December 2022 Medium/Long Range Pattern Discussion Thread

[Carvers Gap]

And this is why the CMC has to be considered in the medium to long range...

[Carvers Gap]

The CMC continues to advertise the potential for light freezing rain in the valley on the morning of the 22nd.

[snowmaker]

The CMC looked some better for west and middle tenn and even points further East to a extent. At least it appeared that way to me. 

[Matthew70]

So looks like 3 days below freezing then by NY near 60.  That is with rain of course. Hopefully we don’t have flooding & severe wx in January.  It would not be the first January to have those. What once looked promising for a few weeks of winter is fading quickly.  Crazy how quickly things change.  

[Carvers Gap]

La Nina years are full of extremes.  Take that to the bank pretty much every year we have them.  That is what makes them crazy.  We are going to be approaching some record lows.  The sheer power of the cold will be impressive, even for long time weather watchers.  We are 100% fighting seasonal climatology - it doesn't want to snow here until January through early March.  We have been spoiled w/ a few early season snow storms in the valley during the past 10-12 years.  Prior to that, the valley experienced very few big, early season snow storms - even when I was younger.  I encourage everyone to enjoy the potential for snow showers and cold weather for Christmas.  It could be so much worse on many levels.  

[Carvers Gap]

Flooding is quite common during even the most severe of winters, and so is severe weather.

[snowmaker]

3 minutes ago, Carvers Gap said:

Flooding is quite common during even the most sever of winters, and so is severe weather.

How do you feel about the chances for west and middle tenn to get a inch or 2 out of the late week system?

[Carvers Gap]

1 minute ago, snowmaker said:

How do you feel about the chances for west and middle tenn to get a inch or 2 out of the late week system?

I truly don't know.  The difficulty with tracking systems so far out is that inaccuracy is plentiful.  We will know more by Tuesday morning.  I think our best chance is for the cold to rush into that front.  If the cold hangs up even slightly it is cold chasing rain.  However, this front is powerful and the dynamics are going to be extremely difficult for modeling to handle well IMO.  We see fronts like this maybe once out of every four or five years.   

[Holston_River_Rambler]

CMC still holding strong overnight with the relaxation only idea

 

GEFS looks toasty: 

EPS:

EPS looks like a compromise between the GEFS and GEPS, at least to me. 

[Carvers Gap]

The GEFS may be right here, but it mishandled the upcoming pattern pretty badly in the LR.

 

The verification scores above actually show the CMC scoring higher than all other modeling on multiple occasions at that range.  I lean it’s direction for now.

 

Until the GFS shows me otherwise at d10+, I am weighting it less in the LR.  The EPS could be right as that is a phase 7 MJO?  That said, what we are seeing sure looks like a reload of the current pattern and it should be as the current pattern’s clock doesn’t really run out until mid Jan to early Feb - 4-6 weeks.

if one can ignore the Cfsv2’s cold bias, it’s evolution at 500mb seems reasonable this morning.  It looks like the Canadian.  The Canadian nailed the upcoming cold pattern and it’s intensity...prob due to its own cold bias.   The GEPS was great at 500mb.

[PowellVolz]

So looks like 3 days below freezing then by NY near 60.  That is with rain of course. Hopefully we don’t have flooding & severe wx in January.  It would not be the first January to have those. What once looked promising for a few weeks of winter is fading quickly.  Crazy how quickly things change.  

The pattern is loaded for Firehose February


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[tnweathernut]

9 hours ago, Matthew70 said:

So looks like 3 days below freezing then by NY near 60.  That is with rain of course. Hopefully we don’t have flooding & severe wx in January.  It would not be the first January to have those. What once looked promising for a few weeks of winter is fading quickly.  Crazy how quickly things change.  

As @Carvers Gapnoted, expect wild swings with Nina driving the bus.  If the CMC ensembles (and to a lesser extent the EPS) are onto something, you could be tracking something wintry as easily as you could be tracking a round of golf in the days around the New Year. 

