2014-15 winter outlook

[Bob Chill]

Well, there goes 1/3 of our winter then. Hopefully January and February will be a little colder.

 

oops. I was just cracking a joke. I honestly don't have any concrete thoughts on Dec yet. It's just funny how (as jburns said) all these lr forecasts start popping up Oct and for whatever reason they are almost all cold and snowy. Like there is nothing ever bad about the pattern or early signs leading in. 

 

If I posted a warm forecast right now my popularity poll would look like this:

 

 

 

I'll go with bitter, cold, and snowy until proven otherwise even if I don't believe myself.  

[Cold Rain]

oops. I was just cracking a joke. I honestly don't have any concrete thoughts on Dec yet. It's just funny how (as jburns said) all these lr forecasts start popping up Oct and for whatever reason they are almost all cold and snowy. Like there is nothing ever bad about the pattern or early signs leading in.

If I posted a warm forecast right now my popularity poll would look like this:

HM pop poll.jpg

I'll go with bitter, cold, and snowy until proven otherwise even if I don't believe myself.

Bob, meet Snowstorm. He's one of our, shall we say, less optimistic residents. We'll introduce you to jshetley in due time...but you sorta gotta work up to that.

[Cold Rain]

Disco? I just had a space-time thing there, I think!

You guys are right though. Most of the time this time of year, there is a broad lean toward cold for the winter. That's fine -- it makes it more fun, even if there's really no good for it. The fact of the matter is most want cold and are going to be looking for reasons to support that outcome. And the reality is, things don't generally become clearer until probably mid-November, if then.

This year, the data thus far appears to support the colder outcome, but we'll see. Things can and do change. Still, I'm quite optimistic.

[superjames1992]

Northeast US Weather.com like the SE for cold and snow:  http://www.northeastusweather.com/2014-2015-preliminary-winter-outlook/

 

Must be a cover site for SE winter weather weenies...  Total weenie maps...

 

 

[superjames1992]

oops. I was just cracking a joke. I honestly don't have any concrete thoughts on Dec yet. It's just funny how (as jburns said) all these lr forecasts start popping up Oct and for whatever reason they are almost all cold and snowy. Like there is nothing ever bad about the pattern or early signs leading in. 

 

If I posted a warm forecast right now my popularity poll would look like this:

 

HM pop poll.jpg

 

 

I'll go with bitter, cold, and snowy until proven otherwise even if I don't believe myself.  

 

 

You should post a 1997-1998 analog.  Prepare for tropical rains! 

[GaWx]

Bring it ! I want a winter similar to what we had in the late 70s or 80s. I hope Atlanta gets a foot of snow and sub zero temps. 

 

 That would be something, indeed! For the fun of it, I was checking KATL history. We know that literally getting a foot of snow, even for the entire season, is extremely rare. Looking back to the late 1800's, I could find only two possible instances of this and both were before 1900. (I'm not counting the 12"+ that the NW burbs got in 1993 from the blizzard.) So, they're very much overdue! However, KATL has had twelve 7"+ seasons. Based on climo, 7" is a huge season for ATL and a major benchmark to reach. They've occured about once every 11 years on average. However, half of those 12 occured between ~1880 and 1904 or a whopping once every four years!! Since then, they've occured on average only once every 18 years. Climate change?? The last three were in 2010-1, 1982-3, and 1981-2.

 For these 12 winters, I checked to find the coldest: -9, -5, 0, 4, 4, 5, 8, 8, 9, 14, 15, and 21. So, an impressive nine of these 12 very snowy winters had their coldest in the colder than average single digits or colder vs. the longterm average for all winters of mid teens.

KATL has been below zero in seven winters or about once every 19 winters. The last two were in 1984-5 and 1981-2. Three of the seven were within 1884-1899! The other four were all within 1963-1985! So, they were all within two clumps. Will a new clump start soon? Nobody knows, but the odds don't seem high to me based on this history. The odds would seem to favor the next winter with 7"+ of S/IP occuring before the next below zero temp. We'll eventually see.

[Bob Chill]

You should post a 1997-1998 analog. Prepare for tropical rains!

