December 19-20 Talking Points - Part 3

[eduggs]

It seems like these mysterious vorts are popping up out of nowhere in these runs. I find it hard to believe it's convective feedback because EVERY model has it. Any thoughts?

It's not convective feedback.

[Allsnow]

The GFS ensembles are a bit more amplified than 18z--but don't do the trick.

Question whats the point at looking at the ensembles if every run of the gfs has a diff solution? Not once since sunday it seems had looking at the ensembles help us.......12z they where a great hit....18z way east

[winterwx21]

It seems like these mysterious vorts are popping up out of nowhere in these runs. I find it hard to believe it's convective feedback because EVERY model has it. Any thoughts?

Exactly. When this many models have this solution, the convective feeback theory is pretty weak.

[Dsnowx53]

Question whats the point at looking at the ensembles if every run of the gfs has a diff solution? Not once since sunday it seems had looking at the ensembles help us.......12z they where a great hit....18z way east

The GFS ensembles almost always seem to do what the OP does.

[Rtd208]

This is one of those storms where the models can really try your patience and play with your emotions, with that being said, things are not looking the greatest tonight but could certainly look alot worse. I am really not sure what the Euro will show and I am not about to make assumptions like some are in this thread, 12z tomorrow will be the final nail in the coffin for me as far as I am concerned, and whatever the models are showing at that point I will go with, right or wrong.

[earthlight]

It's not convective feedback.

Agreed

[Isotherm]

The GFS ensembles almost always seem to do what the OP does.

I'm not sure how much worth the emsembles have except to confirm that the op run was not completely outlandish/out of whack.

[earthlight]

I'm not sure how much worth the emsembles have except to confirm that the op run was not completely outlandish/out of whack.

I think we're on life support with this threat now, Tom..and believe me I want this to work out more than anybody because I've been screaming about this specific threat for weeks.

[am19psu]

No doubt there is some convective feedback. You don't generate the modeled vorticity couplets without it. But, I think tornadojay is right with his theory of interference from the Gulf s/w. It has to be a real feature if the "feedback" is showing up in multiple models.

[NittanyWx]

There is definitely at least some convective feedback, I've never seen random vorts pop up like that without it.

EDIT:

No doubt there is some convective feedback. You don't generate the modeled vorticity couplets without it. But, I think tornadojay is right with his theory of interference from the Gulf s/w. It has to be a real feature if the "feedback" is showing up in multiple models.

Beat me to it.

[jm1220]

I think our chances greatly improve if this Gulf vortmax isn't real or is being overemphasized (which we've seen before prior events). Hopefully tonight's Euro salvages a decent hit for most of us, and then 12z/0z tomorrow trend back west. The 500mb pattern overall look favorable for a hit across much of the area-it won't fail because of the PV being in the way or a poor northern stream. We have to hope that Gulf vort is false so our developing storm has more energy to itself. If it's real, we're almost certainly screwed and maybe even New England outside the Cape.

[Zir0b]

Well that about does it....GGEM/UKMET are both way less amplified and with the s/w properly sampled along with them both using the 4DVAR initialization scheme, I expect the Euro to follow suit.

[eduggs]

Disagree with the last...GFS is not bad this run except at the surface.

I don't really understand that comment. Surface pressures (in the mid-latitudes) strengthen, weaken, and move based on upper level dynamics. The surface low track is less than ideal on the GFS chart because of the mid/upper levels. Maximum vorticity advection and associated upper level divergence are offshore - hence the offshore surface track. The southern stream s/w - if you can even identify it as such - is just not very impressive. Therefore the height field is flat and unimpressive. Sure the entire longwave structure is moving toward a huge cutoff in the Atlantic, but we are in a race to get the surface low center up the coast before the entire height structure slides east off the coast.

[Jefflaw77]

when does the euro come out?

[Snowlover11]

when does the euro come out?

1:30 ish

[HSNN4]

I think we're on life support with this threat now, Tom..and believe me I want this to work out more than anybody because I've been screaming about this specific threat for weeks.

I would strongly agree with that statement, we been doing this a long time and right now I do not see a block buster storm for New Jersey, If you would go by some in the media and the government that the world is coming to an end with this system. Have to admit it's been fun to watch for the last week. also very happy to see the board back up and running.

[mattinpa]

when does the euro come out?

Around 1:30 AM. It might go east, but hopefully not too much. Seems we get all down at night and prospects improve during the day, so we'll see what tomorrow brings.

[am19psu]

I'm really not trying to pick on you here, but...

The surface low track is less than ideal on the GFS chart because of the mid/upper levels.

