Monitoring first regional significant winter impact event. Magnitude likely tempered. At this time NE PA/SE NY and SNE primarily. Jan 7/8.

[Typhoon Tip]

First and foremost ... Happy New Years everyone. 

Significant impacts farther N into central or even northern New England cannot obviously be ruled out at  6+ days, but at this time ( and given the conceptual points below) a  NE PA through SE NE and southern New England are implicated the most. 

I feel pretty strongly that these systems ( and there are really 3 in the pipe-line;  7, ~11th and ~15th) are all likely to attenuate some as these date ranges subsequently near.  The reason for this is two fold, both a bit theoretical - but do offer a solid plausible basis for limiting their realized significance toward something lower than the 'magnificence' of their D10 model entertainment.  

The first is related to model handling of velocity saturation, a circumstance that's been reproducible during recent winters . This has been both anecdotally observed over recent years, discussed by yours truly and any others amid the 'forumsphere.'  But recently at least tacitly corroborated by publications, such as Nov 30 2023, "Fast upper level jet stream winds get even faster under climate change," found in the Nature Climate Change periodical.  (just one example; I'm not aware of any other formal science)

Why this is prudent?   Models tend consummately toward too much amplitude in the D6+ range, ... gradually losing some percentage as handled embedded wave spaces near and pass through the abruptly improving performance window around D4..5 lead.   The reason for this, I believe, is because as the models are correcting the flow faster - in keeping with the above, the +d(v) outside the local wave space, robs from said wave mechanics.  It's speculation on why that amplitude bias ( and there's other plausible arguments related to chaos logistics..etc..) is apparently endemic to the technology in general. I see this occurring in all guidance sources.  

This is a candidate scenario to express this phenomenon, and if we rob some mechanics from the S/W itself ( think 'velocity absorption') it will tend to pancake the latitude of the disturbance envelope, converting the system into more of a 'needle threader' scenario.   (these are tendencies, not absolutes).   This can also be compensated by the S/W being sufficiently powerful enough to offset that taxation ( heh, being rich enough).

The second of the reasons, the teleconnector spread is not very supportive of mid latitude amplification east of 100W across the continent and hasn't been for long while in the projections that are based from all three ens clusters.  The PNA is in fact entering negative delta during this week, and ends up negative spanning week 2.  The fact that we are also attempting to eject troughs east across the continent means that the larger Rossby wave function is in destructive interference.  If you loop the ens mean 500 mb g-pot anomaly products, this is likely why there is a repeating pattern during these recent days of guidance to increasingly flatten/open up the waves as they come east in the cinema. 

Summary:   This is as of now logic. 

-- Should the back ground telecon change

-- Should the Pacific relay enough S/W mechanical power to offset the inevitable speeding up the circulation canvas.  T

Of these two offsets, the 2nd one is more likely to be realized.   *It should be noted that the governing mechanics for the Jan 7 event are still out over the N Pac. 

Graphics to help elucidate this are welcome ... I'll probably be contributing some but wanted to get this thread started.

For now I suspect a middling event "precipitates" (heh) out of the total pros and cons with this Jan 7 system.   I suspect that the 12z GFS may correct N ... unless it has some special handling out over the open Pacific that makes no interpretive model analysis ever necessary again ( ), which is less likely to be the case.  But I'm not sure of the GGEM type intensity..   It's more likely to modulate down based on the constraints discussed above. But we'll see.   There are two ways to limit impacts IYBY:   Size and latitude of storm.  

[STILL N OF PIKE]

6 minutes ago, Typhoon Tip said:

First and foremost ... Happy New Years everyone. 

Significant impacts farther N into central or even northern New England cannot obviously be ruled out at  6+ days, but at this time ( and given the conceptual points below) a  NE PA through SE NE and southern New England are implicated the most. 

I feel pretty strongly that these systems ( and there are really 3 in the pipe-line;  7, ~11th and ~15th) are all likely to attenuated some as these date ranges subsequently near.  The reason for this is two fold, both a bit theoretical - but do offer a solid plausible basis for limiting there realized significance to something lower than the magnificence of their D10 model cinema.  

The first is related to model handling of velocity saturation, a circumstance that's been reproducible during recent winters . This has been both anecdotally observed over recent years, discussed by yours truly and any others amid the 'forumsphere.'  But recently at least tacitly corroborated by publications, such as Nov 30 2023, "Fast upper level jet stream winds get even faster under climate change," found in the Nature Climate Change periodical.  

Why this is prudent?   Models tend consummately toward too much amplitude in the D6+ range, ... gradually losing some percentage as handle embedded wave spaces while nearing and through the performance window around D4..5 lead.   The reason for this, I believe, is because as the models are correcting the flow faster - in keeping with the above. I have observed many times, the speeding differential as late mid ranges shorten, in guidance depictions.  This d(v) eventually robs from the wave mechanics of the embedded S/W, wave spaces.  

I suspect some of this to be a candidate scenario to express this phenomenon. If we rob some mechanics from the S/W itself ( think 'velocity absorption') it will tend to pancake the latitude and convert the system into more of a 'needle threader' scenario.   (these are tendencies, not absolutes).   This can also be compensated by the S/W being sufficiently powerful enough to offset that taxation ( heh, being rich enough).