That would be a good analog except I think it's too cool and wet. I'm thinking warmer and drier. Haha

Honestly, I'm not pessimistic about this winter. Seems pretty ripe for some decent periods but i'm not buying door to door stuff unless we enter Dec with a near perfect lw pattern and classic npac ssta config.

I get why 79-80 and other 70s analogs get tossed around. I can even see how an 02-03 can be added to the list. However, I personally can't just toss years like 03-04 and 04-05. You can argue against them for some reasons but you can do that to any analog in a weak or neutral enso state.

The overall general warmth in the Pac north of the eq looks 04ish more than any weak nino year I can find in Sept. Things are changing now and the pattern seems to want to promote further cooling in regions that would support a +pdo establishing itself again. Huge + if it does but it's only late Sept.

Gun to head, I think we will have several periods of good blocking and an overall tendency for a +pna on the means for DJF. But we will also suffer a hostile period or 2. Like a -pna and storm track to the west for a time or 2. Temps with 2 degrees of normal one way or the other for DJF. One month (or 4 week period) is likely to be pretty cold in both our regions. Just a wag for fun attm.

Snow is tricky for both of us. We average 12" of precip in winter but on average only 1-2" fall as frozen in our region in the large majority of winters. Our chances of climo+ snow seem decent for both our regions but if we come in below I won't be shocked or bummed.

Let's get a big coastal that hits ga to sne so most of the board can enjoy the same storm. That would be sweet.

[Disco-lemonade]

Disco? I just had a space-time thing there, I think!

You guys are right though. Most of the time this time of year, there is a broad lean toward cold for the winter. That's fine -- it makes it more fun, even if there's really no good for it. The fact of the matter is most want cold and are going to be looking for reasons to support that outcome. And the reality is, things don't generally become clearer until probably mid-November, if then.

This year, the data thus far appears to support the colder outcome, but we'll see. Things can and do change. Still, I'm quite optimistic.

 

Haha! Yea I made a post that I later rescinded.

[Met1985]

 I have to vouch for ORH for his objectivity, largely based on his "Climate Change" forum posts. That along with his inteligence, written communication skills, and wx knowledge makes him someone to which people should pay attention imo. That being said, predicting the wx is a very tough job and nobody is even close to perfect, of course.

Good post about ORH. I read a lot about the pattern in the northeast thread. He is very knowledgeable and full of info. Him and Coastalwx.

[griteater]

Ensembles are to be trusted IMO, ORH is also a great met and people should take what he says seriously. I've never known him to hype stuff.

Agree on both points

 

Monster Aleutian low is setting up on the ensembles starting about Oct 5th...really favorable pattern to get the NPI where we want it for October (in El Ninos). It actually looks very similar to how October 2002 developed....so we'll have to see how it looks deeper into the month. It is definitely a very good sign though IMHO.

 

Here's the 18z GFS Ensemble at Day 9.  Aleutian Low / very negative AO-ish.  It's a good look for October going into winter.  Euro Ensemble is similar.

 

[Kory]

Agree on both points

Here's the 18z GFS Ensemble at Day 9. Aleutian Low / very negative AO-ish. It's a good look for October going into winter. Euro Ensemble is similar.

That should definitely help get some snow in the upper mid latitudes.

[Cold Rain]

So with the whole SAI thing, do we want it to snow like a mofo now south of 60N through 10/31 so that a -AO is favored? Or is it more how the snowpack advances over the last couple of weeks of the month? Should we route for snow now or do we want it to hold off for a bit longer?

[packbacker]

So with the whole SAI thing, do we want it to snow like a mofo now south of 60N through 10/31 so that a -AO is favored? Or is it more how the snowpack advances over the last couple of weeks of the month? Should we route for snow now or do we want it to hold off for a bit longer?

Darn good question, that's what I thought too. I would also like this Nino thing to get a move on. Hopefully a late blooming Nino is good?

[griteater]

So with the whole SAI thing, do we want it to snow like a mofo now south of 60N through 10/31 so that a -AO is favored? Or is it more how the snowpack advances over the last couple of weeks of the month? Should we route for snow now or do we want it to hold off for a bit longer?

 

It's above my pay grade, but here's my best shot from what I gather...the wintertime, stratospheric polar vortex is in its infancy stage in October.  The wave pattern associated with an Aleutian Low in Oct tends to offer resistance to the polar vortex's early strengthening, which can help down the road in winter to prevent a strong polar vortex outcome (+AO).  