No, the mid/upper levels are fantastic. Look at the s/w over the TN Valley at T+54

Maximum vorticity advection and associated upper level divergence are offshore - hence the offshore surface track.

This is true, but if you remove the feedback, you develop a stronger ridge closer to the shore and the s/w tracks farther west.

The southern stream s/w - if you can even identify it as such - is just not very impressive. Therefore the height field is flat and unimpressive.

Actually, it is way more impressive than it was in any model save the 12z Euro.

I'm not feeling nearly as bullish as I was 6 hours ago because of the GEM and UKM. But, I think everyone throwing in the towel is being a little premature as well.

[winterwx21]

This is one of those storms where the models can really try your patience and play with your emotions, with that being said, things are not looking the greatest tonight but could certainly look alot worse. I am really not sure what the Euro will show and I am not about to make assumptions like some are in this thread, 12z tomorrow will be the final nail in the coffin for me as far as I am concerned, and whatever the models are showing at that point I will go with, right or wrong.

That might even be a little too early. We've seen storms where the models didn't agree even 24 hours before the event. In a pattern like this, I think there can be very late changes.

[ChrisM]

thoughts on tonight's Euro?

I literally can't imagine it whiffs after two successive runs of trending further west.

[Allsnow]

Around 1:30 AM. It might go east, but hopefully not too much. Seems we get all down at night and prospects improve during the day, so we'll see what tomorrow brings.

no....by 1:15am we will know our fate....it starts on the paid sites at 1250am

[IsentropicLift]

oddly enough, its been the 12z runs that we've done the best on...12/14 12z gfs and 12/16 12z ECMWF

[Collegestudent11]

I doubt the POPs would be in the likely to definite range if this was mainly OTS.

[earthlight]

I doubt the POPs would be in the likely to definite range if this was mainly OTS.

The pops are high because many of the 12z operational models were far enough west to bring significant precip.

[tmagan]

I'll say one thing about the 00Z UKMET, regarding the last midwest cyclone, it was way south and east of the model consensus at the 72 hour forecast before correcting itself.

By the way, I know it was deleted, but the 12Z Russian model, did have something regarding the further east track.

[Collegestudent11]

The pops are high because many of the 12z operational models were far enough west to bring significant precip.

I do understand that, however, my point is they decided not to really hedge their bets on the 0z showing something so far away from 12z, and thus put it within that range. Even 100% does not mean 12+, it could just be 1 inch, however, with the 500mb setup it does not seem as if the solution is entirely correct.

[LVblizzard]

Actually, isn't the Euro good with resolving any feedback issues? If that's the case then I expect it to be like last night's 0z...

[Collegestudent11]

Did we not go through this yesterday on the models, most were east and the euro was west? While the southern sw is sampled better, it does not mean that subtle features are not placed incorrectly.

[eduggs]

No, the mid/upper levels are fantastic. Look at the s/w over the TN Valley at T+54

I'm not saying it's insufficient to get a rapidly deepening low center. Just that it won't form in time for us. I just don't see it as sufficient to modify the fields to get moisture and dynamics back to the mid-atlantic coast. Maybe EMa Maine, and the Maritimes.

This is true, but if you remove the feedback, you develop a stronger ridge closer to the shore and the s/w tracks farther west.

I really hope this is right. I don't see the feedback, or rather I'm not familiar with this sort of feedback mechanism. And I don't understand how it would significantly alter the model output in this case.

Actually, it is way more impressive than it was in any model save the 12z Euro.

Yeah I agree that it looks a little more impressive than 18z. And I also readily concede that if I saw the chart without a week of prior model runs to consider I would be intrigued by the potential. But considering several days of runs with the specific synoptics, I still believe we need improvements.

[am19psu]

I'm not saying it's insufficient to get a rapidly deepening low center. Just that it won't form in time for us. I just don't see it as sufficient to modify the fields to get moisture and dynamics back to the mid-atlantic coast. Maybe EMa Maine, and the Maritimes.

I really hope this is right. I don't see the feedback, or rather I'm not familiar with this sort of feedback mechanism. And I don't understand how it would significantly alter the model output in this case.

These two points are tied together. And let me be clear again, it's not just feedback. I agree with Jay, there is a real s/w coming out of the Gulf that is also helping push everything off the coast. However, with a weaker s/w coming out of the Gulf, you'll get more warm advection farther west and build the ridge closer to the coast, causing a solution west of consensus. That's the point I'm trying to make.

Like I said, I am far less bullish than I was before I saw the GEM and UKM, but I wouldn't write this off just yet.