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Pattern February Discussion Part II

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Storm5 said:
not gonna be able to dig that much with such a flat flow

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If you look at the 12z run from Thursday you can see too that the 500mb flow across the SE had already backed to the WSW and this run its NW...hard to get anything going diving down the backside of a trough unless it's a real monster wave. The kicking energy in the west isn't helpful either. The trend to separate the energy and delay the wave is at least enough to keep me mildly intrigued

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I wouldn't call it strange or odd just yet. Lets see what Jon's graphic shows and why the solution was not good this run.
 
Nope, we don't even get to see that spinning low OTS on this run... (may be there but even further OTS)
 
Sucks if this Friday thing doesn't work, cause you can see the cold really rolling out quickly and the torch building back in TX, ready to pounce!
 
Shawn said:
I wouldn't call it strange or odd just yet. Lets see what Jon's graphic shows and why the solution was not good this run.
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Well, the disturbance was doing good in till 132+. That's not the right angle for it to be coming in for a winter storm. The track is more like a clipper. The reason why I say this run was strange because the past GFS runs did not show this solution, not quite.

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For those relying on the GFS on this upcoming possible storm.......the trends aren't good for you...


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I don't think most folks realize how unusually positive the GEFS PNA prediction peak is for midmonth. I didn't realize how extremely rare this would be til this evening. Many members are predicted to either approach or even exceed +2.0 around 2/14-5! And the GEFS bias is actually not being + enough! Since 1950, only 3 days in all of DJF have reached +2.0!!! All 3 had +AO:

2/28/1983: +2.081 (ATL cold rain)
2/28/1968: +2.291 (ATL T of SN)
2/29/1968: +2.353 (ATL 2.3" SN)

Are we about to make history? Again, this is near the peak for much of the SE for major SN. Also, one of, if not THE, strongest correlations to SE snow and cold is when there is a +PNA. Furthermore, the MJO is forecasted to then be in high amp phase 8, which has averaged solid cold in the SE. As if that weren't enough, the bias adjusted AO is forecasted to be solidly negative, which also correlates to cold.

However, model consensus is currently suggesting no colder than slightly below normal around 2/14-5 and no threat of wintry wx despite this great combo. Might this change as we get closer?

I had put this together just before the 0Z GFS was released. I see that this run is, indeed, MUCH colder for ~2/13-15 than prior consensus. I think it is onto something.
 
How's the GFS ensemble members looking like...not the snowfall members but the surface members

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I'm merely about half intrigued by 10-11. I don't think this will end well though. Either we see nothing or we see a storm but it's much warmer.
 
00z gefs took a step back. it's not completely horrible but it's a step back IMO

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GaWx said:
I don't think most folks realize how unusually positive the GEFS PNA prediction peak is for midmonth. I didn't realize how extremely rare this would be til this evening. Many members are predicted to either approach or even exceed +2.0 around 2/14-5! And the GEFS bias is actually not being + enough! Since 1950, only 3 days in all of DJF have reached +2.0!!! All 3 had +AO:

2/28/1983: +2.081 (ATL cold rain)
2/28/1968: +2.291 (ATL T of SN)
2/29/1968: +2.353 (ATL 2.3" SN)

Are we about to make history? Again, this is near the peak for much of the SE for major SN. Also, one of, if not THE, strongest correlations to SE snow and cold is when there is a +PNA. Furthermore, the MJO is forecasted to then be in high amp phase 8, which has averaged solid cold in the SE. As if that weren't enough, the bias adjusted AO is forecasted to be solidly negative, which also correlates to cold.

However, model consensus is currently suggesting no colder than slightly below normal around 2/14-5 and no threat of wintry wx despite this great combo. Might this change as we get closer?

I had put this together just before the 0Z GFS was released. I see that this run is, indeed, MUCH colder for ~2/13-15 than prior consensus. I think it is onto something.
Click to expand...

Here's to hoping things are changing and possibly seeing something fun around my birthday. But then again we've seen those indices not play out...


