December/January 2019/20 Winter Speculation Thread

[Mr. Kevin]

2 hours ago, Carvers Gap said:

...Also, the temps under that 500 pattern are not warm.  Be sure to look at temp anomalies along with the 500 pattern.

Carver, i am in ne Arkansas btw. SSW events like i have been mentioning are tricky. I guess we shouldn't focus on them too much. I would like to get cold from them. Its been a long time since we have. Mjo is confusing people right not it seems like. What it will do moving forward. 

[TellicoWx]

13 hours ago, Carvers Gap said:

Great winters can definitely happen due to SSWs and they can also ruin good patterns IMHO.  Notable SSW events that really enhanced and helped great winters to occur were Jan 1977, Jan 1985, and Jan 2009.  IMHO, last year's SSW did actually propagate correctly to tropospheric levels.  That SSW split into multiple vortices.  Incredible cold and blocking did result as a trough tucked itself over the northern Rockies for months.  Island Park, Idaho, set multiple snow records.  As I had mentioned before, I was in MT/WY/ID during late March and early April of this year.  In West Yellowstone, the snow was stacked up to second floor windows.  They did not have much winter prior to the split of the PV which was a result of the SSW.  February was epic.  Folks couldn't even get to the river's edge on the Madison near 3$ Bridge without skis.  Then, they had to find an entry point to the water.  Some drifts were 10-12' high at the river's edge.  For us, it screwed-up a return to a decent pattern.  Remember how November was cold and that has a reasonable correlation to a cold winter.  Well, the pattern changed on time to a warmer pattern last December after a massive head-fake to cold(multiple head fakes seem to be common during SSW events).  The SSW lasted for much of the second half of December, and the PV split.  The West, which hadn't had much winter at all, then had winter on steroids that lasted well into late June.  

As a note, warming at 10mb, 30mb, and 50mb can occur much earlier than the actual PV split event at the troposphere.  There is great debate (on whether an SSW that does not result in a PV split at the troposphere) can result in major changes in weather at the surface.  I am in the camp that the warming itself is a great indicator of blocking.  What is the great unknown is where the blocking actually develops.   The SSW during later winter and spring of 2018 resulted in a very cold spring with plenty of frozen precip and cold during March and early April.  It took some time for the troposphere to react to that event.  Last winter, the atmosphere reacted well before the event even occurred.  So another variable is lag time.  Those two variables, lag time in affecting the surface and where the blocking sets up, create total havoc in modeling.  We don't have enough analogs to really know how that occurs.  Things like ENSO, solar, and QBO also have to factored into SSW events...and that creates incredibly small analog packages.  

As for the great winters of '77, '85, and '09.  The all had them.  Again, it is important to remember that SSW events usually begin well before the PV splits.  Seems like '09 had warming early in December.  The winter of '85 was a pretty ho-hum winter until mid January.  I don't remember much in NE TN that was overlay notable prior to that split.  The second half of that month and early February would be the some of the worst winter weather(interpret "worst" act cold and snowy) that I have ever experienced.  Spent many sub-zero nights in a crawl space trying to fix broken pipes with my dad.  I remember how tough it was to actually get the frozen water out of the pipe so it wouldn't melt later and ruin the solder joint for the new pipe.  The winter of '85 reminds me very much of what the northern Rockies experienced last winter...very average winter that suddenly flipped to extreme cold and snow.  I don't remember much about '77, just that it was really snowy.  It is of course, the benchmark of what many will say is winter.  

In conclusion, SSWs don't always result in PV splits.  However, IMHO they can still impact high latitude blocking, but not always.  During an SSW look for abnormally strong spikes in teleconnection indices.  Big unknowns about SSWS and ensuing PV splits are where the blocking sets up and how much of a lag(time from SSW to PV split at high altitude to propagating to troposphere) there is.  Those two variables IMHO can create total havoc in modeling.  A small rule of thumb that I use is that when bitterly cold air is dropped into NA, weather models go haywire.  I have also noticed that SSWs can cause models to flip-flop at the last minute as they did last winter.  Many great winters did not have SSW events, but the many of the worst ones have them.  Also, someone check and see if 14-15 had an SSW - that winter is probably the snowiest winter that we have had since 95-96(not an SSW) in Kingsport.  

