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February Mid/Long Range Discussion


George BM

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24 minutes ago, Bob Chill said:

I'm surprised there hasn't been more talk about it. It's been showing up for at least 3-4 days now. One thing HM doesn't say is...if it isn't too little too late...then how many blizzards should we expect over the next 3 weeks?

 

21 minutes ago, frd said:

HM normally does not talk up splits and the strat. I view his increased interest in the strat recently as a vote of confidence that there is at least some potential for the event to occur. 

HM is excellent. One of the best. No hype. Not hesitant to kill weenie hopes when a setup isn't good and his hit rate when he honks is hall of fame level. 

All that said even if we get some blocking from this my several say digging into past Nina events  and the nao shows not every nao will lead to a hit. We had some fails. But it did seem that they all lead to legit chances.  And so there would be a reason to think it could work. So I'll take it. 

I wonder how many years went wall to wall positive nao with no even transient -nao periods. 

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17 minutes ago, psuhoffman said:

It lost it at 12z but the 6z gefs actually showed a pretty darn good look late. It's jumpy lately so the fact it showed once means the possibility is there. 

IMG_3772.thumb.PNG.f870b29af28a775c767b6b5323ec6b86.PNGIMG_3771.thumb.PNG.f57953532c85c1961abdb124489ed622.PNG

I saw that this morning too. If you dont look at the surface temps(I rarely do on LR ens) and just h5, its basically just run to run noise- 12z looked just as good to me. The next few runs should give a us better idea of where this is headed- if the GEFS is really on to something (in the NAO domain), or if its yet another false alarm.

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2 hours ago, frd said:

Talk of a Strat split similar to Feb 1989 in terms of timing and Nina background state, as alluded to by Tom Crawford.  

This year he states the trop vortex is weaker. He stated the  event in Feb. 1989 seemed to have little impact on the strong vortex that year. 

 

Interesting because this year thus far is very close temp wise and total snowfall thus far. 

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1 hour ago, psuhoffman said:

It lost it at 12z but the 6z gefs actually showed a pretty darn good look late. It's jumpy lately so the fact it showed once means the possibility is there. 

IMG_3772.thumb.PNG.f870b29af28a775c767b6b5323ec6b86.PNGIMG_3771.thumb.PNG.f57953532c85c1961abdb124489ed622.PNG

So...can President's Day save the MA from frozen futility in Niña's snow-robbing clutches? Find out next time on as the NAO turns!

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1 hour ago, Ji said:

I think we are going to rebound to better looks soon.

Let’s hope we have better rebounding skills than the Wizards! Sorry. Apologies. Are we in storm mode for the AM white rain showers that will close school everywhere? Oh damn.  :poster_oops:This could be the wrong thred. Meant to reply to WBAL’s Tony Pann and his Deep Thunder model snow predictions. 

 

Eta: Puts down Bells Hopslam and realizes that s*** is evil!

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1 minute ago, Scraff said:

Let’s hope we have better rebounding skills than the Wizards! Sorry. Apologies. Are we in storm mode for the AM white rain showers that will close school everywhere? Oh damn.  :poster_oops:This could be the wrong thred. Meant to reply to WBAL’s Tony Pann and his Deep Thunder model snow predictions. 

That guy is deep is something. 

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Weeklies aren't as awful as I thought. Not good. A whole lot of ambiguous. But...they actually imply some chances for nao help and given that's what we need they might actually offer more chance to get lucky with one event then a continuance of the epo regime would. I'm not unhappy with it. I've given up on anything more then getting lucky once or twice and it offers that possibility imo. 

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4 minutes ago, psuhoffman said:

Weeklies aren't as awful as I thought. Not good. A whole lot of ambiguous. But...they actually imply some chances for nao help and given that's what we need they might actually offer more chance to get lucky with one event then a continuance of the epo regime would. I'm not unhappy with it. I've given up on anything more then getting lucky once or twice and it offers that possibility imo. 

Pretty much exactly as expected based on the 0z run. Will likely look quite different next Monday. I'll leave it at that lol.

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

Pretty much exactly as expected based on the 0z run. Will likely look quite different next Monday. I'll leave it at that lol.

