December 2018 Pattern And Forecast Discussion

[Holston_River_Rambler]

On 11/26/2018 at 2:59 PM, Holston_River_Rambler said:

I don't think sliders or overrunning or clippers or -NAOs are going to get it done in the split flow

Starting to look like I may be eating crow on the sliders next week (gladly), although I do worry it will try to cut more and be more of a Miller B type coming in from that trajectory. No bueno for Knoxville, but maybe better for TRI/ Blunderstorm/ and Western areas. Still way off though. One thing I find interesting about this set up is the amount of energy. The FV3 keeps trying to have a more southerly secondary piece of energy develop (12-12) after the main wave (12-9/ 10). 18z GFS has it but makes more of a connection with piece one. 

Another thing I think is interesting is that the EURO/ CMC has this 12/4 - 5 system much more suppressed, but still has a similar solution for the 12-9/ 10 one. How would look on the GFS if the more southerly solutions on those two actually come to pass? 

Final thought in an image:

On the left is GFS forecast for 12/12/18 and on the right is 12/10/14. Not perfect matches and one still to be determined,  but the overall 500mb and surface pattern is close. Thought I'd put that on the table after the discussion of 14-15 as a similar year. 

[Carvers Gap]

18 minutes ago, Holston_River_Rambler said:

Starting to look like I may be eating crow on the sliders next week (gladly), although I do worry it will try to cut more and be more of a Miller B type coming in from that trajectory. No bueno for Knoxville, but maybe better for TRI/ Blunderstorm/ and Western areas. Still way off though. One thing I find interesting about this set up is the amount of energy. The FV3 keeps trying to have a more southerly secondary piece of energy develop (12-12) after the main wave (12-9/ 10). 18z GFS has it but makes more of a connection with piece one. 

Another thing I think is interesting is that the EURO/ CMC has this 12/4 - 5 system much more suppressed, but still has a similar solution for the 12-9/ 10 one. How would look on the GFS if the more southerly solutions on those two actually come to pass? 

Final thought in an image:

On the left is 12/12/18 and on the right is 12/10/14. Not perfect matches, but the overall 500mb and surface pattern is close. Thought I'd put that on the table after the discussion of 14-15 as a similar year. 

LOL.  All of us hobby folks eat crow all of the time.  Don't feel bad.  Sometimes we are on the money and sometimes off the mark.  Heck, I missed the entire month of November.  Won't be the first and definitely won't be the last.  Just the way it goes.  

Still way out there...this thing might cut, might be a coastal, might be a slider.  I think it fits well with the NAO rising and end/reset of a cold time frame.  Definitely worth a look, and you may still be right.  Plenty of options still on the table.

I am liking the 14-15 analog.  That said, I dug up another analog, 94-95, that I am looking at as it has a similar 500 setup and ENSO state.  Seems like that winter was a dud, but I can't remember.  Anyone else know?

[Holston_River_Rambler]

I remember 94-95 as not so good. I have distinct memories (the whole reason I'm addicted to this stuff) of 93 and 95-6.  I remember 94 (Jan - Feb) as cold, but that is about it. 

Went back through the 94-95 500 mb and surface reanalysis (Dec. 1 -April 1). There is a weird cutoff around Dec 20 -23 and Jan 15-17; March 2 or so looked like it might have had potential and March 8-9. Other than that, several of storms cut right across TN. 

Ray's (http://www.raymondcmartinjr.com/weather/) doesn't have much, but he doesn't always include southern events. 

Radar, Dec. 2014: https://mesonet.agron.iastate.edu/current/mcview.phtml?prod=usrad&java=script&mode=archive&frames=1000&interval=60&year=2014&month=12&day=1&hour=0&minute=0  (Dec. 4 - Dec 6, 2014 looks very similar to what's depicted on 18z GFS, Nov. 30 -Dec 2, 2018; at least for surface reflectivity)

The Iowa site I use only goes back to 95, so no Radar from 1994.

