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AMZ8990

December 2018 Pattern And Forecast Discussion

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The 0z GEFS looked to be heading into the Euro camp for d10-15.   The 6z left that camp, and doubled down on nationwide cold.  The GEPS continues w a nationwide cool down from Christmas onward.  The GEFS mean does hint at a winter storm signal from d10-15.  I am sure you all see the same things I see on the operational modeling in regards to that.  The 0z EPS moved quite a bit overnight by placing a bit more trough in the east.  It is almost(not quite) a reversal w its 850 d10-15 temps.  At 12z yesterday there were warm 850s over the SE.  This morning they are reversed w cold in the nation's mid-section and cooler air over the forum area.  Again, I look at 5 day means for trends in this regard.  The change is noticeable.  In some ways, it looks like modeling wants to go w a full latitude NA trough w the cold dropping west and spreading east.  Honestly, it feels like deja vu.  Last winter, the models were cold in the very LR, flipped warm, and then gradually returned to their original solution by late December.  Then, it turned very cold.  Anyway, understandably a very fluid situation at that range...and again, this is pure speculation and not a forecast.  

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42 minutes ago, AMZ8990 said:

I didn’t realize we were at -4 though

When I saw that on the NWS climate data, I thought I was reading it incorrectly. Didn't think there could be that much diff. across the state. As far as I can tell though, that was it.  

Also want to quickly ay that I was not trying to put words in anyone's mouth with my thought last night, just trying to say I saw what looked like a misunderstanding, so apologies if it came off as though I was trying to say anything else. 

No big changes as far as can tell this AM (EDIT for the above: mostly talking about cold returning overall and the strat. Carver's has got the 500 mb and temp trends covered). 

Stratosphere still looks like some sort of warming is coming, but actual effects at midlevels and surface/ how the warming itself evolves still up in the air. I would say that even if it happens (looks likely to me, though again how it plays out and eventual results are murky at best).

One interesting feature that the GFS is struggling with is some cut off 500 mb energy over TX/ N Mexico/ Gulf in the day 8-10 time frame.  GFS really wants it to just set there and spin for a bit. Today's 6z run it links it up with some N stream energy coming in hot and pops an east coast storm. This is just one run of one model at 8 -10 days so very, very unlikely at this point.  But I am interested to see how this evolves.  Having some energy sit over the Gulf or N. Mexico could get interesting in a variety of ways if the timing is good, but no point in talking details on anything like this I'd say until much closer.  Sure it could get tapped into as part of a bigger storm, but it could also just scoot out to the Atlantic.  Sometimes we use football analogies and I think a good one for this situation is the "if you want to beat a big team, keep it close into the 4th quarter". The longer that energy sits there, the more chances it has to cause mischief. It's there on the Fv3, maybe 5-6 6zGFS ensemble members have it, and I'd say maybe 30-40% of Euro ensemble members have it too, but everything deals with it in different ways at different times, as you'd expect with a cutoff at 8-10 days just close enough to the overall flow to be impacted by it. 

 

 

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Looks like the end of December is coming into a little better focus now. I'm thinking it might actually get seasonably cold Christmas week. Probably it will not be all week though. Could be another few warm days between Christmas and New Years.

A look at the tropical Pacific and Indian ocean shows a cluster of convection around Indonesia a warm signal valid coming right up. Some of it is diurnal though (weaker warm signal), right over the Islands, so a CF ahead of Christmas is reasonable. Meanwhile a bigger blob of convection lurks in the Indian Ocean. Should it emerge into the Pacific, viola the warm days between the Holidays.

Then the bigger return to cold pattern should commence in January. CFS wants another warm week, but nah. ECMWF weekly due out tonight has been cold. Both agree around Jan 7-10 get some robust cold going. That is week 5-6, but at least they agree. Look for the MJO to shift toward colder signal phases.

@Daniel Boone I was pretty sure you were talking about outside this subforum Region. I appreciate all of your posts! Certainly agree respect goes both ways. I give students/hobbyists the same professional treatment as Mets because it's the right thing to do. Everybody here has important knowledge from local effects to technical discussion. Flip side is I press, which is actually a sign of professional respect, because I know everyone here can provide reasoning.

