Winter 2014-2015 Pattern Discussion Thread I

[RONALD B]

https://www.facebook.com/l.php?u=https%3A%2F%2Ftwitter.com%2FRaleighWx%2Fstatus%2F541719904228237313&h=BAQFecTGo Allan seems too think all the models are showing a great set up in this time range I happen too agree !

[LithiaWx]

I know, I can't believe I am even responding to that post.

 

 

It's a great look but it's only the 18z GEFS, Euro is close, hopefully things keep getting better.

You,asked me what I want. I want the epic winter I was told was coming by so many folks. Maybe we get there, maybe we don't. But you can't sit here and tell me the models show that yet and be serious.

[CAD_Wedge_NC]

The 18z looks meh, Nino look as Bob chill said, but heights just don't look low enough over Canada to give the U.S. a decent source of cold air to draw from. The problem with those maps remain the lower heights and coldest air over in Russia on the wrong side of the globe. An epic US and SE winter can't commence until that changes. As of this post we haven't seen ANYTHING to suggest that change is coming. Some mets continue to suggest an epic winter is coming but I haven't seen the evidence yet that the arctic hammer with snowstorms is coming yet. It may end up happening but until we see some long range indicators of a major flip we wait and the anxiety builds for me.

Bob Chill

 Agree on 2m temps. Very broad brushed once you get beyond d7. But the turnaround in Canada to bn is really quick. Just making the point that once you shut off the pac flood things can turn quick.Normal temps in central Canada are plenty cold for our source. If h5 verifies there will be plenty of cold pooling there and down through the lakes.    

 

He also believes that the pattern change to below normal in Canada will happen quickly.       

[RONALD B]

Bob Chill

 Agree on 2m temps. Very broad brushed once you get beyond d7. But the turnaround in Canada to bn is really quick. Just making the point that once you shut off the pac flood things can turn quick.Normal temps in central Canada are plenty cold for our source. If h5 verifies there will be plenty of cold pooling there and down through the lakes.    

 

He also believes that the pattern change to below normal in Canada will happen quickly.       

Good post !

[packbacker]

I don't see any blocking that helps the SE on the GFS Ensembles. Maybe Im not looking at it correctly but I don't see it. If anything it looks like a +AO on the 18Z map posted above. I'm hoping for a major pattern flip that gets the SE cold and snowy. I don't see that yet. Also I don't live in Waycross, my climate isn't that far off from NC, it snows here almost every year.

 

Dude, why didn't you tell me you didn't know how to read a 5h map.  This makes complete sense, so what you are looking at is a solid -AO and slightly -NAO.  For an ensemble mean at day 14 is fairly good sign.

 

Also, you average about 2" of snow a year, the piedmont of NC averages 7-9".  Your climatology would be like me comparing central NC snow climatology to Baltimore.

[snowlover91]

A below normal December for the east and northern central plains is highly unlikely. Just because NC ends up below doesn't mean the rest of that area is.

Let's all be real here, a below normal December isn't in the cards for the areas that some were looking at. The same people and places I'm calling out as likely wrong.

For much of the nation a wall to wall winter is off the table when you see what December has for the country.

What do you base that off of? December was always forecast by Cosgrove to be the month we see a transition and to be rocky with normal/slightly above normal and then cool shots, so far this has verified nicely and it's possible we could finish here in the southeast below normal for December based off of temps so far as well as the next few weeks. The wall to wall cold was forecast for January through February with end of December being the point of things changing to colder and then the cold unleashing in January. Models are agreeing with a colder pattern setting up by December 20th and will likely see that pattern continue to look better as we draw closer. Not worried at all, everything is right on schedule and verifying very nicely.

[LithiaWx]

Dude, why didn't you tell me you didn't know how to read a 5h map.  This makes complete sense, so what you are looking at is a solid -AO and slightly -NAO.  For an ensemble mean at day 14 is fairly good sign.

 

Also, you average about 2" of snow a year, the piedmont of NC averages 7-9".  Your climatology would be like me comparing central NC snow climatology to Baltimore.

If that's the perfect pattern with a +PNA and a -AO and a -NAO I'm shocked. I don't believe that is the case but if it is, it is and I'm wrong. I'm not going to debate climo with you. I Didn't say marietta gets more snow than Apex. I said are climates aren't that different.

[SnowGoose69]

I don't see any blocking that helps the SE on the GFS Ensembles. Maybe Im not looking at it correctly but I don't see it. If anything it looks like a +AO on the 18Z map posted above. I'm hoping for a major pattern flip that gets the SE cold and snowy. I don't see that yet. Also I don't live in Waycross, my climate isn't that far off from NC, it snows here almost every year.

