• 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

A Kelvin Wave currently over the Indian Ocean should finally give us a temporary break from the +IOD & its propagation into the West-Central Pacific will probably trigger an EPO flip at the very end of Dec into early Jan which both the GEFS & EPS are showing.


28.gif


download (50).png

download (49).png
 
Myfrotho704_ said:
Dang, can already see that tropospheric pv lobe in Canada
Click to expand...

Yeah it's typically there in the means and a big -EPO is a fantastic way to dislodge the TPV and force it southward into North America. The sensible response here in the SE US just favors more extremes (both warm & cold) during patterns like this so it's not guaranteed we get cold right away. I think however in this case because there's such a strong high frequency component to the tropical forcing (thanks to the CCKW) & given some of the -NAO preconditioning that will be ongoing ahead of this, we may turn cold sooner rather than later.
 
Nomanslandva said:
While the EPS may be warm late in the run the number of members showing snow next weekend is up. All hope is not gone yet.
Click to expand...

Very good point. Despite the lack of operational model support (esp from the GEFS/GFS) the EPS has been quietly ramping up support for our solstice system over the last several runs.

I certainly don't think we're out of the woods quite yet.

Webp.net-gifmaker (6).gif
 
Webberweather53 said:
Very good point. Despite the lack of operational model support (esp from the GEFS/GFS) the EPS has been quietly ramping up support for our solstice system over the last several runs.

I certainly don't think we're out of the woods quite yet.

View attachment 28234
Click to expand...

Here's the snowfall output for comparison.

12z yesterday
download (52).png



0z today
download (51).png



Moral of the story: don't go to sleep on this event just yet.
 
The GEFS & EPS have been digging this trough off Atlantic Canada more & more in the medium range which ramps up our supply of cold air & strength of the cold air damming in advance of this system near the solstice.

gfs-ens_z500trend_namer_10 (1).png


gfs-ens_mslptrend_namer_10.png



The big vortex off of Newfoundland & Atlantic Canada was likely the key large-scale puzzle piece that was missing w/ last week's minor glazing event that likely prevented it from being a big deal. We'll have it in spades this time around.

gfs-ens_z500a_namer_18.png
North America NCEPR1 z500a NC Miller B Winter Storms (1948-2019).png
 
Webberweather53 said:
The GEFS & EPS have been digging this trough off Atlantic Canada more & more in the medium range which ramps up our supply of cold air & strength of the cold air damming in advance of this system near the solstice.

View attachment 28238


View attachment 28237



The big vortex off of Newfoundland & Atlantic Canada was likely the key large-scale puzzle piece that was missing w/ last week's minor glazing event that likely prevented it from being a big deal. We'll have it in spades this time around.

View attachment 28242
View attachment 28240
Click to expand...


Here's the z500a during last week's minor glazing event as a reference. You can see exactly what I'm talking about here. All of the waves are roughly in the right place but notice the Atlantic Canada vortex is displaced further north and coupled to a +NAO. This trough being further north suggests a weaker cold push into New England & SE Canada and the +NAO coupled w/ this vortex being embedded into deeper westerly flow also argues for a more transient cold air mass.
gfs_z500a_namer_1.png
 
Webberweather53 said:
Very good point. Despite the lack of operational model support (esp from the GEFS/GFS) the EPS has been quietly ramping up support for our solstice system over the last several runs.

I certainly don't think we're out of the woods quite yet.

View attachment 28234
Click to expand...

This is a very interesting trend.

I think it’s easy to toss a storm when models repeatedly show a no-storm scenario in the mid/long range.

BUT think of it this way. If models were locking in on a Carolina storm right now being 5-6 days out what would we be scared of? The dreaded NW trend that happens almost every time.

Now watch this trend on the EPS. BE33AB9E-C26B-4560-BF67-E9BED9E0F0EF.gif

I’m more optimistic this morning than I have been most of this storm threat. Why? Because 99% of the time we see storms trend more north and west in the 3-5 day period.

I wouldn’t count this out yet. ESPECIALLY with EPS “leading” the way.



06z GFS technically did come back west. Too early to say it’s a trend though.

6C1610FE-8897-4EA7-B14B-1E0EC8F56C88.gif
 
Honestly I’m really hoping models jump back onto this enough to for us to make a thread for it ... simply for the fact that we can name the thread .. the solstice system 21/22 ..in all honesty though I’ve never let my eyes off this threat .. let’s keep the trends going at 12z
 
Well, that nice pattern sure did go out the window this weekend. :(. Oh well, it's December. The thing that bothers me is the no matter what, it seems more often than not, the western trough just won't die. It's like it wants to just stay there forever. If we can't get legitimate eastern troughs, even if the -EPO does come back, we're not gonna get cold enough air east for winter weather imo. The -NAO regime is just not doing work. Not sure what we need to root for to kick that thing east.

1576505052072.png
 
Webberweather53 said:
At least we won't have to hear some nonsense about how the sun angle is screwing us over w/ this storm, it literally won't be any lower in the sky than near December 21st.

I've also kinda gotten a kick out of watching the americanwx SE US forum capitulate over losing the GFS/GEFS for this storm.
Click to expand...

Maybe if we could just turn the sun off for that day? Then we would be satisfied with the sun angle??

Yeah honestly the gfs is still pretty bad. It always loses storms in the mid range. This is a classic model timeline for our major events. Gfs has lost several of our major storms in the mid range.

Also that’s 9 EPS members with a legit storm for Western NC. That’s just shy of %20 and more than “outlier members” IMO.

**look below at your own risk** haha

365A6FEF-B16A-4C16-B32F-176566F2138B.gif
 
06z EPS has a little bit of a spread with low centers scattered along the SE coast to east of VA, a few inland as well.
4f7529ac4dcfe768614fdd4270de0d3c.jpg


Sent from my SM-J727U using Tapatalk
 
Webberweather53 said:
At least we won't have to hear some nonsense about how the sun angle is screwing us over w/ this storm, it literally won't be any lower in the sky than near December 21st.

I've also kinda gotten a kick out of watching the americanwx SE US forum capitulate over losing the GFS/GEFS for this storm.
Click to expand...
Well I watched 2.5 inches of snow pile up in less than 3 hours during the day back on 4/2 following a 60 degrees high the day before, so I’ll never listen to the sun angle argument again.
 
IWC said:
FWIW the Christmas Eve storm in 2009 got lost for a few runs. Then reappeared for Christmas Night.
Click to expand...

I think that was 2010, but yes, that did happen. Models showed it way out, then lost it, and then it showed up again about 48 hours out.
 
You must log in or register to reply here.
Back
Top