At any rate we got a good thing going in this subforum Region. I do not plan to post about the Euro weeklies unless they change significantly. Figure January cold will start West and work in here. Timing could still be by the New Year.

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Jeff's analysis above definitely covers the range of outcomes from now until the cold potentially returns during the second week of January.  The 12z EPS is definitely back in the camp of a warm-up between New Year's and Christmas.  It does look like it is retrograding a trough from the West Coast to a position in the Pacific(SE of AK) where it could pump a -EPO in early January.

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Thanks Jeff, its all good man. Great analysis ! In hopes, with the right timing we can score a Christmas surprise. 


Yeah you do a great job and Tennessee fan here also.


.
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I am assuming that the quiet pattern discussion thread means that we all see what is cooking in the long range.   Looks like a cool shot around Christmas followed by roughly a couple of weeks of warm temps if the Weeklies are even remotely correct.  A quick look at the day-by-day means on the Weeklies show a trough in the West establishing itself after Christmas.  Sometime around January 7th, that pattern breaks down at 500 and BN heights develop slowly over the SE.  It takes maybe another 7-10 days for 2 meter temps to respond.  By the third and fourth weeks of January we are in business.  This is why Nino winters drive me crazy.  The are often backloaded for the second half of winter.  Even when I know this is going to happen, it tests my patience.  That said, we have stolen a couple of storms from the pattern already.  The progression is a classic, classic Nino progression.  Now, I don't like seeing the cold pushed back...but it makes sense.  (I also don't like what the JAMSTEC just outputted.)  As soon as I saw the big blue blob over AK, I knew the tough out West was going to be a pain.  

Now, the pattern is still highly active.  It can and does snow during warm-ups during El Nino winters.  We had marginal cold for this last storm and still managed a whopper in NE TN.  So, really all I can urge right now is patience as we begin what will likely be a warm 3-4 week time frame which will have some cold embedded.  I am just hoping that my warm-up prediction mojo reverts back to its November form.  Ha!

Now, for an ounce of hope...the American operational suite is not totally buying the prolonged warm-up and is blocky.  Per JB, how the Euro suite and American suite is handling the MJO might be different.  It may be possible that the Euro is stalling the MJO in phase 4.  If so, hence the warmth(Jeff mentioned that yesterday I thing) after Christmas.  I just have a difficult time seeing the trough tanked in the West knowing what we know about Nino winters.  One caveat, the SOI is (from what I understand) still hanging around in Nina territory. Also, the QBO just recently flipped positive....

Anyway...the skinny is warmth after Christmas for 2-3 weeks with a backloaded winter still likely.  My thinking has not changed a bit on that....

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Regarding d10-15....That was a significantly warm run of the 12z EPS.  The EPS within four runs has shifted d10-15 500 mean from a weak trough over the East to a very stout ridge.  The control has some daily +23C 850 temps AN over Michigan. +15C here late in that time period.  The mean for 850s is about +5-7C AN.  We can only hope this busts as badly as it did in November.   The actual mean 2m temps are roughly +4-7C late in the period(not a 5 day mean...).   The control has some daily 2m temps that are nearly +20C over the eastern Plains and western Ohio River Valley late in that time period.  Not as bad here, but you get the picture.  I give it much less credence after that month.  The GEFS is not nearly as bullish nor is the GEPS.  That is a pretty big swing by the EPS within four runs of the 5-day mean.  It is also out there where it is less than accurate, but still...the Euro suite has gotten very consistent with this look. 

One final note on the Weeklies.  The NAO mean was modeled to go negative around the New Year.   At the same time the -AO will couple with that teleconnection around the same time frame.  The +PNA goes weekly positive shortly after.  If you had just shown me the teleconnections, I would have guessed that the model output would have been much colder.  Maybe it is a source region problem after the Canadian torch passes through just prior.  Not sure.  So, it is unusual to see the model respond so slowly to those teleconnections in terms of cold.

I expected some warmth during an El Nino winter, but maybe not to that level....Hopefully this is muted as what is modeled on the EPS is well past anything that I had envisioned. Hoping the American suite takes the W on this one.  As for the Euro, this gif pretty much is for it.......

tenor.gif?itemid=3441243

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Now, we are about to test a theory from last spring.  I think there is some science behind it.  I just can't remember where I read it, and am too lazy on Friday afternoon to Google it.  Remember when the WAR went crazy, and then the strat split happened.  I wonder if exceptional warmth over NA(especially the eastern half), precedes it?  

