December 2012 Pattern Analysis

[bluewave]

6z GEFS and the op agree on the storm for early next week. Way different than the Euro.

http://raleighwx.ame...emblep12156.gif

Looks like the difference could be the GFS bias of being too weak with the ridge that will be along the coast.

[Storm At Sea]

I'm still unsure where folks are getting the idea of "interesting after the 20th." At least from what I can see, NAO tanks up until Dec. 16 and then rapidly rises between Dec. 17 - 20, which is normally a sign of east coast precipitation event (possibly snow). Thereafter, the AO and NAO remain positive to neutral for at least a week. So in short, a marginal event possible around Dec. 19-20 followed by a warmup with things improving late in the first week of Jan.

[MJO812]

12z GFS looks really interesting for the weekend storm. This run depicts a miller b further south than the 6z run.

[earthlight]

I'm still unsure where folks are getting the idea of "interesting after the 20th." At least from what I can see, NAO tanks up until Dec. 16 and then rapidly rises between Dec. 17 - 20, which is normally a sign of east coast precipitation event (possibly snow). Thereafter, the AO and NAO remain positive to neutral for at least a week. So in short, a marginal event possible around Dec. 19-20 followed by a warmup with things improving late in the first week of Jan.

I don't see any signs of a big + NAO after the 20th. The blocking over Central Canada, on almost every model, is slow to move out after it builds in on the 17th-19th. With the MJO impulse forecast to continue at that time, and the block continuing to retrograde in tandem with support for a building ridge near the Aleutians...I don't see any support for a torch around Dec 20 at all.

[Kaner587]

Overrunning with redevelopment. Those can be nice storms for us so long as they stay south of our latitude

[MJO812]

GFS shows 3 potential storms coming up. One for this weekend, another one for the 20th and then one near Christmas. I am not sure if this weekend storm will be a GLC because we have a - NAO in place . Redevelopment sounds about right IMO.

[CooL]

I'm still unsure where folks are getting the idea of "interesting after the 20th." At least from what I can see, NAO tanks up until Dec. 16 and then rapidly rises between Dec. 17 - 20, which is normally a sign of east coast precipitation event (possibly snow). Thereafter, the AO and NAO remain positive to neutral for at least a week. So in short, a marginal event possible around Dec. 19-20 followed by a warmup with things improving late in the first week of Jan.

Are you basing this off the nao graph? I wouldn't do that

[earthlight]

On a situation like this you have to watch the low level cold air. Even though that may look like snow for you guys, the bl temps are pretty warm like the late november storm.

Yeah, agreed especially as the pattern is still becoming established. The low level cold air source is rather moderated.

[PB GFI]

I'm still unsure where folks are getting the idea of "interesting after the 20th." At least from what I can see, NAO tanks up until Dec. 16 and then rapidly rises between Dec. 17 - 20, which is normally a sign of east coast precipitation event (possibly snow). Thereafter, the AO and NAO remain positive to neutral for at least a week. So in short, a marginal event possible around Dec. 19-20 followed by a warmup with things improving late in the first week of Jan.

Rapidly decreasing SOI , so the PAC shuffles the RIDGE gets pushed NE towards Alaska and the trough axis eventually gets shunted east and the cold air slides over the snowcover currently being laid down in the upper midwest and canadian praires

In my opinion that puts the trof into the east around day 10

I look up stream for pattern changes not downstream

Pac more influential than the NAO IMO .

[earthlight]

Rapidly decreasing SOI , so the PAC shuffles the RIDGE gets pushed NE towards Alaska and the trough axis eventually gets shunted east and the cold air slides over the snowcover currently being laid down in the upper midwest and canadian praires

In my opinion that puts the trof into the east around day 10

I look up stream for pattern changes not downstream

Pac more influential than the NAO IMO .

It's not like the Atlantic side is crap, either. But some of the GEFS runs over the last 24 hours have been real weenie solutions with the retrograding west based NAO block hooking up with the Aleutian ridge and developing a cross polar flow near Christmas time.

[PB GFI]

It's not like the Atlantic side is crap, either. But some of the GEFS runs over the last 24 hours have been real weenie solutions with the retrograding west based NAO block hooking up with the Aleutian ridge and developing a cross polar flow near Christmas time.

I know , The only retrogression i`ve seen come to fruition in the last 14 days was in the PAC where this dam thing has held like the Maginot line ( lets hope it meets the same fate ) .

I am not good enough to pick out indivuals 10 days out so i will not even try , but I am counting on a nice Kelvin wave to push the pattern east .

If we get a hook up over the top , then with a NEG PNA its game on . but i just wana see trof come east , then you guys figure out where the damage will occur

[earthlight]

12z GFS looks really interesting for the weekend storm. This run depicts a miller b further south than the 6z run.

The models are starting to catch on to the building block over Greenland that is splitting off the ridge from the other side of the pole and moving south. So they are forcing that storm system and the ones a few days after that underneath this blocking to the south of where they had it previously. You can see the progression on the 6z GEFS as the above normal height anomalies build south over Greenland to Central Canada very rapidly.

