February/March 2020 Winter's Last Chance Thread

[Carvers Gap]

While we are killing time waiting for the next set of model runs.  Check out Horse Shoe Farms in Hendersonville, NC, just over the mountain from the E TN folks.

https://www.resortcams.com/webcams/horse-shoe-farm/

[Carvers Gap]

12z GFS is fairly strung out.  Jumps on the second wave of energy.  Third wave is there but gets tamped out.  Anyway, if you look at the mslp 6rh precip map on TT...at 162 that is a better organized system with a comma shape.  Maybe a bit more organized than 6z?  Now my day gets busier.  Hopefully will be able to check back.  

[nrgjeff]

I agree with Carvers that we are hunting for a quick break within an awful pattern. The coveted 2-3 weeks of cold is almost off the table. The freak storm on a sharp baroclinic boundary? Heck, that can happen into March historically. Seriously, I think in the current regime we have February to get lucky.

Normally sustained cold is hard to come by after February 15. However a one-off snow can happen almost as easily in late February as in early Feb. Even if the troughs do not reshuffle (see Carvers previous pages too) the other path is a stout system ginning up on that (forecast) tight temperature gradient early to mid-month. Upstairs the jet stream will probably be strong too. Miracles can and do happen on sharp baroclinic zones. 

Of course it could be heavy rain or severe too. Despite my rants, look for me in the severe thread, I still hope for something winter. Forget the charts for just a minute. January and February I consider the snow months. It's only half-time.

November and December are dark cold months, less daylight than here at the end of January, but also less snow. While starting 3rd period (hockey) for cold temps / met winter, it is just half-time for snow. Of course it needs to be below freezing to stick daytime after 15 Feb.

And we need some really big breaks!

[jaxjagman]

8 hours ago, weathertree4u said:

Here is the link...

 

That's a pretty sickening look the last couple decades

[weathertree4u]

13 minutes ago, jaxjagman said:

That's a pretty sickening look the last couple decades

Yea, allot of dates after 2000

[Carvers Gap]

Well...shall we talk about the disappearing eastern ridge on the EPS?  LOL.  The 12z Euro operational has no western trough - zip.  It has a cut-off and that is it.  It ain't great, but the trough in the West does not hold.  The 12z EPS is much different for the better.  Have a project going on this afternoon.  Maybe I need to do that more often.  The SER is over TN for no more than 72 hours.   EPS backs up the operational in that it cuts of a low in the Southwest.  The "parent" trough moves east and leaves it.  The cut-off tries to form a new trough which is promptly kicked into the middle of the country and eventually eastward by the -EPO.  Not sure any of that jives with the MJO, but those are pretty massive improvements at 500.  One could make a case now that the trough never holds in the West just based on that run(there are reasons it could be there in reality...mainly the MJO). The SER on that run of the EPS is literally just rolled out.  That run is a continuation of the trend to cut-off the low in the Southwest, and that changes everything downstream.

Nice run of the 12z Euro which definitely puts E TN in the game for snow with the third wave.  Nice look.

In a hurry.  Feel free to discuss.  Nice improvements across the board on the Euro.  Will they continue?  Who knows.  LOL.

For those new to the board, @nrgjeff with a great post above.  Just another reason we have a great subforum and why I will be pulling for the Chiefs on Sunday.

That is all from me until later.  Have a great weekend, everyone!

[Carvers Gap]

One last nugget until later.  The EPS control is an eastern trough from Feb 5 to the end of the run with zero western trough.   It just reloads with one cold shot after another.  Everyone knows the rules...huge grain of salt as reversals can always be reversed.  

[Holston_River_Rambler]

1 hour ago, Carvers Gap said:

.  The EPS control is an eastern trough from Feb 5 to the end of the run with zero western trough.

18z GFS on board too, but later in the run. 

[PowellVolz]

One last nugget until later.  The EPS control is an eastern trough from Feb 5 to the end of the run with zero western trough.   It just reloads with one cold shot after another.  Everyone knows the rules...huge grain of salt as reversals can always be reversed.  

The 5th is Wednesday. Surly we can somewhat trust a mod at d5/6?


.

[jaxjagman]

3 hours ago, weathertree4u said:

Yea, allot of dates after 2000

 

Middle Tennessee Weather History

 

On January 31, 1951...
Five inches of snow and ice fall, much of it during the evening, producing a water equivalent of 3.83". This is the greatest one-day precipitation event for January in Nashville's history.