It could have been way worse. I actually thought it was going to lock that day 15 look in for a while and just put winter out of its misery 2012 style. But it didn't. Nothing great but some periods that something could happen. 

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18 minutes ago, psuhoffman said:

It could have been way worse. I actually thought it was going to lock that day 15 look in for a while and just put winter out of its misery 2012 style. But it didn't. Nothing great but some periods that something could happen. 

Agree. Expectations were pretty low, but there are some hints of good periods, and the big picture look isn't awful, despite the relatively persistent "apparent warmth" based on h5 height and 850 mb temp anomalies.

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13 minutes ago, psuhoffman said:

It could have been way worse. I actually thought it was going to lock that day 15 look in for a while and just put winter out of its misery 2012 style. But it didn't. Nothing great but some periods that something could happen. 

I think the reason the weeklies changed is the incredible amplitude in phase 6 , hardly ever seen this before.

Also, the Euro MJO forecast, as mentioned last week, was biased and wrong, where as the GFS was much better. 

 

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17 minutes ago, psuhoffman said:

It could have been way worse. I actually thought it was going to lock that day 15 look in for a while and just put winter out of its misery 2012 style. But it didn't. Nothing great but some periods that something could happen. 

I've seen worse. We seem to be in some sort of state of flux right now in the LR. It's less clear than any other time this winter. Maybe the strat sets us up from something workable. I'm with you pretty much. Hopefully we pull off a decent event. If not its another dud on the books and i'm ready for mild temps and longer daylight.  We have 5 weeks left before climo starts fighting back pretty hard. 

 

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Just now, frd said:

I think the reason the weeklies changed is the incredible amplitude in phase 6 , hardly ever seen this before.

Also, the Euro MJO forecast, as mentioned last week, was biased and wrong, where as the GFS was much better. 

Yeah its been mentioned a few times in recent days. The recent EPS runs are quite possibly "off" due to the MJO forecast being incorrect. And of course the latest edition of the weeklies were also impacted as the new run was based off the 0z EPS, which was pretty awful.

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4 hours ago, Bob Chill said:

I'm surprised there hasn't been more talk about it. It's been showing up for at least 3-4 days now. One thing HM doesn't say is...if it isn't too little too late...then how many blizzards should we expect over the next 3 weeks?

Get it to day 9-10 and I think chatter will start picking up. My understanding is that strat forecasts are less reliable past day 10 compared to H5. A split also takes less time to see effects than a SSW.

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5 hours ago, Bob Chill said:

I want to hear from @Isotherm about this. Using the op for wow factor but the ens look the same. Euro splits 10-50mb by d10. Probably too little too late but we haven't seen anything like this in a lot of years. 

gfs_Tz10_nhem_26.png

 

 

Bob,

 

Posted this elsewhere in reply to a strat inquiry, and it is pertinent here. I think the most salient question at this point is trop-strat coupling and consequently the propagating effectiveness of a w-2 induced split to materially alter the troposphere. One of the most significant predictors of whether tropospheric blocking will occur following SSW is if tropospheric blocking exists prior to the event.

 

1. All stratospheric events -- displacements, splits, are highly idiosyncratic and disparate in terms of evolution.

 

2. Each stratospheric event will have a different impact in the troposphere, depending upon depth of split/orientation of vortices, and tropospheric-stratospheric coupling. There have been wave-2 induced split events that were poor propagators in the past.

 

3. Case example. January 24th, 2009 was our last w-2 induced split event, modeled fairly similarly to the evolution on the GEFS for mid month. The month following this major split event did not produce severe winter weather in the United States. Below are the February 2009 temp departures. Temperatures actually warmed after the split event, relative to January 2009's cold departures. There was no effect on the NAO modality, and the tropospheric AO only became mildly negative.

 

24b23ae.png

 

 

4. The follow-up wave 2 event as discussed, via tropospheric precursor and associated potent tropical forcing (through latent heat release induced rossby wave alterations and concomitant breaking,) is occurring.

 

The question is: a) Will wave amplitudes be as high and persistent as evinced by the GFS?, and further, B - will it propagate effectively, subsequently inducing large scale tropospheric alterations.

