January 2019 Medium/Long Range Pattern Discussion

[BullCityWx]

9 hours ago, weathertree4u said:

Yea, hard to believe that it has. What is the accuracy of the model at this range?

It has not been doing well outside of day 6. From what I understand, it's done pretty okay within 6 days. 

[John1122]

All the models are a crap shoot beyond day 6, especially for details more specific than the 500mb pattern and even then small feature changes have big consequences in OP runs. They are pretty decent at sniffing out a storm, it's the track that gives major troubles and we are always on such an edge that 40 mile shifts make huge differences for rain vs snow and at any kind of range they will have 300-500 mile wide windows, think of the day 7 hurricane cones. Using the ensembles is a decent way to smooth out biases of individual models per some NWS mets I've read. 

When you have such an intense cold press coming down, models tend to underestimate it's speed and it's ability to push SE as well. Very often these situations are ones that lead to freezing rain/sleet events as the cold is so dense it undercuts  a rainy system that's riding up the edge of the front. That happens on the FV3 between 252-264.  There's nearly a 30 degree gradient from NWTN to NETN and NETN isn't very warm. 

The FV3 has extremely high resolution (as high as 1k-3k and it's supposed to be able to model individual clouds from what I've read) but is still behind the Euro in performance days 7-10.  For the December 9th storm it had the features almost exactly in place at D 11-13, which was probably it's best performance of winter.

That said, it appears to have a cold bias but part of it's extreme cold solutions is that it's putting down heavy snow cover. If you have arctic air, heavy snow cover and it's this time of year, below 0 is not at all uncommon. 

The GEFS snow mean has steadily been in the 3-6 inch range forum wide with the 2 inch mean line well into Miss/Ala/Ga.  All indicators say arctic cold is about 6-8 days away for our forum area. The pattern looks stormy. It looks like we'd just have to have bad luck (and we have plenty) not to cash in at some point in the January 20th-30th timeframe. With luck we can cash in a few times.

[John1122]

This, for a 5 day ens average at 500 in January is about as nice as it gets, and I say about, because it actually gets better 12-16. This also aligns with a day 7-13 AN precip forecast for the region.

[jaxjagman]

2 minutes ago, John1122 said:

This, for a 5 day ens average at 500 in January is about as nice as it gets, and I say about, because it actually gets better 12-16. This also aligns with a day 7-13 AN precip forecast for the region.

Yeah the control run would agree.Looks like somewhere into wk3-4 of Jan the NAO COULD possibly get into  -ve.With a -ve AO being shown it looks like it could get real cold upcoming,PNA looks+ve just as well.We keep getting cutters right now,either west of the Tn River or coming smack into the Tn Valley,not real conductive for snows here without cold in place.East Asia looks fairly active the next few days upcoming.Think we have to wait a few more days but it's going to get cold

[John1122]

24 minutes ago, jaxjagman said:

Yeah the control run would agree.Looks like somewhere into wk3-4 of Jan the NAO COULD possibly get into  -ve.With a -ve AO being shown it looks like it could get real cold upcoming,PNA looks+ve just as well.We keep getting cutters right now,either west of the Tn River or coming smack into the Tn Valley,not real conductive for snows here without cold in place.East Asia looks fairly active the next few days upcoming.Think we have to wait a few more days but it's going to get cold

 

This map is probably what the FV3 snowfall map would look like at 384. We may get unlucky and not score anything in the cold pattern, heck, we only need to look at Christmas til late January last year to see that struggle. Even that was a stormy pattern, the ridge in the Pacific was just too big last year and it suppressed everything. The cold and snow means showing up at 1.5 inches in Central Alabama shows that there are some low road solutions hitting in there still. 2009-10 and 2010-11 were two of my favorite winters because it stayed cold enough for snow and cold enough for the snow to stick around, but it wasn't 5-15 below zero and there wasn't as much suppression. Unfortunately that meant south of 40 areas weren't nearly as snowy as areas north of 40. We need to find the happy medium between the Gulf coast getting snow and people along 40 and south changing to rain or staying 33 and rain.  I believe Jan 85 was that, it got extremely cold obviously, but the pattern was also good for valley wide snow events from Memphis north and west. 