 

This was a heck of a storm in  1951 this time frame

https://www.weather.gov/ohx/1951icestorm

[Carvers Gap]

19 minutes ago, PowellVolz said:

The 5th is Wednesday. Surly we can somewhat trust a mod at d5/6?


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It they all showed something like that.  Maybe.  The spread on modeling after the 10th is massive.  Trend is to diminish the western trough on the GEPS/EPS...but the MJO is a major problem.  While the GEFS has been woefully inaccurates, prob going to need to see it jump on board.  I have been out of pocket much of the afternoon.  I will dig through the emsembles this evening if I get a chance.  Before I get too invested, I am going to need that run of the EPS ensemble backed up by several runs.  My guess is that things are going to keep bouncing around.  This has been a one step forward, two steps back kind of winter.  I am ready for two steps forward abd one step back.  

[Carvers Gap]

I think the Euro control shows one option.  If the low truly cuts off in the Southwest...that is a plus.  That would mean the main trough could roll into the East.  But is it right?  Anyone claiming certainty this winter will be humbled quickly.  The GEFS at 18z shows another, less wintry option. Lots of great discussions on this forum about the pattern in November repeating itself during winter.  Would be neat to see that idea bear some fruit.

[PowellVolz]

I think the Euro control shows one option.  If the low truly cuts off in the Southwest...that is a plus.  That would mean the main trough could roll into the East.  But is it right?  Anyone claiming certainty this winter will be humbled quickly.  The GEFS at 18z shows another, less wintry option. Lots of great discussions on this forum about the pattern in November repeating itself during winter.  Would be neat to see that idea bear some fruit.

Isn’t the Euro notorious for screwing up energy leaving the four corners region?


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[Carvers Gap]

4 minutes ago, PowellVolz said:

Isn’t the Euro notorious for screwing up energy leaving the four corners region?


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Oh yeah.  On top of that the West Coast has been a mess on ensembles for several days after Feb 10 with some solutions that have been head scratchers.  We have overcome poor MJO phases in prior winters, but we have to have a lot of cold in the pattern to do it.  

[PowellVolz]

Oh yeah.  On top of that the West Coast has been a mess on ensembles for several days after Feb 10 with some solutions that have been head scratchers.  We have overcome poor MJO phases in prior winters, but we have to have a lot of cold in the pattern to do it.  

I believe I read that it has rained everyday since December 20ish in Portland


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[weathertree4u]

56 minutes ago, PowellVolz said:

 

I believe I read that it has rained everyday since December 20ish in Portland


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Portland Tennessee? I believe it!

[PowellVolz]

Portland Tennessee? I believe it!

Oregon


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[Carvers Gap]

1 hour ago, PowellVolz said:

 

I believe I read that it has rained everyday since December 20ish in Portland


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LOL.  That is crazy.   We want their trough.  They want our ridge.  

[jaxjagman]

Looks like a pretty crappie look through the Feb,but the details they decribe look about accurate as there looks to be a more stationary Equatorial Rossby Wave around the IDL with Kelvin moving through the IO the next couple days that gets into or around the IDL mid month,past that the MJO signal gets murky

Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks
NWS Climate Prediction Center College Park MD
300PM EST Fri Jan 31 2020

Week 3-4 Forecast Discussion Valid Sat Feb 15 2020-Fri Feb 28 2020

A complicated perspective emerges when considering possible tropical drivers of the midlatitude circulation as of late January. Over the past week the RMM index tracks the Madden-Julian Oscillation (MJO) inside the unit circle with an accompanying uncharacteristic westward shift driven by equatorial Rossby wave activity, with a recent re-emergence over the West Pacific (Phase 6). Decomposition of canonical equatorial waves suggests this signal is tied to a Kelvin wave near the antimeridian, while dynamical model forecasts of the RMM show the MJO re-emerging over the Indian Ocean or Maritime Continent by the second week of February. At the lower frequencies, the sea surface temperature (SST) gradient remains robust across the Pacific in an east-west sense, with the latest Nino 4 SST anomalies of +0.9 degrees C and Nino 1+2 checking in at -0.2 degrees C. Persistent negative outgoing longwave radiation anomalies have been observed near and just west of the Date Line since late November. Given this complex perspective, any possible MJO influence is downplayed as the envelope appears to be in flux at present with the Phase 6 signal being tied to Kelvin wave activity that typically fails to couple with the extratropics. The convective pattern over the Pacific does project weakly onto a subseasonal El Nino-like response, despite SSTs increasing from east to west. As a result, the resultant Week 3 and 4 outlook primarily leverages dynamical model guidance with some deference to long-term trends and a slight adjustment toward canonical El Nino conditions.

