Absolute Vorticity

Been a bit breezy up this way. I'd say gusts nearing 30 to 35 mph. Took the truck door out of my hand.

On today's OP GFS run, the PNA looks to go more towards neutral by the end of the run. It is in fantasy land but the pattern is slowly improving if this is correct as we end 2021 and kick off 2022. Again I am not discounting the possibility of some snow between Christmas and New Year's, but from a pattern recognition standpoint, I think it becomes more favorable, as I've been saying in January.

12Z GEFS doesn't look very cold thru the end of the run (1/1/22) but it's not very war, either. Temps look to be seasonal, highs in the 40s lows in the 20s which you would expect. I think chances for frozen precip are there with a well timed shortwave. -EPO / -NAO pattern but the -PNA isn't going away at all with ridging over the South. That might cut off the Gulf for moisture laden systems however. We'll have to wait and see on that part. Anyway.. we'll see what happens. Not a total shut out pattern just not the greatest thru the end of the year.

Rain is knocking on the door just to the NW of the Metro. A good chunk of Indy and our I-70 Dayton posters are getting wet, or will about to get wet depending on location. Should be a wet drive home for most folks.

A lot of uncertainty for Christmas Eve / Day timeframe next week. GFS didn't show much but the Euro wants to bring in some rain and a decent amount at that Christmas Eve in the afternoon. GFS doesn't bring in any rain until the 26th. CMC has a brief period of frozen precip, probably sleet changing to rain on Christmas Day. 12Z GEFS members also differ on timing as well as precip types. I think we'll be dry Sun - Wed with seasonal temps and a decent amount of sunshine but after that, I have low confidence this far out as to exactly what to expect. Stay tuned...

tron777 wrote: ↑Thu Dec 16, 2021 1:53 pm A lot of uncertainty for Christmas Eve / Day timeframe next week. GFS didn't show much but the Euro wants to bring in some rain and a decent amount at that Christmas Eve in the afternoon. GFS doesn't bring in any rain until the 26th. CMC has a brief period of frozen precip, probably sleet changing to rain on Christmas Day. 12Z GEFS members also differ on timing as well as precip types. I think we'll be dry Sun - Wed with seasonal temps and a decent amount of sunshine but after that, I have low confidence this far out as to exactly what to expect. Stay tuned...

I agree Les and believe models will end up seeing a stormy set up late next week and yes snow will be a bigger part of the equation but exactly where in the Ohio Valley is way to early to determine. Just by having the AO and NAO going to neutral or negative will bring in some colder air as the storm track will swift further south. How far south is still the big question.

tpweather wrote: ↑Thu Dec 16, 2021 2:02 pm

tron777 wrote: ↑Thu Dec 16, 2021 1:53 pm A lot of uncertainty for Christmas Eve / Day timeframe next week. GFS didn't show much but the Euro wants to bring in some rain and a decent amount at that Christmas Eve in the afternoon. GFS doesn't bring in any rain until the 26th. CMC has a brief period of frozen precip, probably sleet changing to rain on Christmas Day. 12Z GEFS members also differ on timing as well as precip types. I think we'll be dry Sun - Wed with seasonal temps and a decent amount of sunshine but after that, I have low confidence this far out as to exactly what to expect. Stay tuned...

I agree Les and believe models will end up seeing a stormy set up late next week and yes snow will be a bigger part of the equation but exactly where in the Ohio Valley is way to early to determine. Just by having the AO and NAO going to neutral or negative will bring in some colder air as the storm track will swift further south. How far south is still the big question.

There should be a storm somewhere in the 24-26th period based on what we're seeing right now. All modes of precip type are possible. It's going to depend on the timing because I think we get a shot of cold air Christmas. But does the storm form as the cold is coming in, or as the cold is leaving? That would make it a wintry precip to rain deal or a rain ending as flakes deal. I think something like that looks good at this very early stage.

Then I think around NYE or NYD we'll have another system to deal with that may bring the kitchen sink again as (I hope) a colder pattern with some staying power begins to take shape. We'll need to deal with our current rain maker then Christmas timeframe first before we even get to New Year's lol Point is... an active pattern as we expected is occurring. Just hope we can muster up a little something for December, but the chances are low to be completely honest. I like our higher chances in January.

tron777 wrote: ↑Thu Dec 16, 2021 2:09 pm Then I think around NYE or NYD we'll have another system to deal with that may bring the kitchen sink again as (I hope) a colder pattern with some staying power begins to take shape. We'll need to deal with our current rain maker then Christmas timeframe first before we even get to New Year's lol Point is... an active pattern as we expected is occurring. Just hope we can muster up a little something for December, but the chances are low to be completely honest. I like our higher chances in January.

