Absolute Vorticity

Posted: **Wed Dec 13, 2023 6:32 pm**

tron777 wrote: ↑Wed Dec 13, 2023 5:37 pm 18Z GFS is back to showing a pretty wet Sun and Mon period with a full phase and an Apps runner type track. This continues to be the only model doing this as the 12Z CM and Euro continue to only bring in light rain with the northern stream feature on Sat night into Sunday.

Hey Les and the CMC is not showing much but the Euro does have a phase though just a little further east but to close for comfort. The latest gfs like you mentioned is quite the rain maker

Posted: **Wed Dec 13, 2023 7:01 pm**

If only the latest gfs was in mid-winter the path would be wonderful for a nice snowstorm.

Posted: **Wed Dec 13, 2023 7:33 pm**

tpweather wrote: ↑Wed Dec 13, 2023 7:01 pm If only the latest gfs was in mid-winter the path would be wonderful for a nice snowstorm.

I know it Tim! If only that northern shortwave had some cold air coming in behind it, we'd score big time! Sigh... no such luck for us snow starved weenies.

Posted: **Thu Dec 14, 2023 4:07 am**

Good Morning and looks like the storm for the weekend is much closer than we thought a few days ago. Rainfall totals could be in a big range from west to east with this system as well. Snow and yes it may need to be added for later Sunday though not expecting much these systems that phase can really produce some cold air associated with the upper system and especially to the east of us in the mountains I would expect snow to be added to the forecast. Still plenty of warm air in many layers of the atmosphere but these can cool quite fast especially when you get some heavier precip to fall.

Models are starting to show changes for Christmas week as well and though I have been early on the call of 12/21 the change should happen Christmas week and if we are lucky maybe some snow that week..

Models get so out of whack sometimes and late last month showing the change to colder around the 20th or so but then kept putting that date further away and before you know it some folks are calling off winter lol. We really have not even entered winter so calling it off was maybe a little premature.

Mother Nature will balance the earth out as always and she really never looks at the models.

Posted: **Thu Dec 14, 2023 4:42 am**

Good morning all! 22 IMBY this morning, one of the colder mornings we've had in a while. The 0Z GFS is picking up right where the 18Z run left out. CMC and Euro aren't quite as dramatic as the GFS since the phasing is a bit later but they are beginning to come around IMO. We may very well have a wet Sun and Mon on our hands if this does come to fruition. The Euro was interesting as ?Tim mentioned with some light snow at the end. This has EPS support too. There is much more digging of the second shortwave and the upper low or 500 MB low actually closes off so you can certainly pull down enough cold air from upstairs on the back side of this system. Hmmm...

This system is one to watch. Not so much for snow but wind and rain prospects. Although if you can get a strong enough system as the Euro is showing some light snow Sun night into Mon would absolutely be the end result. This system would also help usher in a colder pattern for Christmas. Maybe a strong storm is just what we need to shake things up a bit.

Concerning Christmas and beyond, models are definitely turning colder. Not arctic cold or anything like that, more near normal if not a touch below which is just cold enough for snow should a well timed shortwave move thru. For snow lovers, it is still a long shot here but it's not looking quite so bad as in a shut out. Hopefully we will see that trend continue. I'm pretty much agreeing with Tim's above post lol

Posted: **Thu Dec 14, 2023 4:58 am**

tron777 wrote: ↑Thu Dec 14, 2023 4:42 am Good morning all! 22 IMBY this morning, one of the colder mornings we've had in a while. The 0Z GFS is picking up right where the 18Z run left out. CMC and Euro aren't quite as dramatic as the GFS since the phasing is a bit later but they are beginning to come around IMO. We may very well have a wet Sun and Mon on our hands if this does come to fruition. The Euro was interesting as ?Tim mentioned with some light snow at the end. This has EPS support too. There is much more digging of the second shortwave and the upper low or 500 MB low actually closes off so you can certainly pull down enough cold air from upstairs on the back side of this system. Hmmm... This system is one to watch. Not so much for snow but wind and rain prospects. Although if you can get a strong enough system as the Euro is showing some light snow Sun night into Mon would absolutely be the end result. This system would also help usher in a colder pattern for Christmas. Maybe a strong storm is just what we need to shake things up a bit.

Concerning Christmas and beyond, models are definitely turning colder. Not arctic cold or anything like that, more near normal if not a touch below which is just cold enough for snow should a well timed shortwave move thru. For snow lovers, it is still a long shot here but it's not looking quite so bad as in a shut out. Hopefully we will see that trend continue. I'm pretty much agreeing with Tim's above post lol

You pretty much summed up what I was coming on here to say re: weekend storm. The GFS has much more support now as you said with the Euro and GDPS moving in that direction. The Euro is SO CLOSE to giving us more than a few snow showers as well. Little quicker timing with the phase with that new piece of energy diving in and we would be talking about our first snowfall event of the season IMO. Something to watch...

