

That Velocity potential and irrotational wind map (I guess that's what it is?) map makes it look like our area may be getting close.

Perceptible waters are just amazing. Wave after wave of 250 - 300% abv. normal on the GFS and Euro. 

If forced to make a forecast now I'd say 4" - 6" over the next 15 days with some localized areas approaching 10" depending on where/ how long everything sets up. 

Looks like it will last a couple more weeks before finally weakening

Tropical Monitoring    North Carolina Institute for Climate Studies.png

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NW areas of the valley are looking more and more likely to have some frozen precip in a few days. The 12k NAM and 3k NAM are beginning to show some widespread ice in areas west of Nashville. It even looks like Davidson itself could get some ice on the NW side if the 12K NAM is to be believed. Southern Kentucky could also see some decent ice. The FV3, being the FV3 is a near catastrophic ice event in the NW areas with some places getting .60 inches of ice per the model. The regular GFS and Canadian are both slightly north and mainly effect SW Kentucky.

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