 

On the SAI, yeah, ideally you would want to keep this as the mean pattern through the month (Aleutian Low / above normal heights across northern Eurasia), as opposed to having it now, but then flipping to an opposite pattern in the second half of Oct (Aleutian Ridge / Low heights across northern Eurasia). 

[griteater]

Keep in mind too that the image I posted was for Oct 9, and not Oct 1

[Cold Rain]

It's above my pay grade, but here's my best shot from what I gather...the wintertime, stratospheric polar vortex is in its infancy stage in October.  The wave pattern associated with an Aleutian Low in Oct tends to offer resistance to the polar vortex's early strengthening, which can help down the road in winter to prevent a strong polar vortex outcome (+AO).  

 

On the SAI, yeah, ideally you would want to keep this as the mean pattern through the month (Aleutian Low / above normal heights across northern Eurasia), as opposed to having it now, but then flipping to an opposite pattern in the second half of Oct (Aleutian Ridge / Low heights across northern Eurasia). 

 

So what you're saying here is that the pattern evolution you described would promote less snow south of 60N through mid-month and then really ramp up snow cover south of 60N through the end of the month?  Am I understanding or am I way off base?

 

By the way, thanks for all of your contributions and research.  You're a valuable contributor and I always look forward to reading the info you provide.

[griteater]

So what you're saying here is that the pattern evolution you described would promote less snow south of 60N through mid-month and then really ramp up snow cover south of 60N through the end of the month?  Am I understanding or am I way off base?

 

By the way, thanks for all of your contributions and research.  You're a valuable contributor and I always look forward to reading the info you provide.

 

Thanks Cold R, I really appreciate it.  Take a look at this post I made in the snowcover thread.  It talks about the 500mb pattern associated with high vs. low snow advance Octobers.  Also, here's a composite of the two Octobers that had the highest snow advance on record.

 

 

My take from what I read is that this type of October pattern puts a lot of strain on the stratospheric polar vortex that begins to develop in the fall, with the key features being the Aleutian Low and the above normal heights across northern Eurasia.  In terms of timing, I think the key thing is that you'd like to see this type of pattern as the mean pattern for the month of October, but especially so in the second half of October based on the SAI.  You wouldn't want to see the opposite pattern...below normal heights across northern Eurasia with above normal heights south of the Aleutians extending into central / southern Asia.

[Cold Rain]

Thanks, Grit.  That makes sense.  The top graph, correlating to the two largest snow advances on record looks an awful lot like the GFS image you posted earlier, hence your enthusiasm for it.  I know a -AO doesn't guarantee cold, but it does somewhat correlate to a -NAO.  Though neither guarantees cold and snow, I'd still rather have them in the negative phase than not.  So anything that transpires to increase the chance of that happening is good in my book!

[Cold Rain]

Here's the 6Z GFES mean for D10:

 

[Brick Tamland]

It's all about the persimmons, baby.

[griteater]

The OPI guys from Italy are back on the main board - http://www.americanwx.com/bb/index.php/topic/44592-october-pattern-index-opi-monitoring-winter-season-2014-2015/?p=3070991

 

They took a lot of criticism, but I like the work they are doing.  Last winter, the OPI predicted a DJF AO value of +1.6.  I believe the group's actual forecast was lower, like +1.0.  Actual DJF AO from NOAA was +0.4.  Looking at their correlation chart below, it looks like last year was a top 5 bust for them...it happens.  We'll have to see how they do this year.  The first OPI number came out today, and it is showing an off the chart negative AO....like -17, lol.  That doesn't mean much now...but by mid-Oct, the full month number will be more reliable since it is based off actual conditions through the days of Oct + GFS forecast out to 10 days.

 

[packbacker]

The OPI guys from Italy are back on the main board - http://www.americanwx.com/bb/index.php/topic/44592-october-pattern-index-opi-monitoring-winter-season-2014-2015/?p=3070991

 

They took a lot of criticism, but I like the work they are doing.  Last winter, the OPI predicted a DJF AO value of +1.6.  I believe the group's actual forecast was lower, like +1.0.  Actual DJF AO from NOAA was +0.4.  Looking at their correlation chart below, it looks like last year was a top 5 bust for them...it happens.  We'll have to see how they do this year.  The first OPI number came out today, and it is showing an off the chart negative AO....like -17, lol.  That doesn't mean much now...but by mid-Oct, the full month number will be more reliable since it is based off actual conditions through the days of Oct + GFS forecast out to 10 days.

