• Hello, please take a minute to check out our awesome content, contributed by the wonderful members of our community. We hope you'll add your own thoughts and opinions by making a free account!

Pattern The Great December Dump

Webberweather53 said:
Like the EPS has been faring any better inside day 10-12...
Click to expand...

To your point about the EPS as well as the other models in the 11-15:

"Skill has been low when forecasting past a week of lead time, as models struggle to handle a level of variability observed since the second half of November. As an example of the low skill, modeled 850mb temperatures in the 11-15 Day period averaged an anomaly correlation to observation of –0.06 in the past week over North America. The Euro EN itself averaged a correlation of near zero." from Maxar
 
If there's one thing the EPS has absolutely sucked at this year, it's sniffing out a -EPO.

You don't have to go back far to find an example of failure. While I think the GEFS has a -EPO bias in the longer-term, the EPS also loves to hold big troughs over Alaska & mask out higher frequency, shorter wavelength disturbances within the North Pacific jet.

We were supposed to warm up in a big way in mid-Dec at one point & in the process the EPS never saw the sharp western North America ridge/+PNA that eventually ensued.

Other large-scale indicators gave some legitimacy to the EPS a few weeks ago for the current period but its forecast for a huge vortex encompassing both Alaska & NW Canada fell flat on its face.

 
We are definitely in a repetitive pattern when it comes to getting precip here. I have gotten rain every weekend for the past four weekends, counting today. Would be nice if that continued and eventually hooks up with the cold so all this rain becomes snow.
 
So, even the best model, the Euro ens has been no better than just going with climo during the 11-15! So, in a sense, looking at models past day 10 during the last few weeks hasn't even been giving us a clue as to what the wx pattern will actually be! It has literally been just for entertainment! We're totally blind as to post day 10 prospects. Will that continue?

So, not only have the post day 10 GFS maps been pretty much useless, but also even the ensemble maps haven't been any better!

So, who knows where we're going for late month? If the models don't know, then who knows? JB? JC? LC? HM? BAMWX? Maxar? The wooly worms? The birds? The bugs? The fish?
 
Last edited:
GaWx said:
So, even the best model, the Euro ens has been no better than just going with climo during the 11-15! So, in a sense, looking at models past day 10 during the last few weeks hasn't even been giving us a clue as to what the wx pattern will actually be! It has literally been just for entertainment! We're totally blind as to post day 10 prospects. Will that continue?

So, not only have the post day 10 GFS maps been pretty much useless, but also even the ensemble maps haven't been any better!

So, who knows where we're going for late month? If the models don't know, then who knows? JB? JC? LC? HM? BAMWX? Maxar? The wooly worms? The birds? The bugs? The fish?
Click to expand...
No one "knows", Larry. Not even 72 hours out. But there are clues and signals ... it's almost like generating a "model" in your brain ...which is why this whole hobby is so much fun; models don't run the show ... they are just a part of the equation ...
 
This is just hateful
bc084f78a38b553e795614d89417e277.gif


Sent from my SM-G975U using Tapatalk
 
SD said:
This is just hateful
bc084f78a38b553e795614d89417e277.gif


Sent from my SM-G975U using Tapatalk
Click to expand...

Guess this will be the theme of winter. Maybe just maybe we can get lucky once in January or February


Sent from my iPhone using Tapatalk
 
In a perfect world the ridging through the Rockies is a little more amplified and less progressive so those waves in the lakes can dive in and phase with the main wave and we get what we have all been looking for.
0caeb7214a5f9da09b3140933787a10d.jpg


Sent from my SM-G975U using Tapatalk
 
Jessy89 said:
Guess this will be the theme of winter. Maybe just maybe we can get lucky once in January or February


Sent from my iPhone using Tapatalk
Click to expand...
Split flow and overall progressive nature to the pattern across the lower 48 is going to keep looking like this until we start to block more and slow down. The good thing is our chances of getting a storm aren't 0 the bad thing is to get anything we have to be timed perfectly. I do wonder if maybe we transition into a rex block type look in the 2-3 week period with ridging along the Canadian coast and a trough along the US west coast. We are basically at mid December now and the iod is backing down. If the warm pool in the Pacific and the overall base state are going to act like a Nino we should really start to see the characteristics show. I wouldn't need surprised to start seeing the Pacific jet slow a bit in the east pac and into the US and more of an appearance from the STJ. I also wouldn't be shocked to see ridging and above normal heights extending from near Hawaii to the canadian coast. I fear that even if we get a decent construct there we somehow find a way to get the Pv and below normal polar heights in Siberia to alaska and that cuts off any ridge amplitude. This would leave us with a juicy STJ but with a lack of big time meridional flow the higher latitude jets end up more zonal so we lack substantial cold and we end up near average with above normal precip and overall meh

