Ending out December with a Potential Pattern Change

[ORH_wxman]

That's probably a good way of looking at it. But then we're left with the conclusion that everything but a torch on the horizon is a "good pattern."

I pretty much agree with that. But 50-60" spread out over a winter means that even good patterns are going to fail to produce much more often then they deliver.

Right. I think that is why we try to convey to a lot of people that a good pattern doesn't always mean tons of snow. But we will take our chances.

Also, if we know where longwave features are going to set up, then we can tweak whether a non-torch pattern is slightly more or less favorable for snow than other non-torch patterns. An example might be that the mean trough axis will be over Ohio and Tennessee with a mean -NAO block in the Davis straight. This type of non-torch setup would probably be described as more enhanced for threats than a mean trough over New England which would probably be too far east.

Again, none of this is a deterministic forecast, it is simply highlighting increased or decreased chances for snow. I don't think that is bad science. It is bad science for someone to take that information and then assume it is deterministic.

[TalcottWx]

I think that's a good point. In the mid-Atlantic and probably in the big cities up to Boston, snow is much more likely to come with significant cold.

Without a cold antecedent airmass or hp support, onshore winds really trash coastal chances unless we have good track. Of course, the more the ocean cools and the further we head into winter onshore winds have less of an effect on surface temps. As you already know.

[moneypitmike]

Speaking of snow on the ground, took a ride up to my other house yesterday (at Bretton Woods) and was really surprised by how much more damage the storm did there than in Bartlett. Not pretty snow but pretty much full snow cover here, while patches are left there. CAD FTW?

 

 

It was interesting to see how much more Bartlett had than Bretton Woods.  The western areas of town really do well--typically getting more snow and holding it better than the eastern areas.

 

Without a cold antecedent airmass or hp support, onshore winds really trash coastal chances unless we have good track. Of course, the more the ocean cools and the further we head into winter onshore winds have less of an effect on surface temps. As you already know.

 

Particularly before February.  As for MBY, the systems that have you through Tolland tainting work so very well.

[TalcottWx]

Forecasting is just about evaluating modeling bias, indices, comparing it to other setups historically, considering climo of that time period, and making educated guesses in the end. You can have a perfect pattern not deliver while a marginal one does. But any way you define or slice pattern, its importance can't be denied.

I've found through my own maturation process and failing on forecasts that it is often best to look at a reason why a storm won't deliver versus why it would. Weenies often latch onto an idea, ignore red flags, and wishcast. The older guys here are often more cautious and right in the end because they stick by their historical knowledge and guns when it comes to forecasting. Experience is the most important thing in meteorology like other occupations. This is why someone like Will is so valuable. He has an ability to remember dates, patterns, and storms like a computer.

Patterns don't produce snow, storms do. But without a decent pattern, you cant produce snow. No matter how you cut it. There are subtle indicators inside 7 days that you can look at to see a colder pattern coming. Euro colder runs have been trying to drop pv near Hudson Bay which is good. Plus Canada is cooling down. I don't remember whether it was ginx or not that brought that canadien departure page into the limelight but that is also another great indicator of incoming patterns.

[CoastalWx]

Right. I think that is why we try to convey to a lot of people that a good pattern doesn't always mean tons of snow. But we will take our chances.

Also, if we know where longwave features are going to set up, then we can tweak whether a non-torch pattern is slightly more or less favorable for snow than other non-torch patterns. An example might be that the mean trough axis will be over Ohio and Tennessee with a mean -NAO block in the Davis straight. This type of non-torch setup would probably be described as more enhanced for threats than a mean trough over New England which would probably be too far east.

Again, none of this is a deterministic forecast, it is simply highlighting increased or decreased chances for snow. I don't think that is bad science. It is bad science for someone to take that information and then assume it is deterministic.

I think that's what is going on, but the probabilistic part of it is getting lost. People hear enhanced or favorable pattern for snow, but get all antsy if a storm whiffs south or cuts west. I mean how many people would salivate over the Feb 2010 pattern, but look what that did.

[ORH_wxman]

I think that's what is going on, but the probabilistic part of it is getting lost. People hear enhanced or favorable pattern for snow, but get all antsy if a storm whiffs south or cuts west. I mean how many people would salivate over the Feb 2010 pattern, but look what that did.

Yeah feb 2010 is a good example of the uncertainty that Eduggs is describing. But at the same time, you probably want to gamble with that setup again.

[eduggs]

Right. I think that is why we try to convey to a lot of people that a good pattern doesn't always mean tons of snow. But we will take our chances.

Also, if we know where longwave features are going to set up, then we can tweak whether a non-torch pattern is slightly more or less favorable for snow than other non-torch patterns. An example might be that the mean trough axis will be over Ohio and Tennessee with a mean -NAO block in the Davis straight. This type of non-torch setup would probably be described as more enhanced for threats than a mean trough over New England which would probably be too far east.

