Absolute Vorticity

Welcome to December! It is the first month of Met Winter and the last month of 2022! Blocking is looking promising in the EPO and NAO domains. I have been touting a pattern change to winter sometime in the 12/10 - 12/15 time frame.





As you can see from the above.... the EPS is looking promising in the Day 10-15 range. A close up look is below.


We are of course watching the MJO, currently in Phase 7, to see if we can get 8 or not out of it. We shall see. Right now, the prospects of a slow moving frontal boundary producing rain in Week 1/ Hoping the cold can seep southward in week 2 for more ice and snow chances across the area to set us up by week 3 for snow and cold! At this time, Dec 7 - 9th is probably the first legit attempt at wintry precip that I see. The cold may or may not seep far enough south. The SE ridge produced from the Nina forcing is going to fight the -EPO / -NAO / -AO blocking. The bottom line.... our pattern will be active as the battle unfolds.

tron777 wrote: ↑Sat Nov 26, 2022 6:33 pm Welcome to December! It is the first month of Met Winter and the last month of 2022! Blocking is looking promising in the EPO and NAO domains. I have been touting a pattern change to winter sometime in the 12/10 - 12/15 time frame.





As you can see from the above.... the EPS is looking promising in the Day 10-15 range. A close up look is below.


ecmwf-ensemble-avg-nhemi-z500_anom-0587200.png


We are of course watching the MJO, currently in Phase 7, to see if we can get 8 or not out of it. We shall see. Right now, the prospects of a slow moving frontal boundary producing rain in Week 1/ Hoping the cold can seep southward in week 2 for more ice and snow chances across the area to set us up by week 3 for snow and cold! At this time, Dec 7 - 9th is probably the first legit attempt at wintry precip that I see. The cold may or may not seep far enough south. The SE ridge produced from the Nina forcing is going to fight the -EPO / -NAO / -AO blocking. The bottom line.... our pattern will be active s the battle unfolds.

I'll take our chances with this pattern, especially compared to the last several Decembers. The opportunity for wintry weather is definitely there for the Midwest. As usual, it is yet to be determined if AV land is on the colder or warmer side of the battle. The increase in precipitation that looks to be coming is what has my curiosity peaked. It looks as though the precipitation will be there, whether it is rain or snow or some combination of both in AV land is yet to be seen.

I'll be keeping tabs on 12/7 and again for 12/12-12/15.

dce wrote: ↑Sat Nov 26, 2022 6:55 pm I'll take our chances with this pattern, especially compared to the last several Decembers. The opportunity for wintry weather is definitely there for the Midwest. As usual, it is yet to be determined if AV land is on the colder or warmer side of the battle. The increase in precipitation that looks to be coming is what has my curiosity peaked. It looks as though the precipitation will be there, whether it is rain or snow or some combination of both in AV land is yet to be seen.

Me too, Doug! It'll be a gradient pattern with waves of overrunning precip along a stalled out frontal boundary Probably rain Week 1. We'll see come Weeks 2 and 3.

Going by satellite, MJO looks to be weakening rather rapidly along the 7/8 boundaries

Bgoney wrote: ↑Sun Nov 27, 2022 8:14 am Going by satellite, MJO looks to be weakening rather rapidly along the 7/8 boundaries

As of 11/25, officially, the MJO is in 7 headed towards 8. It is about halfway there. So fast forward to today and the satellite presentation makes sense as the wave encounters those cooler SST's that you have mentioned numerous times. So with that stated, the look we may see should this hold, it the cold trying to push in from the NW, and the SE ridge attempts to fight it off. You can bet we'll be right in the thick of things. Probably rain to start off with then as it gets colder, more ice and snow chances should come by Weeks 2 or 3. I still think that is a good call at this time.

12Z GFS showing a big 1057 MB High in Western Canada inside of 10 days now (Day 9). That brings us to that first legit chance again around Dec 7-9th time period. This is a little ahead of my pattern change timing but one of those keep one eye open type of systems should the cold press in far enough. We of course do not yet know how strong the -PNA will be controlling the pattern by then. The SE ridge could still be too strong. The cold could overwhelm too. So we need a good balance of the two of course to cash in with this set up.

tron777 wrote: ↑Sun Nov 27, 2022 11:44 am 12Z GFS showing a big 1057 MB High in Western Canada inside of 10 days now (Day 9). That brings us to that first legit chance again around Dec 7-9th time period. This is a little ahead of my pattern change timing but one of those keep one eye open type of systems should the cold press in far enough. We of course do not yet know how strong the -PNA will be controlling the pattern by then. The SE ridge could still be too strong. The cold could overwhelm too. So we need a good balance of the two of course to cash in with this set up.