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I feel like everything is in a wait and see mode, like the parts in a rube-goldberg machine are being built and about to be set off. There's so much going on that seems to be setting up more and once it all starts, where shall it go? 

We have a Nino that is a little west based, a little east based for now: sst.daily.anom.gif

We have a stratospheric polar vortex that is getting manhandled and redirected like a Cobra Kai kid trying to fight off Mr. Miyagi.

We have an MJO that is weakish (going by CPC latest discussion http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf, pages 16-17), but hopefully lining up to come back to the more favorable phases by early Jan. 

 

I think it will be interesting to see how all this plays out once it happens and how the models deal with it as it begins to impact their starting conditions.

 

I feel like Gandalf and Pippin in Return of the King: 

Pippin: "It's so quiet."

Gandalf: "It's the deep breath before the plunge."

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I should have added to my "parts" above, a southern stream that just keeps on keeping. Remember when this system we were dealing with now, looked like it would cut to the lakes? If you'd told me that it would end up as a cut off rolling over our heads at that time, I wouldn't have thought it. Usually once we get a good storm (not trying to say everybody did, but it was favorable for some) we have to reset. We kind of are, but these lows taking the low road just don't want to stop. 

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Additionally, it is worth noting that it was the GFS nailed that strat warm last spring from nearly 16 days out, and it also modeled the pattern that followed quite well.  It is notable that its warm-up is quite muted when compared to the Euro right now.  So, after we get through the pre-Christmas warm-up, it appears I will be 1-1(one loss, one verification) on warm-ups during the past two months.  I have yet to cast a lean or vote on the post-Christmas 2-3 week warm-up.  I am also not saying that it won't snow.  I do think the scales tip in our favor by mid-Jan though. As noted in other sub-forums, getting that trough out of the west and getting Canada cold/snowy is going to take some time.  To echo others, just have to be patient.  That said, we do not want this pushed past the third week of January.  For now, I will enjoy running on pavement...my usually jogging routes have been a wreck!

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11 minutes ago, Holston_River_Rambler said:

I should have added to my "parts" above, a southern stream that just keeps on keeping. Remember when this system we were dealing with now, looked like it would cut to the lakes? If you'd told me that it would end up as a cut off rolling over our heads at that time, I wouldn't have thought it. Usually once we get a good storm (not trying to say everybody did, but it was favorable for some) we have to reset. We kind of are, but these lows taking the low road just don't want to stop. 

Yeah, the southern stream is rolling for sure.  Ninos are notorious for 50s for highs and upper 30s for lows along with a consistent amount of precip.  Should have a nice surplus of water by spring.  If we can get some cold to interact over a 2-3 week period w that southern stream...I think we all would be happy.  And I don't think winter is done by a long shot.  However, it may take a longer break than I had anticipated...and I didn't have winter getting rolling until mid-Jan anyway.  So, I think we are on track in terms of climatology.  The JAMSTEC flipping warm definitely gets my attention.  Also, the stubborn Nina-esque SOI is also an issue.  But as you noted, we need to know where this strat split is headed....

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7 minutes ago, Carvers Gap said:

it is worth noting that it was the GFS nailed that strat warm last spring from nearly 16 days out,

What's crazy about what it is showing right now is that it is not only showing one wave of warming, but another one, just as strong at the end, that pushes the SPV toward our half of the hemisphere. Maybe this is pretty subjective/ confirmation bias (i.e. maybe I've only paid attention when it was showing warming)  but, I feel like it's been pretty solid, from even long leads this/ last month with how all the SPV situation has progressed so far. 

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Just now, Holston_River_Rambler said:

What's crazy about what it is showing right now is that it is not only showing one wave of warming, but another one, just as strong at the end, that pushes the SPV toward our half of the hemisphere. Maybe this is pretty subjective/ confirmation bias (i.e. maybe I've only paid attention when it was showing warming)  but, I feel like it's been pretty solid, from even long leads this/ last month with how all the SPV situation has progressed so far. 

Where the cold goes will be key....if we get a split or heavy nudge, we need the cold over here or at least split evenly between hemispheres.  But I am about above my pay grade w strat warm stuff.  I follow Amy Butler on Twitter.  She is usually money with these things.