Dynamical model circulation guidance generally features a robust negative Pacific-North American (PNA) pattern with a positive North Atlantic Oscillation (NAO), both of which are consistent with the Week-2 forecast. These patterns translate into an amplified 500-hPa pattern featuring anomalous ridging south of the Aleutians, positively-tilted troughing over the West, and ridging extending from Mexico through New England. The outliers lacking this pattern come from the Subseasonal Experiment (SubX) model suite, in the way of the CCSM4, GEFS, and FIM models. These three models feature more ridging over the west and weakness or troughing in the East, in line with the typical MJO response to a Phase 6 event. Given the apparent Phase 6 signal being Kelvin-wave oriented, these models are discounted in the construction of the final outlook.

Much to the chagrin of any snow lovers in the East, the continued NAO+ outlook and enhanced subtropical ridge over the Southeast favors a tilt toward above-normal temperatures, while the MJO re-emerging over the Maritime Continent would likely further lock in east coast warmth. Troughing across the West results in below-normal temperatures being favored, although there is some uncertainty regarding how far south and east any cold air mass would extend. A west-east dipole favoring above- and below-normal temperatures respectively is forecast across Alaska tied to the forecast ridge-trough pattern across the Pacific and western North America. El Nino influence across the Northern Tier tends to wash out long-term trends which are slightly below-normal, while decadal trends further support the increased chances for above-normal temperatures in the east, resulting in these probabilities being enhanced relative to the dynamical model guidance.

The PNA- pattern supports a suppressed Pacific jet resulting in below-normal precipitation chances for areas adjacent to the Gulf of Alaska and along the West Coast. Dynamical models extend below-normal precipitation chances across the Southwest, further supported by decadal precipitation trends being negative for the region. There is some uncertainty with how far north and east this dry pattern would extend, further confounded by upslope precipitation potential along the High Plains tied to below-normal temperatures behind the anomalous trough. A mean frontal zone can be inferred at the trough-ridge interface, resulting in above-normal precipitation chances being elevated from the Lower Mississippi Valley through Ohio Valley.

SST anomalies in the vicinity of Hawaii continue to range from +1 to +2 degrees C, supporting above-normal temperatures being favored across the islands. Model guidance supports a weak gradient in precipitation with wetter (drier) conditions favored across eastern (western) portions of the state, in line with observed conditions across the state in early 2020.

 

[Holston_River_Rambler]

Long range pattern is like a Venus fly trip this year, and we are the fly, lol. It has decided we are getting wise to its tricks, so it must sweeten the nectar to draw us back in:

We have to double reverse psychologize the pattern by acting uninterested, lol:

 

[Holston_River_Rambler]

In more critical news, would be nice to see a EPS spaghetti plot to see if that is just a washed out with a variety of solutions, or if that sort of bland, general trough over North America is what many members see. 

[Holston_River_Rambler]

0z GEFS kinda bit on that look too. 

[Holston_River_Rambler]

The more I think about it this year, I wonder if these long range flip flops are due to how strong the SPV is and how well coupled it has been. It's like have a single cyclone determining the N Hemisphere pattern. Any little change affects everything. 

[weathertree4u]

3 minutes ago, Holston_River_Rambler said:

The more I think about it this year, I wonder if these long range flip flops are due to how strong the SPV is and how well coupled it has been. It's like have a single cyclone determining the N Hemisphere pattern. Any little change affects everything. 

I hope all of those are rhetorical questions you are posing because at this point I do not know of very many that can or have been able to figure this pattern out with any certainty much less where we are headed; based upon the way the models have done recently, I would say it is another head fake as much as I want to believe the opposite!

[Holston_River_Rambler]

@Carvers Gap Strat got interesting overnight after a few bland runs:

Euro (sadly only out to ten days):

Yeah it does reconsolidate n the Euro, but that is the first time this season I've seen the Euro do anything like a split at the 10 mb level. Before it only made it up to 50 mb. 

GFS:

shows how that reconsolidation could be like a rubber band being stretched. Once you stretch it out, even if it temporarily returns to its original shape, there's still built up momentum that has to be worked out

[weathertree4u]

3 minutes ago, Holston_River_Rambler said:

@Carvers Gap Strat got interesting overnight after a few bland runs:

Euro (sadly only out to ten days):

Yeah it does reconsolidate n the Euro, but that is the first time this season I've seen the Euro do anything like a split at the 10 mb level. Before it only made it up to 50 mb. 

