January Med/Long Range Discussion

[psuhoffman]

What's frustrated is that we can't even get a fantasy storm to show up on consecutive model runs. At least give us a few runs to look at something.

you could look at the individual ensemble runs from the GEFS and EPS, usually some nice hits scattered among them each run. 

[leo2000]

I don't think were being picky, a few days ago all the long range guidance was developing a sweet pattern in the 10-15 day period, great blocking, split flow, active stj, and it was showing this consistently for days.  The last few days its been slipping away, the pattern doesnt look awful but every run seems to pick away at some of the ingredients we need.  Block breaks down, we lose the PNA/EPO, Ridging develops over the northeast, STJ decides to disappear...its something.  The one constant is for the last few days (other then one 18z GFS run) we have not been able to put it all together and get a run that shows a flush hit.  I still think we could get something, the pattern is not hostile, but looks less perfect then it did 3 days ago. 

The weekly CFS goes against what the GEFS is showing with temperatures cold trending back to normal values. 

[psuhoffman]

I dug around the 12z GEFS run and hr 276 stood out to me all the way around. There are enough pieces in place to consider this a pretty good signal at range. There's no 50/50 so the HP will be sliding but it's kinda silly to even think that deeply.

 

The short story is good shortwave/vort placement, decent block, confluence, favorable hp placement, good thermodynamics, and a nice cluster of member SLP placements. A real miller A look to the precip pattern to our southeast.  IMO- this is a legit setup but too far out to overthink or get invested in.

 

 

That is the window the euro kinda hints at some potential also, and its the period where the GFS has popped something interested on a couple op runs the last few days.  Definitely our best hope in the foreseeable future. 

[Bob Chill]

you could look at the individual ensemble runs from the GEFS and EPS, usually some nice hits scattered among them each run. 

 

Funny you should say that. In some ways seeing a long range op hit is nothing more than a byproduct of error growth so you almost don't want to see one. lol

[psuhoffman]

Funny you should say that. In some ways seeing a long range op hit is nothing more than a byproduct of error growth so you almost don't want to see one. lol

That was sort of what I was getting at in jest.  Your posts are excellent by the way.  When i want a quick update of whats going on I just skim through looking for your posts.  

[leo2000]

A blend of these don't work?  I know this isn't the typical MA HECS pattern you guys expect but someone should be able to see an accumulating snow out of this pattern.  Especially for you you guys...

 

Pac low is in a pretty good spot with -EPO/-AO with wsw flow with active STJ, hmmm, maybe not

 What does it show at the end of the run?.

[Bob Chill]

That was sort of what I was getting at in jest.  Your posts are excellent by the way.  When i want a quick update of whats going on I just skim through looking for your posts.  

 

Appreciate the compliment. It's mutual. I enjoy yours as well. 

 

The ironic thing about getting good at figuring out the snow puzzle on guidance is it becomes really easy to see the problems and why it's not going to happen. 8 years ago when I didn't know squat about models, a 360 hour storm in what others said was a "bad setup" still made me happy to see one. haha. Now I don't get excited too often. Especially when we haven't seen anything even remotely close inside of 7 days so far this year. Maybe that changes later this week into next. 

 

Last 2 years were pretty fun though. Quite a bit of mental exercise with winning results. 

[Ji]

Funny you should say that. In some ways seeing a long range op hit is nothing more than a byproduct of error growth so you almost don't want to see one. lol

Ive seen model runs where the GFS shows 3-4 snowstorms and we end up getting 0 after all is said and done lol

[WEATHER53]

The analogs > the models as the analogs foretold back in September that this would be a tough winter to get cold and snow. It's rare for me to forecast 10" or less of snow at dca and over the next 1-5 weeks look for the models to show all the scenarios but eventually settle in on mild and rain

[SnowGoose69]

Ive seen model runs where the GFS shows 3-4 snowstorms and we end up getting 0 after all is said and done lol

 

The fact most of our activity likely comes from somewhere in the southern stream the next 2-3 weeks likely means the GFS won't be doing a great job picking it up.  The GFS does best when all activity is coming from the northern stream or out of Canada, if its wave coming from CA or the southwest and Texas the GFS is usually terrible. 

[Bob Chill]

EPS improved slightly with heights and temps d11-15. Seems to back off on a complete Pac onslaught. Trough in the GOA is a bit further west compared to 12z. Very strong + height anomaly showing up south and SE of Greenland towards Iceland. 

 

About the same mix of snow chances and muddy coastal signal d11-13. I suppose it's supportive of the GEFS in most ways. 

