January 2019 Medium/Long Range Pattern Discussion

[Carvers Gap]

6 minutes ago, tnweathernut said:

Yeah, the PV looks to continue taking a beating which has the potential to be a very good thing. or devils advocate maybe not.  lol. 

I guess that cold air HAS to go somewhere, right?

I have read some discussion that the MJO might have led to the strat split(prob HM or one of other folks on Twitter...can't remember).  Basically the idea is that it disrupted the PV, and helped split it.  We are either going to look back at the MJO as a disruptor of what could have been a good winter pattern or a catalyst of a good winter pattern.  Jury is still out, but will make for some great discussion during the coming years.  

[Holston_River_Rambler]

Satellite in the tropics looks sooooo much better today:

http://rammb.cira.colostate.edu/ramsdis/online/loop.asp?data_folder=himawari-8/full_disk_ahi_true_color&width=800&height=800&number_of_images_to_display=30&loop_speed_ms=100 

As I understand it (and could be way off base) the extraordinary tropical convection in SE Asia/ Maritime Continent (lift) fueled the (subsidence) highs in China/ Tibetan plateau on the lee side of the Himalaya (positive mountain torque) and that in turn directed a part of the jet up toward the SPV at the pole, carrying the relative warm rush that disrupted it. Then as the SPV began to spread/ split and shred out it sent vort filaments and swirlies (technical term  ) and lobes carrying relatively cooler temps toward the tropics at the bottom of the strat. and this created some sort of positive feedback by further fueling the convection, enhancing the process that started it all to begin with.  Throw in the coronal hole and it really is a perfect storm. 

Throwing the above there for critique of what I have here too, to try and understand it better. Jeff had mentioned looking at MSLP maps last month too, wonder if he was hinting at something like this? Being able to understand the drivers of the Pac jet would definitely help understand our patterns downstream.

23 minutes ago, *Flash* said:

Sure seems a lot of these teleconnections are at the poker table ready to go 'all in'. Will be interesting to note where the strong amplifications set up.

And there's the key to it all. What now? One extreme leads to another to help maintain equilibrium? I think it is still hard to say until we get all this to settle. I think the last piece to look at is the strat now, since convection seems to be (for now anyway) doing its part, and weakening, moving east. Once the SPV finishes whatever it's going to do I think we will finally have some stability for a bit. 

[tnweathernut]

With the SOI tanking, the MJO being sniffed out to be a bit stronger in the cold phases, and the ensembles showing changes beginning around day 7, I won’t be surprised If more and more operationals begin to throw out some crazy looks over the next several days.

[Carvers Gap]

To quote Bob Kesling (spoken after one of the great reversals of all time) after looking at the 12z GFS, "What a turn of events."  

[Carvers Gap]

Great looking 12z suite(both ensembles and operationals).   Reminds me so much of what happened during early November and of the SSW late last winter.  I learned my lesson this time...sort of.  After watching run after run after run of non-winter...this is pretty much my reaction to the reversal depicted today.  I was expecting a reversal...but maybe not as rapidly as the last two runs.

edit:  I probably should explain.  I was laughing, because I was not expecting that quick of a move in modeling.  In other words, it got me(caught me off guard) kind of like someone slipping in a sneaky joke into a conversation when I am not listening or mentally half asleep.  When I finally start paying attention, I realize I have been had.  Indeed, I have been half paying attention for a couple of days...and then things reversed while I was passively watching.  Something about a watched pot never boils....

[Carvers Gap]

The 18z GEFS continues to advertise a pattern reversal at 500 beginning about Jan9/10.  It is a great look that supports @John1122's November research that correlates to cold temps during January.   Hopefully, this look will continue its move forward and be a sustained, new pattern.  I am a bit skittish after a couple of weeks of warm model runs that had some head fakes.  I think, as others have mentioned, that the look of AN heights over AK and Greenland coupled w a strat split likely means some fairly cold temps are in play for eastern NA.  I am encouraged that almost all modeling is recognizing amplifying troughs over eastern NA.  I think we will see the eastern NA ridge try to reform after each trough, only to be undercut and pushed down by the cold from those departing storms.  Eventually, I think the trough forms over eastern NA and establishes itself.  How long?  IDK.  This winter is a great example of nothing behaving as it should.  That said....if we get cold during mid-Jan or just before, then maybe weak El Nino climatology and strat split climatology are actually doing their work.  Basically, the move to a colder pattern would be on time.  Again, not a fan of back-loaded winters...well, not a fan until they get here!  Have a great weekend, everyone.