I would tend to agree with this, I went through a list of many cities at work today and most likely won't end up below normal, the first 5 days and likely another 3-4 days next weekend into the early part of the next week will make it tough. ATL was one I looked at, my projection is they'll end somewhere around +2, they will fall below 2012 and 2013 December in all likelihood but it may be close on 2013. This will likely be the warmest 3 consecutive Decembers they've ever had I would think

[RONALD B]

http://t.co/mwOf3ifitu nother post from allan on the pattern. GEFS 18 !

[Webberweather53]

Greenland doesn't match at all, and Eurasia is only a weak match. Doesn't bode well.

 

? Remember though one is for the month as a whole, the other is only a forecast for a 5 day increment of that month, sure they're on different timescales, but that's not bad at all, especially when we're only correlating one variable (high northern hemisphere snowpack) to monthly temperatures, not to mention we're looking only for general trends.. I wouldn't say Eurasia is a weak match in this case (it will turn even colder against averages over the next few weeks), it even has the temperature distribution right in North America, the cool tongue off Japan (+PDO), etc. Greenland is the only place where there's appreciable divergence...

 

I should have thrown SSTs which naturally exhibit less daily, weekly, & even intraseasonal variance, & in there, you can see the strong SST tripole in both the Atlantic & Pacific oceans (esp w/ the cool tongue near the "critical" latitude in & around 40N where in the mid-latitudes the cooler sea surface feeds back to lower heights, thus encouraging equatorward propagation of the mid-latitude jet. By virtue of conservation of angular momentum, with the mid-latitude jet forced to circumnavigate across a larger region of the globe (which is the reason why the subtropical jet nudged in the upper levels between the Ferrell & Hadley Cells is generally slower than the polar jet stream) a slower jet possesses lower potential inertia, thus it has a greater capacity to meander & do so meridionially. This kind of pattern tends to favor a reduction in temperature (thus also wind which= a weaker polar night jet (a feature develops in the autumn at the intersection of the region of growing semi-permanent darkness in boreal winter & areas w/ sunlight, where in, large contrasts in temperature exist, giving rise to the polar vortex) & there's also a lowering of the mean westerlies with a weaker polar night jet, leaving the polar vortex susceptible to upwelling intrusions from underneath by wave breaking of Rossby Waves that deposit easterly momentum accelerations up into the mean flow as they dampen (i.e. lose amplitude) & this can help revitalize displacement (more risky in terms of getting blocking) versus actual splitting complete annihilation of the PV (generally more conducive to blocking & a lower (more negative) AO & NAO because I hypothesize that there's a considerably longer recovery period in the latter scenario.) Consequently vast discrepancies in geopotential height are also prevalent, and overall, the cool SSTs in & around 40N given this aforementioned information serve as a viable proxy not only for a high northern hemisphere snowpack, but also a predominantly -AO regime as it is indicative of an extensive jet that is more conducive to high latitude blocking (-AO/NAO) which is where we're headed this winter...

 

NH SST regression Oct N hem snowpack w/ one month lead on November SSTs

 

 

Since we observed the largest northern hemisphere fall snowpack on record this year, I also thought it would be applicable to see what the SSTs look like, once again, very similar. Correlation is stronger than just using October alone...

 

The resulting 500mb...

 

 

This year's SSTs (for reasons explained above) are amazing if you like a -AO...

 

Latest weekly SST anomalies

 

OND SST correlation to DJF -AO

[Bob Chill]

Ensemble means in the d10+ range are just a tool to see the most likely pattern way beyond the op's skill. Op's skill beyond just 7 days is probably no better than a single ensemble member. The gefs has 20 members and the EPS has 52. I personally weight op's well below ensemble means beyond 6 days. I could care less what ops show beyond d8 and even then that's a big stretch unless the pattern is stable.

The latest ensemble runs show a great pattern for cold HP's to drop down in the middle of the country and head se. Not drop down the spine of the Rockies and bleed east while modifying the whole time.

The 500mb pattern shows the door open for a continuation of southern stream storms and or energy undercutting the pna ridge and northern stream energy riding over the top of the pna/epo ridges. Most important the pattern would favor not letting storms cut west and to the lakes.

If anyone ends up on the n and w side of a storm in that pattern the odds favor frozen.

Ensembles are not good for sensible wx. There's always spread so taking temps verbatim is not good practice. I can look at the 18z gefs and the calendar and feel comfortable saying it's a pattern that is conducive for frozen precip anywhere in the se/tn valley/ma. Obviously the further south and/or closer to the coast the odds decrease. That applies to any setup.