 

I'm not looking forward to the extreme cold in the days before Christmas.  Unfortunately for insurance guys/gals this just means popping pipe claims as the weather starts warming back up.

[Carvers Gap]

Just digging into the dreaded MJO, the GEFS looks like it is forecasting the MJO on a different planet compared to other models.  That is likely why it is putting the trough out West d10+.  It is trying to stay in the warm phases when virtually all other modeling rolls into the colder phases.  Could it be right?  Sure, but would be the first time in several months for it to be right at d10+.(really since the fall upgrade).  

[Daniel Boone]

2 hours ago, PowellVolz said:

The pattern is loaded for Firehose February


.

Wouldn't be surprised, lol. Hopefully that firehouse runs into a huge eastern, Arctic Jet driven Trough and overflows it with Snow ❄️

[Daniel Boone]

11 hours ago, Carvers Gap said:

Flooding is quite common during even the most sever of winters, and so is severe weather.

Yeah, late December '69 a good example. Very cold, snowy winter. '95-96, overall cold and very snowy had bouts of heavy rain and flooding. Winter '63.. etc.. could go on and on. 

    P. S., felt should throw this in. There have been a few exceptions to the rule of severe Winter's having their thaws and flooding. 76-77 and '77-78 come to mind. 76-77 did flood but, wasn't till Spring. April 4th. 

      Those are extremely rare and exceptions to the rule, however. 

[Carvers Gap]

Both the CMC and GFS at 12z are picking up on northern stream energy around the 27th.  The GFS solution is wild - dives the system through west TN all the way to the GOM and brings it back up the coast.  The CMC has a slider.  Something definitely worth watching.

[tnweathernut]

Does it bother anyone else the American modeling (GFS) was way off for the system for late this week when it showed a major east coast snowstorm a few days ago, but was dead on for the low traversing the northern gulf region, expected to slide harmlessly beneath us the next 24-48 hours from about the same lead time out?  lol

[PowellVolz]

Does it bother anyone else the American modeling (GFS) was way off for the system for late this week when it showed a major east coast snowstorm a few days ago, but was dead on for the low traversing the northern gulf region, expected to slide harmlessly beneath us the next 24-48 hours from about the same lead time out?  lol

I honestly don’t know what to make of anything right now. Mods are crazier than my Ex Girlfriend


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[tnweathernut]

4 minutes ago, PowellVolz said:

I honestly don’t know what to make of anything right now. Mods are crazier than my Ex Girlfriend


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I guess there's always a need to change/tweak modeling (as the atmosphere is constantly changing), but I remember back in the day if the Euro and Ukie showed something at Day 4 to 5, you could almost lock it in............   

[John1122]

1 hour ago, tnweathernut said:

Does it bother anyone else the American modeling (GFS) was way off for the system for late this week when it showed a major east coast snowstorm a few days ago, but was dead on for the low traversing the northern gulf region, expected to slide harmlessly beneath us the next 24-48 hours from about the same lead time out?  lol

Every model just struggles any time they show snow here. At one point the Euro had us with blizzard conditions but the ICON of all things started showing the cutter first. 

 

However, suppressed, dry or rain storms. A+ on all model verification. 

[buckeyefan1]

2 hours ago, tnweathernut said:

I guess there's always a need to change/tweak modeling (as the atmosphere is constantly changing), but I remember back in the day if the Euro and Ukie showed something at Day 4 to 5, you could almost lock it in............   

We called it the EE rule. When the Euro and the ETA (now the NAM) agreed, it was game on  

[tnweathernut]

47 minutes ago, buckeyefan1 said:

We called it the EE rule. When the Euro and the ETA (now the NAM) agreed, it was game on  

I remember that also….  Back when easternwx was in operation…

[Itryatgolf70]

I wished we could get a phenomenal change in the pattern that would get us in the ice age to have colder stormier winters again. Or at least more cold winters than warm winters 

[buckeyefan1]

21 minutes ago, tnweathernut said:

I remember that also….  Back when easternwx was in operation…

Indeed! That rule still applies today  

[Matthew70]

5 hours ago, John1122 said:

Every model just struggles any time they show snow here. At one point the Euro had us with blizzard conditions but the ICON of all things started showing the cutter first. 