[Carvers Gap]

Here is what I am kicking around.  This is not a forecast.  It is not even a serious idea at this point, just something that I looked at this evening.  It is likely an example of a winter where there should have been winter during Jan/Feb...but I seem to remember it as a dud.  This is why analogs are squirrelly (they can be deceptive).  94-95 was barely a moderate El Nino.  It, however, was aging and would eventually move to a La Nina soon after the winter season.  The top graphic is December of 2014 and then the second graphic is the Jan/Feb that would follow.  I am admittedly cherry picking, folks.  This probably ought to go in banter.  The bottom graphic is d14 of the 12z EPS(that one, the model that is struggling at that range...so buyer beware).  Look how similar the top and bottom graphic are.  One big difference though is eastern Eur-Asia.  The shape of and placement of the cold over AK is similar as is the warmth over eastern NA. Notice that the Jan/Feb graphic looks very similar in its portrayal of elongated cold along the EC.  I don't have a ton of confidence in this as an analog yet, but just sharing it.  If weighting analogs just based on the LR models today...prob would give 06-07, 14-15, 94-95 some consideration.  But again, I want to stress that I am not even sure the Euro suite is correct...see the monster post earlier.  ***Update: One BIG difference between this year and 1994 is that the 500mb heights look quite warm for November of '94.  Those graphics have not been included so as to save storage space.*** 

 

 

[John1122]

November 94 was a blowtorch, +5 AN in my area. December continued that trend and it was +5 as well. January was +1 and February was -2 with a few snow events. The biggest was 6 inches in early February. It was one of the top 5-10 warm Novembers around the Valley region in the last 70 years.

[Carvers Gap]

11 minutes ago, John1122 said:

November 94 was a blowtorch, +5 AN in my area. December continued that trend and it was +5 as well. January was +1 and February was -2 with a few snow events. The biggest was 6 inches in early February.

Thanks for that.  I had updated the November piece probably just right before you posted....that is indeed a major difference.  That said, we had major warmth to begin this fall.  I don't think we get anywhere near +5...the first couple of weeks will be too cold.  I don't disagree completely with the January or February progression though.  I thought the 500 maps were close enough to consider.  To be fair one is a snapshot of one day during Dec while the other is an analog of an entire month.  And I think it does illustrate how analogs can be a bit deceptive in their nature.  Still, it will be interesting to see.  If anything, even though 94-95 was a dud here, the overall pattern evolution is not terrible.  +1 during January will work north of I-40.  I also think it shows that El Nino winters can come back even if there is warmth during December, and that some Ninos still don't pan out even if they do.  I lived in Knoxville and was at UT during that time, so I have no memory of what happened during Kingsport at the time.  Like I said, just kicking around the year.  I am still not buying this EPS trend quite yet.  I want to give it a few days to see if it moderates like it did last time.

[Daniel Boone]

5 minutes ago, John1122 said:

November 94 was a blowtorch, +5 AN in my area. December continued that trend and it was +5 as well. January was +1 and February was -2 with a few snow events. The biggest was 6 inches in early February. It was one of the top 5-10 warm Novembers around the Valley region in the last 70 years.

Yeah, a terrible winter overall. Severe storms and flooding in the heart of it. Feb. Was cold with several minor snowfalls (1-2" deals)here. March ha a rain to thundersnow event that produced a quick 4 inches in the valley's with much more upper Lee County and Wise Co. and Harlan and Letcher counties in Ky. Where over a foot fell.

[John1122]

Tri-Cities coldest Januarys + November anomaly.

January 1977 coldest at Tri. November 76 coldest ever at Tri -9.2.

January 1978 2nd coldest at Tri. November 77 AN same as Crossville.

January 1940 3rd coldest at Tri. November 39 -5.

January 1985 4th coldest. November 84 -5.

January 1970 5th coldest. November 69 -7

January 2014 6th coldest. November 13 -4.5

January 1981 7th coldest. November 80 -2.8

January 1966 8th coldest. November 65 -.5

January 1948 9th coldest. November 47 -3.2

January 1979 10th coldest. November 78 +3 (2003 was colder at Crossville and came in it's top 10 over 1979, 2003 was 11th at Tri)

This year is odd in that Tri and Crossville are around .5 of each other in what constitutes normal temps. All these years are the same during the era of record keeping at Crossville for coldest Januarys and the November temps are easily within 1 degree or so at each location. Except this year Crossville is at -6 and Tri is at -2. Huge gap that seems to have never been the case over the last 70 years.

 

 

 

[Carvers Gap]

Also, a heads-up to everyone.  Give me about 5-10 minutes after a big post.  Sometimes I can't see the full post in my editor.  So, I will post and then amend if something does not look right.   Also, I try to get typos as well(some self inflicted, some due to autocorrect).  