It's still far out in time but looks far better than where we are now.

[pcbjr]

Same

 

Drums keep pounding

 

Beat goes on ....

 

[RONALD B]

Ensemble means in the d10+ range are just a tool to see the most likely pattern way beyond the op's skill. Op's skill beyond just 7 days is probably no better than a single ensemble member. The gefs has 20 members and the EPS has 52. I personally weight op's well below ensemble means beyond 6 days. I could care less what ops show beyond d8 and even then that's a big stretch unless the pattern is stable.

The latest ensemble runs show a great pattern for cold HP's to drop down in the middle of the country and head se. Not drop down the spine of the Rockies and bleed east while modifying the whole time.

The 500mb pattern shows the door open for a continuation of southern stream storms and or energy undercutting the pna ridge and northern stream energy riding over the top of the pna/epo ridges. Most important the pattern would favor not letting storms cut west and to the lakes.

If anyone ends up on the n and w side of a storm in that pattern the odds favor frozen.

Ensembles are not good for sensible wx. There's always spread so taking temps verbatim is not good practice. I can look at the 18z gefs and the calendar and feel comfortable saying it's a pattern that is conducive for frozen precip anywhere in the se/tn valley/ma. Obviously the further south and/or closer to the coast the odds decrease. That applies to any setup.

It's still far out in time but looks far better than where we are now.

Good post chill!

[packbacker]

If that's the perfect pattern with a +PNA and a -AO and a -NAO I'm shocked. I don't believe that is the case but if it is, it is and I'm wrong. I'm not going to debate climo with you. I Didn't say marietta gets more snow than Apex. I said are climates aren't that different.

Yep, your wrong, I would post the PNA/AO/NAO graphs but what's the point.  Nobody said it was a perfect pattern, Bob's post say it best above.  Nobody is calling for snow, nobody said it's a wintery pattern on the 22nd.  All I said was the ensemble runs are getting better and better, that's it.

[Bob Chill]

Yep, your wrong, I would post the PNA/AO/NAO graphs but what's the point. Nobody said it was a perfect pattern, Bob's post say it best above. Nobody is calling for snow, nobody said it's a wintery pattern on the 22nd. All I said was the ensemble runs are getting better and better, that's it.

Yea,predicting snow at long leads would require perfect modeling of shortwaves embedded in the longwave flow. We can't do that at 3 days yet let alone 15. Lol

We seem to be heading towards a pattern that "could" produce snow. That's all we can really ask for anytime during winter. And its not perfect yet. Nao is trending better but not ideal.

[Snowless in Carrollton]

Atlanta met Kirk Mellish updated his blog today and says that the last 10 days of Dec through March look cold, not non stop cold, but colder than average.

[franklin NCwx]

Yea,predicting snow at long leads would require perfect modeling of shortwaves embedded in the longwave flow. We can't do that at 3 days yet let alone 15. Lol

We seem to be heading towards a pattern that "could" produce snow. That's all we can really ask for anytime during winter. And its not perfect yet. Nao is trending better but not ideal.

yeah the nao is a piece of the puzzle we are missing. At least we are building higher heights in Eastern Canada and the Davis straits.

[packbacker]

Yea,predicting snow at long leads would require perfect modeling of shortwaves embedded in the longwave flow. We can't do that at 3 days yet let alone 15. Lol

We seem to be heading towards a pattern that "could" produce snow. That's all we can really ask for anytime during winter. And its not perfect yet. Nao is trending better but not ideal.

 

Agreed!  Like you said earlier, the ensembles aren't pushing things out further and further, which is great to see.  Weeklies should be fun tomorrow (knock on wood).

[LithiaWx]

I would tend to agree with this, I went through a list of many cities at work today and most likely won't end up below normal, the first 5 days and likely another 3-4 days next weekend into the early part of the next week will make it tough. ATL was one I looked at, my projection is they'll end somewhere around +2, they will fall below 2012 and 2013 December in all likelihood but it may be close on 2013. This will likely be the warmest 3 consecutive Decembers they've ever had I would think

Thank you for posting in this sub forum. Your thoughts are always appreciated in here.

[franklin NCwx]

Agreed! Like you said earlier, the ensembles aren't pushing things out further and further, which is great to see. Weeklies should be fun tomorrow (knock on wood).

the weeklies should be a continuation of the EPS tonight. So what they look like at day 15 we can extrapolate from there.

