December 2021 Weather Discussion

[tpweather]

12Z GEFS is an improvement if you look at the North American View on Tropical Tidbits and use 500 MB anomalies. If you look at the entire run, you can see the -EPO and -NAO develop. -NAO looks very nice but the -EPO is a little too far west still. Pretty much an Aleutian Ridge. But you can see the cold is over most of Canada and into the Lakes and NE states. The SE ridge retrogrades towards Texas. This is not a classic wintry pattern for us but it is an improvement over what is going on right now. This would be a gradient pattern for the OV with all modes of precip possible depending on where the baroclinic boundary sets up and how far south the cold air can get with each passing wave of low pressure. Again not ideal but not a shut out pattern either IMO.

I agree with this post. Not perfect but it does bring in chances of winter type precip. Very cold in northern Canada especially the northwest terr. This is usually the place we want to get the supply of cold air from. Love to see more snow cover to the northwest in the next five days which makes it easier to transport southward. I just hope when the nao goes negative it does not bomb southward too much. That can lead to cold and dry conditions which I have no desire for during the winter though it beats warm and wet I guess.

[Bgoney]

12Z GEFS is an improvement if you look at the North American View on Tropical Tidbits and use 500 MB anomalies. If you look at the entire run, you can see the -EPO and -NAO develop. -NAO looks very nice but the -EPO is a little too far west still. Pretty much an Aleutian Ridge. But you can see the cold is over most of Canada and into the Lakes and NE states. The SE ridge retrogrades towards Texas. This is not a classic wintry pattern for us but it is an improvement over what is going on right now. This would be a gradient pattern for the OV with all modes of precip possible depending on where the baroclinic boundary sets up and how far south the cold air can get with each passing wave of low pressure. Again not ideal but not a shut out pattern either IMO.

I think we do get a - NAO, but I think getting the EPO domain to hook up with it is asking a lot at this stage . It needs to make quite a trek from its current position and to hold that position for more than 2 or3 days. 50/50 chance

[tron777]

12Z GEFS is an improvement if you look at the North American View on Tropical Tidbits and use 500 MB anomalies. If you look at the entire run, you can see the -EPO and -NAO develop. -NAO looks very nice but the -EPO is a little too far west still. Pretty much an Aleutian Ridge. But you can see the cold is over most of Canada and into the Lakes and NE states. The SE ridge retrogrades towards Texas. This is not a classic wintry pattern for us but it is an improvement over what is going on right now. This would be a gradient pattern for the OV with all modes of precip possible depending on where the baroclinic boundary sets up and how far south the cold air can get with each passing wave of low pressure. Again not ideal but not a shut out pattern either IMO.

I agree with this post. Not perfect but it does bring in chances of winter type precip. Very cold in northern Canada especially the northwest terr. This is usually the place we want to get the supply of cold air from. Love to see more snow cover to the northwest in the next five days which makes it easier to transport southward. I just hope when the nao goes negative it does not bomb southward too much. That can lead to cold and dry conditions which I have no desire for during the winter though it beats warm and wet I guess.

I think it'll be tough to get a cold and dry pattern with the -PNA.

[tpweather]

No doubt patterns have been very stubborn this year and many many different reasons. Over the past day or two models are hinting at changes and when that happens we usually will see a bigger change within a few days. Like Les mentioned earlier about the mjo there is a lag with info and that is also true with the models and they will lag behind a pattern change as well. That is why during the winter we see these models flip on a dime though they tend to throw out a few hints before hand.Over the next week those changes look to happen. One example is Fairbanks,Alaska is showing -40 at this moment. By this time next week it could be near 30 so we are talking about 70 degree rise in a week. When this happens there is going to be movement in the pattern. We had the last big storm in Alaska I guess about 10 days ago but that went much further to the northwest and only enhanced the pattern at the time. This go around they will get more snow in the next 5 days but a big warming trend for them will no doubt send the cold further east and south but how far will be determined by how quickly the blocking is to the north. Also when we have some pieces of energy that will affect Alaska over the next five days these will also head east and south. These pieces of energy will be able to pick up some cold air on the way and though the snow pack is not great just to our northwest these pieces of energy should help in forming a much broader area of snow in the northern plains and upper midwest.