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Yep, Butler is the way to go. Wholeheartedly agree.  I think the cold usually goes to Eurasia, but not always. I think I remember reading that it has something to do with the fact that Eurasia has more land in the high latitudes, but could also be misremembering something else.  I think it did go to Eurasia at first last year and then it slowly bled west and helped create a block that retrograded into a big -NAO.  As the flow blocked up, the storm track drifted south and eventually we got a good track, but it was something like mid March.  I remember thinking, man, if that had only happened about Dec 25th... Well......

One of her papers suggests that on average SSWs in El Ninos, (no distinction made for displacements vs splits) tends to lead to Greenland blocking and -AO over the 60 days following and, if I'm reading it correctly, that this is more likely during a Nino winter than a Nina.

https://www.earth-syst-sci-data.net/9/63/2017/essd-9-63-2017.pdf

Of course a SSW still has to happen and Butler isn't sold that it will be a major one just yet. 

In terms of blocking I think I'd prefer a more amplified PNA ('93; hey I can dream) to get waves under us and aimed at the Gulf to reduce the risk of the dreaded Miller B or A/B hybrid (worse for my location because it gives false hope), but these can work for others in the area so I will be happy for them if they do well.  And if I can get snow out of some wonky Miller B with uber cold, I'll take it. 

EDIT Here we go: https://www.esrl.noaa.gov/csd/groups/csd8/sswcompendium/

Butler's compendium in the public domain. Anyone can go in, select a date for a SSW and an anomaly, and get a reanalysis plot for 0-30, 0-45, or 0-60 days

If nothing else it gives us a list of events for comparison.

 

 

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Finally managed to grab an EPS stratosphere map (from the NE forum) for comparison. I think it's happening. EPS, GEPS, and GEFS agree. Big question is how big (warm) is it and does this affect us (mid-late Jan- Feb)? And how does it all evolve as it happens? 

I think it offers a reshuffle, but the question is, which deck did we start the game with, and which game were we playing? 

eps strat .png

 

That is to say, how do our current and particular iteration of ENSO along with low solar and other base states this year impact and change this as it evolves?

 

 

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So this system next Friday/ Saturday looks a little interesting. Around half of the EPS members give some area in our region some snow with it, whether it be dynamic cooling snow as it wraps up the coast, or NW flow. 

As it stands now, it's not too far from being a big Gulf low riding up I 95.

Curious to see how it evolves over the next few days, for better or worse. I'll post an Fv3 image here. Euro a little further west/ more cut off with the energy dig. Not a terrible look for 5 - 6 days. 

fv3p_z500_mslp_us_27.png

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6 hours ago, Holston_River_Rambler said:

So this system next Friday/ Saturday looks a little interesting. Around half of the EPS members give some area in our region some snow with it, whether it be dynamic cooling snow as it wraps up the coast, or NW flow. 

As it stands now, it's not too far from being a big Gulf low riding up I 95.

Curious to see how it evolves over the next few days, for better or worse. I'll post an Fv3 image here. Euro a little further west/ more cut off with the energy dig. Not a terrible look for 5 - 6 days. 

fv3p_z500_mslp_us_27.png

Yeah, I've had my eye on this for a few days. Probably too progressive (I.e. 'cold chasing rain' scenario) at the end of the day. At the same time, the aerial teleconnections intrigue me. The NAO is retreating to neutral/slightly BN as the +EPO briefly relaxes. The +PNA is in our favor helping to sharpen a neutral-tilt trough. 700/850/925 will cooperate by 156 (off 0z GFS), but as always, will we have enough moisture left in the tank? 925 too warm at 150. Perhaps it will be snowing like crazy a few thousand feet above our heads. Also, this is mostly my eyes talking, but the trough seems notably sharper than the ridge here. Accordingly, I'm not buying the low cutting east of the Aps let alone a sufficient cold source. But hey...at least it's something to watch which we should all take in phase 3-5 MJO. 

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12z CMC/GFS continue to show interesting elements to the weekend storm (pretty sure 0z Euro has the signal as well). Plenty of vort maxes to go around but where they set up is key. Atmospheric carousel at 500 mb. Sooo much spin regardless of what slice of the atmosphere you select for your animation.