 

[Carvers Gap]

18z GFS is very cold just inside of 200 with no snow on the ground.  Though I really don't worry about specifics at that range...still pretty impressive.  If one likes winter, those types of runs are a very good indicator.

[weathertree4u]

18 minutes ago, Carvers Gap said:

18z GFS is very cold just inside of 200 with no snow on the ground.  Though I really don't worry about specifics at that range...still pretty impressive.  If one likes winter, those types of runs are a very good indicator.

That kind of cold not good for things with no snow cover though imo

[jaxjagman]

If its right of not is to be seen, but the GEFS starts to build the heights up into the GOA and Greenland,then look at a couple days later.Only problem will be any system could be suppressed.ButT his is a cold look with it.We'll see what happens.

 

 

[jaxjagman]

19 minutes ago, weathertree4u said:

That kind of cold not good for things with no snow cover though imo

Depends really with a strong -ve NAO,for us anyways,the east can score unlike us.I cringe at strong -ve NAO'S,IT'S A 

[John1122]

The pattern is finally reeled in imo. 6-10 and 8-14 look good.  Wed-Saturday may be the last N/AN temps we have for a long while.

 

 

 

[John1122]

Those are actually yesterdays, I always forget that hotlinking those always gives weird results. But the entire valley is BN 6-10 and 8-14.

[jaxjagman]

5 minutes ago, John1122 said:

Those are actually yesterdays, I always forget that hotlinking those always gives weird results. But the entire valley is BN 6-10 and 8-14.

[PisgahNCWeather]

35 minutes ago, weathertree4u said:

That kind of cold not good for things with no snow cover though imo

I find it funny that people are scoffing at some of the cold that is modeled. It may or may not happen but certainly if it were to take place the ingredients are there considering the time of year and the strat split, etc. Seems to me strat splits are one of the essential major precursors in having historic cold. Agree that it is much better to have snow cover vs. not as the ground can freeze much deeper with being barren, which could lead to even more problems.   

[jaxjagman]

7 minutes ago, John1122 said:

Those are actually yesterdays, I always forget that hotlinking those always gives weird results. But the entire valley is BN 6-10 and 8-14.

See what you are talking about,this is todays

[John1122]

3 minutes ago, PisgahNCWeather said:

I find it funny that people are scoffing at some of the cold that is modeled. It may or may not happen but certainly if it were to take place the ingredients are there considering the time of year and the strat split, etc. Seems to me strat splits are the only major precursor to ever having historic cold. Agree that it is much better to have snow cover vs. not as the ground can freeze much deeper with being barren, which could lead to even more problems.   

I can see why it's showing up. If what FV3 especially is throwing out there actually happens both at the surface and at 500, widespread subzero is likely into the upper south.

[jaxjagman]

15 minutes ago, John1122 said:

I can see why it's showing up. If what FV3 especially is throwing out there actually happens both at the surface and at 500, widespread subzero is likely into the upper south.

Look at the cold air in the NA side,the only problem is this is a +ve NAO,nothing but transient cold

 

[Carvers Gap]