Great discussion, everyone, and Happy Thanksgiving!

You didn't happen to hijack the teleconnects on the LR EPS today did you lol? AO mean has been slowly stepping down the last 3 runs for Dec heading into Jan (now in the 0 to +0.5 range for monthly average). If the trend continues and we can get into the 0 to -0.5 range, there is 10 timeframes that fall into that area. Once you start eliminating the ones that don't closely resemble QBO, Nino 3.4...etc the list narrows to 3. Here's an overview on one of the 3...Nino 3.4 (.8), AO (-0.24), QBO (1.69), PNA (-.5), NAO (-1..outside the range, but models keep hinting at one), EPO (negative regime DJF)..and featured a SSW split.....Dec 1977. Thought it was funny 1977 was brought up, then when the teleconnections came in and was looking at different similar analogs, 1977 pops up (first time so far). I usually start with the AO mean (if don't have a cold source, rest dont amount to much), then comb thru every other indice and trend to narrow the list. Still on the fence for this winter, but the analog years have been getting better last few runs (was spitting out only torch years 2011, 2006, 1951 examples). Last couple runs have come up with some better ones like 1977...1986 was an interesting ones last run. Mainly cause it is remembered for the record cold, but up until Dec 20, 1986 TYS was actually AN temp wise...then the bottom completely fell out.

[John1122]

The GFS is hilariously inconsistent in the LR regarding theA0/ NAO region. You couldn't have a bigger flip on the 18z to 00z runs.  

[weathertree4u]

1 hour ago, John1122 said:

The GFS is hilariously inconsistent in the LR regarding theA0/ NAO region. You couldn't have a bigger flip on the 18z to 00z runs.  

As far as I can tell the model, the one thing consistent is that the long range will always be different!

[Carvers Gap]

5 hours ago, John1122 said:

The GFS is hilariously inconsistent in the LR regarding theA0/ NAO region. You couldn't have a bigger flip on the 18z to 00z runs.  

The 0z EPS had some fairly big shifts as well in the LR.  I would lean warm for mid-Dec, but I think things are far from settled as evidenced by the flip-flopping.  Maybe things will settle down as we leave the shoulder season.  Not sure I like the trends...but as weathertree stated, just wait for the next run as it will be different.  

 

[Carvers Gap]

Pretty ugly looking MJO forecast from the Euro and GEFS this morning.  Must be starting to see the convection from the IO moving into MJO regions.  The Euro/GEFS look like they are going to attempt to take a crawling tour of the warm phases of the MJO.  That means that once we turn warm in mid-December, could be a while before the cold returns if that verifies.  Not a great sign.  We better hope that SSW delivers...if not, the possibility of a fairly warm December with a touch of torch at times is on the table and possibly extending well into January.  It is true that there are some similarities to last year from a forecast perspective - meaning flip flops.  Still, not sure many expected a cool(edit) December this year as opposed to last year's bullishly cold winter forecasts.  I hadn't looked at the MJO forecast when I made my earlier comments today...I would say that(in my mind) the chances for a warm December have risen to roughly to a 70-75% chance.  That is still not written in stone - the SSW likely still wrecking havoc modeling as previously noted.  Then danger with that slow tour is that once the MJO cycles back to colder phases, does it skip them like last year and rotate back into warm phases?   At the speed the MJO is taking...that would not be a good thing.  It shouldn't do that during an El Nino and with the SOI where it is, but that would be a worst case scenario.  Maybe this year we get the reverse of last year...meaning modeling that has very poor source cold on ensembles flipping back to cold and holding.  A few runs of the GFS have hinted at the possibility in the LR, but those don't seem to hold.  Right now if I was isotherm, I would be feeling pretty darn good about that forecast.  I still hold out hope that the SSW is masking what actual hemispheric circulation patterns will be once it has run its course.