[tnweathernut]

FV3 at 6z entertains a full Tennessee Valley threat in the 6-7 day period. Also, some modeling is hinting at the PV coming to visit the lower 48 (ala the Euro control).  Overall, a change to a colder period suitable to find a threat appears on track when looking at the ensembles.

The only thing I don’t like when looking at the ensembles from yesterday........ they were almost all perfect in the extended.  Why is that bad?  Typically modeling in the 10-15 will begin to move those features around a bit and a simplistic view means the perfect can become much less desirable.  

Either way, just getting out of this raging PAC mess will be welcomed with open arms.  Especially as we head into prime snow season in the Tennessee Valley and Mid-South.

[Carvers Gap]

Snowgoose with some really interesting commentary in the MA forum this morning...Here is one o them.  

 

[AMZ8990]

1 hour ago, Carvers Gap said:

Snowgoose with some really interesting commentary in the MA forum this morning...Here is one o them.  

 

Good stuff,  that’s one thing I like about Americanwx and the forums we have inside it.  There is always something to learn or ponder on in just about every forum you look at.  Side note- It’s hard not to like the extended outlook from the Euro monthly outlooks for  feb, March and April.  All I’ll say is February looks like a high electric bill month if the Euro is correct. 

[AMZ8990]

MJO continuing the move in a favorable direction as of this morning as well.  Hopefully phase 7 and 8 can lead to wintry conditions for the Tennessee valley forum!

[Holston_River_Rambler]

So, now that the ensembles (at least for now) seem to be continuing to agree on overall changes ahead, maybe some closer range interest?

Thoughts on Jan 13 - 15? About 30 of the EPS members give parts of the forum area 1"+ (hey beggars can't be choosers). A few nice storms thrown in there, but mostly little ones. That's 2 runs of the EPS that have been similar and I think 12z had a few more hits. 

Euro OP has the storm but keeps the N stream and S stream separate until off the eastern seaboard.

GFS is progressive and far south (probably a good sign at this stage). GEFS ensemble means are as well and the Z500 48 hour trend looks nice https://imgur.com/a/WNIpEBC 

CMC is some wild, phasing, wound up, slow storm that snows on some parts of the far eastern valley for 60 hours. Would be beautiful for eastern areas. Had a pic of its snowfall in banter earlier, but maybe not totally bantery since it is at least a possibility. 

Fv3 brings two pieces of energy out and both give some snow. 

UKMET only out to 144 hours at 500 mb to me looks more like the CMC than the Euro. Kind of surprising to me. More amped ridge out west gives energy more room to dive under us.

Probably way to early to get too invested in, especially since A) the N stream seems key here and it has been hard for models to pin short waves down at any range; B ) models do seem to be gradually changing 500 mb flow depending on where and how strong they initialize with tropical convection; and C ) still over 5 days out

May be worth keeping an eye on though.  I really like that the EPS mean is 1-2 inches BUT that mean doesn't come from 1 or two oddball big dogs and 48 shutouts, but maybe 25+ little events across ensemble members in that time period. I think there were even 3 that were south of our area, which seems to always a good sign at range.

[tnweathernut]

Good post, Holston.

My simplistic view is that once we get the nice cold shot next week and have a week or two of back and forth (troughs and ridges) we will need to start looking for threats.  We haven’t had a shortage of storms under us this year and that looks to continue. There seems to be just enough cold air for fun and games, at times.  I wouldn’t be surprised if someone scores before we get to what looks like the “money” time frame (late January into Feb)

[Holston_River_Rambler]

Sounds like some good news:

 

[Holston_River_Rambler]

SOI jumped back up to -8 today. Now that is 100% better than what it has been, but a big jump up. It may do some wonky things over the next week as the cyclone that was initially near Darwin, Australia loops back across N. Australia and may emerge over Darwin into the Indian Ocean.  Since a low SOI depends on Tahiti and Darwin having similar MSLP (seems like the higher the pressure is in Darwin the better), wouldn't be surprised if it jumps back up to positive , but since this is a tropical cyclone and not necessarily an expression of MJO convection it may not be that big of a deal. 