Again, none of this is a deterministic forecast, it is simply highlighting increased or decreased chances for snow. I don't think that is bad science. It is bad science for someone to take that information and then assume it is deterministic.

I just don't think we are very good at this yet.  It's difficult to pin down longwave features beyond 5 days or so with a high degree of skill.  And then the small-scale variations really determine regional weather.

 

I actually do see a lot of what I consider bad science.  In meteorology more than any other natural science.  I don't mean to bash on the field.  I wanted to be a meteorologist throughout most of my childhood and adolescence.  I see too much guesswork and gut feeling and not enough understanding of statistics and causality. 

[eduggs]

Yeah feb 2010 is a good example of the uncertainty that Eduggs is describing. But at the same time, you probably want to gamble with that setup again.

Hell yes.  But you often don't know you're in that kind of regime until you're in the midst of it.  Sometimes it telegraphs itself well, but not often.  And that's just the limitations of modeling.

[TalcottWx]

A lot of us are guilty of looking too much at qpf model output too. A day or two before a storm half the board will be forecasting a 10-14" region wide bomb without blocking on a quick hitting system. I guess meteorology not modelogy applies to that beautifully.

Comparable to that novie storm this year that had a decent track but screaming south/se winds at 700mb. Looked snowy at first glance but it was of tropical origins. Had a very spotty radar and convection south of LI. The waa pumping in really messed around with everything and resulted in a mixed bag of garbage. we never got that front end omega dump to organize for us. Looked and almost felt more like a rain event in May in the end.

Like boxing day.. another qpf obsessed storm that screwed many in the end. Modeled Mid level tracks were ignored in favor of modeled qpf and places like Hartford ended up with a bust. That cf near Boston saved that area and it was still a tremendous storm for my locale in Southie due to the enhancement along the coast.

[CT Valley Snowman]

Nice to be below freezing again for the first time since Sunday.

[ORH_wxman]

Hell yes. But you often don't know you're in that kind of regime until you're in the midst of it. Sometimes it telegraphs itself well, but not often. And that's just the limitations of modeling.

Patterns like feb 2010 I think are usually forecast very well because they are extreme. We saw that pattern coming a mile away. We just couldn't have known small details would screw us out of a couple of monster snowstorms.

[CoastalWx]

Yeah feb 2010 is a good example of the uncertainty that Eduggs is describing. But at the same time, you probably want to gamble with that setup again.

Oh yeah, definitely. But it's akin ( to an extent ) of this pattern. It looks good overall for snow, but the small scale nuances just can't be seen so if it doesn't work out, sometimes you chalk it up to that.

[N. OF PIKE]

A lot of us are guilty of looking too much at qpf model output too. A day or two before a storm half the board will be forecasting a 10-14" region wide bomb without blocking on a quick hitting system. I guess meteorology not modelogy applies to that beautifully.

Comparable to that novie storm this year that had a decent track but screaming south/se winds at 700mb. Looked snowy at first glance but it was of tropical origins. Had a very spotty radar and convection south of LI. The waa pumping in really messed around with everything and resulted in a mixed bag of garbage. we never got that front end omega dump to organize for us. Looked and almost felt more like a rain event in May in the end.

Like boxing day.. another qpf obsessed storm that screwed many in the end. Modeled Mid level tracks were ignored in favor of modeled qpf and places like Hartford ended up with a bust. That cf near Boston saved that area and it was still a tremendous storm for my locale in Southie due to the enhancement along the coast.

 

 

Like boxing day.. another qpf obsessed storm that screwed many in the end. Modeled Mid level tracks were ignored in favor of modeled qpf and places like Hartford ended up with a bust. That cf near Boston saved that area and it was still a tremendous storm for my locale in Southie due to the enhancement along the coast.

where the heck did the mid level lows track with that thing

 

we all know where the pivot was haha "its always right there" just kidding Will

[SnowMan]

Lol wow what in the world is going on in here. Can't even imagine a month from now when we have only had a couple light events.

[HoarfrostHubb]

Lol wow what in the world is going on in here. Can't even imagine a month from now when we have only had a couple light events.

It happens every year at some point

[jamesnichols89]

I think we can still get an inch or two of snow from the 30th event, the SREFs and NAM still have the secondary wave of precip hitting the region, while most guidance envelopes do not, especially operational EURO and the GGEM which lost the second wave several runs ago.  While I need to check the snow probs on the 21z SREFs my best guess is that the EURO and GGEM tonight will be in more in favor for a few inches of snow on the 30th.  Now the 3-5th event looks warm as the pattern reloads into the Midwest US and trough position changes to a favor of Lakes storms.

[jamesnichols89]

Latest guidance going back to a stronger second wave of low pressure along the stalled frontal boundary, NAM and SREF are bullish with it.

