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Winter 2014-2015 Pattern Discussion Thread II


JoshM

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Despite Don being knowledgeable (he would be even more brilliant if he took a step back from the models), I think this is quite premature on his part... Aside from the multitude of other variables that don't match up w/ 1991-92 (multi yr El Nino event 1986-88, hurt -AO chances, the Atlantic SST distribution this year is the exact opposite, we observed a stronger El Nino, multidecadal +AO phase, stronger solar max, later/weaker easterly QBO peak, etc)... I've touted for quite some time now that December is the most boring month of an El Nino winter, & the only thing December has revealed about the overall winter is that it's following right in line w/ what is expected in a Weak El Nino/+TNA...

 

North-America-temps-Weak-El-Nino-TNA-DJF

ncep_cfsr_noram_t2m_anom.png

US-Winter-Monthly-Temps-DJF-El-Nino-Plac

 

 

The polar vortex behavior is certainly not reminiscent of some of the more recent predominantly +AO winters, including 1991-92...

Note how large the polar vortex was at this time in 1991-92, 2011-12, & last winter...

vtx_nh_1991-1992.png

vtx_nh_2011-2012.png

vtx_nh_2013-2014.png

 

This year on the other hand, womp...

vtx_nh.png

 

The claim that Don mentioned in his post which originated from DT that a strengthening easterly QBO is bad for the winter has little basis in the actual data, there are plenty of examples of cold winters that featured strengthening easterly QBOs... Just to name a few..

2009-10, 1995-96, 1976-77, 1962-63, etc...

 

http://www.esrl.noaa.gov/psd/data/correlation/qbo.data

Looking @ Sam Lillo's recent research in terms of MQI (Multivariate QBO Index) phase space & SSWEs which promote -AO bursts & can serve as a proxy for how the atmosphere modifies the QBO signal, it shows that an easterly QBO regime w/ the shear zone in & around 30-50mb is least favorable for SSWEs (exactly why this is the case, is unknown to me) however, oncoming & relatively fresh easterly QBO regime is actually quite favorable along w/ of course the weakening Easterly QBO as it descends below 50mb, via viscous diffusion. Also, because of the thermal wind relationship, the emergent westerly shear descent invokes warming in the upper levels to downwell in the stratosphere...

Timing-of-SSW-MQI.png

 

 

The easterly QBO shear zone is currently located within & is entering this unfavorable 30-50mb band, which along w/ transient tropical forcing, & a distorted Walker Cell thanks to the Indian Ocean, probably explains why we're struggling to crank out a SSWE despite the favorable SAI/SCE w/ the relatively unimpressive support from the sun also worth mentioning...

time_pres_UGRD_ANOM_ALL_EQ_2014.gif

 

MQI-Phase-Space-Dec-12-2014.png

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Despite Don being knowledgeable (he would be even more brilliant if he took a step back from the models), I think this is quite premature on his part... Aside from the multitude of other variables that don't match up w/ 1991-92 (multi yr El Nino event 1986-88, hurt -AO chances, the Atlantic SST distribution this year is the exact opposite, we observed a stronger El Nino, multidecadal +AO phase, stronger solar max, later/weaker easterly QBO peak, etc)... I've touted for quite some time now that December is the most boring month of an El Nino winter, & the only thing December has revealed about the overall winter is that it's following right in line w/ what is expected in a Weak El Nino/+TNA...

 

 

IMO Don hasn't done anything other than highlight what the models are showing as a possibility and bringing out those that are in the process of cancelling winter. Is it possible for a winter of warmth to happen..YES.....is it possible for winter to give us at least one (if not more) chances of a winter wonderland.....YES.  The point is, everything we are looking at says it should be a great winter, but for whatever reason the atmosphere is acting more Nina like than Nino at the moment.

From Don......

The latest teleconnection forecasts offer only more misery. Forecasts for a deeply negative EPO have been withdrawn almost as suddenly as they had first appeared. The PNA is now forecast to creep into negative territory.

 

What’s that immense tower in the distance? It dwarfs even the world’s tallest structure. Look closer. That’s the latest GFS ensemble forecast for the Arctic Oscillation. One member even takes the AO toward +5 during the first week in January.