[Carvers Gap]

So...it appears we are back to last year's discussion of a back-ended winter.  I do think that works this year.  We have kicked around some "benchmark analogs."  I have no idea if we get close to those stellar winters.  However, the MJO taking a very extended tour through the warm phases likely does a ton of damage to the PV.  What that sets up is the PV being displaced during the second half of winter.  Yeah, I know...that is (edit)four to six weeks away.  However, many truly great winters didn't get going until mid-January.  Do I think we go wall-to-wall warmth (for the duration of winter) after next week?  No, but who knows.  The weather has a way of humbling those who speak in absolutes  as if they know what is coming next.  I don't claim anything but my opinion...and it certainly does not have to verify as true.  I like my forecast ideas that I posted back in June.  If I was going to tweak them, I would bring January to normal.  So, December would be AN.  Jan would be normal to just above.  Feb below normal.  But I am not going to tweak them.  Why?  I still think cold(maybe very cold air) lurks during the second half of winter.  Same conversation as last year...but this is not last year.  The QBO should be descending instead of rising to positive.  That is a big deal.  Unfortunately, looks like we will have to weather 2-4 weeks of AN temps beginning around mid-Dec.  If anything, I do think were are actually in a Nino pattern now as evidenced in that we are seeing highs in the 50s and lows in the upper 30s to low 40s.  Seems like much of the 90s had winters just like that, excluding some notable and well-discussed exceptions.  So, if we are in a Nino pattern...should get Nino results which is backloaded winter and a warm December.  Last winter, not sure the Nino ever coupled with the atmosphere. While it is certainly disappointing to see some warm ensembles and operational runs, it is no surprise.  But who knows, maybe we flip back and what is being modeled is just a relaxation and not a pattern change...good question that we don't have an answer to just yet.  Meanwhile, the SSW lurks.

[Carvers Gap]

....And the 18z GFS "Happy Hour" rides again.  The Miller A parade d10+...some warm, some cold.

[Carvers Gap]

That would be not one but two major storms during the d10-15 time frame on the 18z GFS.  Now let's see if subsequent runs depict storm in that time frame...they won't be exactly the same due to it be in the LR - just a general stormy pattern will suffice.  Might be we have to watch the timeframe from Dec10-15.  JB mentioned it this AM, but I brushed it off as a passing comment.  That said, plenty of storms parading underneath.  Not a lot of cold to work with, but such are El Nino winters.  El Nino winters can and do have snow during warm-ups.  My thoughts on temps are not really any different...but it might be a fairly stormy period even with the 500 configuration.  

[jaxjagman]

Be careful with the atmospheric River being shown this time of year in So Cali for our parts,usually it's when we see a more  battle with heights and it kicks out the Upper Level Ridge out to fast,if this was winter tho

[Holston_River_Rambler]

I think last year's December storm was while the MJO was in 3. Would fit for this year too if one were to materialize. 

Overall I'm still much happier with the tropical convection situation than last year. I think even the worst case depiction on the Wheeler diagrams only takes it to the end of 3 toward 4. Looks to me like most models want to take it back into the COD. 

The Euro definitely wants to extend the Pac jet, but also looks like the oft tweeted Sea of Okhotsk/ Kamchatka low that is helping to drive that jet is pumping up a big EPO ridge. 

Further east that translates to some blocking and maybe forcing some storms further south, just not sold yet that energy can get beneath us. But we have an interesting NWP coincidence where the Euro and GFS have energy in similar places over North America at the a similar time.

[The GFS gif begins after the Euro one ends, sorry for any confusion]. 

