• 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

Snowless & Grumpy said:
That's so annoying how it skyrocketed right on December 1st. And it'll probably stay that way until March. I think that's one of the main reasons the I-20 corridor has been constantly disappointed since 2011 and that wont change unless that tele changes. As far as the CAD regions we've had to deal with Miller Bs and slop events but not quite as dependent on the NAO.
Click to expand...

Annoying, yes, but not at all surprising. Back in the summer when we had that record long -NAO, I had mentioned the very low to zero correlation between summer and winter NAO. That doesn’t mean a summer -NAO favors a subsequent winter +NAO, but it does mean the following winter’s prospects for a -NAO are not increased to a nontrivial degree by even a deeply -NAO during the prior summer.
 
GaWx said:
But in general for cold prospects for the SE US, a very strong +NAO can’t in itself be good news, right?
Click to expand...
yeah, I like cold from the pacific block but with a -NAO things can lock in longer and give you good results (example : 2010), and that - NAO can help keep things less transient and more cold (if you don’t got a transient -NAO anyways) , maybe we’ll see the -NAO come back at the end of December and Hopefully not those crappy transient ones, if you got a +NAO with no North Pacific blocking and a El Niño state, odds are definitely stacked against you, but at least we got that Pacific block which keeps things from torching
 
But that modeled forecasted ZR from the CMC is plain wrong and likely a instance where it’s over doing it
 
GaWx said:
But in general for cold prospects for the SE US, a very strong +NAO can’t in itself be good news, right?
Click to expand...

Here's the 500mb anomaly composite for all winter storms in NC since 1948 that occurred in December (68 events, 125 days).

Although the mean NAO value of all these days is ~-0.15, the median value is +0.1, and there are more positive NAO days than negative ones in December where a winter storm is occurring in NC. The mean composite anomaly configuration shows hints of a +NAO w/ a poleward displaced subtropical ridge south of Greenland & Iceland. The -NAO is a more prominent feature in January, February, & March winter storms historically speaking anyways.

North America NCEPR1 z500a NC December Winter Storms (1948-2019).png
 
Last edited:
Most Gefs members is showing what I agree with, minor/maybe moderate ice to rain,almost all members have this

92D2A5C2-E83C-4028-810E-3FF25034782D.jpegAC2CDD25-E670-48AB-BF98-E44CC4B43116.jpegC30CFA3F-BFE8-4C4E-B19E-C3BF5775AFF5.jpeg
 
Last edited:
Webberweather53 said:
Here's the 500mb anomaly composite for all winter storms in NC since 1948 that occurred in December (68 events, 125 days).

Although the mean NAO value of all these days is ~-0.15, the median value is +0.1, and there are more positive NAO days than negative ones in December where a winter storm is occurring in NC. The mean composite anomaly configuration shows hints of a +NAO w/ a poleward displaced subtropical ridge south of Greenland & Iclands. The -NAO is a more prominent feature in January, February, & March winter storms historically speaking anyways.

View attachment 27483
Click to expand...

ENSO's apparent footprint on the frequency of Miller A cyclone events is evident here, note how the Miller A & El Nino winter storm composites are virtually identical:

Conclusion: El Nino increases the frequency of Miller A (coastal cyclone) events in NC & this heightened frequency of Miller As likely explains the enhanced seasonal gradient between Greensboro/Winston-Salem & Raleigh-Durham that's also observed in El Nino winters.

North America NCEPR1 z500a NC Miller A Winter Storms (1948-2019).png
North America NCEPR1 z500a NC El Nino Winter Storms (1948-2019).png

In La Ninas, there's also a negative NAO in the composite, but it's displaced much further east & equatorward of both the NINO & Miller A composite.

North America NCEPR1 z500a NC La Nina Winter Storms (1948-2019).png

Worth clarifying that both of these above 500mb anomaly composites above include every winter storm that's occurred in NC since 1948 during El Nino or La Nina, with both composites including nearly 100 events. Therefore, the conclusions attained from them are much more likely to be significant & meaningful.

This post is definitely something to put in your back pocket.
 
Last edited:
@Brent I believe the euro gives you some snow. What are your thoughts on this?
1576029600-9YptF3UAix8.png
 
I know everyone wants snow in the deep south early on in the year (like last year), but sometimes climo talks for many of us.

Can we please be thankful for Tennessee's possible chances.. I feel like they're on their own while many of us say "fail" they could be seeing something soon.
 
Ollie Williams said:
@Brent I believe the euro gives you some snow. What are your thoughts on this?
1576029600-9YptF3UAix8.png
Click to expand...

I feel like I've seen this story before... As much as I want it to happen my guess is the precip will clear out earlier like usual. That's been how we've missed out prior events

its interesting because the NAM follows my thinking and has zero snow, usually its the other way around lol
 
Last edited:
You must log in or register to reply here.
Back
Top