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12z GFS is freaking close to something big. Energy rolling west big highs dropping out of Canada. Might be something to watch for as we get closer to this weekend. Out to hour 120. 

 

I noticed that.  The- AO is actually flexing on this run.  The last 24 hours is the first time I've seen the models trend colder in the mid range.  Totally non scientific, but I take that as a good sign.

 

Edit: It might be a suppression case.  But light snow is better than no snow.

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Don told you the bad news about the AO, but the NAO does look to go solidly positive. The PNA looks to average somewhere around neutral or maybe slightly negative in the LR. Back to the AO, it does look to go negative in the short time before going positive in the LR; but to be honest, these indices have been switching/flipping like the op models. I don't trust the long range for anything. Having the AO go negative just for a short time can pull some cold to our side of the hemisphere; also at this time of year we can build some cold as long as there is sufficient snow cover in Canada. **keep the PNA at least neutral and give me a positive NAO and I think we could get something wintery.

 

http://www.cpc.noaa.gov/products/precip/CWlink/daily_ao_index/teleconnections.shtml

 

Edit: My bad about the NAO... going positive is badddddd... So hopefully that is wrong as well

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I noticed that.  The- AO is actually flexing on this run.  The last 24 hours is the first time I've seen the models trend colder in the mid range.  Totally non scientific, but I take that as a good sign.

 

Edit: It might be a suppression case.  But light snow is better than no snow.

 

Man it's trying. 1036 high coming into the Dakotas is forcing that energy to stop it's lift going to the lakes and help suppress it. Might end up being a good run for TN. 

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IMO Don hasn't done anything other than highlight what the models are showing as a possibility and bringing out those that are in the process of cancelling winter. Is it possible for a winter of warmth to happen..YES.....is it possible for winter to give us at least one (if not more) chances of a winter wonderland.....YES.  The point is, everything we are looking at says it should be a great winter, but for whatever reason the atmosphere is acting more Nina like than Nino at the moment.

From Don......

The latest teleconnection forecasts offer only more misery. Forecasts for a deeply negative EPO have been withdrawn almost as suddenly as they had first appeared. The PNA is now forecast to creep into negative territory.

 

What’s that immense tower in the distance? It dwarfs even the world’s tallest structure. Look closer. That’s the latest GFS ensemble forecast for the Arctic Oscillation. One member even takes the AO toward +5 during the first week in January.

 

The only thing I wish he hadn't done is talk about that one member...clearly an outlier I doubt it goes that positive...it's 11 days away so to bring that up was kinda like...alright what's the point....That's like me saying there's a -3.9 at the end of the run so we got that going for us. The AO spread on the GEFS has been horrible and continues to be horrible. The 06z PARA OP AO actually went negative on Jan 2nd...lol Also the EPO still looks to go grossly negative and stay negative through the first week of Jan on all models except the canadian I believe goes toward neutral?, not sure what he's talking about there.

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For cold lovers I have a feeling the GFS is going to make them very happy today at least in the mid range. This run looks fantastic at hour 163 so far. You've got the PV dropping major cold into the MN and central Canada is in the ice box. Meanwhile big highs keep falling. 5h has some energy flying around but nothing major so far. 

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Dare I say it? At 168 it has a Jan. 2013 look to it almost...we'll see how far this PV can drop. 

yeah that PV piece is just going to swing around east....different look than bottling up the cold around the hudson, cold incoming.

 

the only thing the euro has been missing is that ridge out west...if it finds that, the cold is there...looks like GFS was firs to the punch with this pattern, but the euro was first to the punch with getting our cold on this side of the globe and over the hudson so we can work with it, now we see a PV breakoff...

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For cold lovers I have a feeling the GFS is going to make them very happy today at least in the mid range. This run looks fantastic at hour 163 so far. You've got the PV dropping major cold into the MN and central Canada is in the ice box. Meanwhile big highs keep falling. 5h has some energy flying around but nothing major so far. 

Yeah Burger and Larry the medium range looks very reasonable on this run shoot more than reasonable. A nice deep trough in the East with a nice ridge out West

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