The second of the reasons, the teleconnector spread is not very supportive of mid latitude amplification east of 100W across the continent and hasn't been for long while in the projects that are based from all three ens clusters.  The PNA is in fact entering negative delta during this week, and ends up negative spanning week 2.  The fact that we are also attempting to eject troughs east across the continent means that the larger Rossby wave function is in destructive interference.  If you loop the ens mean 500 mb g-pot anomaly products, this is likely why there is a repeating pattern during these recent days of guidance to increasingly flatten/open up the waves as they come east in the cinema. 

Summary:   This is as of now logic. 

-- Should the back ground telecon change

-- Should the Pacific relay enough S/W mechanical power to offset the inevitable speeding up the circulation canvas.  T

Of these two offsets, the 2nd one is more likely to be realized.   *It should be noted that the governing mechanics for the Jan 7 event are still out over the N Pac. 

Graphics to help elucidate this are welcome ... I'll probably be contributing some but wanted to get this thread started.

 

Happy new year

So you wouldn’t be surprised if the 7’th comes in flatter / weaker and a little south . Fair general assessment?

 

[Typhoon Tip]

1 hour ago, STILL N OF PIKE said:

Happy new year

So you wouldn’t be surprised if the 7’th comes in flatter / weaker and a little south . Fair general assessment?

 

Correct, buuuut, as I also *(tried at least ) to point out, there are ways to offset why.   Those limiting constraints I discussed are very real ... However, so is the uncertainty as to what truly gets communicated out of the Pacific.   If it is very strong ... some of it will be absorbed but there'll be enough left to cause problems/get an event out of it.

Assimilation tech is not the same as it was 20 years ago?  Back then it was more gappy.  I mean, we used to have this kind of cushion of 'still can happen' relief, because the system in question would be out near the Date Line. The population of the model initializations of the time were largely interpolated and/or supplemented by satellite soundings that were perhaps more primitive than now.  The last time a system relayed off the Pacific and abruptly re-appeared on the guidance after having faded was the Boxing Day storm back in 2010 ( I believe it was..). That one appeared suspiciously like it was 'lost then found'

It seems those gaps have been filled in recent times.  I've noticed better performance/less morphology in handling system/storm depictions post relays etc.. Still, with the flow being fast, I suspect this re-introduces some error proneness.

 

[weatherwiz]

Excellent initial post for this! Great point too about the tendency for over-amplification in the medium range. I know you and several others have really hit on this the past few years. 

[78Blizzard]

Hopefully we will get some agreement among the op models going forward.  The Euro was the biggest deviator from 0z to 12z.  They all have different ideas on what that high to our north is going to do.

[Typhoon Tip]

16 minutes ago, 78Blizzard said:

Hopefully we will get some agreement among the op models going forward.  The Euro was the biggest deviator from 0z to 12z.  They all have different ideas on what that high to our north is going to do.

We will ..  I mean D6+ is far enough ahead that it's probably more academic that there are disagreements.   

I'll tell ya, ... if you compare the Euro to the GFS (this 12z run) the differences are almost entirely spatial.  The actual mechanics are not really sufficiently different enough to imply a different result based on that alone, but the GFS has it's 500 mb trough structure approaching the lower M/A whereas the Euro's is approaching the upper M/A.  That's really the difference here. 

The GFS does have a weaker surface response to all this by some, but ... say it were N like the Euro, it would carry at least a pedestrian albeit regional snowfall across the area. 

This 12z guidance suite appears to be more about "where" ... less so about "if" a system will be on the charts. 

[ORH_wxman]

Going to post in here just for archive purposes. EPS clusters below

 

[H2Otown_WX]

16 minutes ago, ORH_wxman said:

Going to post in here just for archive purposes. EPS clusters below

 

Looks pretty tucked in

[40/70 Benchmark]

20 minutes ago, H2Otown_WX said:

Looks pretty tucked in

Its sliding ene, though.

[CoastalWx]

Can probably move the storm posts here from the other thread now that it’s in between runs.

[ORH_wxman]

3 minutes ago, 40/70 Benchmark said:

Its sliding ene, though.

Yeah this one is gonna reach a certain point and then slide ENE most likely unless the shortwave mechanics change a lot. 
 

The good thing about that is it will likely prolong the CCB snows where that happens so it could give us a higher ceiling. The bad news is that it could be frustrating if you’re just north of the goods. You’d keep expecting the heavy bands to get to you but they never quite reach or they weaken by the time they do. 

[FXWX]

16 minutes ago, ORH_wxman said:

Yeah this one is gonna reach a certain point and then slide ENE most likely unless the shortwave mechanics change a lot. 
 

The good thing about that is it will likely prolong the CCB snows where that happens so it could give us a higher ceiling. The bad news is that it could be frustrating if you’re just north of the goods. You’d keep expecting the heavy bands to get to you but they never quite reach or they weaken by the time they do. 