Side note: As some of you know, I lost out on chasing Diego last Sunday due to my wife’s illness so I probably should say my interest in this storm is largely based on the probability of finding appreciable snow three hours from MBY. Thus, any optimistic tones will be influenced by regional trends in the days ahead. Figured I’d share that as a quick disclaimer. Hopefully whatever digging we need for the forum will get diggin’ soon. 

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Both the 12z GEFS and GEPS show the way out of this upcoming warm-up around the New Year.  JB commented in a post today that the 0z EPS was finally beginning to depict an eastern NA that is compatible w a phase 5 MJO.  Once we get the 500 pattern to switch-up around Jan 1, then it will take about 7-10 days IMHO before we see the first affects at 2m in the SE.  The huge wildcard in all of this is the SSW that is lurking.   Does the strat split?  How does it impact NA?  We saw last spring how abruptly things can change in terms of blocking.  Even the latest Weeklies depicted this abrupt switch w its teleconnections, but for whatever reason the mid-latitudes failed to respond in a way that one would think w those in place.  Of note, the pattern reshuffle has been pushed back a couple of weeks which is no surprise.  For my future reference...those deeply BN heights are a signal of a western cold shot that is very slow to mitigate.  Additionally, if the strat indeed splits...the antecedent warmth over eastern NA is remarkably similar to last spring before it split.  Again, is that a hint that the troposphere is responding in a symptomatic way to the upcoming change or is it proactive element at the lower levels of the atmosphere?  Finally, if we get a decent cold snap of duration during the second half of winter following a December warm-up...that is right out of the El Nino playbook.  I will probably go w Bob Chill in the MA forum(hopefully this is correct), I am not a huge fan of waiting on back-loaded winters.  Thankfully, we had some winter early on.  And I do remain fairly confident(as confident as one can begin when trying to predict chaos), that this winter will feature a second half that holds much winter wx potential.

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MJO just got out of the IO today into the more warm phases.Looks like a potential wet pattern upcoming.Towards the end of the month there should or could be a potential severe threat.I like what Carver said above.All signs seem to be going into the right direction.It really looks good especially towards mid Jan.,we'll see :)

RRWT   Consonant Chaos.png

1.png

2.png

3.png

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I think that's (Wayne Browning?) High Knob Landform (https://www.highknoblandform.com/)  guy. I love his blog. Based on topography I could see how High Knob could kill Big Stone Gap's snow. Still unbelievable how "microclimate" that must have been if Wise got snow and BSG did not.  Wise ought to be downsloped too, I think. I guess there is that big hill between the two on hwy 58. 

Awesome that a local paper is publishing info about things like ageostrophic forcing.  

Is "Thermally Indirect Mesoscale (TIM) Circulation" a thing? Works for me, but haven't heard it before. 

AND High Knob got 40" !!!!!

amazing. 

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4 hours ago, Holston_River_Rambler said:

I think that's (Wayne Browning?) High Knob Landform (https://www.highknoblandform.com/)  guy. I love his blog. Based on topography I could see how High Knob could kill Big Stone Gap's snow. Still unbelievable how "microclimate" that must have been if Wise got snow and BSG did not.  Wise ought to be downsloped too, I think. I guess there is that big hill between the two on hwy 58. 

Awesome that a local paper is publishing info about things like ageostrophic forcing.  

Is "Thermally Indirect Mesoscale (TIM) Circulation" a thing? Works for me, but haven't heard it before. 

AND High Knob got 40" !!!!!

amazing. 

At that point when we are talking about such localized areas the idea of microscale meteorology comes into play. Where even the hills begin to cause a significant effect on the weather in a given location. The truth is the effects of these mountains are always in play always affecting the weather. It's just that winter storms especially with borderline temperatures can better visualize this effect with the amount of snow. A difference between 72 and 75 degrees is negligible but a difference between 32 and 35 degrees can mean all the difference between a dreary day with some snowflakes passing by and being absolutely buried. In a few years time in this hobby I have learned to respect the influence of terrain on microclimates. This storm only furthered my perception of the importance of location especially in regions with mountainous terrain. It leaves me to wonder how anyone could accurately forecast for an area in a major mountain range like the Rockies or Alps.

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