I am not exactly what the chances of a white Christmas is for us locally but I believe its like 15p/c or so to have 1 inch on the ground at 7am Christmas morning. Looking at the pattern and how systems may move through here over the next 10 days or so I would put that at around 20p/c chance which is still not great 10 days away but those chances are probably similar to those you see most seasons.

[tron777]

12Z GEFS is an improvement if you look at the North American View on Tropical Tidbits and use 500 MB anomalies. If you look at the entire run, you can see the -EPO and -NAO develop. -NAO looks very nice but the -EPO is a little too far west still. Pretty much an Aleutian Ridge. But you can see the cold is over most of Canada and into the Lakes and NE states. The SE ridge retrogrades towards Texas. This is not a classic wintry pattern for us but it is an improvement over what is going on right now. This would be a gradient pattern for the OV with all modes of precip possible depending on where the baroclinic boundary sets up and how far south the cold air can get with each passing wave of low pressure. Again not ideal but not a shut out pattern either IMO.

I think we do get a - NAO, but I think getting the EPO domain to hook up with it is asking a lot at this stage . It needs to make quite a trek from its current position and to hold that position for more than 2 or3 days. 50/50 chance

It is asking for a lot. No question. I like the -NAO's position but the -EPO is not in an ideal spot as we both have noted. We need it further eastward mote into Alaska and Western Canada to have a shot at both ridges hooking up. I see no signs of that yet at the present time.

[tpweather]

12Z GEFS is an improvement if you look at the North American View on Tropical Tidbits and use 500 MB anomalies. If you look at the entire run, you can see the -EPO and -NAO develop. -NAO looks very nice but the -EPO is a little too far west still. Pretty much an Aleutian Ridge. But you can see the cold is over most of Canada and into the Lakes and NE states. The SE ridge retrogrades towards Texas. This is not a classic wintry pattern for us but it is an improvement over what is going on right now. This would be a gradient pattern for the OV with all modes of precip possible depending on where the baroclinic boundary sets up and how far south the cold air can get with each passing wave of low pressure. Again not ideal but not a shut out pattern either IMO.

I agree with this post. Not perfect but it does bring in chances of winter type precip. Very cold in northern Canada especially the northwest terr. This is usually the place we want to get the supply of cold air from. Love to see more snow cover to the northwest in the next five days which makes it easier to transport southward. I just hope when the nao goes negative it does not bomb southward too much. That can lead to cold and dry conditions which I have no desire for during the winter though it beats warm and wet I guess.

I think it'll be tough to get a cold and dry pattern with the -PNA.

Les you bring up a good point and what I have seen from this season is still the southwest ridge has been really strong and was part of the equation for the severe outbreak this past weekend. Very dry in the southwest and south central areas even though the STJ has awaken from the dead it still has been pushed further east then I like to see in the winter. If the nao goes too negative which does help the eastern seaboard that sometimes can put us in that cold and dry area for a period of time. I believe we need to see how Mother Nature realigns everything over the next few weeks as we know all the knowledge in the world and she will make a fool of us quite often.

[MVWxObserver]

Two of my wx friends from FB, Matt from Newton, IA and David from Topeka, KS, are both under a High Wind Warning for several hours on Wed for gusts of 60 to 70 mph! Prayers / thoughts with them and scores of others under wind alerts for tomorrow.

Currently 54 here in G'ville.

[tron777]

12Z EPS thru Day 10 is doing the same thing. SE ridge goes to Texas. Still have that -PNA to deal with and the -EPO is too far West. Nice -NAO though. It's not an overly cold pattern and you'd need a little luck for snow, but in our area you usually need some luck anyway lol

[tpweather]

Usually when you have the QBO in an easterly phase blocking is usually stronger. We saw this in the early fall season but in recent weeks that has gone away. Hopefully if this returns to a more normal pattern in regards to the QBO then plenty of blocking should happen over the next 6 weeks or so. Yes we need the correct blocking but sometimes we get a -NAO or -AO but the cold air is either stale or not available. This is not the case as the cold is there but its widespread over much of Alaska and western and central Canada. Just need the highway to bring it southward and late Dec and early Jan is usually a great time if you want a long lasting cold spell. We will see of course but the old delayed but not denied school of thought is there but sometimes if that wait is too long then we miss the train.