 

[Holston_River_Rambler]

I know it's the day 10+ GFS, but too pretty not to share:

 

 

[nrgjeff]

ECMWF Monthlies go cold in February, lingering into March. IFF they are right, it is last year a month ahead of schedule following a SSW also about a month earlier than LY. We'll have to just hope, after all the delays.

Parts of Eurasia have been very cold, which IIRC got cold first last year. Regrettably my global 500 mb and surface pressure anomaly site is a victim of the government shut-down. I cannot speculate on where we are headed from there.

[jaxjagman]

Euro is close to being 2-3" Saturday, still would like to see the 2m's slightly better,850's  look fine

 

 

ECMWF Deterministic FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                                            12Z JAN06
                 2 M     850    1000    FZING    SFC     SFC    6 HR    SNCVR
                 TMP     TMP     850     HGT     WIND    PCP     QPF     LIQ 
                 (C)     (C)     THK    (FT)    (KTS)   TYPES   (IN)    (IN) 
SUN 12Z 06-JAN   2.7     9.2     135   10733    19003           0.00            
SUN 18Z 06-JAN  13.7    10.1     135   10945    16002           0.00            
MON 00Z 07-JAN   8.9    10.6     136   11572    16005           0.00            
MON 06Z 07-JAN   7.0    11.5     136   12022    17005           0.00            
MON 12Z 07-JAN   7.7    11.4     136   13131    18008           0.00            
MON 18Z 07-JAN  15.9    10.4     136   13024    19012           0.00            
TUE 00Z 08-JAN  13.6     8.3     136   10235    20010           0.04            
TUE 06Z 08-JAN  12.5     6.4     135   10318    20008           0.02            
TUE 12Z 08-JAN  12.3     7.3     135   10364    22007           0.05            
TUE 18Z 08-JAN  16.3     6.6     135   11109    26010           0.03            
WED 00Z 09-JAN  10.0    -0.1     133    6184    31008           0.00            
WED 06Z 09-JAN   4.7    -2.5     131    2785    31006           0.00            
WED 12Z 09-JAN   2.5    -3.8     130    1533    30007           0.00            
WED 18Z 09-JAN   4.8    -7.9     129    3560    31011           0.00            
THU 00Z 10-JAN   1.6    -6.8     129    8878    33007           0.00            
THU 06Z 10-JAN  -2.5    -3.6     127    9808    35007           0.00            
THU 12Z 10-JAN  -5.0    -0.8     127    9390    00005           0.00            
THU 18Z 10-JAN   0.7    -0.3     128    8274    35004           0.00            
FRI 00Z 11-JAN  -0.1     1.2     129    7173    01003           0.00            
FRI 06Z 11-JAN  -1.9     1.9     129    6412    04004           0.00            
FRI 12Z 11-JAN  -1.2     0.8     130    4963    06003           0.00            
FRI 18Z 11-JAN   3.4     0.1     130    4394    07002           0.00            
SAT 00Z 12-JAN   3.3    -1.5     131    3421    02003           0.00            
SAT 06Z 12-JAN   2.9    -2.4     131    2713    10001           0.00            
SAT 12Z 12-JAN   1.2    -3.6     129    1250    21001           0.06            
SAT 18Z 12-JAN   2.1    -4.0     129     793    02001           0.17            
SUN 00Z 13-JAN   1.5    -3.8     129     689    01004           0.10     

 

[John1122]

This are looking more and more interesting for next weekend. GFS and Canadian are suppressed. FV3/Euro much less so. Last couple of runs of the Euro have gotten a little more juicy. 1-4 inches valley wide, heaviest in the eastern mountains. FV3 bullseyes NW Valley and has all but the far southern valley looking pretty good. GFS major bias is suppression. Canadian was more in the Euro/FV3 game until the last run or two.  Good set up on the FV3 for classic overrunning valley wide. LP in Texas working across the Gulf. High in Canada with super cold temps up there in Southern Canada. -20s to -30ish. Temps in the 20s/low 30s here when precip arrives. 850s fall into the -1 to -3 range for all but the extreme southern areas as snow overspreads the area. If the path/temp set up from the FV3 comes to pass, it's probably vastly underestimating the snow fall potential, especially from Nashville and points eastward. It has the precip shield just drying out with the LP over the Western Florida panhandle. I would be surprised if that were the case.