Second paragraph is perfect!  That's exactly what I am expecting, and something that is fairly common.  Of course, it is going to produce an outcry of "I was screwed"  or "another meh storm" from folks sitting just north of the east/northeast hvy snow axis.   Barring any over amped short wave trends, the large scale flow should limit the northward extent of the best snows.

[CoastalWx]

I know for my area, I do like seeing the cold push down into Maine and then into the GOM. As winds go east, I’ll need that source region. Euro was pasty here verbatim for a majority. 
 

Probably a nice CF near Ray for a bit. 

[40/70 Benchmark]

34 minutes ago, ORH_wxman said:

Yeah this one is gonna reach a certain point and then slide ENE most likely unless the shortwave mechanics change a lot. 
 

The good thing about that is it will likely prolong the CCB snows where that happens so it could give us a higher ceiling. The bad news is that it could be frustrating if you’re just north of the goods. You’d keep expecting the heavy bands to get to you but they never quite reach or they weaken by the time they do. 

I could see that happening to me.

[CoastalWx]

3 minutes ago, 40/70 Benchmark said:

I could see that happening to me.

Euro verbatim was pretty sweet there. Good inflow above 850 where it’s in the DGZ. 
 

H7 gets pretty far north. 

[40/70 Benchmark]

Just now, CoastalWx said:

Euro verbatim was pretty sweet there. Good inflow above 850 where it’s in the DGZ. 
 

H7 gets pretty far north. 

Yea, well the OP was a N outlier.

[STILL N OF PIKE]

11 minutes ago, 40/70 Benchmark said:

I could see that happening to me.

In all my time on the boards I always hear Scott say you look good or will be fine . So you may want to ask the pope 

[CoastalWx]

8 minutes ago, 40/70 Benchmark said:

Yea, well the OP was a N outlier.

I know, just speaking verbatim. 

[CoastalWx]

2 minutes ago, STILL N OF PIKE said:

In all my time on the boards I always hear Scott say you look good or will be fine . So you may want to ask the pope 

My definition doesn’t have to mean a jack look like he expects.

[Damage In Tolland]

16 minutes ago, CoastalWx said:

I know for my area, I do like seeing the cold push down into Maine and then into the GOM. As winds go east, I’ll need that source region. Euro was pasty here verbatim for a majority. 
 

Probably a nice CF near Ray for a bit. 

Can we finally score the interior mashed potato power outage storm that has proven so elusive for so many years? 

[CoastalWx]

Just now, Damage In Tolland said:

Can we finally score the interior mashed potato power outage storm that has proven so elusive for so many years? 

Probably not

[CoastalWx]

Just now, Damage In Tolland said:

Can we finally score the interior mashed potato power outage storm that has proven so elusive for so many years? 

Unless it tucked into LI maybe.

[ORH_wxman]

Just now, Damage In Tolland said:

Can we finally score the interior mashed potato power outage storm that has proven so elusive for so many years? 

Unless this really hugs I don’t think so. Looks like 20s and powder for much of interior with any offshore track. 

[dryslot]

Its the ENE slide i never care for.

[Damage In Tolland]

5 minutes ago, ORH_wxman said:

Unless this really hugs I don’t think so. Looks like 20s and powder for much of interior with any offshore track. 

Just once .. I just don’t get why those don’t happen like they used to .  One day 

[CoastalWx]

2 minutes ago, Damage In Tolland said:

Just once .. I just don’t get why those don’t happen like they used to .  One day 

Your best chances is probably March or early in season. Tough to get paste at your location in January. 

[Damage In Tolland]

7 minutes ago, CoastalWx said:

Your best chances is probably March or early in season. Tough to get paste at your location in January. 

We’ve had them though. But it’s been so long since we’ve even had 6+ paster I don’t even recall. Like the one they had last December from Westfield NW into the Berks and ORH hills.

[ORH_wxman]

2 minutes ago, Damage In Tolland said:

Just once .. I just don’t get why those don’t happen like they used to .  One day 

Give me an example of previous ones. Other than Dec ‘92. Huge pasters aren’t THAT common. They typically are smaller events. 
 

Anyways, there’s a long ways to go in this one. Could easily fall apart but today was a good day for model runs since we’re getting inside 6 days now where you’d expect things to start falling apart if they are going to. Hopefully we can keep this strong on guidance for the next couple days and that will get us inside 100 hours. 
 

 

[CoastalWx]

Just now, Damage In Tolland said:

We’ve had them though. But it’s been so long since we’ve even had 6+ paster I don’t even recall. Like the one yet had last December in from Westfield NW into the Berks 

I’d say Jan into Feb is probably the hardest time to get paste for you. 

[Damage In Tolland]

5 minutes ago, ORH_wxman said:

Give me an example of previous ones. Other than Dec ‘92. Huge pasters aren’t THAT common. They typically are smaller events. 
 

Anyways, there’s a long ways to go in this one. Could easily fall apart but today was a good day for model runs since we’re getting inside 6 days now where you’d expect things to start falling apart if they are going to. Hopefully we can keep this strong on guidance for the next couple days and that will get us inside 100 hours. 
 

 

Well they don’t need to be huge. Even just like 6-10” or something.