I agree and going to be a 2 week period where both rain and snow are possible and becomes the old timing issues. The only reason I feel somewhat better in terms of winter weather is tons and I means tons of cold and snow in Canada and Alaska. The snow pack on this side of the planet no doubt is outdoing folks in Siberia.

Models are all over the place at 500mb over the next 10-14 days , none of it especially good for the OV as has been eluded too . EU at Day ten has an awesome over the top block .....for the GOA and just off the west coast. Mods are having quite the conundrum of with the NPac block and the ensuing dump of Arctic air, somewhere in the west.

tpweather wrote: ↑Thu Dec 16, 2021 2:17 pm

tron777 wrote: ↑Thu Dec 16, 2021 2:09 pm Then I think around NYE or NYD we'll have another system to deal with that may bring the kitchen sink again as (I hope) a colder pattern with some staying power begins to take shape. We'll need to deal with our current rain maker then Christmas timeframe first before we even get to New Year's lol Point is... an active pattern as we expected is occurring. Just hope we can muster up a little something for December, but the chances are low to be completely honest. I like our higher chances in January.

I agree and going to be a 2 week period where both rain and snow are possible and becomes the old timing issues. The only reason I feel somewhat better in terms of winter weather is tons and I means tons of cold and snow in Canada and Alaska. The snow pack on this side of the planet no doubt is outdoing folks in Siberia.

Def agree with you Tim in terms of cold air and snow pack. No doubt about it. Unlike last year, the cold and snowpack have built up nicely in Nov and Dec so we do have plenty of cold air to work with. The problem is getting it in here with a shortwave timed correctly. It's there just need the right 500 MB pattern to deliver it. Today's GEFS AO forecast has quite the spread. The cold air looks to be on the move. You've got 2 members putting the AO back positive but everybody else is weakly to deeply negative in that range so I like the odds there. For the NAO, you've also got quite the spread from weakly positive to negative so I guess an avg would be neutral. The point being with the Ensemble members showing such a spread in those teleconnections, there is a lot of uncertainty for the last week of Dec going into January. Much can change since today is only 12/16.

For the MJO per the Aussies, we're back in phase 6. It's doing the loop from 7 back to 6 then we'll eventually get back into 7 again. This is because of the West PAC typhoon action that Bgoney and I have discussed. I looked at Kyle MacRitchie's experimental MJO model today and it's got it in Phase 6 as well for today. Phase 7 by around 12/20 or so (estimating here) then Phase 8 as we approach NYE. Phase 1 by 1/10. So again if correct, I like our chances come January if this happens to be correct of course.

EDIT: This post really ties in to what Bgoney just posted. Probably why the model chaos is occurring.

A steady light rain now... we're on the board... 0.01"

Bgoney wrote: ↑Thu Dec 16, 2021 2:20 pm Models are all over the place at 500mb over the next 10-14 days , none of it especially good for the OV as has been eluded too . EU at Day ten has an awesome over the top block .....for the GOA and just off the west coast. Mods are having quite the conundrum of with the NPac block and the ensuing dump of Arctic air, somewhere in the west.

I agree Bgoney and no this is not the perfect pattern for snow but I believe the biggest part I take away from the pattern is when a system can be far enough north either in Alaska of southern Canada it can grab some of the cold air and deliver it further south especially if the AO becomes more negative. That is why I believe the next two weeks are just a mix of possible rain or snow or both with certain storms. Sure we can get some snow with the pattern and with the added cold that helps but if we get the south central ridge does this put a hamper on moisture from the GOM. The GOM was well above normal before the storm hit last week and my guess the water temps are still well above normal because cold fronts have been few and far between for that area of the country. Those warm waters also had an influence on the wicked weather of last week as well.

tron777 wrote: ↑Thu Dec 16, 2021 3:01 pm A steady light rain now... we're on the board... 0.01"

I was out in the Burlington area this morning to see my mom and had a few 2 minute downpours but that was about it at the time.

tpweather wrote: ↑Thu Dec 16, 2021 3:04 pm

tron777 wrote: ↑Thu Dec 16, 2021 3:01 pm A steady light rain now... we're on the board... 0.01"

I was out in the Burlington area this morning to see my mom and had a few 2 minute downpours but that was about it at the time.

