Texas Fall 2021

[Cerlin]

West based -NAO and connecting -AO showing up on the ensembles. Chances of a colder Thanksgivings growing. That block has been the persistent theme of the past 12 months.

It's also important to understand what it is you are blocking. That was a key I've been mentioning the past few days, build the cold air first then when you block it, you are working with colder continental air vs maritime.

Yep! I've been noticing it as well. There's likely going to be cold air spilling into the continental U.S. at that time, just a question of if it is far enough west to really affect us. Operationals have largely shown it spilling east but the ensembles seem relatively split. I'm gonna enjoy watching this play out over the next week!

[EnnisTx]

West based -NAO and connecting -AO showing up on the ensembles. Chances of a colder Thanksgivings growing. That block has been the persistent theme of the past 12 months.

It's also important to understand what it is you are blocking. That was a key I've been mentioning the past few days, build the cold air first then when you block it, you are working with colder continental air vs maritime.

Yep! I've been noticing it as well. There's likely going to be cold air spilling into the continental U.S. at that time, just a question of if it is far enough west to really affect us. Operationals have largely shown it spilling east but the ensembles seem relatively split. I'm gonna enjoy watching this play out over the next week!

The potential is definitely there, like you said, it will be fun watching this play out.

[Brent]

Hopefully the Euro is wrong with the cold east of us But the EPS does show promise still

Also no surprise but the GFS has totally lost that snowstorm from last night

[Ntxw]

I think the initial shots will definitely steer east but as the block retrogrades (along with Pacific jet retraction) it will bleed westward with time.

[HockeyTx82]

You all can blame me either way for this. I booked a bounce house for my soon to be 4 year old son's party on the 27th.

[bubba hotep]

I would like to the the Pacific jet shifted farther southward as we move out in time, but that will be hard to get with the current PSV setup. That is one of the major limiting factors that I see, if you are looking for extreme cold. These are D10 maps, the GFS is a mess but the Euro looks pretty good, just shift the WCAN Ridge westward and we are in business for cold.

[Quixotic]

I would like to the the Pacific jet shifted farther southward as we move out in time, but that will be hard to get with the current PSV setup. That is one of the major limiting factors that I see, if you are looking for extreme cold. These are D10 maps, the GFS is a mess but the Euro looks pretty good, just shift the WCAN Ridge westward and we are in business for cold.

https://www.tropicaltidbits.com/analysis/models/gfs/2021111512/gfs_z500aNorm_namer_41.png

https://www.tropicaltidbits.com/analysis/models/ecmwf/2021111512/ecmwf_z500aNorm_namer_11.png

That strong low out west of Baja California seems incongruent with the ridge in terms of how strong it is. Maybe just me.

[Brent]

GFS has absolutely zero cold air. Thanksgiving in the 60s in Dallas. The end of the run which is December is pretty much a nationwide torch

Euro and CMC also look rather mild and unsettled for Thanksgiving. Again no cold air to be found around here

[gpsnowman]

It feels and even smells like a late April morning right now. Yuck.

[cstrunk]

It feels and even smells like a late April morning right now. Yuck.

I had the exact same thought on my way to work this morning. I would be OK with it, if we were looking at some storms coming through in a day or two, but just a slight chance of a light shower.

[TeamPlayersBlue]

Seeing what NTx has been saying. That blocking could be huge. Will be a game changer if it can hold. Much of what is going on in the pacific has not been very friendly for cold air at all, but just the slightest shift westward and we could see big changes. I still stand by my prediction that Dec will be below normal for the nation.

[starsfan65]

GFS has absolutely zero cold air. Thanksgiving in the 60s in Dallas. The end of the run which is December is pretty much a nationwide torch

Euro and CMC also look rather mild and unsettled for Thanksgiving. Again no cold air to be found around here

GFS is a warm bias.

[HockeyTx82]

GFS has absolutely zero cold air. Thanksgiving in the 60s in Dallas. The end of the run which is December is pretty much a nationwide torch

Euro and CMC also look rather mild and unsettled for Thanksgiving. Again no cold air to be found around here

GFS is a warm bias.

But the GFS also nailed the February cold outbreak and we still were Iike it's out to lunch.

[starsfan65]

GFS has absolutely zero cold air. Thanksgiving in the 60s in Dallas. The end of the run which is December is pretty much a nationwide torch

Euro and CMC also look rather mild and unsettled for Thanksgiving. Again no cold air to be found around here

GFS is a warm bias.

But the GFS also nailed the February cold outbreak and we still were Iike it's out to lunch.

Ya'll saying that the GFS could be right?

[EnnisTx]

No one is saying one model is right or wrong, it's still to early to be expecting anything for sure. Mostly wish casting is ongoing for most. It will all play out soon enough.

[Ntxw]

GFS has absolutely zero cold air. Thanksgiving in the 60s in Dallas. The end of the run which is December is pretty much a nationwide torch

Euro and CMC also look rather mild and unsettled for Thanksgiving. Again no cold air to be found around here

GFS is a warm bias.

But the GFS also nailed the February cold outbreak and we still were Iike it's out to lunch.

Every situation is different. GFS was superior in that case because it was the most consistent. It's flaked in other cold snaps being too warm. Once you see a model or models become consistent then you start to weigh it more because it's figured something out. Some cases the Euro is better and others the GFS.

This one isn't a clear cut case. There's been some swings of warm and cold, which tells us they are still resolving the ridge and trough placement.

[Ntxw]

Here is such an example over the weekend if you look over Greenland had a trough in the vicinity of Greenland blocking. Now it's a massive monstrous ridge. That's like predicting a forest fire one run then heavy flooding some time later for the same period. Still though we're looking at 10 days out.

[TheProfessor]

I'm late to the discussion, but one thing about teleconnections (and I've mentioned this before iirc) is that how they trend is just as important as where it is on the graph. In the midterm the PNA is expected to trend positive, but then that trend becomes more neutral or even slightly negative, which would favor us. A low amplitude negative trend isn't a bad deal for us as long as the AO, EPO, and NAO aren't going in the wrong direction too. It does seem like we could see what Ntxw was mentioning with the cold air sliding east at first and then retrograding westward with time.

[starsfan65]

I'm late to the discussion, but one thing about teleconnections (and I've mentioned this before iirc) is that how they trend is just as important as where it is on the graph. In the midterm the PNA is expected to trend positive, but then that trend becomes more neutral or even slightly negative, which would favor us. A low amplitude negative trend isn't a bad deal for us as long as the AO, EPO, and NAO aren't going in the wrong direction too. It does seem like we could see what Ntxw was mentioning with the cold air sliding east at first and then retrograding westward with time.

how long is the PNA is going to be positive?

[Brent]

I think it's becoming clear the Tuesday cold is east of us what happens just after Thanksgiving is the big question. Theres still signs of something bigger for us the issue is of course we're talking about beyond day 10 and it's hard to trust anything. The end of the euro has a snowstorm in the Panhandle but again it's the day after Thanksgiving so a long way out

I will go back to what I probably said weeks ago though... November cold the last few years hasn't helped us in the winter so I mean if its delayed it's not the worst thing.