GFS:

shows how that reconsolidation could be like a rubber band being stretched. Once you stretch it out, even if it temporarily returns to its original shape, there's still built up momentum that has to be worked out

Interesting - which of the two models has done better with this, not only in this season but in the past?

[Carvers Gap]

So, I think there are still two camps.   Trough digs into the West or low gets cut-off in the West and the trough comes East.  Great arguments for both, but at least there are two camps and not the one crappy camp.  The 0z EPS doubled-down on the eastern trough never leaving after the 5th.  Glad to have it in our corner as it generally scores the best.  The 0z GEPS lends it some support but later.  The 0z CMC cuts off the low.  The 6z Euro operational does so, but not as much as 12z yesterday.  0z GEFS is western trough. The GEFS has been awful of late, but I think we still need it before feeling better about trends.   @jaxjagman's share about the MJO definitely should sober-up even the most diehard snow lovers in the crowd - me being one of those.  

So some things to really watch:

1.  The EPO ridge.  It was very strong on the Euro operational and on the EPS.  It does show some retrogression into the Aleutians on the EPS but is also strong on it.  

2.  Does the EPS teleconnect well?  Sort of.  Sort of not.  Europe cools which is a good sign and that fits with the eastern US being cool.  Aleutian highs don't exactly scream cold in the eastern US.   There is sort of a weak weak low east of Hawaii.   Heights do build into most of Alaska which teleconnects well to cold in the East.

3.  The MJO.  Have to think the MJO looks worse on the GEFS when compared to other models.  The only think I can think that is driving the EPS is that the cold simply is so strong that it just wins the day.

4. Source region for cold.   How strong is it?  Source regions have not been terrible this winter.   Fairbanks, Alaska, just logged a really cold January according to Joe D'Aleo.  We just haven't had a mechanism to get it here.  

5.  Changing wavelengths.   I would guess that the shorter wavelengths would make a big, western trough less likely.  Granted, the EPS is actually longer wavelengths.  LOL.

6.  Does the low cutoff in the Southwest?  As @PowellVolznoted the Euro has a tendency to hold energy in the Southwest too much.  Right now, it seems to do it the least.  Seems like the GFS/GEFS combo are having more troubles or they are scoring a coup.  So we are probably stuck with two ironies here.  Either the Euro solved the Southwest cut-off first or the GFS scores a coup.  Not sure which horse to bet on there.

7.  AO region in Canada.  That might be the one of the main differences in the GEFS and EPS.  The EPS raises heights in that region

Final thoughts:  As many have suspected, that low in the Southwest holds the key after Feb 10th along with where the EPO ridge is.  As noted last night, there is a lot of spread just after the trough comes through next week, but a good chunk of February probably rests on what happens in about a 24-48 hour timeframe in the Southwest and whether it cuts off.  Time will be at a premium today for me and tomorrow.  Busy times.  As for 12z...I am not holding my breath, but am also hopeful.

[Carvers Gap]

1 hour ago, Holston_River_Rambler said:

@Carvers Gap Strat got interesting overnight after a few bland runs:

Euro (sadly only out to ten days):

Yeah it does reconsolidate n the Euro, but that is the first time this season I've seen the Euro do anything like a split at the 10 mb level. Before it only made it up to 50 mb. 

GFS:

shows how that reconsolidation could be like a rubber band being stretched. Once you stretch it out, even if it temporarily returns to its original shape, there's still built up momentum that has to be worked out

I think what we have to hope for is that is gets beat-up enough that it won't be as consolidated as it was during January.   We just need it to not be wrapped-up so tight.  I probably should have placed this in my "things to watch" list.  Good find.

[Carvers Gap]

Feb 5-7 window update:

Looks like the deal where we get three waves of energy is still in play.  The 0z CMC has a great track for portions of middle and west TN.  That model has been better or equal to the GFS lately if what I have read is accurate.  Both the GFS and Euro have the final wave, but are too far to the east to make a difference for E TN - but just by a hair.  Will be interesting to see if modeling jumps on one of the three waves and really accentuates on of those last two waves.   Not letting my guard down, just in a hurry.  

[Holston_River_Rambler]

1 hour ago, weathertree4u said:

Interesting - which of the two models has done better with this, not only in this season but in the past?

GFS has done better the past two years, but this year's SPV is a beast.