Yeah I had some sprinkle activity earlier, but the steadier rains are here for the next few hours as the cold front works its way thru.

12z EPS is pretty much the same. A nice NAO block over Greenland but the Pacific needs some help. The EPO ridge is too far west so the core of the cold will be over Western Canada and the Western CONUS. -PNA rules... We can get snow with this, and kitchen sink systems but a bigger snow event is going to be tough until we see some more changes esp in the Pacific.

Wow... MN did have a confirmed TOR for the first time ever in December. Wisc did as well, and it was an EF2. That's crazy!!!

A nice steady rain coming down and hitting the windows with the wind. No doubt much cooler later tonight and through most of the weekend. Could see a little spike overnight Friday but it will be a short-lived and many folks will stay in the low 40's.

tron777 wrote: ↑Thu Dec 16, 2021 3:17 pm 12z EPS is pretty much the same. A nice NAO block over Greenland but the Pacific needs some help. The EPO ridge is too far west so the core of the cold will be over Western Canada and the Western CONUS. -PNA rules... We can get snow with this, and kitchen sink systems but a bigger snow event is going to be tough until we see some more changes esp in the Pacific.

End of the EPS run for a visual:

tron777 wrote: ↑Thu Dec 16, 2021 3:33 pm

tron777 wrote: ↑Thu Dec 16, 2021 3:17 pm 12z EPS is pretty much the same. A nice NAO block over Greenland but the Pacific needs some help. The EPO ridge is too far west so the core of the cold will be over Western Canada and the Western CONUS. -PNA rules... We can get snow with this, and kitchen sink systems but a bigger snow event is going to be tough until we see some more changes esp in the Pacific.

End of the EPS run for a visual:


EPS.png

A great visual Les. You can see by this that much of the coldest air is on this side of the globe so that is where I am seeing some hope for cold air working its away into our area.

Just want to add to the post above. We talk about cross-polar which can bring us some of the coldest air each winter. That is usually true as Siberia is normally the coldest area by far. Yes they are still cold but all we need to do is tap the air in the western part of Canada this season and really some of the coldest periods is when we tap the Yukon area which is downright chilly and tons of snow on the ground.

tpweather wrote: ↑Thu Dec 16, 2021 3:44 pm

tron777 wrote: ↑Thu Dec 16, 2021 3:33 pm

tron777 wrote: ↑Thu Dec 16, 2021 3:17 pm 12z EPS is pretty much the same. A nice NAO block over Greenland but the Pacific needs some help. The EPO ridge is too far west so the core of the cold will be over Western Canada and the Western CONUS. -PNA rules... We can get snow with this, and kitchen sink systems but a bigger snow event is going to be tough until we see some more changes esp in the Pacific.

End of the EPS run for a visual:


EPS.png

A great visual Les. You can see by this that much of the coldest air is on this side of the globe so that is where I am seeing some hope for cold air working its away into our area.

We need some help on the Pacific side. Either need the EPO ridge to slide to the East some or that really deep -PNA to relax. We'll see what happens but Phase 7 and esp 8 for January in a La Nina show the PNA becoming weakly positive in 7 and very positive in 8. So again, it's the same thing we've been hammering home. Need the MJO to leave the West Pac and move over to the Western Hemisphere and Africa.

Phase 7 - La Nina in January:


Phase 8 - La Nina in January:

My high was 62 before the rain came. 55 now with 0.15" in the books. Still seeing light rain attm. Same story at CVG with 0.19" there. 0.19" also at the Boone Co mesonet site. Rian should be done in that 6-7pm window for the Metro. A little later out East, a little earlier to the West. Temps will drop into the 30s behind the front for tonight. A chilly day tomorrow in the 40s with rain coming back in in the afternoon ahead of the front lifting back north as a warm front. Rain should be heavy Fri night into Sat morning with rising temps. We should rise into the U50s to near 60 Sat before the cold front finally clears the area with falling Temps Sat afternoon. Cold, but sunny in the 30s for your Sunday.

Event total for me from Thurs is .30"

DAY set a new record high and low Wed of 63 and 49.

Currently 50 here in G'ville and progged for around 27 Fri morning.

0.24” here