Was commenting to a friend a few minutes ago that every system will have to be watched with the kind of blocking and cold lurking.  It is highly likely that modeling will at times underestimate how far south the cold will get.  That means that the storms that run that boundary will have tracks that are likely significantly "off" outside of d5(maybe even at closer range than that), because the cold is tough to model.  I do think in the intervals between cold, systems will try to sneak in between the two.  Warm-up and rain type stuff.  Now, don't take that to be a negative.  I think that is temporary, and exists early in the pattern.  IMHO, with the trough being a mainstay in eastern NA, it is likely only a matter of time before two systems line up, and we get system one driving the cold down behind it and system two overrunning the cold left behind.  The great thing about an active STJ and an eastern trough with good source regions is that snow storms will be further south than they have been for the past month or so.  I do agree w Jax that said suppression is likely our foe vs cutters over the long haul.  As noted we may get a cutter or two before the trough gets firmly established.(Please note that the starting point for the pattern is roughly Jan 20...I am not talking about this upcoming work week)  Then, I like the modeled temp gradient where the most sever cold is centered over the lakes and the southern boundary is over the forum area....those storms will eventually run that boundary IMHO.  Once the cold is established, I think it is a matter of just waiting for that active STJ to attack the cold.  The duration of this cold spell might be a bit longer than the normal 1-2 week cold shots that we get during other winters due to SSW influence(tends to create enhanced duration blocking...not sure if that is a term).  Now, when this finally snaps...I think we get quite warm.  Duration is still a bit of a question mark.  No idea when that happens, but would guess late February or early March(basing the duration of this blocking episode on last year's SSW event so shaky ground there on my part).  So, it looks like we have a very good window for winter and just about all that we can ask for at this latitude.  Try to enjoy the looks that you are seeing at 500 at high latitude...we don't see those every winter...big highs over AK and Greenland w an expressway setup up for cold to head due south.   We have also seen a strat split along with early season cold.  Yes, we saw a warm-up that ate up 4-5 weeks of winter.  But many great winters had thaws around the same time frame.  Not saying this will be one of those great winters....but I'm not saying it won't be either.

edit:  BTW....when saying I am seeing big blocking highs being modeled, I am speaking at ensemble runs.   For the moment, I give the operationals the same weight as an individual ensemble member after about d6.  As always, there are ways that the pattern can get into unintended mischief that is not productive for winter wx over the Upper South.  Jeff did a great job of outlining those.  And every once in a while, you can see a run with those features pop-up, mainly the SER.  You can actually see a slight retrogression of the trough on both the 18z GEFS and 12z EPS into the nation's mid-section.  Fortunately there is a nice -NAO in place that likely will help with confluence over this area.  

[Icy Hot]

57 minutes ago, weathertree4u said:

That kind of cold not good for things with no snow cover though imo

What do you mean not good for things? Like nature???

[jaxjagman]

8 minutes ago, jaxjagman said:

Look at the cold air in the NA side,the only problem is this is a +ve NAO,nothing but transient cold

 

It actually tries and build a -ve   NAO .Starting to wonder tho if this model has taken  the crown from the CMC to have become the new cold biased model

 

 

 

[Carvers Gap]

Without getting too much into specifics, it looks like there are two storm tracks which we discussed in this thread a couple of pages back... one over the OH River Valley and the inland runner track where the energy goes to our SE in relation to the forum area.  The primary as Jeff pointed out is right now from KC to DC.  I think as the trough gets established, that track shifts south...unless a storm can sneak in between retreating cold and incoming cold(as noted early on in the pattern.). Here is the 16d snow mean from the GEFS.  It drives boundary for 2" of snow well into the forum area with amounts of 6+" in northern and high elevation areas.  The great thing about a snowpack over the Midwest is that the cold will be able to move in more quickly and be at the ready should a coastal amplify.  We may even see a SE track that hugs the coasts, retrogrades to inland runners, and retrogrades again to where even Memphis is in the storm track which runs southwest to NE.  Just depends on the size of the trough and if it actually retrogrades westward.  It may actually be that the trough encompasses a good chunk of NA...and the area of confluence if over the forum area w the -NAO modeled on ensembles.   I should add that there are even traces of snow being modeled into Louisiana and almost the FL Panhandle.  Not seen on this perspective...but northern Louisiana has a 2" snow mean.  That is a great signal for cold air.

[Carvers Gap]

JB has a video out this evening.  Needless to say, he has been sweating this out as their seasonal forecast is very cold.  He leans cold most winters, and this one is no different.  He likes the cold to last through February and into some undetermined time in March.  Food for thought...his analogs for January and February are:

Single weighted:  66, 78, and 87

Double weighted: 03, 07, 10, 15

I think I listed those correctly.  Not saying he is right or wrong, but thought it was a interesting nugget.

[Carvers Gap]

Someone shared with me that the track on the 18z GEFS MSLP and Anomaly(Lower Dynamics drop down on TT) is pretty good for next weekend.  I was kind of surprised given the look on the operationals.  Now, it might be that the GEFS bias of being too progressive is playing into that.  But the Euro bias of being west might be in play as well.  

