December Mid-Long Range Discussion

[Ji]

GFS again going nuts with the blocking towards the 17th....hard to believe we would miss a white christmas if that scenario plays out

[mitchnick]

GFS again going nuts with the blocking towards the 17th....hard to believe we would miss a white christmas if that scenario plays out

never dismiss our ability to overachieve when it comes to under performing

otoh, I do think we do OK this winter, but with the best chances after New Years

[ORH_wxman]

GFS again going nuts with the blocking towards the 17th....hard to believe we would miss a white christmas if that scenario plays out

Well you managed (most of the east did) to do it in 2010.

[Amped]

GFS again going nuts with the blocking towards the 17th....hard to believe we would miss a white christmas if that scenario plays out

PNA/EPO still isn't cooperating.There's a chance it will by the end of the month. However not a bad pattern by 384hrs. Jet stream is pretty far south and there's blocking.

[EasternUSWX]

EURO is nothing but, ugly. Shield eyes.

[aldie 22]

and H2O....who is probably who I was remembering but it was all in good fun.

He posted a picture of a bunch of angry old ladies who were standing at a bus stop and posted this.

You made these old ladies mad, Wes.

Lol...i get it.....you know I was joking right?

[H2O]

i remember you were hesitant to give the analog of the storm you were thinking about but you finally did 3-4 days you said before the storm was suppose to hit when the GFS was showing 20 inches of snow for us. The models had us getting snow until the last 3 days when they switched to ice.

Had it been all snow...we would of gotten 20 or so inches. Instead we got 5 inches of cement

i have a really good memory for stupid stuff and i know you mentioned at some point that Feb 1983 was a potential analog for the VD 2007 storm. It wasnt that far off based except it didnt snow

I remember every winter you cancel before it starts so your words don't mean much anymore.

[H2O]

Lol...i get it.....you know I was joking right?

Wes knows we him. Even if he is the bearer of bad news we appreciate it. I much rather have him say the pattern sucks for a while than be like JB who always says a storm is coming in 7 days

[mattie g]

PNA/EPO still isn't cooperating.There's a chance it will by the end of the month. However not a bad pattern by 384hrs. Jet stream is pretty far south and there's blocking.

Though I know very little, I know enough to see that the Pacific is doing whatever it can to screw us over in the face of some pretty damn good blocking down the road.

[clskinsfan]

The problem is the PV or lack of a PV. The blocking needs to displace the PV south to get any cold air in here. And that is not happening on these model runs.

[usedtobe]

Lol...i get it.....you know I was joking right?

Of course. I was just happy you read it. I thought Mitch had read the piece too but from his comment he evidently didn't. I took it as having fun.

[usedtobe]

Though I know very little, I know enough to see that the Pacific is doing whatever it can to screw us over in the face of some pretty damn good blocking down the road.

It is and the super ens mean D+11 centered on Dec 16th from Dec 5th is still ugly.

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hgt_comp_sup814.gif

and the NAEFS Dec 13-19 period is still giving us a greater than 60% probability of the period averaging warmer than normal. The pacific continues to be bad with the rPNA. Even the GEFS which shows a nice westerly neg nao has problems getting lows to track to our south. most members still have the storm track to our north because of the negative PNA.

[Bob Chill]

Looking at the 0z and 6z guidance the look is still the same in the lr. I'm starting to feel a bit more confident the second half of the month (at least the last 10 days) could be "ok" for us.

It's obvious we have to deal with a storm track to the west through at least 8 days but all the models strengthen the -nao and shift it west. IMO- the deep trough in the west will slide east (and relax a bit of course). The -pna will relax as well and guidance is pointing towards a slow and gradual relaxation. If the -nao can asset itself enough then we get a stormtrack to our south. Or even a miller b type of track which is still fine. I don't think anyone is expecting a big storm. I'm sure not until the pna can go + in conjunction with the the -ao/nao.

If the 12z gfs continues to show a strong -nao that is shifting west then it's been 4 runs in a row for the most part. Euro looks like it's doing the same thing @ d10.

[Bob Chill]

Probably nothing but the gfs slides a little weak low to the se after the cold front/cutter passes next week. Every once in a while trailing energy post frontal passage aligns itself just right. Doesn't look like the case this time but it's the first run to show it so in the face of REALLY boring winter weather...it's worth a watch.

[WxUSAF]

GFS ensemble mean is loving some -NAO mega-block in the post Day 10 period. With the mean trough out west, we need something like this for any hope of cold and snow. But, a block like that might be able to do it. Would certainly be...disconcerting...to lose out on an extended period of big -AO/-NAO because of the craptastic Pac.