Snow talk aside, much better confidence in adding higher rain PoPs for the weekend.

Posted: **Thu Dec 14, 2023 5:07 am**

It’s just nice to be tracking a winter characteristic storm even without the cold temps. Seeing the evolution of a nothing-burger except for the coastline, to what it has potentially become is fascinating to watch. Phase, no phase, phase , this is winter time tracking

Posted: **Thu Dec 14, 2023 5:17 am**

Bgoney wrote: ↑Thu Dec 14, 2023 5:07 am It’s just nice to be tracking a winter characteristic storm even without the cold temps. Seeing the evolution of a nothing-burger except for the coastline, to what it has potentially become is fascinating to watch. Phase, no phase, phase , this is winter time tracking

You know it!

The GFS has quite a widespread wind event for the east coast! Lots of power outages with that kind of action going on.

Posted: **Thu Dec 14, 2023 5:22 am**

With how deep the low is expected to get, I think we are not quite done with more interesting things showing up on the models. Like I said the Euro was SO CLOSE to giving us accumulating snow. It's so rare this time of year to have a low that deep with no wintry side. Earlier phase and we are talking fun stuff around here.

Posted: **Thu Dec 14, 2023 6:55 am**

Great Post from all. Les I agree we have been looking for the storm that can help change the pattern. Need a strong storm and one that can head much further north in Latitude closer to the USA. Models are also trying to put a stronger ridge towards Alaska down the road which we need as well and maybe have the low off the southwest coast of Alaska moved further west which is something we need as well. Also it looks like some cooler waters near the SA coast which will should weaken the El NIno but how quickly will also have a say on this winter. Saw a -56 in Siberia this morning so cold but nothing unheard of. Still would love to see a few more storms that head into the Lakes to produce snow cover to our north and west but again its only Dec 14th and though later than normal for that area its not to late by any means.

Posted: **Thu Dec 14, 2023 7:39 am**

I hit 23 this morning and a nice frost this morning. Probably get one more frosty morning Friday as well. Will be on and off the forum the next few days and another funeral on Friday. My sister-n-laws father passed at the age of 90. Hopefully by Saturday we have a nice storm to watch even if its an all rain event but one that strengthens plus all-day football sounds perfect

Posted: **Thu Dec 14, 2023 8:04 am**

Sorry to hear Tim.

The GEFs are significantly further east with the Low( east of Apps) than the op Gfs, which makes a big difference in QPF for our region. Might expect a correction to the East in future runs

Posted: **Thu Dec 14, 2023 8:09 am**

Bgoney wrote: ↑Thu Dec 14, 2023 8:04 am Sorry to hear Tim.

The GEFs are significantly further east with the Low( east of Apps) than the op Gfs, which makes a big difference in QPF for our region. Might expect a correction to the East in future runs. EPS are also further east

Posted: **Thu Dec 14, 2023 8:15 am**

It's all about the path of least resistance. I favor a more inland track versus coastal or OTS. I think the setup is such that will allow this thing to track up the Apps (probably eastern side, but western side is possible). I think the OP GFS matches this thinking most closely. The incoming trough should help tug it northward as well.

Posted: **Thu Dec 14, 2023 10:39 am**

The phasing will have a lot to do with the track also. An earlier phase means a stronger storm and a further westward track. A later phase means a weaker storm and a further eastward track. We preach timing, timing, timing on here and that is always the case in weather especially when the potential exists for a strong storm system. Regardless of the final outcome, as others have stated, it is definitely going to be a fun one to watch.

Posted: **Thu Dec 14, 2023 10:43 am**

tpweather wrote: ↑Thu Dec 14, 2023 7:39 am I hit 23 this morning and a nice frost this morning. Probably get one more frosty morning Friday as well. Will be on and off the forum the next few days and another funeral on Friday. My sister-n-laws father passed at the age of 90. Hopefully by Saturday we have a nice storm to watch even if its an all rain event but one that strengthens plus all-day football sounds perfect

I keep forgetting to start my car in the morning to avoid scraping the windshield. Oh how I miss remote start.

Posted: **Thu Dec 14, 2023 10:53 am**

12Z GFS will be a further east track vs 0Z since the phasing is occurring a bit later. You can see that at hours 66 and 72.

Posted: **Thu Dec 14, 2023 11:04 am**

tron777 wrote: ↑Thu Dec 14, 2023 10:53 am 12Z GFS will be a further east track vs 0Z since the phasing is occurring a bit later. You can see that at hours 66 and 72.