[Carvers Gap]

WxUSAF shared this on the MA forum from Twitter.  I think this gives added support that we are very close to a cold pattern being realized.  Interesting product anyway.

 

[jaxjagman]

2 hours ago, Carvers Gap said:

WxUSAF shared this on the MA forum from Twitter.  I think this gives added support that we are very close to a cold pattern being realized.  Interesting product anyway.

 

Hard to tell tho with this map,looks to be wind chill but over all chances of 0 wind chill of 50% would seem to be cold

[jaxjagman]

1 minute ago, jaxjagman said:

Hard to tell tho with this map,looks to be wind chill but over all chances of 0 wind chill of 50% would seem to be cold

Looks to be a new toy

https://www.cpc.ncep.noaa.gov/products/predictions/short_range/cold/wc_814.php

[John1122]

GFS is a cutter/miller B parade. Warms up, rains, very cold, rinse and repeat. Actually happened just like that in I believe December of 1982. Rain and then below 0 temps, then back to rain again.  Not saying that's going to happen here but it's happened before and the GFS is throwing it out there, so it's possible. 

[jaxjagman]

The hammer is fixing to beat down.I haven't checked yet to see what record temps will be towards the end of the month into Feb,but i'd suspect some will be potentially broken somewhere in the SE.Not really focused on storms but more the cold.Something sooner than later  is going to pull that cold down from the strat down into the troposphere.That coldest daughter on our side has been showing on our side for days,nothing has changed even today.

[John1122]

The EPS sets up the triple play, Pacific blocking, -NAO/-AO.

[weathertree4u]

4 hours ago, John1122 said:

GFS is a cutter/miller B parade. Warms up, rains, very cold, rinse and repeat. Actually happened just like that in I believe December of 1982. Rain and then below 0 temps, then back to rain again.  Not saying that's going to happen here but it's happened before and the GFS is throwing it out there, so it's possible. 

Middle TN looks close in allot of those....but, like you said, it is possible.

[Carvers Gap]

I think right now I would not trust modeling on specifics due to the amount of cold air that is in play.  I do think cutters are definitely possible early on until the trough establishes itself.  What we need is a 1-2 punch during the early period of blocking.  First storm drags down the cold behind.  The second system overruns it.  Not a given, but that is one scenario that will work.  And agree, the warm-up and rain deal is always possible.

Actually, that is not the reason that I came on here to post this AM.  Wow, when I look at the GEFS and especially the EPS this AM...No idea if this is shown in the future, but the EPS, which has had a tendency all winter not to amplify troughs enough during d10-15, brings the PV into the Great Lakes late during the period.   During days 14-15, there are -8C departures over the upper Midwest(lower peninsula of Michigan).  That is very cold for an ensemble at that range.  Again, no idea if that is there on the next run, but given the configuration on the blocking that is certainly a higher probability now than during normal winters.  

Back to the cutter scenarios, there (as Jeff and I had kicked around) have been two storm tracks this winter ....There is the primary from KC to DC that Jeff had mentioned as the primary.  However, there have been some storms take the low road up the coast.  I think both of those continue.  Now, if the PV drops in...that completely changes all of that.  Heck, that might even change the duration of the cold as the cold would eventually be used-up and the pattern would end sooner.  But man, would it be really cold if that happened!  We are still about one week from this pattern really locking in.  I have a hunch that the storm track associated with the cold doesn't show itself until the cold is here.  Right now, the models are just now "figuring out the pattern" - meaning placement and evolution of the said trough.  So, I expect the details to be sketchy.  In my thinking, I sort of thought that we might not see a storm until the end of the month....but some models during the past couple of days hurried that look a bit and have since backed off which is not uncommon.  So, I suspect the storm pattern for the Upper South will arrive, but not as quickly as it looked a couple of days ago. I think a PV that is pressing southward will likely(highly likely) suppress the storm track, hopefully we will get a few shots before Mobile, AL, does!