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fc45fc3d89460a67661d19890b3df092.jpg
6beeaec8fed465a3ab864b6ad7ef494d.jpg


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I've seen worse gefs looks!?
 
I made this graphic after the 18z run, I'm sure it will still be helpful when looking at the 00z and subsequent runs as well
hETzoLX.png


Basically runs on the left are SE storms (1,2,3), runs on the right aren't (4,5,6).. top left is 12z OP run from yesterday, bottom right is 18z from today...

Visualized in thumbnails it's easy to see what we need to get lucky here.
-The west coast ridge needs to be more positively tilted, if you will...seen in frame #1. This allows that energy seen in frames 1-3 to dig deep into the SE. You'll notice there's no energy hanging back, it doesn't matter. Once that energy digs SE, it pulls that finger of strung out energy along the ridge with it, phases, and we have our storm over the SE.
-You'll see in #4 why a tall ridge is NOT what we need. Energy digs south, but the tail end of the energy is basically vertical, this leads to the storm going positive-tilt out to sea that run due to the ridge-axis being way too far east, thus the trough is way too far east.
-The "trend" for 18z Thursday on the GFS is moving the ridge east, that's not good. However, the GEFS mean trend is is beating down the ridge a bit, so that is a good sign and the 00z mean from tonight on the GEFS is over Arizona, which is good also.

Check out how flat the ridging is on one of our storm solutions
kpuJhrS.png


versus the most recent run
H5QGTE5.png


We need to see the flat ridging with energy digging early, as early as 120hrs or so, in order to cash in on anything significant here.
 
The 0z GFS OP did have the ridge taller at first but the ridge started to flatten out but it was too late. That's why we saw the low in a higher latitude on the 0z run than past runs. It depends on the cutter storm too, if that low from the cutter is further south this will make the trough dig deep causing the ridge to buckle taller. We want to see that low from the cutter more north at an earlier time to allow the winter storm to dive into the Plains and not the upper Plains.

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7ea793726117f8fcb7fd1ee99ca8516c.jpg


And here's the next frame. Very good! Also the western ridge is a little weaker and tilts more neutral than negative on this run.


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I just updated my NCEP NCAR Reanalysis Multivariate ENSO Index (MEI) thru January 2017... We're still just shy of La Nina conditions, and we would probably be even closer to neutral if it wasn't for OLR & Precipitation which have been the only components of the MEI that have remained consistently supportive of a La Nina this fall and winter, granted they're traditionally also the 2 weakest MEI constituents...

http://weatheradvance.com/home/weat...-Raw-Data-Rankings-1948-January-2017-v2.0.txt

NCEP NCAR Reanalysis Standardized Bi-Monthly Component Timeseries Jan Dec 2016.jpg

NCEP NCAR Bi-Monthly MEI Ranks (1987-Present)
Dark red = Super El Nino
Red= Strong El Nino
Orange= Moderate El Nino
Yellow-Orange= Weak El Nino
Regular text = Neutral
Very light blue = Weak La Nina
Light blue = Moderate La Nina
Blue = Strong La Nina
Dark Blue = Super La Nina

Screen Shot 2017-02-03 at 10.29.54 PM.png
 
whatalife said:
Here's to hoping things are changing and possibly seeing something fun around my birthday. But then again we've seen those indices not play out...
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Click to expand...

If we get the extremely rare +2 PNA, there'd be legit hope for around midmonth considering the -AO and MJO 8. Only 1 in 2,000 DJF days has had a +2 PNA (last one in 2/1983)!

I'm not giving up on 2/10 either. What I think is that there will be two opportunities, 2/10 and ~2/13-16. If 2/10 turns out be nothing, I have a feeling that midmonth is going to get mighty interesting. I think model consensus for midmonth is likely going to change and the much colder 0Z GFS for then may turn out to be the first hint of changes to come.
 
There was a slight increase in more than just minor events on this run but there was quite a few that completely whiff.
 
GaWx said:
If we get the extremely rare +2 PNA, there'd be legit hope for around midmonth considering the -AO and MJO 8. Only 1 in 2,000 DJF days has had a +2 PNA!

