GEFS through the end of the run:
The much-improved look in the 50/50 region is the cause for that!
The much-improved look in the 50/50 region is the cause for that!
-
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 January 2021 - Joyless January
- Thread starter TheBatman
- Start date
Getting closer to something here, if we can get that N/s wave in Canada closer to phase with that stuff near the NE
Keep pushing that block towards Greenland and the trends will only get better.
RVD
Meteorology Student
I've always understood the +PNA to be favorable by just implying troughy weather downstream, but I've also recently begun to notice the stark impact that the Rockies have on eroding our cold air source, a secondary reason that a +PNA/tall west coast ridge is so important. A zonal westerly (or worse: SWerly) flow onto the west coast drives upstream flow directly perpendicular to the major axis of the Canadian Rockies in particular. If precipitation falls out of this orographic lift, then there is a strong adiabatic compression/warming east of the Rockies (a Chinook wind). This coupled with the strong -NAO block is leading to an accumulation of much warmer than average temperatures across Canada (still below freezing though), with effects extending southward into the US:
Note the sharp line of warmer than average temperatures east of the Canadian Rockies. Even on this frame though, there's evidence of below average temperatures associated with an active southern stream undercutting and moderating conditions across the southern US (e.g. anomalies in Texas and Florida). As the 12z GEFS rolls forward, a west coast ridge begins to appear just after day 10. The Chinook wind is still present, but it's clearly dampened here with more legitimate below average temperatures across the board:
These below average anomalies spread east and persist through the end of the model run.
Note the sharp line of warmer than average temperatures east of the Canadian Rockies. Even on this frame though, there's evidence of below average temperatures associated with an active southern stream undercutting and moderating conditions across the southern US (e.g. anomalies in Texas and Florida). As the 12z GEFS rolls forward, a west coast ridge begins to appear just after day 10. The Chinook wind is still present, but it's clearly dampened here with more legitimate below average temperatures across the board:
These below average anomalies spread east and persist through the end of the model run.
Getting real close to something here 
Yeah, the low still tracks into central NC, but we got high pressure to appear this run.
I wouldn’t think we’d do it with some of the first waves but clearly we’re getting close to something here
RVD
Meteorology Student
I don't think this necessarily means we need a strong or persistent +PNA though. Having deep vodka cold in Canada is not necessary to pull off a big storm... at the very least since we don't live in Canada, and colder usually implies drier. We will need some west coast ridging to pull of a storm, though, even if transient. Long range ensemble models are beginning to hint at a +PNA though, in part as the high latitude block retrogrades, which is great. Hopefully that evolution sticks around.
Maybe another wave ? Lol 
It looks weaker, albeit much colder considering that that wave #1 looks like it will get stuck in the 50/50 region.
Is that a mini TPV lobe lol ?! 
This looks much colder, super phase?! There's another wave behind it too!
RVD
Meteorology Student
Already seeing close calls/favorable trends before any +PNA pops is a nice sign. I'd be impressed if this one works for anyone outside the NC mountains, but I like its implications for a setup with a bit more cold air (which, if the long range ensembles are right, could be as soon as the 10-15th).
TPV time 
Now this will get your blood pumping..
It’s like the better pattern is gradually speeding up and sneaking up on us, lol
And it literally is retrograding south westward ... that’s some serious -NAO and we’re bound to go boom soon
I find this acceptable
RVD
Meteorology Student
I'm planning on heading back to Raleigh for school sometime around the 10th, though I can wait a few days longer. It sure would be nice to sneak in something before I have to go willfully degrade my snow chances.
There’s a reason why we’re seeing storms similar to December 2009 pop up 
RVD
Meteorology Student
Cadi40
Member
How do we have to trend to make it more favorable for the Upper SE, specifically the piedmont region?
Get a stronger 50/50 low.
Stronger 50/50 low/N/S injection but honestly with that look towards the end of the euro I’m almost worried things would be to suppressed
Cadi40
Member
Well regardless of any snow it's definitely nice to have a change of patterns compared to the previous years.
I wouldn't worry about suppression if the wave coming onshore is tapping into some real good Pacific moisture.
It’s getting better as it gets closer, it’s slowly becoming less of a mirage ????
Certainly feel better after the 12z runs so far versus 12/24 hours ago
I hope we see more positive trends for less ridging over the NE. This look would be terrible for us east of the mountains.
Snow mean starting to respond to that stuff that the euro/CMC picked up on, same footprint as that December 2009 storm. 
RVD
Meteorology Student
Oh man, that looks great! Love the trend out west with the weakening trough and better ridge. I think @Ollie Williams has noted a few times that models seem to be underestimating the +PNA in the long range.
?
SnowNiner
Member
Webb mentioned the block ridging ideally shifts more north to get more cold, we could get more ridging up on alaska, and I'd like to see stronger lower heigts off the east coast/eastern canada for stronger 50/50 lows. Don't see that on models so far through the first half of January. Hopefully we can benefit later down south. First half of the month the northeast and perhaps the midatlantic will likely score big.
Webberweather53
Meteorologist
Got a pretty good feeling that we’re gonna hand off the first storm or two in this pattern to the mid Atlantic. We could use a little snow cover to our north to help further lock in this great pattern. As we see a few storms run their course thru the first half of the month and lay some snow down to our north, the Greenland block begins to couple with the stratosphere, & continues retrograding poleward and westward, the air masses that plunge southward will become increasingly deeper/colder as we get into mid-January
Hence, I think the mid Atlantic and perhaps the mountains could score here inside the first 10-12 days of the January. Our window in the SE probably does not legitimately open up until about Jan 15 or so given the above info, but it should last for basically the rest of January at a minimum and given the SSWE, February is also looking favorable atm
Hence, I think the mid Atlantic and perhaps the mountains could score here inside the first 10-12 days of the January. Our window in the SE probably does not legitimately open up until about Jan 15 or so given the above info, but it should last for basically the rest of January at a minimum and given the SSWE, February is also looking favorable atm
Not a bad mean, but most members stay to the north.
Good probabilities north of I-85.
Good probabilities north of I-85.
It’ll probably start to crawl south more as it did compared to last run