[jamesnichols89]

The 29th event is out to sea, the 30th event is still on the models.  Next up the 00z GFS and 00z GFS para.

[weathafella]

Latest guidance going back to a stronger second wave of low pressure along the stalled frontal boundary, NAM and SREF are bullish with it.

nam and srefs are out of their useful range of 3 hours.

[N. OF PIKE]

I think that's what is going on, but the probabilistic part of it is getting lost. People hear enhanced or favorable pattern for snow, but get all antsy if a storm whiffs south or cuts west. I mean how many people would salivate over the Feb 2010 pattern, but look what that did.

I don't think the probabilistic part is getting as lost as you think. Although I can see how it looks that way.

 

Non-"Pros" will be  more "emotional" over misses even understanding the probabilistic part of the forecast, as a snow lover it is difficult to not post your disappointment on a weather lover's forum. This is the natural place to convey the disappointment. I think its normal for most at different times over the season, I mean we take time out of our day to post on a weather forum....a weather forum lol.  Many of us like to think positive, this carries over into hoping to see something produce, hoping to see a storm modeled then show consistency on the modeling. I think the Pros here do an excellent job with all aspects of the forecast.

 

This is the best weather resource and place to be when a storm is on the way, and soon enough the odds are.. we will be celebrating some snow.

[jamesnichols89]

Yeah Jerry, they are still guidance and as long as some part of the guidance is showing something different, I obliged to listen and wait it out until they are on the same page.  GFS is normally late to the party, and with the NAM showing a new piece of southern stream energy getting absorbed by northern stream energy over the Great Lakes and at 700mb showing a classic signature of a snowstorm for SNE, then I am going to pay attention.  Both the SREFs and NAM pay attention to the second wave.  This is the time period where the models change solutions and begin to get consistent, so we will have to see what the rest of the guidance shows in the near future.

[SnowGoose69]

The NAM is often amped at that range, that solution it shows right now is a positive sign but it ain't enough yet, you probably have to drop that 100-150 miles south and you'll have your 00Z GFS solution, you'd want to see the precip up in WRN NY on that NAM run to get excited but its certainly a move in a direction I did not expect.

[weathafella]

Yeah Jerry, they are still guidance and as long as some part of the guidance is showing something different, I obliged to listen and wait it out until they are on the same page.  GFS is normally late to the party, and with the NAM showing a new piece of southern stream energy getting absorbed by northern stream energy over the Great Lakes and at 700mb showing a classic signature of a snowstorm for SNE, then I am going to pay attention.  Both the SREFs and NAM pay attention to the second wave.  This is the time period where the models change solutions and begin to get consistent, so we will have to see what the rest of the guidance shows in the near future.

I'd average 120 inches per year if nam 72 hour snowstorms verified..lol.

[jamesnichols89]

I think we will be celebrating snow on the 30th of DEC.

[jamesnichols89]

The NAM is often amped at that range, that solution it shows right now is a positive sign but it ain't enough yet, you probably have to drop that 100-150 miles south and you'll have your 00Z GFS solution, you'd want to see the precip up in WRN NY on that NAM run to get excited but its certainly a move in a direction I did not expect.

 

I definitely did not expect that solution at all, I like where its at right now for SNE coastal plain, any further north and the 700mb levels flood with warmth on that run.  SO I like it where the NAM shows it to be, question will be whether or not the other models catch onto the second wave idea for snow on the 30th rather than the 29th and the evolution will be similar.

[SnowGoose69]

I definitely did not expect that solution at all, I like where its at right now for SNE coastal plain, any further north and the 700mb levels flood with warmth on that run.  SO I like it where the NAM shows it to be, question will be whether or not the other models catch onto the second wave idea for snow on the 30th rather than the 29th and the evolution will be similar.

 

The 12Z UKMET at 72 hours looked pretty amped, I thought the Euro would follow and it did not, at that point I pretty much figured this event was dead.

[jamesnichols89]

NAM really emphasizes the energy within the southern stream.  It is wicked amount of energy ejecting from the southwestern US trough.  Differences in the models is how much energy phases with the northern stream Grt Lakes troughing.

[jamesnichols89]

The 12Z UKMET at 72 hours looked pretty amped, I thought the Euro would follow and it did not, at that point I pretty much figured this event was dead.

 

 

Why?  Because one or two model runs dropped the low?  If the UKMET model still maintains an amplified trough in this period, would the EURO eventually cave in like we have seen previously?

[SR Airglow]

NAM is nice to see, but you want to see something that's not the NAM showing it... That's probably several inches though for most verbatim if it was extrapolated.

 

The other thing to realize is that we're just coming into NAM range. This threat is still 3.5 days out, which in model land, is an eternity. Down but not out IMO.

[dendrite]

Everyone has to learn with the NAM and the SREFs the hard way.