 

Given the magnitude of the MJO wave in this case, I feel fairly confident we will disturb the SPV sufficiently to attempt an official SSW event. If this occurs, it would likely be February 15th-18th based upon historical data of geopotential height preconditioning via wave 2. This is a multi-step equation though, and results are stochastic/non-linear. Even if we have a split in this period, my point is - there's no way to unequivocally state that severe winter weather will result, just yet. Given the tendencies of the AO this winter and going forward, my guess is that if we have a split mid month, it won't induce a severely negative AO. But we'll see where we stand in a week or so as far as coupling potential.

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Great post @Isotherm. Most of it makes sense. Lol.

I totally understand and also would never expect a simple strat split = winter wx equation. The one thing that is painfully clear is the only thing that will give the MA a decent chance at an event going forward is high latitude blocking.  If the strat were to work some magic and help trop blocking between now and the first 10 or so days of March then it's something to keep an eye on. We clearly need some help this year. If it doesn't work out then fine. At least I have something to track other than head fakes  in the med range and rain storms in short range. 

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39 minutes ago, Bob Chill said:

Great post @Isotherm. Most of it makes sense. Lol.

I totally understand and also would never expect a simple strat split = winter wx equation. The one thing that is painfully clear is the only thing that will give the MA a decent chance at an event going forward is high latitude blocking.  If the strat were to work some magic and help trop blocking between now and the first 10 or so days of March then it's something to keep an eye on. We clearly need some help this year. If it doesn't work out then fine. At least I have something to track other than head fakes  in the med range and rain storms in short range. 

I looked at the nao numbers. We have only had 5 days of winter so far register a - and they were barely negative so really neutral. That would be by far the least -nao of every Nina if it doesn't go negative at all the rest of the way. The most similar years to this nao were 1984 1989 and 2012 but all 3 still had at least 15 or so negative nao days and at least one period of legit -nao. We haven't had a single day get to -1. 1984 and 2012 both flipped negative late in winter but 2012 did no good for us as North America was blow torched before it and couldn't recover that late in a warm season for the whole conus. 1984 we had several snow late. None were epic but there were a few that almost were. 1989 just sucked right to the end and never had any significant nao help. 

I guess from a purely stats probability pov it suggests we will get some nao help. It would be absolutely unprecedented to go wall to wall without any -nao at all. Never in 20 times since 1950 has that happened. Even last year we had 3 legit -nao periods. Early January with the near miss. Late January into feb but we were fighting warm air left over from the torch but we got a couple perfect track storms and cold rain then the near miss just to our north lol. And the march period and sleet storm. 1989 was the closest but it at least had a couple transient -nao periods early. Wall to wall + nao would be an epic fail. So I suppose we should assume the nao is unlikely to stay positive straight to march 20.

Keep in mind getting one -nao period doesn't guarantee anything. Odds would still be against us as we would be putting all our eggs into one basket and a single fail means total fail. But at least we would have a chance. 

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1 hour ago, psuhoffman said:

looked at the nao numbers. We have only had 5 days of winter so far register a - and they were barely negative so really neutral. That would be by far the least -nao of every Nina if it doesn't go negative at all the rest of the way.

Just from the graph on the CPC site it looked like we had had 0 days below 0, but a closer look shows that 12/1, 12/3 and 12/4 were all slightly negative, and so was 12/27, and by slight I mean SLIGHT.  I don't have the daily numbers  for 2018, but there must have been another day in January.  By the looks of the graph I would say 1/10 or thereabouts.

So three of our measly 5 negative days were in the first four days of December.  Stingy.

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1 minute ago, cbmclean said:

Just from the graph on the CPC site it looked like we had had 0 days below 0, but a closer look shows that 12/1, 12/3 and 12/4 were all slightly negative, and so was 12/27, and by slight I mean SLIGHT.  I don't have the daily numbers but there must have been another day in January.  By the looks of the graph I would say 1/10 or thereabouts.

So three of our measly 5 negative days were in the first four days of December.  Stingy.

None of them were truly negative just neutral but technically 5 days did register a below 0 value. But we have had no -nao effectively. That has never happened wall to wall in a Nina. I wonder if it's ever happened in any winter. I'll look later. 

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