[Carvers Gap]

5 minutes ago, John1122 said:

Tri-Cities coldest Januarys + November anomaly.

January 1977 coldest at Tri. November 76 coldest ever at Tri -9.2.

January 1978 2nd coldest at Tri. November 77 AN same as Crossville.

January 1940 3rd coldest at Tri. November 39 -5.

January 1985 4th coldest. November 84 -5.

January 1970 5th coldest. November 69 -7

January 2014 6th coldest. November 13 -4.5

January 1981 7th coldest. November 80 -2.8

January 1966 8th coldest. November 65 -.5

January 1948 9th coldest. November 47 -3.2

January 1979 10th coldest. November 78 +3 (2003 was colder at Crossville and came in it's top 10 over 1979, 2003 was 11th at Tri)

This year is odd in that Tri and Crossville are around .5 of each other in what constitutes normal temps. All these years are the same during the era of record keeping at Crossville for coldest Januarys and the November temps are easily within 1 degree or so at each location. Except this year Crossville is at -6 and Tri is at -2. Huge gap that seems to have never been the case over the last 70 years.

 

 

 

John, what does this November rank for TRI just on its own with no correlation to January?  I do think -2ish seems about right.

I think the cold centered in a more vertical fashion just west of here...that likely caused the disparity between the recording sites.  At first, I thought something might be up with the KTRI station.  However, it looks about right given the national map.  It is just a lot colder as one goes west on the November temp map in TN.

[John1122]

The November/January correlation is the same for BNA as it is for Crossville. Same years as well. So being -4 for the month in Nashville should be a positive there. Knoxville has 3 different years vs those two, 1918, 1994 and 1912 for their top 10 coldest January temps. All three of those saw -2.5 to -4 for November. Knoxville and Cha may be the only stations in the region that didn't have January 1977 as the coldest. They are 3-5 degrees warmer than Tri, Crossville and Nashville for January of 77. Must have gotten warm nosed more often.

[John1122]

5 minutes ago, Carvers Gap said:

John, what does this November rank for TRI just on its own with no correlation to January?  I do think -2ish seems about right.

I think the cold centered in a more vertical fashion just west of here...that likely caused the disparity between the recording sites.  At first, I thought something might be up with the KTRI station.  However, it looks about right given the national map.  It is just a lot colder as one goes west on the November temp map in TN.

Tri is at -2 through yesterday and will fall some with todays cold anomaly. It's currently the 26th coldest November at Tri. If it falls to -2.4 from it's current (very possible) and could finish there it would rise into the top 20 range of coldest Novembers.

It's bizarre as this looks like the first time it's happened in such a dramatic fashion, or at least the first time since Tri has been keeping records. Literally every other year is very close across the entire region. The rest of the Valley region from Jackson Ky to Knoxville to Chattnooga to Huntsville is within 2 or so degrees of each other and Tri is 4 degrees different. 

[John1122]

5 minutes ago, *Flash* said:

BNA UHI will forever annoy me. Dickson is -6.1 as of today. Only 40 minutes west of Nash...the negative departures increase rapidly.

The departures are also around -6 just to the East of Nashville. It's an ever expanding heat corridor with so much development in the metro area.

[Carvers Gap]

25 minutes ago, John1122 said:

Tri is at -2 through yesterday and will fall some with todays cold anomaly. It's currently the 26th coldest November at Tri. If it falls to -2.4 from it's current (very possible) and could finish there it would rise into the top 20 range of coldest Novembers.

It's bizarre as this looks like the first time it's happened in such a dramatic fashion, or at least the first time since Tri has been keeping records. Literally every other year is very close across the entire region. The rest of the Valley region from Jackson Ky to Knoxville to Chattnooga to Huntsville is within 2 or so degrees of each other and Tri is 4 degrees different. 

Yep.  Reminds me of the 1970s maps that I used to see on TV.  Here is the updated map for departures across the US.  The temperature gradient is almost NNE over TN.  I think it illustrates nicely the difference in west TN and extreme E TN.  That is one cold November for most of the lower 48 and a good chunk of the NA continent.  Credit to WxBell for the map.

