Absolute Vorticity

Agreed that we are still well within range for changes and model disagreement to continue. The guidance yesterday and last night was a pretty big shift, but as I explained in my post the models struggle with huge airmass changes like this. I am lowering my PoPs a bit in my extended outlook though. I am driving home the uncertainty which as Tim said you don’t get with weather apps.

tpweather wrote: ↑Thu Jan 11, 2024 6:06 am

tron777 wrote: ↑Thu Jan 11, 2024 5:57 am 6Z GFS has a two part system and this has been a signal on other models as well. At CVG, we get 0.10" of QPF Sun night into Mon then the main piece late Mon night into Tues where an additional 0.24" of QPF occurs. This system should not be wrote off yet by any means.

Exactly Les and if those totals happen with the cold air we are talking about 4-6 inches. Not only that but 4-6 inches with this type of cold is different than 4-6 and temps near 30. You get that glaze of ice underneath and after awhile salt does not work because its too cold. Do those two pieces interact and they may and it could happen to the east of us and lets see Saturday afternoon models and compare them do yesterdays Euro.

No doubt Tim! The air mass will be colder with the second piece then it will be with the first piece, This will be a light powdery snow and as we've discussed... every single flake will stick. If you get the two pieces to interact, or get one piece altogether, then you get a CMC or UKMET solution with big dog totals. Otherwise, you get the GFS's solution and to some extent the Euro, although the Euro seems to be the outlier solution at this time in my mind.

Trevor wrote: ↑Thu Jan 11, 2024 4:39 am

dce wrote: ↑Thu Jan 11, 2024 4:13 am For what it's worth. And I'm not sure it's worth anything, but the UKMET is all in for this system. By far the strongest for AV land.

Lock it in!

I will!

Trevor wrote: ↑Thu Jan 11, 2024 6:09 am Agreed that we are still well within range for changes and model disagreement to continue. The guidance yesterday and last night was a pretty big shift, but as I explained in my post the models struggle with huge airmass changes like this. I am lowering my PoPs a bit in my extended outlook though. I am driving home the uncertainty which as Tim said you don’t get with weather apps.

I agree Trev. As I said yesterday, there is much uncertainty with this system. We still have La Bomba 2.0 to get through. Way too early to come up with an accumulation forecast for this system. I won't be putting out any numbers until perhaps Saturday to be honest.

tron777 wrote: ↑Thu Jan 11, 2024 6:18 am

Trevor wrote: ↑Thu Jan 11, 2024 6:09 am Agreed that we are still well within range for changes and model disagreement to continue. The guidance yesterday and last night was a pretty big shift, but as I explained in my post the models struggle with huge airmass changes like this. I am lowering my PoPs a bit in my extended outlook though. I am driving home the uncertainty which as Tim said you don’t get with weather apps.

I agree Trev. As I said yesterday, there is much uncertainty with this system. We still have La Bomba 2.0 to get through. Way too early to come up with an accumulation forecast for this system. I won't be putting out any numbers until perhaps Saturday to be honest.

Yes agreed. I was a little too optimistic about going with a first call today but I am going to wait. Late tomorrow or Saturday sounds like a better idea.

EPS continues its steady trend of a more moisture starved and southern shift of qpf, with a deeper push of drier arctic air. Giving most of our tri-cities a .10” or less of qpf(mean)

UKMET / CMC have the most moisture, GFS is in the middle with the Euro, EPS, and even the GEFS showing the least amount. Still quite a bit of model spread to sort through for sure. I think it boils down to 1 piece or two? How much energy gets held back? These are the kinds of questions we are waiting on the models to sort out. A complete miss is just as much on the table as seeing warning criteria snows.

I gave the Euro a hard time this morning but also the GFS made a big move yesterday from the system heading straight out to sea and of course to a two tier system. That is normal for the GFS to be way to fast compared to the Euro which holds back energy especially weaker energy in the four corners area. Watch the CMC as it tends to do well within 3-4 days and then for some unknown reason within 36 hours gets goofy. We know the bias of each model and sometimes there is a reason and it works for them but many time they correct themselves and especially when you have an active pattern like we are in at the moment.

6z GEFs qpf is similar to the EPS for our region

6Z Euro stops at 90 hours but if you compare it with the 0Z run... it's not quite as flat. The Western US ridge is taller on the new 6Z run which is a good thing. The shortwave is able to dig a little more as a result. Very little snow being shown at 90 hours out in the S Plains on the 0Z run, but with the 6Z run, you see a nice area of light to moderate snow over OK and S Kansas. This was a step in the right direction. Hopefully the 12Z run later today continues with that idea.

6z GFS still gives us a nice hit, even with the two part system. It’s not 10”, but it’s also not zilch.

Just wanted to see what channel 5 was saying because they use the Euro. They have light snow Sunday night and then for Tuesday Winter Storm? So this tells me they are not so sure about the Wednesday model run

As some of us has stated.... we should gain more clarity by later Fri or early Sat once La Bomba 2.0 moves thru. We should see how strong the incoming arctic high is pushing down from Canada by then, as well as the incoming energy from the Pacific. A 2 part system is gaining some traction. A weak wave for Sun night into MLK then the main system for Mon night into Tues evening. When you're in an active pattern like this, a lot of the time you're just not going to know until we get close to game time. Also, this is an extremely cold air mass coming in that will absolutely having some staying power. Due to these factors, please be patient with us forecasters on here. We will throw out our calls as soon as we feel comfortable to do so.

I think we are continuing to see the same thing we saw last week. The models can only handle the potent storm into the weekend, before they can decide what will happen next week.

fyrfyter wrote: ↑Thu Jan 11, 2024 8:49 am I think we are continuing to see the same thing we saw last week. The models can only handle the potent storm into the weekend, before they can decide what will happen next week.

Totally agree Aaron! When you're in an active pattern, each passing storm sets the table for the next one.

Yesterday this system was stronger in the four corner area but trended much weaker the past 24 hours. This run of the Nam looks like its hedging back to a somewhat stronger system. Again I agree with Les it may be Saturday before we get a clear picture of this system

Nam just looks slower overall but only goes out to 84 hours. Will be interesting to see the other models today

12Z GFS is coming in weaker with the system overall. Not as much of a dig with the second piece. PNA ridge not quite as tall as 6Z.

The weaker and suppressed look kills the snowfall. It seems each passing storm is hell bent on making sure we don't get any snow.

GFS with a spread out 2 day event with .10”-.20” qpf for the region

Canadian looks good still for us. And the GFS doesnt look horrible this far out.

Certainly looking more and more like it'll be a 2 part system. First wave is weak, and we want the PNA ridge to be taller so the main wave can dig more to pull up more Gulf moisture.

12Z GFS has 0.05" for wave 1 on MLK and an additional 0.14" for wave 2 on Tues.

mikeyp wrote: ↑Thu Jan 11, 2024 11:11 am Canadian looks good still for us. And the GFS doesnt look horrible this far out.

CMC holds less energy back and it's still showing only 1 main system. That is the best chance for us to get better snows. I just don't think that it is going to be right unless we see more models go that route. I'd feel better if the GFS and Euro weren't showing the 2 part deal but it is what it is.

FWIW, the 12Z ICON has been another model showing the 1 storm deal and it's a nice hit too! Wonder if the UKIE will still show the 1 wave deal like it has been or does it cave to the GFS and Euro solutions?