 

However, suppressed, dry or rain storms. A+ on all model verification. 

This is so true!  
If it’s going to be dry. 99% correct 10 days out. 

If it’s going to rain.  99% correct 10 days out.

If it’s going to be HOT.  110% correct 2 weeks out! 

 

Now for cold & snow.  One has to go outside wear flip flops & a speedo & look for a rock if can find one. Then you will know if it is cold & snowy. 

[PowellVolz]

This is so true!  
If it’s going to be dry. 99% correct 10 days out. 
If it’s going to rain.  99% correct 10 days out.
If it’s going to be HOT.  110% correct 2 weeks out! 
 
Now for cold & snow.  One has to go outside wear flip flops & a speedo & look for a rock if can find one. Then you will know if it is cold & snowy. 

The GOM giveth and taketh away. We need the GOM 85% of the time for big snows but it’s a double edged sword. We are basically the same Lat as Oklahoma, West Arkansas and Texas panhandle. Those areas get big snows, they don’t really feed off the GOM and they have to fight off dry air from Arizona. Our life would have been so much easier had the App mountains not had a break in it around Chattanooga or the southern valley. It’s like a unrestricted pipeline for WAA.


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[Carvers Gap]

The CMC has a major winter storm in the 27th.  Modeling is all over the place with that system.  Something to watch, 

[Carvers Gap]

Looking down the road....The system on the 27th looks to close out the current cold cycle.  The cold has been spent and the Pacific is not going to yield a PNA/EPO pattern without a fight (as models once hinted they would).  In fact a stubborn GOA low is trying to set up shop.  To me it looks like the pattern will be anomalously warm from December 28th to roughly January 10th.  There are some signs that is a new pattern - cold in West and SE ridge hooked into HB block.  That said, we have seen that error during late fall and early winter on more than one occasion.  So, I am not ready to go there quite yet.  The 12z GEPS is only slightly budging when it comes to keeping a trough in the East.  But it has budged enough for me to think the Canadian ensemble is in error.  The culprit?  You know when we start talking about the MJO warmth is on the way.  The MJO stalls like it is hitting a brick wall between phases 7 and 8.  Phase 7 during December will work, but not January.  I am nearly certain the cold equatorial/dateline Pacific SSTs are stalling the MJO waves from reaching prime longitude.  There are some hints in LR modeling that the cold will return quite harshly after the 10th, but add a few days  at least to account for can kicking.

[Carvers Gap]

Since we have a thread for the last seven days of the month, I have started a January thread as we are getting close enough to actually see it on ten day forecasts tomorrow.

[Daniel Boone]

2 hours ago, Carvers Gap said:

Looking down the road....The system on the 27th looks to close out the current cold cycle.  The cold has been spent and the Pacific is not going to yield a PNA/EPO pattern without a fight (as models once hinted they would).  In fact a stubborn GOA low is trying to set up shop.  To me it looks like the pattern will be anomalously warm from December 28th to roughly January 10th.  There are some signs that is a new pattern - cold in West and SE ridge hooked into HB block.  That said, we have seen that error during late fall and early winter on more than one occasion.  So, I am not ready to go there quite yet.  The 12z GEPS is only slightly budging when it comes to keeping a trough in the East.  But it has budged enough for me to think the Canadian ensemble is in error.  The culprit?  You know when we start talking about the MJO warmth is on the way.  The MJO stalls like it is hitting a brick wall between phases 7 and 8.  Phase 7 during December will work, but not January.  I am nearly certain the cold equatorial/dateline Pacific SSTs are stalling the MJO waves from reaching prime longitude.  There are some hints in LR modeling that the cold will return quite hardly after the 10th, but add a few days  at least to account for can kicking.

Excellent post Carver's ! Nothing needs added. Right on the Money imo.