Will be keeping tabs on the 7th time frame e.g. on whether or not my folks and I may have to reserve a couple of rooms at the Fairfield Inn & Suites by Marriott Cincinnati Uptown/University Area.

I think our first system for December will feature a frontal boundary that stalls out bringing rain for a day or two. Thinking this event begins around the 4th.

Good Evening and some wonderful posts above concerning December. The -pna and it is really negative is a concern early in the month but hopefully just to get it into neutral will help in getting the cold to drift further and further south. Though the coldest air is in Siberia its not where we don't have a possible highway later in December to get a cross polar flow. Northern Canada still cold so no problems there plus we are getting into the time of year where there is no sun in the polar regions so it should continue to get colder the next few weeks. How long does it take and still going the 3rd week of December before we are really into the pattern change but again you can always get a rain to snow on the back end but that usually does not pan out well in terms of snow and just gets us cold for a day or two like this Wednesday. Many times we need the warmth first to get colder later and this looks to happen the first two weeks of December.

Will believe the pattern change when we are a couple days away. past history shows long range was always premature or never happening. i think the first 2 weeks of December will be average temps and more wet then white. i am more hopeful for possible colder and snowier the last 2 weeks of the year though

airwolf76 wrote: ↑Mon Nov 28, 2022 1:22 am Will believe the pattern change when we are a couple days away. past history shows long range was always premature or never happening. i think the first 2 weeks of December will be average temps and more wet then white. i am more hopeful for possible colder and snowier the last 2 weeks of the year though

I'm sticking with my 12/10-12/15 call, but can adjust if the data suggests to do so. Right now for the first week to 10 days, I like stalled fronts bringing us mainly rain but the cold and snow is not far away. We need the cold to seep in just enough for snow. Too much of a good thing and you're left with a cold and dry pattern. Such a delicate balance for wintry weather in this area for sure. MJO is on the boarder of phases 7/8 as of 11/26 so we'll see how much further it can get before it dies out.

tron777 wrote: ↑Mon Nov 28, 2022 7:52 am

airwolf76 wrote: ↑Mon Nov 28, 2022 1:22 am Will believe the pattern change when we are a couple days away. past history shows long range was always premature or never happening. i think the first 2 weeks of December will be average temps and more wet then white. i am more hopeful for possible colder and snowier the last 2 weeks of the year though

I'm sticking with my 12/10-12/15 call, but can adjust if the data suggests to do so. Right now for the first week to 10 days, I like stalled fronts bringing us mainly rain but the cold and snow is not far away. We need the cold to seep in just enough for snow. Too much of a good thing and you're left with a cold and dry pattern. Such a delicate balance for wintry weather in this area for sure. MJO is on the boarder of phases 7/8 as of 11/26 so we'll see how much further it can get before it dies out.

Yeah we will see bruh just not sold on any major wholesale changes yet. i am still torn on December being good or another average ( dud ) honestly i have reasons based on what has happened so far to go both ways. right now i am leaning more for a upper midwest, new england and parts of ohio valley to see some descent cold and snow this winter.

Great video by Brian and it may be in the November discussion. He talks about everything we have been seeing for weeks and the big word of the day is patience. Going to be a pattern flip but as we know that takes time and really I would rather have a gradual change then one quick change because what I have noticed in the past is a quick change looks good early but tends to be rather short in nature. A more gradual change usually keeps the new pattern going somewhat longer. So yes we can get some winter precip in here before mid-month but usually a rain to snow type of storm. Do I believe there will be a bigger storm in the next two weeks and no doubt since the cold should be heading south and east and we have a nice heat pump really over the Yucatan that is trying move northward. We don't always get this pattern as many southeast ridges have the heat further east and south of the Bahamas that moves in. So Les your time period of Dec10-15th is possible but I do believe we see some winter weather then but I still believe starting the 3rd week which would be the 16 is my timeline. As usual the actual changeover is probably somewhere in the middle but we are both looking at the same outcome.