Euro has more mixing issues and more precip.  Not sure why the Euro has the mixing issues, 850s are very very favorable valley wide.

[Holston_River_Rambler]

EPS looks about the same as yesterday in terms of snowfall spread. ~30 members giving 1-4". Maybe 3 big dogs or so. 

[jaxjagman]

9 minutes ago, *Flash* said:

The simple fact you're posting these again is visual music to my eyes.

It's shouldn't be that far off to be all snow..IMHO,least right now

 

ECMWF Deterministic FORECAST FOR: BNA    LAT=  36.12 LON=  -86.68 ELE=   591

                             12Z JAN06
PRESSURE LEVELS  SFC  1000   950   925   900   850   800   700   600   500      
                 MB    MB     MB    MB    MB    MB    MB    MB    MB    MB      
                (C)   (C)    (C)   (C)   (C)   (C)   (C)   (C)   (C)   (C)      
SUN 12Z 06-JAN    3     7    11    11    10     9     8     2    -6   -13       
SUN 18Z 06-JAN   14    13    10    10    10    10     8     3    -5   -13       
MON 00Z 07-JAN    9    14    12    12    12    11     8     3    -3    -9       
MON 06Z 07-JAN    7    11    13    12    12    11    10     4    -2    -9       
MON 12Z 07-JAN    8    10    11    12    12    11    10     5    -1   -10       
MON 18Z 07-JAN   16    15    12    10    10    10     9     6    -1   -10       
TUE 00Z 08-JAN   14    15    12    11     9     8     7     2    -5   -11       
TUE 06Z 08-JAN   12    14    12    11    10     6     6     2    -6   -14       
TUE 12Z 08-JAN   12    13    11    10     9     7     5     2    -3   -13       
TUE 18Z 08-JAN   16    16    12    10     8     7     4     2    -5   -14       
WED 00Z 09-JAN   10    12     9     7     4     0    -2    -1    -6   -13       
WED 06Z 09-JAN    5     6     4     2     0    -2    -5    -5    -5   -15       
WED 12Z 09-JAN    2     3     0    -1    -3    -4    -7    -4    -5   -17       
WED 18Z 09-JAN    5     4     0    -2    -5    -8    -4    -1    -6   -17       
THU 00Z 10-JAN    2     2    -1    -3    -5    -7    -4     1    -6   -16       
THU 06Z 10-JAN   -2    -2    -6    -8    -9    -4    -1     1    -6   -17       
THU 12Z 10-JAN   -5    -5    -9    -9    -5    -1     2     0    -7   -17       
THU 18Z 10-JAN    1    -1    -5    -7    -5     0     2    -2    -8   -17       
FRI 00Z 11-JAN    0     1    -3    -4    -2     1     2    -3    -9   -17       
FRI 06Z 11-JAN   -2    -1    -3    -4     0     2     1    -4    -9   -17       
FRI 12Z 11-JAN   -1    -1    -2    -2     0     1    -2    -4   -10   -19       
FRI 18Z 11-JAN    3     3    -1     0     1     0    -2    -4   -10   -17       
SAT 00Z 12-JAN    3     4     2     1     1    -1    -2    -4    -9   -17       
SAT 06Z 12-JAN    3     4     3     1     0    -2    -3    -5   -10   -19       
SAT 12Z 12-JAN    1     1     0    -1    -2    -4    -4    -5   -11   -18       
SAT 18Z 12-JAN    2     1    -1    -2    -2    -4    -5    -7   -12   -19       
SUN 00Z 13-JAN    2     1    -1    -2    -3    -4    -5    -7   -13   -21       
SUN 06Z 13-JAN    1     1    -1    -2    -3    -5    -4    -8   -15   -24   

[John1122]

Massive shift on the 18z GFS. Front end thump for everyone just about  and then back end dump for eastern areas. The increase in precip made for an increase in 850s.  Another great track though in a much more favorable time of year vs the December event. 

[jaxjagman]

11 minutes ago, *Flash* said:

Not a huge fan of 925's/surface temps/surface wind direction* as most will need a better dynamic cooling mechanism, but the weekend trends are encouraging. Wherever the rain/snow line sets up, it will be the closest we've been in a month. Gotta start somewhere.