[John1122]

I first read that map as f departure but then notice it was c departures. Still may be a shade too warm.

[Holston_River_Rambler]

There's a really weird set up evolving for the Dec. 4-5 period. It looks like there is a block over the N. Plains forcing everything south. This potential has actually trended south instead of a cutter.  Even if we don't see any wintery weather it will be interesting to see how it evolves and how it impacts the 8-10 potential once it finally moves through.

 

[Carvers Gap]

Medium range note:  That d9-12 time frame still has a decent signal.  The 0z EPS snow mean jumped a bit overnight for that time frame.  The individual members of the ensemble did have some sliders again on this run. Tough really to know any details since it is so far out there.  However, with the depth of this cold and with the NAO rising...that is a pretty good signal for an EC storm.  What we will want to watch is over the next few days is the trend of that snow mean.  (I don't really watch that mean for actual numbers, just to see if the model is seeing a storm.) I have said before that what comes after this weekend's warm-up is what interests me.  

Analog note:  Then after that window....we have a relaxing of the pattern or even a switching of the pattern - IDK which.  I did notice this AM that WxBell did include 94-95 in one of their analog frames FWIW.  They showed the DJF individual month maps for El Nino years w/ super Ninos exuded.  We the 94-95 discussed that last night.  I do like a blend of 94-95, 06-07, and 14-15 as analogs.  

Quick LR note (after the snowstorm window): JB seems to think that the ridge that will roll through mid-month will eventually lift northward, the AK trough will relocate southeast of its modeled location, and the thought will return to the SE by sometime in early January.  That BN height feature over AK could potentially scour Canada of cold.  If it does, once the trough returns it may take a week or two for the source regions to reload...unless the cold in AK discharges into the eastern trough which would speed up the process.

[Carvers Gap]

FYI...from MRX.

Special Weather Statement
National Weather Service Morristown TN
1001 AM EST Thu Nov 29 2018

NCZ060-TNZ012-013-035>037-067>069-071-072-083>087-100>102-291645-
Cherokee-Scott TN-Campbell-Morgan-Anderson-Union-Roane-Loudon-
Knox-NW Blount-Blount Smoky Mountains-Rhea-Meigs-McMinn-
Northwest Monroe-Southeast Monroe-Bradley-West Polk-East Polk-
Including the cities of Murphy, Oneida, La Follette, Wartburg,
Clinton, Oak Ridge, Maynardville, Kingston, Lenoir City,
Knoxville, Maryville, Cades Cove, Dayton, Decatur, Athens,
Madisonville, Coker Creek, Cleveland, Benton, and Ducktown
1001 AM EST Thu Nov 29 2018

...BRIEF SLEET OR FREEZING RAIN POSSIBLE...

A narrow band of showers is moving east off the Cumberland
Plateau and into the Tennessee Valley this morning. Temperatures
are currently hovering near or below freezing where this
precipitation is occurring, and there have been reports of some
light sleet and slick roadways as a result. Some light freezing
rain could occur at higher elevations on the northern plateau.

By 1130 am, temperatures should warm up enough to change
precipitation to all rain. However, until that time some
additional travel hazards could occur so please use caution this
morning as some roads and bridges could have a light glaze of ice
on them.

[Carvers Gap]

3 hours ago, Holston_River_Rambler said:

There's a really weird set up evolving for the Dec. 4-5 period. It looks like there is a block over the N. Plains forcing everything south. This potential has actually trended south instead of a cutter.  Even if we don't see any wintery weather it will be interesting to see how it evolves and how it impacts the 8-10 potential once it finally moves through.

 

Good catch.  Not a bad deal...storm cuts to the Lakes, drives cold air down, and then something slides or develops on the front coming through.  The 12z ICON has a decent upslope event right after that wave along the front.  Watching the rest of 12z roll in as I type.  

The 6z FV3 has a ton of energy in the pattern throughout the run FWIW.

[Carvers Gap]

Will be interesting to see the 12z Euro and FV3.  0z had two storms, one in fantasy land.  The 12z ICON, GFS, and CMC have some variation of the storm if I remember correctly.  I suspect we will see plenty of different variations.  Again, we are now talking December and climatology gets more favorable with each passing week.

[John1122]

That's a snow map north of 40 most of the time on the GFS. That HP over SE Wisconsin would deliver enough cold North of 40 to get the job done in most cases. It's a fairly cold air mass with it, temps appear in the mid-10s under it at mid-day.