tpweather wrote: ↑Mon Nov 28, 2022 10:47 am Great video by Brian and it may be in the November discussion. He talks about everything we have been seeing for weeks and the big word of the day is patience. Going to be a pattern flip but as we know that takes time and really I would rather have a gradual change then one quick change because what I have noticed in the past is a quick change looks good early but tends to be rather short in nature. A more gradual change usually keeps the new pattern going somewhat longer. So yes we can get some winter precip in here before mid-month but usually a rain to snow type of storm. Do I believe there will be a bigger storm in the next two weeks and no doubt since the cold should be heading south and east and we have a nice heat pump really over the Yucatan that is trying move northward. We don't always get this pattern as many southeast ridges have the heat further east and south of the Bahamas that moves in. So Les your time period of Dec10-15th is possible but I do believe we see some winter weather then but I still believe starting the 3rd week which would be the 16 is my timeline. As usual the actual changeover is probably somewhere in the middle but we are both looking at the same outcome.

When I first stated 12/10-12/15 for the timing, I was seeing cold shots back then as early as 12/5. I knew that would be too early and models have backed off. Could I still be too early? Sure. But I will stick with this for now. Once we get to 12/10 I will have made this call a month pout. If I am only off by 1 week, I'll gladly take that as a win.

airwolf76 wrote: ↑Mon Nov 28, 2022 10:29 am

tron777 wrote: ↑Mon Nov 28, 2022 7:52 am

airwolf76 wrote: ↑Mon Nov 28, 2022 1:22 am Will believe the pattern change when we are a couple days away. past history shows long range was always premature or never happening. i think the first 2 weeks of December will be average temps and more wet then white. i am more hopeful for possible colder and snowier the last 2 weeks of the year though

I'm sticking with my 12/10-12/15 call, but can adjust if the data suggests to do so. Right now for the first week to 10 days, I like stalled fronts bringing us mainly rain but the cold and snow is not far away. We need the cold to seep in just enough for snow. Too much of a good thing and you're left with a cold and dry pattern. Such a delicate balance for wintry weather in this area for sure. MJO is on the boarder of phases 7/8 as of 11/26 so we'll see how much further it can get before it dies out.

Yeah we will see bruh just not sold on any major wholesale changes yet. i am still torn on December being good or another average ( dud ) honestly i have reasons based on what has happened so far to go both ways. right now i am leaning more for a upper midwest, new england and parts of ohio valley to see some descent cold and snow this winter.

There is going to be a really interesting battle shaping up esp by mid December. Just hope our locations are in the correct spot to receive.

12Z GEFS has a decent signal for wintry weather for the OV in that 12/8 onwards timeframe. The powerful -NAO continues to show up on all guidance moving forward. We shall see if we benefit or not from it once the pattern gets established over the next week plus.

The Nao that Les has been talking about for weeks is really coming up off the charts and especially for early winter as this feature tends to be more negative once we head into later January and February and another reason the northeast USA tends to have the worst of the winter during the latter half of winter. So normally with a negative Nao it slows the patterns where storms can get more organized over the USA. No problem there but like many things in life something that is too good to be true it usually ends up that way. With the Nao being that negative it affects the weather towards the tropical regions and like I mentioned before getting a southeast ridge where its strongest south and east of the Bahamas is normal. Well this pushes that high further west into the Yucatan and here is the problem we are having and why I believe its going to take a little longer for us locally to really get into a winter pattern. This strong high is not letting some of the cold fronts over the next couple of weeks dip to far south in the south central part of the USA. Yes I believe it will breakdown and part of that is when the Nao starts to head more towards neutral and not so negative the strong high over the Yucatan can move further east into a more lets say normal position. If this happens I also expect the STJ to work its way into Mexico and near the gulf coast of the USA.

So yes we will have some cold weather behind these fronts over the next few weeks and I believe the further in time the cold air seeps further and further south but at first we may end up just with rain to light snow and then cold dry air. So about 95p/c sure cold weather is on tap for us but more of a 50/50 shot of a decent pattern for snow. Will this be just a one time shot of a decent negative Nao and I don't believe so but usually in our area we want a slightly negative Nao and not one to negative and of course very seldom does a positive one work for us.

This is why when you make a general forecast for the winter months you try and figure what pattern seems most likely. We are getting the players on the field at the moment and some are sort of not in their normal position so then you go back to the drawing board and work with what is on the field.

Great post Tim! I think we are both on the same page with regards to the cold seeping in versus slamming in here. It's a matter of when does the cold seep in and do we have a storm system timed correctly when it does? We shall know that answer in the next couple of weeks.