 

 

 

 

[jaxjagman]

If this type pattern would happen into winter i'd be a betting man we'd we would/could see a bowling ball into winter

[weathertree4u]

In this season of thanksgiving, I am thankful for those of you that can do the heavy lifting with model interpretation. I just would like one good snow this year, I do not think I am asking too much. 

[jaxjagman]

4 minutes ago, weathertree4u said:

In this season of thanksgiving, I am thankful for those of you that can do the heavy lifting with model interpretation. I just would like one good snow this year, I do not think I am asking too much. 

We havent seen but one good snow here in the last decade and this was in a Nina pattern

[weathertree4u]

Just now, jaxjagman said:

We havent seen one good snow here in the last decade and this was in a Nina pattern

We had a good snow a few years ago in February - I am north of Nashville - just seems like statistically this overall pattern should break - just afraid Nashvillians will be so spoiled with mild winters even the smallest storm will and does create havoc

[jaxjagman]

Just now, weathertree4u said:

We had a good snow a few years ago in February - I am north of Nashville - just seems like statistically this overall pattern should break - just afraid Nashvillians will be so spoiled with mild winters even the smallest storm will and does create havoc

Right,i left out"but one",i edited it it before you posted this.Think we got about 6 inches here and you got close to 10-12"

[Carvers Gap]

Great to see so many folks talking weather on a Friday night!  I generally follow a rule that the latitude that a storm enters the West coast is the generally the latitude that it exits.  Get storms entering around Los Angeles and that is generally good track for the forum.  Looks like we have some source region problems in terms of cold during that time of higher activity...The 18z GEFS looked workable.  So, some good afternoon trends which fits a strange pattern of warm overnight model suites followed by cooler afternoon suites...least it seems that way to me.

[jaxjagman]

I think this did expectionally well with the MJO and the +IOD the last time the MJO passed.It's seems to be consistently picking up on a paasing  Kelvin Wave  in the Eastern Pac,this would be part of Carvers time frame in the first week of Dec., but the MJO is showing nothing more than being suppressed into the Martitime,right now it seems to me the MJO could get into the western IO but then could weaken then right back into the COD afterwards,i really think the GEFS is more right with the MJO upcoming,least right now

[John1122]

Imagine this is the NAM doing its thing but MRX has me with a 70 percent chance of snow showers Monday. 

[Holston_River_Rambler]

RGEM looks really nice too. 

[Daniel Boone]

Most times models underdo nw Flow snowfall amounts. Particularly Se, Ky and portions of Lee, Wise and Dickenson Counties in Va.. It is these areas that get first "pick" at the lake and wrap around residual moisture. I don't know if this is incorporated in the model's, If not, it should be . Not just elevation. 

    Model's are only as good as what's programmed into or how accurate the data is going into them. 

[TellicoWx]

I wouldn't be surprised if some of the NW flow areas over perform tonight...column is saturated thru 700 and with the ULL passing overhead, the UVV looks good. Decent vertical lift to go along with the orographic enhancement.

[Carvers Gap]

Not a ton to add to Friday’s comments.  Another less than favorable overnight run. Let’s we if the afternoon suites yet again look workable.  Been an odd pattern in modeling for a couple of weeks.  I don’t see a ton right now that shows cold making it this far south and holding.  IMHO, going to have to wait until late December before things shake-up and maybe longer than that.  As stated earlier, I do hold out hope that modeling does flip back.  It could happen.  The last seasonal Cansips is out today. It has flipped completely to a western winter for January and February.  It has a sprawling ridge centered in the western Plains for December which encompasses most of the lower 48. Last year, winter modeling, excluding the Cansips I think, was almost universally cold in the East.  So, TIFWIW.  The SSW probably is going to input some chaos later this month.   Seasonal modeling can be iffy at best...but has some skill if specifics are removed and one looks for general patterns.

[Carvers Gap]

And the 12z GFS continues to advertise a potential storm period from Dec 10-15...hopefully we can get just enough of a cold source region to make that interesting.  