Sorry for the long rambling post just wanted to throw some thoughts out


Sent from my SM-G975U using Tapatalk
 
Last edited:
Looking over the 18z GEFS data, I have came up with a prediction that is a possibility (and it isn't going over board this time) Below is an image that I created based upon looking over some data. This prediction map isn't just something I have made up from thin air, in fact, some members from the 18z GEFS support this prediction. PredictionMap.jpg

Once the S/W makes it's way on (or slightly off of the southeastern coast) I think that's when a phase may occur with a short-wave that dives southeast from the Great Lakes region. Lets take a look at the 500mb(vort) from the 18z GEFS. It's hard to tell from this map, but it looks to me that a short wave does indeed phase with the S/W. The timing with this may change, but if the phase occurs at midnight or sometime after, we're in some luck because the surface and 850 temp anomalies support snowfall.

GEFS 500mb(vort) valid next Sunday at midnight.
gfs-ens_z500_vort_eus_35.png


850mb temp anomalies valid next Sunday at midnight (-1c/-3c)
850t_anom.conus.png


Surface temps also valid at midnight next Sunday. The temps continue to fall as Sunday morning goes on.
sfct.conus.png
 
WxWatch said:
Looking over the 18z GEFS data, I have came up with a prediction that is a possibility (and it isn't going over board this time) Below is an image that I created based upon looking over some data. This prediction map isn't just something I have made up from thin air, in fact, some members from the 18z GEFS support this prediction. View attachment 27992

Once the S/W makes it's way on (or slightly off of the southeastern coast) I think that's when a phase may occur with a short-wave that dives southeast from the Great Lakes region. Lets take a look at the 500mb(vort) from the 18z GEFS. It's hard to tell from this map, but it looks to me that a short wave does indeed phase with the S/W. The timing with this may change, but if the phase occurs at midnight or sometime after, we're in some luck because the surface and 850 temp anomalies support snowfall.

GEFS 500mb(vort) valid next Sunday at midnight.
View attachment 27994


850mb temp anomalies valid next Sunday at midnight (-1c/-3c)
View attachment 27995


Surface temps also valid at midnight next Sunday. The temps continue to fall as Sunday morning goes on.
View attachment 27996
Click to expand...
The pattern has a progressive lean. I'd be cautious about the vertical extent of expected snowfall without a significant phase in an amplified pattern. You mentioned phasing is a possibility, and it is. But unless and until we see some amplification in the pattern, the greater risk, IMO is a more west to east precipitation field, predominantly of the liquid variety. Not saying things can't change, though.
 
I’d rather see a high pressure dominated pattern with an active STJ and some blocking up top. This chaotic split stream stuff is for the birds. I hate trying to time something up. I guess you take a chance on some phaser type stuff but It usually spells “slop” at best for us pitiful folk east of the mountains not NC. Idk. Let’s see what happens in a couple weeks I guess
 
Jimmy Hypocracy said:
I’d rather see a high pressure dominated pattern with an active STJ and some blocking up top. This chaotic split stream stuff is for the birds. I hate trying to time something up. I guess you take a chance on some phaser type stuff but It usually spells “slop” at best for us pitiful folk east of the mountains not NC. Idk. Let’s see what happens in a couple weeks I guess
Click to expand...
The good thing is, at least we're not staring an unending, lock-down shutout pattern in the face.
 
Rain Cold said:
The pattern has a progressive lean. I'd be cautious about the vertical extent of expected snowfall without a significant phase in an amplified pattern. You mentioned phasing is a possibility, and it is. But unless and until we see some amplification in the pattern, the greater risk, IMO is a more west to east precipitation field, predominantly of the liquid variety. Not saying things can't change, though.
Click to expand...
As the development of low begins along the Gulf coast, the precip field would be west to east. But, if a phase occurs on the southeast coast, the precip would wrap around as snow (of course if it would be cold enough) I think we should start to see some OP model support for this scenario anytime now.
Tarheel1 said:
The old cold chasing moisture scenarios! Book it
Click to expand...
This wouldn't be a cold chasing moisture scenario. This would be a wrap around snow event, if true. Wrap around snow events can bring intense heavy snow bands.

Sent from my SM-A102U using Tapatalk
 
Jimmy Hypocracy said:
The good news is that the south appears to the the North American precip target for the foreseeable future. Mid south or southeast? That is the million dollar question
Click to expand...
Can’t believe Chris Goober went above normal snow for us! Now he’s running the show and got that stick-in-the mud Johnny out of there, and bought Cedrick up in there!☃️
 
You must log in or register to reply here.
Back
Top