 

I will say there are a couple monster storms showing up in the ensembles. Probably the biggest I've seen all year. PSU would love #11. Nothing like a 30" dump to get things going. lol

[Ji]

EPS improved slightly with heights and temps d11-15. Seems to back off on a complete Pac onslaught. Trough in the GOA is a bit further west compared to 12z. Very strong + height anomaly showing up south and SE of Greenland towards Iceland. 

 

About the same mix of snow chances and muddy coastal signal d11-13. I suppose it's supportive of the GEFS in most ways. 

 

I will say there are a couple monster storms showing up in the ensembles. Probably the biggest I've seen all year. PSU would love #11. Nothing like a 30" dump to get things going. lol

so it sounds like we are still below average by day 15? that would take us to the 20th....12th to the 20th window?

[SnowGoose69]

EPS improved slightly with heights and temps d11-15. Seems to back off on a complete Pac onslaught. Trough in the GOA is a bit further west compared to 12z. Very strong + height anomaly showing up south and SE of Greenland towards Iceland. 

 

About the same mix of snow chances and muddy coastal signal d11-13. I suppose it's supportive of the GEFS in most ways. 

 

I will say there are a couple monster storms showing up in the ensembles. Probably the biggest I've seen all year. PSU would love #11. Nothing like a 30" dump to get things going. lol

 

The +PNA pattern is IMO one of the hardest patterns over any continent in the world to break when it sets in, the models often try to break it down at some point in the long range when its in place but usually are too early or it does not occur at all.  It can survive even with a raging +AO or NAO as we saw last winter and for parts of the 93-94 winter as well. 

[Bob Chill]

The +PNA pattern is IMO one of the hardest patterns over any continent in the world to break when it sets in, the models often try to break it down at some point in the long range when its in place but usually are too early or it does not occur at all.  It can survive even with a raging +AO or NAO as we saw last winter and for parts of the 93-94 winter as well. 

 

Totally agree. The ensemble look in the pac may be more representative of pac waves punching through or running the top of ridging in the west and not a move towards a -pna + cold west/warm east. Hard to say. 

 

I wasn't mad at the EPS run like I was at the GEFS. I'm not sure which one is more right irt to handling heights in the west and the goa trough. The EPS improves run over run (although nothing great to talk about late in the run) while the GEFS would make any snow lover pretty nervous. 

[kurtstack]

EPS improved slightly with heights and temps d11-15. Seems to back off on a complete Pac onslaught. Trough in the GOA is a bit further west compared to 12z. Very strong + height anomaly showing up south and SE of Greenland towards Iceland. 

 

About the same mix of snow chances and muddy coastal signal d11-13. I suppose it's supportive of the GEFS in most ways. 

 

I will say there are a couple monster storms showing up in the ensembles. Probably the biggest I've seen all year. PSU would love #11. Nothing like a 30" dump to get things going. lol

I have to second the notion on your posts Bob.  I've watched you evolve from a weenie to an expert over the years.  Your understanding of all of the technical factors of forecasting is top notch, and you are now are one of the absolute best in describing scenarios and setting expectations, and knowing when to "bark".  I've got you up there right next to Wes in terms of spotting the right setups without issuing too many false alarms.  Also, your explanations are understandable to the common man as well as the experts.  Keep on doing what you do Bob!! 

 

Oh and I like your comments on the EPS.  That keeps some hope alive for the mid January period.

[SnowGoose69]

Totally agree. The ensemble look in the pac may be more representative of pac waves punching through or running the top of ridging in the west and not a move towards a -pna + cold west/warm east. Hard to say. 

 

I wasn't mad at the EPS run like I was at the GEFS. I'm not sure which one is more right irt to handling heights in the west and the goa trough. The EPS improves run over run (although nothing great to talk about late in the run) while the GEFS would make any snow lover pretty nervous. 

 

I have not been able to look at the GFS ensembles today but the Op run thing at Day 15-16 where it tries to choke off the ridge at the top and split and have it retrograde back into the Pacific is something the GFS loves doing in the long range with that Canada/Alaskan ridge.  The only time I ever saw that be correct was January 2012 when the SSW occurred and that ridge broke off and went west and we were done for the rest of winter, but the GFS does that break/split retrograde all the time.

[psuhoffman]

EPS improved slightly with heights and temps d11-15. Seems to back off on a complete Pac onslaught. Trough in the GOA is a bit further west compared to 12z. Very strong + height anomaly showing up south and SE of Greenland towards Iceland.

About the same mix of snow chances and muddy coastal signal d11-13. I suppose it's supportive of the GEFS in most ways.

I will say there are a couple monster storms showing up in the ensembles. Probably the biggest I've seen all year. PSU would love #11. Nothing like a 30" dump to get things going. lol

Beat me by a few mins. Haven't seen the individuals yet but glanced at the h5 and thought "that's better"

[Ian]

Long lasting PNA ridge is pretty atypical of a strong Nino. Models don't even keep it there for all that long really. Euro ens may be a hair better but it looks almost the same as last night. 