[tron777]

Usually when you have the QBO in an easterly phase blocking is usually stronger. We saw this in the early fall season but in recent weeks that has gone away. Hopefully if this returns to a more normal pattern in regards to the QBO then plenty of blocking should happen over the next 6 weeks or so. Yes we need the correct blocking but sometimes we get a -NAO or -AO but the cold air is either stale or not available. This is not the case as the cold is there but its widespread over much of Alaska and western and central Canada. Just need the highway to bring it southward and late Dec and early Jan is usually a great time if you want a long lasting cold spell. We will see of course but the old delayed but not denied school of thought is there but sometimes if that wait is too long then we miss the train.

QBO is Easterly from 50 MB all the way down thru 30 MB and it continues to fall. I'm still curious as to why it is not driving the pattern yet. La Nina perhaps is over trumping it? I'm not entirely sure to be quite honest. Maybe the QBO will have a little more forcing into the pattern to keep it around longer once it comes. Still... the MJO has been a major pattern driver as well and it's been a pain in our butts, at least for now.

[Bgoney]

Usually when you have the QBO in an easterly phase blocking is usually stronger. We saw this in the early fall season but in recent weeks that has gone away. Hopefully if this returns to a more normal pattern in regards to the QBO then plenty of blocking should happen over the next 6 weeks or so. Yes we need the correct blocking but sometimes we get a -NAO or -AO but the cold air is either stale or not available. This is not the case as the cold is there but its widespread over much of Alaska and western and central Canada. Just need the highway to bring it southward and late Dec and early Jan is usually a great time if you want a long lasting cold spell. We will see of course but the old delayed but not denied school of thought is there but sometimes if that wait is too long then we miss the train.

QBO is Easterly from 50 MB all the way down thru 30 MB and it continues to fall. I'm still curious as to why it is not driving the pattern yet. La Nina perhaps is over trumping it? I'm not entirely sure to be quite honest. Maybe the QBO will have a little more forcing into the pattern to keep it around longer once it comes. Still... the MJO has been a major pattern driver as well and it's been a pain in our butts, at least for now.

Sure looks like its LaNina. We talked about this weeks ago, that the LaNina may be weak according to its Index, but Atmospherically it is coupled, and effects are a notch above weak ( see SOI). Which affected MJO through Nov and beginning of December

[tpweather]

Usually when you have the QBO in an easterly phase blocking is usually stronger. We saw this in the early fall season but in recent weeks that has gone away. Hopefully if this returns to a more normal pattern in regards to the QBO then plenty of blocking should happen over the next 6 weeks or so. Yes we need the correct blocking but sometimes we get a -NAO or -AO but the cold air is either stale or not available. This is not the case as the cold is there but its widespread over much of Alaska and western and central Canada. Just need the highway to bring it southward and late Dec and early Jan is usually a great time if you want a long lasting cold spell. We will see of course but the old delayed but not denied school of thought is there but sometimes if that wait is too long then we miss the train.

QBO is Easterly from 50 MB all the way down thru 30 MB and it continues to fall. I'm still curious as to why it is not driving the pattern yet. La Nina perhaps is over trumping it? I'm not entirely sure to be quite honest. Maybe the QBO will have a little more forcing into the pattern to keep it around longer once it comes. Still... the MJO has been a major pattern driver as well and it's been a pain in our butts, at least for now.

Sure looks like its LaNina. We talked about this weeks ago, that the LaNina may be weak according to its Index, but Atmospherically it is coupled, and effects are a notch above weak ( see SOI). Which affected MJO through Nov and beginning of December

Great Post and no doubt we have talked about this for many weeks. There are going to be ups and downs with these events and though with this one it will go down weak many times it can be coupled with other events and produce some wicked weather. We look back at some of the wicked winters in the 70's and they were weak El Nino's when the final tally was done but I bet their were times that the El Nino was very strong but was also coupled with other events to produce wild weather. Each year we get more and more info to go on but still we are along ways from getting the long term forecasts nailed down. It may be hundred's of years before that happens and I will be really old by then.