[psuhoffman]

The problem is getting the NAO and PNA to phase up the right way. Its not as simple as some think just rooting for a -NAO or a +PNA, the two have to co-exist and play off each other. For instance, we can get Snow with a really +PNA and a neutral NAO, or a neutral PNA and a -NAO. THis far south its difficult to get a storm to track to our south if either the PNA or the NAO is in a really craptastic phase. The NAO going that negative might make this a very good pattern for NYC if the PNA stays this negative. Normally a -NAO of that level would just be cold and dry for New England...but with a PNA like it is...this might work out for them. We need the PNA to just relax some. Its probably futile to hope the PNA helps us at all this winter, but with the NAO and AO looking to cooperate we just need the PNA to be weakly negative for a time or neutral, not stuck in the worst possible position. If we can get the PNA to relax some while the NAO is negative then we are in business.

GFS ensemble mean is loving some -NAO mega-block in the post Day 10 period. With the mean trough out west, we need something like this for any hope of cold and snow. But, a block like that might be able to do it. Would certainly be...disconcerting...to lose out on an extended period of big -AO/-NAO because of the craptastic Pac.

[VAsnowlvr82]

The problem is getting the NAO and PNA to phase up the right way. Its not as simple as some think just rooting for a -NAO or a +PNA, the two have to co-exist and play off each other. For instance, we can get Snow with a really +PNA and a neutral NAO, or a neutral PNA and a -NAO. THis far south its difficult to get a storm to track to our south if either the PNA or the NAO is in a really craptastic phase. The NAO going that negative might make this a very good pattern for NYC if the PNA stays this negative. Normally a -NAO of that level would just be cold and dry for New England...but with a PNA like it is...this might work out for them. We need the PNA to just relax some. Its probably futile to hope the PNA helps us at all this winter, but with the NAO and AO looking to cooperate we just need the PNA to be weakly negative for a time or neutral, not stuck in the worst possible position. If we can get the PNA to relax some while the NAO is negative then we are in business.

What is preventing the PNA from going positive?

[Bob Chill]

The problem is getting the NAO and PNA to phase up the right way. Its not as simple as some think just rooting for a -NAO or a +PNA, the two have to co-exist and play off each other. For instance, we can get Snow with a really +PNA and a neutral NAO, or a neutral PNA and a -NAO. THis far south its difficult to get a storm to track to our south if either the PNA or the NAO is in a really craptastic phase. The NAO going that negative might make this a very good pattern for NYC if the PNA stays this negative. Normally a -NAO of that level would just be cold and dry for New England...but with a PNA like it is...this might work out for them. We need the PNA to just relax some. Its probably futile to hope the PNA helps us at all this winter, but with the NAO and AO looking to cooperate we just need the PNA to be weakly negative for a time or neutral, not stuck in the worst possible position. If we can get the PNA to relax some while the NAO is negative then we are in business.

I pretty much agree. There would be potential with a really strong and west based -nao even down here. We wouldn't get anything big because the flow wouldn't be all amped up but a decent overrunning event is certainly possible. We would just need a system tracking out of the rockies to have enough juice and pass to our south. I suppose we could get a coastal / miller B but I don't think so unless the -pna relaxes. I'll defer to Wes and the other mets on that.

The other thing that is definitely possible is a stronger system coming out of the 4 corners area could leave some ridging in it's wake and really relax the -pna for a bit. This could allow for something amplified and even have the gulf open for business. You have to wonder with such a deep west coast trough that an ull can take the track though the sw and across the gulf coast. If the -nao is a big bully it can keep the stormtrack to our south and have miller A potential.

The flip side is if we had a west based -nao as strong as the models are showing and the pna went + then the stormtrack could easily be supressed and we get squat. RIC might like that. lol

The thing I have to keep reminding myself is that we really need a lot to go right to get snow here. Any flaw in the setup leading up can screw us. But that's just our climo so nothing you can do about it except be realistic and cautious when buying into models that show a storm but also have an obvious flaw. Wes excels at pointing out those flaws (I'm saying that as a compliment.).

[WxUSAF]

The EPAC ridge is very stable. With that ridge there, that forces a big downstream trough over the Rockies. That keeps the PNA negative. We need to move the EPAC ridge west or east, so we can get some ridging on the west coast.

Historically, we get our biggest snow storms when the ridge axis is roughly on a Boise-Las Vegas line.

[Deck Pic]

We could thread the needle or time something perfectly, but we probably aren't getting a good Pacific for the foreseeable future....maybe not til mid January....our best hope is a clipper...or something out of the 4-corners that redevelops and we get front thumped...the odds of a Miller A with the upper level lows passing to our south is pretty unlikely....The good news is the formation of a -NAO in decent position looks pretty reasonable at this point...

[psuhoffman]

combination of being in a long term PDO phase and a crappy PAC SST pattern

What is preventing the PNA from going positive?

[Deck Pic]

combination of being in a long term PDO phase and a crappy PAC SST pattern

which aren't mutually exclusive...there is still a monstrosity of a warm pool in the PDO region

[Bob Chill]

It is anomalous to have the pna run so consistently negative. October and November this year are -1.18 and -1.10 respectively. December is looking like a lock to come in below -1.0 too.