 

[Carvers Gap]

12z FV3....Welp.  The snow map is impressive...and it isn't over even at 240 which is as far as the map goes.

[John1122]

Yep, it has a rain to extremely heavy snow changeover for elevation areas/north of 40. It also appears to be showing rain on it's map but counting it as snow.  Oddly, it has a weaker high further west and less favorable track than the GFS but the source cold with it is much much more impressive. Below 0 cold in the midwest.

Looking at the 850s etc, they are bizarre on there, with random areas of the map being above freezing while areas south are below freezing. Also shows heavy snow over my area with the 850s never getting below freezing until 9 inches have fallen and the 540 line 150 miles NW of me. It shows part of NC under the 552 line, 75 mile NW of the center of the LP getting heavy snow.

All in all, I'd say the snow map is way off. Probably be freezing rain in NW NC, and all rain here.

[nrgjeff]

Warm one-eyed pig continues to be delayed. Confidence is high it will happen; but, it is looking less like the monster it did before. I'll give it 7-10 days in mid-December. @Carvers Gap analog post is reasonable. Dateline convection is already trying to regenerate (cold signal), which would start to battle with the (warmer signal) convection farther east. MJO forecast is a mess, because the actual convection is in two clusters.

Also, the AK ridge has been stubborn. AK troughs have tended to be transient. More broadly, even when it is not Alaska, other areas of blocking remain forecast in the Arctic and near Arctic. Finally, surface press is AN in much of the Arctic. My gut thinks the atmosphere is just cold for parts of the US this year.

My only hard spot is little interest in storm tracking in the immediate future. During cold/stormy periods, NWP does not show cold air in place at the right times. However that could change esp a week out. Then the warm period comes through. After that it will be the heart of winter. Hopefully around the Holidays or shortly after things will get interesting. Wishing for snow.

[Carvers Gap]

1 hour ago, nrgjeff said:

Warm one-eyed pig continues to be delayed. Confidence is high it will happen; but, it is looking less like the monster it did before. I'll give it 7-10 days in mid-December. @Carvers Gap analog post is reasonable. Dateline convection is already trying to regenerate (cold signal), which would start to battle with the (warmer signal) convection farther east. MJO forecast is a mess, because the actual convection is in two clusters.

Also, the AK ridge has been stubborn. AK troughs have tended to be transient. More broadly, even when it is not Alaska, other areas of blocking remain forecast in the Arctic and near Arctic. Finally, surface press is AN in much of the Arctic. My gut thinks the atmosphere is just cold for parts of the US this year.

My only hard spot is little interest in storm tracking in the immediate future. During cold/stormy periods, NWP does not show cold air in place at the right times. However that could change esp a week out. Then the warm period comes through. After that it will be the heart of winter. Hopefully around the Holidays or shortly after things will get interesting. Wishing for snow.

Well, we know when the late November warm-up was forecast...it was delayed and then muted.  Just looking at the 12z GEFS, the mid-Dec timeframe is already much better than it was just a few runs ago.  The dateline convection should teleconnect to a ridge up over the west coast, right(due to the config of the El Nino)?  If the warm-up is just generic warmth or short in duration....that tells me to beware of any LR BN heights setting up shop in AK.  It looked suspicious then....transient would be reasonable.  Definitely hope we continue the base cold pattern.  I think the MJO is causing havoc w modeling, I agree.

I have been flipping through Nino analogs, a good many of them flip cold sometime in early and mid-Jan.  An even bigger number have cold a February.  Interestingly, many of them have a warm-up that precedes the hammer dropping.  Seems like this year is following the script.  Hope it continues.

 

 

[BlunderStorm]

1 hour ago, Carvers Gap said:

12z FV3....Welp.  The snow map is impressive...and it isn't over even at 240 which is as far as the map goes.

Ha, realistically I imagine a low that close would cause a warm nose that would overrun all of us in the east.

[Carvers Gap]

9 minutes ago, BlunderStorm said:

Ha, realistically I imagine a low that close would cause a warm nose that would overrun all of us in the east.