[BlueSkiesFading]

I'm wondering if high temps are gonna bust for interior areas. Still sitting at 52 degrees and socked in with fog in NE NJ. The warm front has cleared Long Island and south of Trenton in NJ with some low 60's showing up, but it's really halted its progress over the last few hours. Dews are actually running between 61 and 63 to our south. Almost summer-like!

[famartin]

I know , The only retrogression i`ve seen come to fruition in the last 14 days was in the PAC where this dam thing has held like the Maginot line ( lets hope it meets the same fate ) .

for the history quip

[famartin]

I'm wondering if high temps are gonna bust for interior areas. Still sitting at 52 degrees and socked in with fog in NE NJ. The warm front has cleared Long Island and south of Trenton in NJ with some low 60's showing up, but it's really halted its progress over the last few hours. Dews are actually running between 61 and 63 to our south. Almost summer-like!

Parents in Ewing are at 60 at this hour.

[earthlight]

The Euro takes the second shortwave that the GFS splits off the Carolina coast and ejects it east. The initial weaker disturbance (the one that the GFS ejects northeast to give us light snow/rain) goes very far north and west. But the second one is very energized..ends up phasing a bit and there's a big time rainstorm at 168 hrs.

[NaoPos]

The Euro takes the second shortwave that the GFS splits off the Carolina coast and ejects it east. The initial weaker disturbance (the one that the GFS ejects northeast to give us light snow/rain) goes very far north and west. But the second one is very energized..ends up phasing a bit and there's a big time rainstorm at 168 hrs.

The wave behind that looks interesting through 198...

Primary in Kentucky, secondary pops in interior sc @204. The boundary is torched, except for extreme NNE

[PB GFI]

The Euro takes the second shortwave that the GFS splits off the Carolina coast and ejects it east. The initial weaker disturbance (the one that the GFS ejects northeast to give us light snow/rain) goes very far north and west. But the second one is very energized..ends up phasing a bit and there's a big time rainstorm at 168 hrs.

It ejects a short wave out of the Ohio Valley off the Mid Atlantic coast and warms the surface ? no CAD ? , Gotta hope its just not seeing low level cold air ( if its there ) like the GFS does and is gassing up the boundary layer .

or the GFS is right , ( cant believe i said that ) its day 7 . Nice to get a sniff though

[famartin]

DT says expect a cold, snowy January... maybe some relaxation in Feb.

[earthlight]

It ejects a short wave out of the Ohio Valley off the Mid Atlantic coast and warms the surface ? no CAD ? , Gotta hope its just not seeing low level cold air ( if its there ) like the GFS does and is gassing up the boundary layer .

or the GFS is right , ( cant believe i said that ) its day 7 . Nice to get a sniff though

Nah -- the second shortwave digs all the way to the TX Panhandle and MS Valley and then amplifies northeast. There's warm air everywhere.

Another storm at 210 with warm air...so two rainstorms and no cold air on the East Coast.

[NaoPos]

Well can't say it isn't stormy on the euro..

Just warm, verbatim...

[SnoSki14]

Completely disagree with the Euro, no matter how accurate we all see the Euro, it is far from perfect and at times is even worse than the gfs. I think the Euro may have a knack for sniffing out major events though days in advance as we've seen with Sandy although that's debatable since there's a huge difference between tropical and extratropical storms and how the models interpret them.

[PB GFI]

Nah -- the second shortwave digs all the way to the TX Panhandle and MS Valley and then amplifies northeast. There's warm air everywhere.

Another storm at 210 with warm air...so two rainstorms and no cold air on the East Coast.

Ahhhh . I will wait for Ensembles to see if they r similar , if they are , then those CFSV2 xmas maps can b used as TP.

[earthlight]

DT says expect a cold, snowy January... maybe some relaxation in Feb.

Great discussion and I can agree wholeheartedly with most of it.

[famartin]

Great discussion and I can agree wholeheartedly with most of it.

Yes, it makes sense to me too. (which is why I posted it )

[earthlight]

Yes, it makes sense to me too. (which is why I posted it )

The one thing I don't agree with is throwing out the retrograding block over Greenland on the ensembles...I think that's a legitimate part of the entire pattern reversal that the QBO analogs he pulled up are revealing.

[NorEaster27]

Nah -- the second shortwave digs all the way to the TX Panhandle and MS Valley and then amplifies northeast. There's warm air everywhere.

Another storm at 210 with warm air...so two rainstorms and no cold air on the East Coast.

This is what Nzuker and I talked about which you dismissed a few days ago. The BIG PV moves north of AK taking the cold air with it, with the -PNA and firehose pac jet, we torch with or without the NAO.

[Isotherm]

DT says expect a cold, snowy January... maybe some relaxation in Feb.

I just skimmed through in about 20 seconds, but happened to hit, "I'm telling ya folks, it's not over yet." Well it damn well better not be, winter just started 10 days ago.

[Wannabehippie]

DT says expect a cold, snowy January... maybe some relaxation in Feb.

So a warm, dry january is in store then?

[kevbo81]

^{pretty good discussion in here! Can a met please explain the implications of the crashing SOI values and how it pretains to our overall weather in the coming few weeks?}