Yep , kind of expected that given the ensemble’s. NAM looks like it’s headed that way also

Posted: **Thu Dec 14, 2023 11:14 am**

Not really buying the east track personally. I think the next couple of runs will bring it back west.

Posted: **Thu Dec 14, 2023 1:28 pm**

Trevor wrote: ↑Thu Dec 14, 2023 11:14 am Not really buying the east track personally. I think the next couple of runs will bring it back west.

Even the Euro trended eastward to the coast on this run. I suspect we are seeing the windshield wiper effect and it will come back a little to the west on subsequent runs. We are still about 3 days out.

Posted: **Thu Dec 14, 2023 1:54 pm**

dce wrote: ↑Thu Dec 14, 2023 1:28 pm
Trevor wrote: ↑Thu Dec 14, 2023 11:14 am Not really buying the east track personally. I think the next couple of runs will bring it back west.
Even the Euro trended eastward to the coast on this run. I suspect we are seeing the windshield wiper effect and it will come back a little to the west on subsequent runs. We are still about 3 days out.

That’s what I’m thinking as well. We’ll see! Even still, both the GFS and Euro both give us 0.75-1.00” or so of rainfall. I have 0.50-0.75” posted on my FB page forecast and that may be on the lower side.

Posted: **Thu Dec 14, 2023 2:27 pm**

Good afternoon and had a few minutes to look things over this afternoon. How strong is the upper low coming through the Ohio Valley on Sunday is key because if its stronger it can help pull the other system. Normally I would bet on the coastal low to win out because its bigger and getting stronger but the problem is there are blocking features like Trevor showed. If the low in the Ohio Valley is weaker then you may have the problem of the low going out to sea which is what we don't want to see.

Posted: **Thu Dec 14, 2023 2:46 pm**

tpweather wrote: ↑Thu Dec 14, 2023 2:27 pm Good afternoon and had a few minutes to look things over this afternoon. How strong is the upper low coming through the Ohio Valley on Sunday is key because if its stronger it can help pull the other system. Normally I would bet on the coastal low to win out because its bigger and getting stronger but the problem is there are blocking features like Trevor showed. If the low in the Ohio Valley is weaker then you may have the problem of the low going out to sea which is what we don't want to see.

Summed it up well. The blocking is there, just need the northern low to be stronger as you said.

Posted: **Thu Dec 14, 2023 4:04 pm**

Trevor wrote: ↑Thu Dec 14, 2023 1:54 pm
dce wrote: ↑Thu Dec 14, 2023 1:28 pm
Trevor wrote: ↑Thu Dec 14, 2023 11:14 am Not really buying the east track personally. I think the next couple of runs will bring it back west.
Even the Euro trended eastward to the coast on this run. I suspect we are seeing the windshield wiper effect and it will come back a little to the west on subsequent runs. We are still about 3 days out.
That’s what I’m thinking as well. We’ll see! Even still, both the GFS and Euro both give us 0.75-1.00” or so of rainfall. I have 0.50-0.75” posted on my FB page forecast and that may be on the lower side.

I llike the lower amounts atm Trev, (maybe slightly lower low of .25-.75”, if we get no moisture pushing back over the Apps to our region , I still think the moisture associated with the northern Vort will be limited

Posted: **Thu Dec 14, 2023 4:19 pm**

Bgoney wrote: ↑Thu Dec 14, 2023 4:04 pm
Trevor wrote: ↑Thu Dec 14, 2023 1:54 pm
dce wrote: ↑Thu Dec 14, 2023 1:28 pm
Trevor wrote: ↑Thu Dec 14, 2023 11:14 am Not really buying the east track personally. I think the next couple of runs will bring it back west.
Even the Euro trended eastward to the coast on this run. I suspect we are seeing the windshield wiper effect and it will come back a little to the west on subsequent runs. We are still about 3 days out.
That’s what I’m thinking as well. We’ll see! Even still, both the GFS and Euro both give us 0.75-1.00” or so of rainfall. I have 0.50-0.75” posted on my FB page forecast and that may be on the lower side.
I llike the lower amounts atm Trev, (maybe slightly lower low of .25-.75”, if we get no moisture pushing back over the Apps to our region , I still think the moisture associated with the northern Vort will be limited

Less moisture of course if we miss the main storm, but still a decent rainfall in an overall dry pattern.

The more I look at things I really don't think the models at the surface are lining up enough with the upper levels. Between 18z today and 18z tomorrow I expect a shift back to the west in the guidance.

Absolute Vorticity

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