 

 

 

Good read!  Only a few more weeks before we start seeing some legit winter forecasts come out.  Would be nice if we see the forecasted ENSO warming start to come together.  In fact, if you compare E1/E2/E3 3.4 CFSv2 forecasts you see it's progressively been ticking higher....

[Cold Rain]

I struggle with how to read all of the maps on the CFS site...what they all mean.  What is the difference between E1/E2/E3?  Does the CFS output a new DJF forecast daily?  Or does it come out once/month?  I like the weekly forecasts (Weeks 1 and 2 and Weeks 3 and 4).  I can figure that out!

 

Re: the OPI, the sign is supposed to correlate to the sign of the AO.  Right now, it's pretty deeply negative, which is good.  But like you said, Grit, it doesn't mean anything yet.  Does the magnitude of the sign matter?  Or does just the fact that it's neg or pos matter?  I assume the magnitude matters...at least it looks that way from the graph.

 

And Pack, I'm with you on the legit winter forecasts.  Can't wait to see 'em.

[griteater]

Re: the OPI, the sign is supposed to correlate to the sign of the AO.  Right now, it's pretty deeply negative, which is good.  But like you said, Grit, it doesn't mean anything yet.  Does the magnitude of the sign matter?  Or does just the fact that it's neg or pos matter?  I assume the magnitude matters...at least it looks that way from the graph.

 

Yeah, based on the correlation graph, the OPI value should matchup closely with the DJF AO averaged value (magnitude should count).

[Cold Rain]

Yeah, based on the correlation graph, the OPI value should matchup closely with the DJF AO averaged value (magnitude should count).

 

Thanks.  That's what I was interpreting, so I'm glad to know I was on the right track.  Hopefully, it can remain in negative territory.  Like I said earlier, I know a -AO doesn't guarantee cold, but I'd rather have that than a raging positive one!

[HKY_WX]

Not shocking we could get a stronger aluetian low this winter with the pacific sst regime. it's pretty much ideal for that. that generally favors a great pacific setup. if we do get the AO to cooperate this winter along with a strong pacific setup, things will be very cold.

 

this would be an exciting sight to see if things setup like this in december.

 

[CAD_Wedge_NC]

Not shocking we could get a stronger aluetian low this winter with the pacific regime. it's pretty much ideal for that. that generally favors a great pacific setup. if we do get the AO to cooperate this winter along with a strong pacific setup, things will be very cold.

 

I am going to go out on a limb here and say that based off of the very high SST's in the north Pacific, and the prospect of a -AO, some cities in the central or eastern US could see there all-time record lows broken. It would seem to favor the southern states. Maybe Louisiana, Alabama or Florida. Going to be a fun winter with a good Pacific and a good Atlantic.

[packbacker]

I struggle with how to read all of the maps on the CFS site...what they all mean.  What is the difference between E1/E2/E3?  Does the CFS output a new DJF forecast daily?  Or does it come out once/month?  I like the weekly forecasts (Weeks 1 and 2 and Weeks 3 and 4).  I can figure that out!

 

Re: the OPI, the sign is supposed to correlate to the sign of the AO.  Right now, it's pretty deeply negative, which is good.  But like you said, Grit, it doesn't mean anything yet.  Does the magnitude of the sign matter?  Or does just the fact that it's neg or pos matter?  I assume the magnitude matters...at least it looks that way from the graph.

 

And Pack, I'm with you on the legit winter forecasts.  Can't wait to see 'em.

 

E1 is from the earliest 10 days, E2 is from the next set of 10 days and E3 is from the most recent set of 10 days.  So it's trending warmer, at least on the CFSv2.

[Cold Rain]

E1 is from the earliest 10 days, E2 is from the next set of 10 days and E3 is from the most recent set of 10 days.  So it's trending warmer, at least on the CFSv2.

 

Ok, I gotcha.  Thanks man!

[Met1985]

Great info from you guys and griteater great data and analysis.