That particular solution would likely drag plenty of cold in with it.  We have dealt with so many weak systems, I can barely remember how a true GOM originated storm works.  Heights would crash quickly.  Was nearly a perfect comma.  Strong coastals that originate in Louisiana and move just inside Hatteras can have snow, sleet, and rain in them.  Some even begin as rain.  When I was younger, we were good with that.  We knew that as the system turned the corner it would change over.  Most truly great winter storms will drag some warm air.  Still a long way to go...but a fun run!

[John1122]

This map isn't as extreme as the map on tropical but it's still close.  The majority of it falls in a 6-10 hour period of heavy wet snow. The areas in our forum area that see snow are generally around 32-33 at the surface, 32-33 at 925 and 32-33 at 850 during the snowburst. It was easier to see temps on Pivotal than on TT.

 

The thing that makes me think there is some kind of model issue or model interpretation issue is that areas of my county show 9-10 inches falling on the southern end and 3-4 falling on the northern end. But when you look at the snow depth map on Pivatol the southern end of Campbell has 5 inches on the ground and the northern area has 7. So clearly something is wrong with the output from the model. Those areas of 8-10 inches in NE Tn show up as 2-4 inches on the ground and some central Eastern Valley areas have more on the ground than what is shown falling.  I don't think that the specifics of this storm are remotely set yet and these snowfall maps are next to meaningless when talking about what will happen on this particular day. But I'm posting them more to speculate on a potential model output issue and keep it in mind going forward.

 

Snow depth

[Holston_River_Rambler]

25 minutes ago, Carvers Gap said:

We have dealt with so many weak systems, I can barely remember how a true GOM originated storm works

Preach it!!!! I want to see one again even if I only get rain out of it.

I've also seen other people (I think WxUSAF in specific) in MA forum say that the FV3 accumulation maps are garbage and ought to be thrown out all the time. 

I know the 12z Euro has a cutter now, but I like its H5 look better from yesterday 12z to today 12z.  Nice PNA ridge and if that N stream dove just a little more... https://imgur.com/a/A39C4mG 

Some talk in the NE forum that the EPS is as good as can be at over a week out, but I don't have access yet. 

Blaarrg! way too early for me to get invested, but I'm addicted. It seems like it's been a long while since there was model agreement on something coming. Cutter, slider, Miller A coastal, Miller B, whatever it becomes, may be wrong, but I think it's coming. 

And like y'all said:  Lord have mercy at the FV3...

In terms of overall pattern beyond, I noticed in the MA forum they've traced the talk of the Modoki's demise back to Crankywx on Twitter. Psu blames another person (fBeccalynch4 I think), but that person is just quoting crankywx and tweeting his images. Based on what I've read from him, I wouldn't put it past him to troll people who wanted a Modoki for its perceived snowiness. But, in watching this unfold, I've noticed that there are two different types of SST maps being used. One comes from a guy that tweets about ENSO in S. America, (map 1:  https://imgur.com/a/thNks9H )  And another is this one: https://www.esrl.noaa.gov/psd/map/clim/sst.shtml They are similar, but one seems a little more dramatic to me since it is zoomed in. In no way trying to start a big debate on ENSO, but was interesting to see how all the talk evolved. 

In a related note, for anybody who wants to learn how to read a hovmoller diagram (I definitely wanted to since I see them all the time on here and had no idea how to interpret one), griteater has a great explanation in the SE forum (page 106 of their mid-long term discussion). 

 

 

[BlunderStorm]

27 minutes ago, Carvers Gap said:

That particular solution would likely drag plenty of cold in with it.  We have dealt with so many weak systems, I can barely remember how a true GOM originated storm works.  Heights would crash quickly.  Was nearly a perfect comma.  Strong coastals that originate in Louisiana and move just inside Hatteras can have snow, sleet, and rain in them.  Some even begin as rain.  When I was younger, we were good with that.  We knew that as the system turned the corner it would change over.  Most truly great winter storms will drag some warm air.  Still a long way to go...but a fun run!

Yeah, you are right as the storm curved the cyclonic wind flow would turn in our favor. Still, so many things have to go just right for something the FV3 depicts. You really need a stout cold air mass behind it. It will be interesting to see what the models eventually settle on in terms of the path the storm takes in the coming days. I'm hoping for one significant event before Christmas. I know it's a long way out but my fingers are crossed. More in range it looks like Wednesday may have some snow showers after the next cold front passes on Tuesday.