12Z EPS is advertising a major west based -AO / -NAO block with a trough centered near the East Coast from around mid month on. If correct, that would be Nor-Easter city for Charles... but this is a 5 day mean or an avg so how we get to this look, maybe we can cash in along the way?

tron777 wrote: ↑Mon Nov 28, 2022 3:29 pm 12Z EPS is advertising a major west based -AO / -NAO block with a trough centered near the East Coast from around mid month on. If correct, that would be Nor-Easter city for Charles... but this is a 5 day mean or an avg so how we get to this look, maybe we can cash in along the way?


EPS.png

No doubt that would be a Nor-Easter pattern but sometimes these troughs will deepen further southwest and that is what we would love to see. Again just a 5 day average and no doubt it looks like a major -AO /-NAO. Way to early but anytime you have this kind of cold around at least you are getting a chance to see snow

Hey Tim... I have no idea what'll happen and neither does anyone else. However, I can't tell you how many times I have read on the internet today with Pro Met's and Hobbyists alike, touting how much the December pattern favors a match to 2010-2011. Dec 2010 was the snowiest on record at CVG with 16.6" falling for the month. It was also the 8th coldest Dec on record as well. January 2011 also had blocking episodes and some fun still continued into January as well. So we'll see I guess. No two winters are alike. But I can say with one thing... having a -EPO and a -NAO in combination with a -PNA.... someone is going to get stomped with wintry weather. That is a great teleconnection combo and one that I really like seeing. With all good looking patterns, sometimes they work, sometimes they don't.

tron777 wrote: ↑Mon Nov 28, 2022 3:55 pm Hey Tim... I have no idea what'll happen and neither does anyone else. However, I can't tell you how many times I have read on the internet today with Pro Met's and Hobbyists alike, touting how much the December pattern favors a match to 2010-2011. Dec 2010 was the snowiest on record at CVG with 16.6" falling for the month. It was also the 8th coldest Dec on record as well. January 2011 also had blocking episodes and some fun still continued into January as well. So we'll see I guess. No two winters are alike. But I can say with one thing... having a -EPO and a -NAO in combination with a -PNA.... someone is going to get stomped with wintry weather. That is a great teleconnection combo and one that I really like seeing. With all good looking patterns, sometimes they work, sometimes they don't.

Les I agree 100p/c and to me I love when December is the month with this set up. So many in the past couple of decades have been bad if you are a winter lover like we are and hopefully this is the year we get hit hard. No doubt the cold is coming and if we can get a good snow pack going over the northern half of the country then when the pattern switches then it takes somewhat longer to melt that snow and you can get an extra 7-10 days out of a pattern for that reason alone.

tpweather wrote: ↑Mon Nov 28, 2022 4:02 pm

tron777 wrote: ↑Mon Nov 28, 2022 3:55 pm Hey Tim... I have no idea what'll happen and neither does anyone else. However, I can't tell you how many times I have read on the internet today with Pro Met's and Hobbyists alike, touting how much the December pattern favors a match to 2010-2011. Dec 2010 was the snowiest on record at CVG with 16.6" falling for the month. It was also the 8th coldest Dec on record as well. January 2011 also had blocking episodes and some fun still continued into January as well. So we'll see I guess. No two winters are alike. But I can say with one thing... having a -EPO and a -NAO in combination with a -PNA.... someone is going to get stomped with wintry weather. That is a great teleconnection combo and one that I really like seeing. With all good looking patterns, sometimes they work, sometimes they don't.

Les I agree 100p/c and to me I love when December is the month with this set up. So many in the past couple of decades have been bad if you are a winter lover like we are and hopefully this is the year we get hit hard. No doubt the cold is coming and if we can get a good snow pack going over the northern half of the country then when the pattern switches then it takes somewhat longer to melt that snow and you can get an extra 7-10 days out of a pattern for that reason alone.

When you see blocking in December like what is coming... you typically will see another episode of blocking in early January before the typical "January Thaw" sets in. So with this stated, we should have a good 5-6 week period of potential (talking mid Dec thru mid Jan here). Also seeing more MJO guidance getting it into 8 before it dies as well. Also very important like what happened back in November with the first cold snap. I honestly have no complaints right now and I like where we are headed.

What’s everyone’s general opinion on YouTuber Ryan Hall?