[Ian]

Interestingly the analog suite on SV has had no major sign of breaking down the blocking pattern thru d30 for a while now. Also keeps the stj rocking. But they also showed the Dec pattern continuing into Jan so I'm mixed on their utility outside the short range. 

[psuhoffman]

Interestingly the analog suite on SV has had no major sign of breaking down the blocking pattern thru d30 for a while now. Also keeps the stj rocking. But they also showed the Dec pattern continuing into Jan so I'm mixed on their utility outside the short range.

Where on SV do you get the analogs?

[Ian]

Where on SV do you get the analogs?

Features dropdown in top bar. Third link down. I'm not sure they're avail to everyone.. know some things aren't. But that's where to look!

[Bob Chill]

Ian, did you mean +PNA's are typical of strong Ninos or atypical? I thought they were typical but I haven't really looked into it that much. IIRC, +enso and +pdo = +pna almost every time. I think 72-73 was a weird one with a -pdo and that year had a -pna. 

 

OTOH- numerical doesn't always equal sensible when looking at the mslp and height plots vs the #

[Ian]

Ian, did you mean +PNA's are typical of strong Ninos or atypical? I thought they were typical but I haven't really looked into it that much. IIRC, +enso and +pdo = +pna almost every time. I think 72-73 was a weird one with a -pdo and that year had a -pna. 

 

OTOH- numerical doesn't always equal sensible when looking at the mslp and height plots vs the #

Well maybe I'm confused on what an idealized +PNA is. Plus I've mostly looked at composites rather than individual years to be honest. I know the n pac low typically feeds a +PNA but often it's further west like near the tail of the Aleutians for that. In strong nino composites (using all years rather than post 1950) pre Feb in particular the anomalously low heights basically bank up to the coast of BC if not pushing further inland than that. That's sort of the region I think of wanting to see big + anomalies for a typical +PNA? 

[Bob Chill]

Well maybe I'm confused on what an idealized +PNA is. Plus I've mostly looked at composites rather than individual years to be honest. I know the n pac low typically feeds a +PNA but often it's further west like near the tail of the Aleutians for that. In strong nino composites (using all years rather than post 1950) pre Feb in particular the anomalously low heights basically bank up to the coast of BC if not pushing further inland than that. That's sort of the region I think of wanting to see big + anomalies for a typical +PNA? 

 

It's tricky in the PNA space because there is definitely an effective and useless version of numerical PNA. Ridge axis right up the coast is ideal and that requires the npac low to be far enough west towards the islands.

 

I think what ends up happening during nino's is higher pressure and heights downs stream from a crappy GOA trough do tend to increase 1000mb pressure levels in the PNA domain space. But that doesn't mean cold air delivery east when the source region is straight from the ocean. 

 

I agree with what you are saying about some of the strong nino composites having bad pressure and height patterns right along the west coast which in turn lead to bad temp patterns downstream in our yard. Even with a "numerical +pna/-ao/nao". This is where numerical vs sensible diverge. I've mostly stopped looking at numerical indices as guidance in judging what I think things look like. h5 and MSLP trump anything the numerical indices say. 

 

Early on when I joined eastern my goto every day was NCEP's numerical page. I jumped to (bad) conclusions way to often doing that. Once I learned recognition through plots my understanding became much deeper and it really isn't that hard. 

[WxUSAF]

It's tricky in the PNA space because there is definitely an effective and useless version of numerical PNA. Ridge axis right up the coast is ideal and that requires the npac low to be far enough west towards the islands.

 

Most big snowstorms in our area actually have the ridge axis in the Rockies.  Boise, ID, was always the rule-of-thumb we used back in the day. 

 

Interestingly, Ian's strong Nino +snow 500mb anomalies all had -PNA, but so did the -snow anomalies, so I'm not sure how much of a difference PNA makes.  Without looking at past big snowstorms in strong Ninos, I'd guess we had a transient +PNA during the time frame, but they must average -PNA on the whole. 

[psuhoffman]

Features dropdown in top bar. Third link down. I'm not sure they're avail to everyone.. know some things aren't. But that's where to look!

Thanks Ian

[SnowGoose69]

Most big snowstorms in our area actually have the ridge axis in the Rockies.  Boise, ID, was always the rule-of-thumb we used back in the day. 

 

Interestingly, Ian's strong Nino +snow 500mb anomalies all had -PNA, but so did the -snow anomalies, so I'm not sure how much of a difference PNA makes.  Without looking at past big snowstorms in strong Ninos, I'd guess we had a transient +PNA during the time frame, but they must average -PNA on the whole. 