When I found Dec of 61 as a similar pattern match to this year there were a couple other years that stood out as similar in the PNA region but not as much elsewhere.

55-56 was -.960 in Nov, -2.07 in Dec, and -1.32 in Jan (even -1.04 in Feb)

70-71 was -1.19 in Nov, -.790 in Dec, and -1.39 in Jan

90-91 was -1.73 in Nov, -1.32 in Dec, and .660 in Jan

96-97 was -.450 in Nov, -1.23 in Dec, and -.020 in Jan.

61-62 is the best match so far because it also featured a good dose of blocking. 90-91 is very similar to this years ENSO but it had a raging +AO in Dec.

Zwyts, do you know how winter was here in 55-56? It featured a good dose of -ao/nao to go along with the raging -pna. It was a strong Nina so it's probably a very bad analog. Just an interesting year nonetheless.

Luckily the PNA is pretty volatile. It's a mixed bag in Jan following December with a monthly of -1.0 or lower.

[Deck Pic]

It is anomalous to have the pna run so consistently negative. October and November this year are -1.18 and -1.10 respectively. December is looking like a lock to come in below -1.0 too.

When I found Dec of 61 as a similar pattern match to this year there were a couple other years that stood out as similar in the PNA region but not as much elsewhere.

55-56 was -.960 in Nov, -2.07 in Dec, and -1.32 in Jan (even -1.04 in Feb)

70-71 was -1.19 in Nov, -.790 in Dec, and -1.39 in Jan

90-91 was -1.73 in Nov, -1.32 in Dec, and .660 in Jan

96-97 was -.450 in Nov, -1.23 in Dec, and -.020 in Jan.

61-62 is the best match so far because it also featured a good dose of blocking. 90-91 is very similar to this years ENSO but it had a raging +AO in Dec.

Zwyts, do you know how winter was here in 55-56? It featured a good dose of -ao/nao to go along with the raging -pna. It was a strong Nina so it's probably a very bad analog. Just an interesting year nonetheless.

Luckily the PNA is pretty volatile. It's a mixed bag in Jan following December with a monthly of -1.0 or lower.

If it weren't for the March K/U it would have sucked..cold Dec, average Jan, torch Feb

[usedtobe]

We could thread the needle or time something perfectly, but we probably aren't getting a good Pacific for the foreseeable future....maybe not til mid January....our best hope is a clipper...or something out of the 4-corners that redevelops and we get front thumped...the odds of a Miller A with the upper level lows passing to our south is pretty unlikely....The good news is the formation of a -NAO in decent position looks pretty reasonable at this point...

The 360 hr ens mean at least has a really nice looking atlantic and might be able to sustain a miller b type storm but it's at 360 hrs and the more likely scenario would be a front end thump providing the 50 50 low was in place to help provide some ridging to our n.

[usedtobe]

If it weren't for the March K/U it would have sucked..cold Dec, average Jan, torch Feb

It was a bad year, DC ended up with 11.3 but 2.3 of it came in November. Dec snow-wise was a waste (0.5), Essentially, the snow came in Jan and March as Feb was also a waste AND i THINK GAVE US zilch.

[WinterWxLuvr]

Is it completely out of the question that next week might bring a little interesting weather round these parts?

[Deck Pic]

Is it completely out of the question that next week might bring a little interesting weather round these parts?

pretty much...but the 20-25th period is starting to look a lot more interesting if you set the bar low...and just want some sort of accumulating snow.....I like Sunday the 23rd for a snowstorm....since it is fun to throw out dates and then claim...I was correct!!....so yeah....we are going to have a 2-5" snowstorm on Sunday 12/23

[usedtobe]

pretty much...but the 20-25th period is starting to look a lot more interesting if you set the bar low...and just want some sort of accumulating snow.....I like Sunday the 23rd for a snowstorm....since it is fun to throw out dates and then claim...I was correct!!....so yeah....we are going to have a 2-5" snowstorm on Sunday 12/23

If I had to pick a time period that would probably be mine as the GEFS mean pattern has the good deep low near nova scotia and some weak system coming eastward from the rockies. The pacific still is not good but there is a hint of a shortwave ridge behind the wave coming out of the rockies. It's the best look so far this dec though the low still could easily track to the oh valley assuming the ensemble mean has any skill at all at that time range which is a pretty bold assumption as it usually doesn't. Still the evolution in the Atlantic is sort of the type of evolution that you usually see.

[WxUSAF]

6z GFS ensemble mean would support the pre-Xmas Zwyts storm. Aleutian ridge retrogrades enough to pull the mean trough off the west coast, which puts us back into a trough with the big -NAO. Not a K/U pattern by any means, but certainly has potential for a small or moderate event.