[tpweather]

Very interesting how the models are starting to pick up on the blocking. Like Les mentioned to usually get a true arctic outbreak we love to see the blocking connect over the top. Saying that with these blocks In Greenland and Alaska that usually means a trough underneath that will have plenty of cold air. Where these set up is key but ones south of Greenland can rotate southwest in time which is possible. The one thing that I see though on the models is still the strong southwest ridge. That ridge if true will try and expand at times to bring some very warm air into the central part of the country. This happens most every year but this ridge is much stronger than normal. So what does mean to us locally and of course way to early to know for sure but I would say overriding events which could no doubt be in the form of frz/rain events which I hate to say the least. Time will tell but at least there is winter weather on the horizon and even some we can start to see of models that are not in fantasy land.

Concerning the rainfall later this week and again very complex in terms of total rainfall. Many folks will probably be in that .75-1 inch range but exactly where that front stalls we could see a few areas of low pressure move along that boundary and produce some very heavy rains in a narrow area southwest to northeast. Models have been pretty centered on this near us but we know these can switch 50 miles and you go from getting a forecast that showed 1 inch and instead you end up with 3 inches and vise versa.

[Bgoney]

EPS 850 temp anomalies , showing Tim's reference to the SW ridge

1725696416_14-kmEPSGlobalNorthAmerica850hPaTempAnom(5).gif.f03c49e46cb4527292ce2be09d345a63.gif

[tron777]

Off topic post before we get back to the weather and I just want folks to know that I created a poll in the AV Forum Updates section. The question is, do you all like that we broke out a separate thread for the last severe wx event or should we continue to put everything in the monthly threads as before? We only have 2 votes to the poll question right now and I'd like for everyone's feedback on this. The breaking out of a separate thread would include decent wintry events also in addition to severe wx threats. We are trying to make our forum a place to please as many of you as we can so vote and make your voice heard. Direct link to the poll:

https://www.absolutevorticity.com/viewt ... ?f=23&t=94

Thank you all now back to your regularly scheduled programming already in progress

[tron777]

Usually when you have the QBO in an easterly phase blocking is usually stronger. We saw this in the early fall season but in recent weeks that has gone away. Hopefully if this returns to a more normal pattern in regards to the QBO then plenty of blocking should happen over the next 6 weeks or so. Yes we need the correct blocking but sometimes we get a -NAO or -AO but the cold air is either stale or not available. This is not the case as the cold is there but its widespread over much of Alaska and western and central Canada. Just need the highway to bring it southward and late Dec and early Jan is usually a great time if you want a long lasting cold spell. We will see of course but the old delayed but not denied school of thought is there but sometimes if that wait is too long then we miss the train.

QBO is Easterly from 50 MB all the way down thru 30 MB and it continues to fall. I'm still curious as to why it is not driving the pattern yet. La Nina perhaps is over trumping it? I'm not entirely sure to be quite honest. Maybe the QBO will have a little more forcing into the pattern to keep it around longer once it comes. Still... the MJO has been a major pattern driver as well and it's been a pain in our butts, at least for now.

Sure looks like its LaNina. We talked about this weeks ago, that the LaNina may be weak according to its Index, but Atmospherically it is coupled, and effects are a notch above weak ( see SOI). Which affected MJO through Nov and beginning of December

Great Post and no doubt we have talked about this for many weeks. There are going to be ups and downs with these events and though with this one it will go down weak many times it can be coupled with other events and produce some wicked weather. We look back at some of the wicked winters in the 70's and they were weak El Nino's when the final tally was done but I bet their were times that the El Nino was very strong but was also coupled with other events to produce wild weather. Each year we get more and more info to go on but still we are along ways from getting the long term forecasts nailed down. It may be hundred's of years before that happens and I will be really old by then.

That's the thing. Great posts! Numbers are numbers and it's the atmospheric response is what counts. Too many people only key in on what an index says or the actual number. Myself included at times on being guilty of this. What we need to pay attention to is the actual atmospheric response. Great posts guys!!!