I'm not giving up on 2/10 either. What I think is that there will be two opportunities, 2/10 and ~2/13-16. If 2/10 turns out be nothing, I have a feeling that midmonth is going to get mighty interesting. I think model consensus for midmonth is likely going to change and the much colder 0Z GFS for then may turn out to be the first hint of changes to come.
Click to expand...

I totally agree. The Aleutian low will also be very strong on that second event.


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Another difference I see is that surface high slips down into the upper Plains at 126 while the 18z GFS had the high over the Dakota's with the low underneath it. With the high sitting over the upper Plains this causes the ridge to buckle taller as well. We don't want that surface high to slip off like that.


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The 00z NCEP model diagnostics disco is interesting! Here's what they favor for the initial cyclone as of 00z.



...SURFACE CYCLONE DEVELOPING ACROSS THE CENTRAL/NORTHERN PLAINS
ON MONDAY...

PRELIMINARY PREFERENCE: 18Z GEFS MEAN/12Z ECMWF ENSEMBLE MEAN BLEND


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Ncep thinks that the initial wave will be slower than the 00z GFS and they think that the 12z ecmwf is off its rocker.


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00z Euro is a carbon copy of the 00z GFS.


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The 0Z Euro has -a strong +PNA day 10 but not as strong as that of the 0Z GFS & w/o the solid -AO of the GFS. One thing that the GFS hasn't been messing up due to bias is the PNA prog. So, I'm looking for future Euro runs to have a stronger +PNA for midmonth and quite possibly make things more interesting.
 
GaWx said:
If we get the extremely rare +2 PNA, there'd be legit hope for around midmonth considering the -AO and MJO 8. Only 1 in 2,000 DJF days has had a +2 PNA (last one in 2/1983)!

I'm not giving up on 2/10 either. What I think is that there will be two opportunities, 2/10 and ~2/13-16. If 2/10 turns out be nothing, I have a feeling that midmonth is going to get mighty interesting. I think model consensus for midmonth is likely going to change and the much colder 0Z GFS for then may turn out to be the first hint of changes to come.
Click to expand...


This is climo at it's best! Direct correlations...as long as it precipitates :)...on those three rare occurrences. I can tell you it is going to be bitter cold when it comes because I have an idiot tree that is putting out leaves behind my house, and another I can see beyond the back yard is leafed out and green as can be, albeit, early spring type leaves. That is just asking for the hammer :) T
 
Pretty good run it looks like on the snow mean from the 6z GEFS. Better for NC/SC, but not as good for TN. I'm guessing there's still 2-3 good members and the rest are whiffs. Interested in hearing if the EPS from overnight improved any.
snod.conus.png
 
More analysis of the 6z GEFS brings much better news. The trough orientation on this run is further west and the western ridge is not as tall. This matches Jon's post earlier about what needs to happen for a SE storm. Here is the 0z and 6z at the same time:
0z
500wh.conus.png


new 6z
500wh.conus.png
 
From what I can tell on the EPS, the trough has shifted farther west from yesterday's run (12z) with the western ridge not quite as tall.
 
packfan98 said:
From what I can tell on the EPS, the trough has shifted farther west from yesterday's run (12z) with the western ridge not quite as tall.
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the eps was horrible for the period we have been discussing . wants nothing to do with it.

moreover, the 06z gefs was a big step backwards from the 00z run. the number of members showing any type of reflection dropped way off

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Storm5 said:
the eps was horrible for the period we have been discussing . wants nothing to do with it.

moreover, the 06z gefs was a big step backwards from the 00z run. the number of members showing any type of reflection dropped way off

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Oh well. All of my research and analysis was for naught I guess. I thought things were looking more favorable with the 5h set up. I wasn't trying to lead folks astray.

I'm a little surprised the individual GEFS members didn't look better. The snow mean jumped up quite a bit from 0z. I guess there was one member with 20 inches and the rest with nothing in order to get the mean to be over an inch?
 
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