 

In the MA I would say 95% of more snow storms have a ridge in the west.  In NYC and north there are a greater percentage that occur in a RNA pattern as a southwest flow overrunning event, those are usually rain or sleet/freezing rain in the MA though.  I think there was a MA snow event in March or February 2012 that occurred with no ridge in the west, I remember at the time thinking I had not seen that in a long time.

[Bob Chill]

Most big snowstorms in our area actually have the ridge axis in the Rockies.  Boise, ID, was always the rule-of-thumb we used back in the day. 

 

Interestingly, Ian's strong Nino +snow 500mb anomalies all had -PNA, but so did the -snow anomalies, so I'm not sure how much of a difference PNA makes.  Without looking at past big snowstorms in strong Ninos, I'd guess we had a transient +PNA during the time frame, but they must average -PNA on the whole. 

 

I was thinking about monthly means in general and not individual storm setups. Totally agree that ideal is ridge intermountain west / axis somewhere near the MS river. 

 

Looking at the op runs today you would think we stand a chance at a quick hitting norther stream vort next week, wouldn't you? Last couple years, every single time the PV dropped down in the long range it always verified not quite as beastly. I'm not sold on a 5-6 period of cold/dry. Something can slide under us. Hopefully in 5 days or so we start seeing a clipperish vort or 2 take a shot at us. A freeking inch is a secs right now.  

[Ian]

It's tricky in the PNA space because there is definitely an effective and useless version of numerical PNA. Ridge axis right up the coast is ideal and that requires the npac low to be far enough west towards the islands.

 

I think what ends up happening during nino's is higher pressure and heights downs stream from a crappy GOA trough do tend to increase 1000mb pressure levels in the PNA domain space. But that doesn't mean cold air delivery east when the source region is straight from the ocean. 

 

I agree with what you are saying about some of the strong nino composites having bad pressure and height patterns right along the west coast which in turn lead to bad temp patterns downstream in our yard. Even with a "numerical +pna/-ao/nao". This is where numerical vs sensible diverge. I've mostly stopped looking at numerical indices as guidance in judging what I think things look like. h5 and MSLP trump anything the numerical indices say. 

 

Early on when I joined eastern my goto every day was NCEP's numerical page. I jumped to (bad) conclusions way to often doing that. Once I learned recognition through plots my understanding became much deeper and it really isn't that hard. 

I admit I rarely even look at the numerical stuff when it comes to these things. Until this year I mostly just referred to things as ridges/troughs in various places. I have spent more time with NAO/AO numbers because I think that's the primary driver around here for big events but even there somewhat limited.  I'm more into studying the patterns themselves on maps.. been a weirdo about that for years, though at this point I'd say I'm pretty skilled at pattern recognition because of it. 

 

I'm not even really sure what the typical +PNA bounds are now that I think about it. I could certainly see where it's shifted a bit east but counts etc.  I don't even feel like the +PNA is good for a whole lot other than cold delivery and even there it's not often the best cold source ever. In strong Ninos it does seem to be a main source for typically brief cold shots, especially the first half of winter, at least based on my somewhat quick looks.

 

As WxUSAF and you talk about further below if you are looking for an idealized ridge axis during a storm you generally look to the Rockies. You can almost draw a line from Scandinavia area over the polar region to the desert southwest or so and the more 500mb ridging you can get in that whole zone the better generally. But as mentioned the other day we often look for perfect patterns when most of our storms come from significantly less.

 

I guess my original statement was more that it seems in stronger Ninos the low anomaly is so close to the coast it often torches that airmass with both PAC air and downsloping. When I said +PNA is atypical I was thinking more in the frame of stopping that from happening. I've looked at enough to think that it must mostly be a transient feature though the Feb composite does back the GOA low west a bit leaving that region more in normal heights.  Of course ENSO strength isn't the be all anyway though in a Nino of this strength I think anyone not focusing on it first is doing themselves a disservice (cough cough, cohen, cough cough).

[WxUSAF]

 

 

Looking at the op runs today you would think we stand a chance at a quick hitting norther stream vort next week, wouldn't you? Last couple years, every single time the PV dropped down in the long range it always verified not quite as beastly. I'm not sold on a 5-6 period of cold/dry. Something can slide under us. Hopefully in 5 days or so we start seeing a clipperish vort or 2 take a shot at us. A freeking inch is a secs right now.  

Yeah, I wondered that.  GFS is really northern stream dominant throughout the 12z run at least.  All of the s/w's pass well to our north though.  I'd say it's a chance, and the type of thing that might not become apparent until we're inside 4-6 days.