[tpweather]

Off topic post before we get back to the weather and I just want folks to know that I created a poll in the AV Forum Updates section. The question is, do you all like that we broke out a separate thread for the last severe wx event or should we continue to put everything in the monthly threads as before? We only have 2 votes to the poll question right now and I'd like for everyone's feedback on this. The breaking out of a separate thread would include decent wintry events also in addition to severe wx threats. We are trying to make our forum a place to please as many of you as we can so vote and make your voice heard. Direct link to the poll:

https://www.absolutevorticity.com/viewt ... ?f=23&t=94

Thank you all now back to your regularly scheduled programming already in progress

I thought it was the correct thing to do. We don't see many events where this is feasible but when such events happen I believe this is the best way to handle the forum.

[tron777]

Very interesting how the models are starting to pick up on the blocking. Like Les mentioned to usually get a true arctic outbreak we love to see the blocking connect over the top. Saying that with these blocks In Greenland and Alaska that usually means a trough underneath that will have plenty of cold air. Where these set up is key but ones south of Greenland can rotate southwest in time which is possible. The one thing that I see though on the models is still the strong southwest ridge. That ridge if true will try and expand at times to bring some very warm air into the central part of the country. This happens most every year but this ridge is much stronger than normal. So what does mean to us locally and of course way to early to know for sure but I would say overriding events which could no doubt be in the form of frz/rain events which I hate to say the least. Time will tell but at least there is winter weather on the horizon and even some we can start to see of models that are not in fantasy land.

Concerning the rainfall later this week and again very complex in terms of total rainfall. Many folks will probably be in that .75-1 inch range but exactly where that front stalls we could see a few areas of low pressure move along that boundary and produce some very heavy rains in a narrow area southwest to northeast. Models have been pretty centered on this near us but we know these can switch 50 miles and you go from getting a forecast that showed 1 inch and instead you end up with 3 inches and vise versa.

The PNA domain Tim is interesting this winter. You would expect a -PNA thanks to La Nina and that's what we're getting. Yet at the same time, the drought out West is terrible and that would argue for a +PNA at times. Just an interesting battle out West and with the SW Ridge as you mentioned.

[tron777]

Off topic post before we get back to the weather and I just want folks to know that I created a poll in the AV Forum Updates section. The question is, do you all like that we broke out a separate thread for the last severe wx event or should we continue to put everything in the monthly threads as before? We only have 2 votes to the poll question right now and I'd like for everyone's feedback on this. The breaking out of a separate thread would include decent wintry events also in addition to severe wx threats. We are trying to make our forum a place to please as many of you as we can so vote and make your voice heard. Direct link to the poll:

https://www.absolutevorticity.com/viewt ... ?f=23&t=94

Thank you all now back to your regularly scheduled programming already in progress

I thought it was the correct thing to do. We don't see many events where this is feasible but when such events happen I believe this is the best way to handle the forum.

Thank you Tim for the feedback. This is what I am looking for.

[tron777]

EPS 850 temp anomalies , showing Tim's reference to the SW ridge



1725696416_14-kmEPSGlobalNorthAmerica850hPaTempAnom(5).gif.f03c49e46cb4527292ce2be09d345a63.gif

You can also see by the animation the importance of what you and I have discussed. The EPO ridge is too far West.

[tron777]

12Z EPS 10-15 Day pattern:

EPS.png

Not terrible, it's workable but need some luck at the same time. Looks similar to the GEFS that I talked about earlier.

[Bgoney]

Nothing says December 2021 like a moderate risk in MN,IA,WI.

[Bgoney]

Still going with 1-2.5" for the Thursday/Friday/Saturday event centered on I-71 coridor. Not much rain Thursday when the front moves through with scattered showers, but when the low develops riding along the stalled boundary Friday night into Saturday the bulk of qpf will fall. Either side of this heavier axis of rain will see considerably less qpf.

[tron777]

Nothing says December 2021 like a moderate risk in MN,IA,WI.

The high wind watches and warnings are also very impressive as far as the coverage area goes. This is without t-storms.

Windy.png

[Bgoney]

Next week looks seasonal atm . Should be dry early week , closer to Christmas is tough to say. The cut off Lows traversing on the west coast is going to be a challenge to figure out when and where energy waves get kicked out for mid to late week.