*This far out, seems the culprit for middle TN will be a warm finger, not a dry slot. Highland Rim locales in elevated areas will gladly take this as opposed to the other way around.

I concur,really want this to start at night time,not during the day

[jaxjagman]

 

That's not a horrible track on the FV3,the deformation band wouldnt be half bad coming in over night,but the thermals are still...meh

[John1122]

GFS remained similar to its 18z with a little less backend action. Still a front end snow event with overrunning. Pretty common way to get snow here. Canadian is similar with the front end but weaker than the GFS. 

The 850s are really encouraging on the GFS. Will just have to see if they remain so. They blowtorched all but the very far eastern areas in early December and were borderline even on the best modeling.

Basically the far Southeastern areas are the only ones with 850 issues this time out.  So I think that even the middle Tennessee areas that it's showing a little more rain in would have a good shot at staying all snow, especially with any decent rates, with such a cold layer in place. 

[John1122]

The Euro looked pretty good. Especially for the western 2/3rd of the forum area. 5-6 days out the Euro/GFS are close. FV3 amped and cutter but still gets wintry in our forum area.  Canadian fairly weak. Still all models show some decent accums around our region. 

[Holston_River_Rambler]

Not much to add to the Jan 13 or so storm this morning. 6z Euro looks basically the same at H5 (only available out to 90 hours). Fv3 and GFS remained about the same as well at 6z. UKMET out to 144 shows a similar evolution to the Euro. Nice that neither Euro or UKMET have the Great Lakes low that the Fv3 and GFS show and both are south of the American models. Interesting that the MSLP locations on the GEFS are mostly south of the Ops track and along the Gulf coast. 

EPS 0z snowfall also improved for the Jan 13 -15 period. Only about 6 or so members blank the forum and the general 1-2" I mentioned a couple of days ago has upped to 2-4" across maybe 15-20 members. Still a few big dogs with 6" or more solutions. 

 

Long range continues to look good. EPS, GEPS, and GEFS in that order:

It looks to me that the trend over the past few days has been an ever so slight delay, but pretty dang good agreement, once the flip happens. In my opinion the EPS looks the best of the bunch this AM.  

 

[Bango]

25 minutes ago, *Flash* said:

12z GFS is a screw job to middle TN. Thermals just don't seem like they'll cooperate this far out.

Take solace that Getting screwed means missing out on a statewide .5 inch or less

[Carvers Gap]

All depends on where you live in the forum area in terms of what a "good run" is.  The 12z CMC(to some extent the 12z ICON though snow amounts are less) is a good run for MBY because it consolidates the energy and takes it to our SE and then north.  The 12z GFS is basically a Miller B which takes a slp into the TN and sends warm air into the almost all of the forum area.  As Bango noted, not a good solution for anyone.  Still a lot of variations for this are out there.  I like the hp that was shown over the GL yesterday...but it seems just a bit too far to the north which might allow the system to drive west of the Apps.  I think the Miller B scenario is very plausible with the way the confluence sets up.  I would also not rule out a Miller A.  Either is possible, especially with several more runs before possibilities narrow.   I lean mostly rain on this one, but could easily be wrong, especially along the northern border of TN.  Sometimes NE TN can steal some snow if the Miller B transfers far enough to the southeast.  Models are all over the place right now which is indicative of the pattern getting ready to change IMHO.  If you live in E TN, you want the energy consolidated, passing to our south, and then NE.  If you live in middle or west TN, you want the slp to drive close to the spine of the Apps or just on either side depending on your location.  At this point, my confidence in it snowing more than inch IMBY would be considered moderately low.

[Carvers Gap]

I would recommend taking a look at the ensembles.  At this range, I would give the operational about the same weight as one of the individual ensemble members....though is trends would matter.

[Holston_River_Rambler]

UKMET looks Miller A/ B hybrid-ish to me:

 

Still not as north as the GFS, but UK took a step in that direction IMO. 

As Carver's said, several tracks on the table. In one way I'm glad I'm not in the bulls eye at 5 days and the major player key for all this an upper low that gets totally shredded on both American and Euro guidance as it hits the W Coast and then has to somehow reconsolidate to the lee of the Rockies:

 

 

Still a ways to go