[Carvers Gap]

The oddity continues(probably coincidence)...and the 12z suite being cooler continues as the GEFS is quite a bit cooler IMHO over the lower 48 for the last half of the run.

edit:  I wouldn't say yet that it has broken with its recent continuity for d8-15, but its run-to-run change when compared to the 6z GEFS is pretty remarkable as it places more of a trough in the eastern half of the US.

Oops!...I accidentally put that in the obs thread earlier.  @TellicoWx had some great thoughts that followed.  Yeah, the 12z Euro has cooled as well with favorable trends during the d8-10 rang at 500.  We will see where the EPS goes...but the 12z suite is again favorable(so far) where the 0z was not as much.  The run-to-run trends on the Euro are pretty good.  Not sure I would say the models have flip-flopped...but if they were to hold that look for 3-4 more runs, then maybe that term might be applicable.  I do agree with Tellico that climatology and ENSO are good counter balances to keep things steady.  Climo does call for a warm December about 2/3 of the time for weak El Ninos...I also operate on the idea that nature tries to balance itself out as evidenced by the West having cold winters and the East some of the time.  The East is due for a cold winter.  While a warm December would certainly make my forecast from June look good....it wouldn't bother me one bit if it busted as being too warm.  I think a warm call for December is still a good one...but the 12z suite does show a more favorable Pacific developing around the 10th.  So, who knows!

[Carvers Gap]

12z EPS again has positive run-to-run trends in the d8-15 range...heights are higher over Greenland, BN heights over the Aleutians.  Let’s see if we can get several more runs like that.  Been difficult to come by...

Of note...a three wave pattern is depicted instead of four.

[TellicoWx]

Upstream radar looking fairly healthy for you NW facing guys.

[John1122]

I've been watching football and didn't even notice that MRX had issued wide spread winter products. Kind of surprising. Did models ramp up snowfall totals? Looked earlier like BL temps would be an issue below 2000 feet.

I'll take this any day of the week. 

Tonight Cloudy. A chance of rain in the evening, then snow likely or a chance of rain after midnight. Snow accumulation up to 1 inch. Lows in the lower 30s. West winds 10 to 15 mph with gusts to around 30 mph. Chance of precipitation 60 percent.
Monday Cloudy. Snow likely or a chance of rain in the morning, then a chance of rain or snow in the afternoon. Snow accumulation up to 1 inch. Total snow accumulation up to 2 inches. Highs in the mid to upper 30s. Northwest winds 10 to 15 mph with gusts to around 30 mph. Chance of precipitation 60 percent.

[John1122]

WVLT's current meteorologist really needs to learn the area. He just came on during the halftime of Chiefs Raiders, ran whatever house model they used that showed .1 to .3 over non Smokies areas and 1 inch at the highest areas and declared the "the highest elevations of the Smokies may get an inch at most". 

I'll be shocked if Newfound doesn't get 5 times that and LeConte might see a foot with it being the primary NW flow spot in the entire southern Apps. 

[TellicoWx]

31 minutes ago, John1122 said:

I've been watching football and didn't even notice that MRX had issued wide spread winter products. Kind of surprising. Did models ramp up snowfall totals? Looked earlier like BL temps would be an issue below 2000 feet.

I'll take this any day of the week. 

Tonight Cloudy. A chance of rain in the evening, then snow likely or a chance of rain after midnight. Snow accumulation up to 1 inch. Lows in the lower 30s. West winds 10 to 15 mph with gusts to around 30 mph. Chance of precipitation 60 percent.
Monday Cloudy. Snow likely or a chance of rain in the morning, then a chance of rain or snow in the afternoon. Snow accumulation up to 1 inch. Total snow accumulation up to 2 inches. Highs in the mid to upper 30s. Northwest winds 10 to 15 mph with gusts to around 30 mph. Chance of precipitation 60 percent.

The column soundings and UVVs have looked good up your way today from the ones I've seen..hope you bust high tonight.