[LithiaWx]

Atlanta met Kirk Mellish updated his blog today and says that the last 10 days of Dec through March look cold, not non stop cold, but colder than average.

http://www.wsbradio.com/weblogs/kirk-mellishs-weather-commentary/2014/dec/07/winter-has-not-been-canceled-yet/#__federated=1

What a great met and he is very bullish.

[Batman]

A below normal December for the east and northern central plains is highly unlikely. Just because NC ends up below doesn't mean the rest of that area is.

Let's all be real here, a below normal December isn't in the cards for the areas that some were looking at. The same people and places I'm calling out as likely wrong.

For much of the nation a wall to wall winter is off the table when you see what December has for the country.

Just my opinion here, but I would say that with regard to "wall to wall" cold, the beauty is in the eye of the beholder. By that I mean of all the super winters we have discussed today (76-77, 77-78, 78-79..), one cold make a good argument that all of these either had a mild spell in December or broke warm in February. Does one consider "wall to wall" cold a winter where DJF all have below average temps? Does a winter lose it's wall to wall status because there is a pretty good thaw thrown in even though the month as a whole is below normal? Just saying that different folks will likely have different answers to these questions. It would appear to me from all of the good info that Larry and Webber have presented that very few winters (even some of our go to cold, stormy winters) had wall to wall cold according to the definitions we are using. I suspect that if the winter plays out the way many have hoped, anticipated, and even forecasted, most will forget that December started above average.

[Cold Rain]

Dude, why didn't you tell me you didn't know how to read a 5h map. This makes complete sense, so what you are looking at is a solid -AO and slightly -NAO. For an ensemble mean at day 14 is fairly good sign.

Also, you average about 2" of snow a year, the piedmont of NC averages 7-9". Your climatology would be like me comparing central NC snow climatology to Baltimore.

Lol. There is nothing +AO about that map.

[SN_Lover]

The polar vortex remains in Siberia with every 11-15 day GFS ens mean i am looking at. Yes there was a stratospheric warming event, but the polar vortex remains in Siberia. And the southeast in the long-term looks to have zonal flow to even some ridging with the GOM WAA. 

[DaculaWeather]

We've had two weak strat warmings so far, but a better chance occurs toward the end of the month. Decembers haven't been a favored month for SSW's in quite a few years. 

[GaWx]

We've had two weak strat warmings so far, but a better chance occurs toward the end of the month. Decembers haven't been a favored month for SSW's in quite a few years. 

 

Per my criteria, I agree that there have been just two fairly weak SW's. I use this:

 

 http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_OND_NH_2014.gif

 

 Here are the dates of the very strong SSW's (based on +28+ C strat. anomalies) that I've found from this ncep strat website:

 

 Dec.: 7, 12, 17, 23, 23, 29, Jan: 1, 9, 14, 22; Feb.: 9

 

 So, peak time is the last half of Dec. to the first half of Jan.

 There have been  ~ 1 very strong SSW every 3 years on avg. since 1979 fwiw. Fwiw, in case there is some kind of cyclical factor, we're overdue for one. However, from what Webber and others have said (I concur), we don't need one to have a strong -AO as well as cold winter. Also, my min. criteria are probably stricter than what some others use.

 

Edit: James, drink up. Sorry, man. Don't take it personally.

[metwannabe]

http://www.wsbradio.com/weblogs/kirk-mellishs-weather-commentary/2014/dec/07/winter-has-not-been-canceled-yet/#__federated=1

What a great met and he is very bullish.

The last three paragraphs are almost word for word what Larry Cosgrove wrote yesterday Lol. I mean like copy and paste word for word. Maybe I am missing something cause i was reading it on my phone but it looks like Cosgrove's article from yesterday

[griteater]

The last three paragraphs are almost word for word what Larry Cosgrove wrote yesterday Lol. I mean like copy and paste word for word. Maybe I am missing something cause ibwas reading it on my phone but it looks like Cosgrove's article from yesterday

 

Sure is.  This is at least the second time he's copied from others without giving credit (did it to WxSouth a few years ago)...unprofessional to say the least.  

[metwannabe]

Sure is. This is at least the second time he's copied from others without giving credit (did it to WxSouth a few years ago)...unprofessional to say the least.

Lol he threw Robert a bone Roberts post from last night about white christmas was in there as well lol.

[Webberweather53]

Sure is.  This is at least the second time he's copied from others without giving credit (did it to WxSouth a few years ago)...unprofessional to say the least.  

 

It's not just merely unprofessional, it's outright plagiarism & is pushing awfully close into legal territory in terms of copyright infringement, especially if he copies from a private company/weather firm for example... Even if by chance what he's doing isn't illegal it's completely dishonest, shameful, and is a breach of unwritten ethical standards.