November Mid-Long Range Discussion

[Bob Chill]

Always appreciate the pop in Will. Please visit often (except when you think we're screwed. lol).

Wes and I went back and forth with AO data last year. When it comes to temps and snow (at least down here) the AO seems to be king and the nao is queen. I wouldn't mind your opinion of how you think the AO shapes up in Dec. It's a strong signal when it's anomalous. Much moreso than the NAO.

Big +AO's in Dec seem to almost always trail into Jan and even Feb. Same goes for big -AO's. I only know the basics but it seems like it can become quite stable when it's anomalous. The NAO seems to bounce around quite a bit more. I'm hoping at the very least that the AO stays close to neutral in Dec. Any signs of it tanking is really good news for us down here in the MA.

[midatlanticweather]

So Early consensus -

NAO looks negative in early December but Not ideal.

AO also going negative

PNA? - not convinced one way or the other

MJO - Not looking the best for EC storms?

[ORH_wxman]

Always appreciate the pop in Will. Please visit often (except when you think we're screwed. lol).

Wes and I went back and forth with AO data last year. When it comes to temps and snow (at least down here) the AO seems to be king and the nao is queen. I wouldn't mind your opinion of how you think the AO shapes up in Dec. It's a strong signal when it's anomalous. Much moreso than the NAO.

Big +AO's in Dec seem to almost always trail into Jan and even Feb. Same goes for big -AO's. I only know the basics but it seems like it can become quite stable when it's anomalous. The NAO seems to bounce around quite a bit more. I'm hoping at the very least that the AO stays close to neutral in Dec. Any signs of it tanking is really good news for us down here in the MA.

The AO has a better correlation than the NAO in DCA by a bit...mostly because the AO includes a lot of the NAO domain but also other important areas such as the EPO region. So when the AO is strongly negative, you are likely to have both the EPO and NAO negative which is a huge cold signal versus just the -NAO where a positive EPO would essentially offset it. The NAO is probably a bit more important for a specific synoptic snow setup versus a generalized AO...but when talking about the overall winter temps, the AO will usually do a little bit better.

[Bob Chill]

The AO has a better correlation than the NAO in DCA by a bit...mostly because the AO includes a lot of the NAO domain but also other important areas such as the EPO region. So when the AO is strongly negative, you are likely to have both the EPO and NAO negative which is a huge cold signal versus just the -NAO where a positive EPO would essentially offset it. The NAO is probably a bit more important for a specific synoptic snow setup versus a generalized AO...but when talking about the overall winter temps, the AO will usually do a little bit better.

Makes complete sense. Bottom line is that we need help with temps down here much more than you guys. Majority of marginal temp setups don't usually go our way so the AO is something I started paying a lot more attention to. Neg nao's can do ok pushing canadian air down here but that's not always enough. Especially when areas like Quebec are running above normal.

I'm just praying that we don't get an AO on steroids again this Dec. That can be a kiss of death in itself. If you see anything interesting with the AO please share your thoughts. We're a paranoid bunch down here (and rightfully so).

[usedtobe]

The AO has a better correlation than the NAO in DCA by a bit...mostly because the AO includes a lot of the NAO domain but also other important areas such as the EPO region. So when the AO is strongly negative, you are likely to have both the EPO and NAO negative which is a huge cold signal versus just the -NAO where a positive EPO would essentially offset it. The NAO is probably a bit more important for a specific synoptic snow setup versus a generalized AO...but when talking about the overall winter temps, the AO will usually do a little bit better.

Even for 4 inch or greater snowstorms, the ao correlates a little better for dc. I think becuase the nao allows the blocking to be pretty far east since the index uses iceland in the calculation and we really want the blocking over greenland and canada with below normal heights to the south of the block.

[Deck Pic]

I like the way you think. And to be honest, my only hope/wish is that we don't get stuck in a tough to break crappy pattern. Normal swings are fine. Winter in these parts isn't supposed to be cold start to finish. Just please don't let the AO go through the roof, the SE ridge build, or let that weenie hope killing vortex set up shop near AK. That's all. Just don't let a 4+ week pattern set up and steal 1/3 of our winter with zero prospects. That's not too much to ask is it?

Can someone post or pm me a list of 6"+ storms in DCA since 1960 or so? Will posted a sweet h5 anom map for all the big storms in NE and KU's. It was really cool to see. I want to do the same for DC but I want to do it for the day of, 3 days prior, and 1 week prior to the storms. I'll post the maps after I'm done. Should be a decent tool to use when things get interesting.

I went back to 1948...all events over 5.5"

1/23-24/48 - 6.0"

1/31/49 - 5.7"

11/6-7/53 - 6.6"

1/22/54 - 6.4"

12/3-4/57 - 11.4"

2/15-16/58 - 14.4"

2/13-14/60 - 6.2"

3/2-3/60 - 7.9"

3/9-10/60 - 5.8"

12/11-12/60 - 8.5"

1/19-20/61 - 7.8"

1/26/61 - 5.9"

2/3-4/61 - 8.3"

2/8/61 - 8.4"

12/23/63 - 5.6"

1/12-13/64 - 8.5"

2/10-11/64 - 8.2"

3/30-4/1/64 - 6.2"

1/26-27/66 - 7.5"

1/29-30/66 - 13.8"

12/13/66 - 6.7"

12/23-24/66 - 7.0"

2/6-7/67 - 10.3"

2/17-18/67 - 6.7"

11/30/67 - 6.9"

12/31/70 - 1/1/71 - 9.3"

2/19/72 - 5.5"

12/16-17/73 - 10.2"

2/7/79 - 5.6"

2/12/79 - 5.6"

2/18-19/79 - 18.7"

1/4-5/80 - 6.9"

1/13-14/82 - 7.1"

12/12/82 - 6.6"

2/10-11/83 - 16.6"

1/22/87 - 10.8"

1/25-26/87 - 9.2"

2/22-23/87 - 10.3"

11/11/87 - 11.5"

1/7-8/88 - 8.0"

3/12-13/93 - 6.6"

1/6-8/96 - 17.1"

2/2-3/96 - 8.4"

2/16/96 - 6.8"

3/9/99 - 8.4"

1/25/00 - 9.3"

12/5/02 - 6.1"

2/6-7/03 - 6.6"

2/15-18/03 - 16.7"

1/25-27/04 - 5.7"

2/11-12/06 - 8.8"

3/1-2/09 - 5.5"

12/18-19/09 - 16.4"

1/30/10 - 6.4"

2/5-6/10 - 17.8"

2/9-10/10 - 10.8"

[usedtobe]

It is torching, but Wes thinks it is temporary

But I may be totally wrong. Forecasting ENSO is not my strength. It looked like the warming was due to the Kelvin Wave but it has been impressive. Looks like I may be able to use on of my tables that I prepared earlier this summer in an article later next week or more likely the week after turkey day.

[MillzPirate]

But I may be totally wrong. Forecasting ENSO is not my strength. It looked like the warming was due to the Kelvin Wave but it has been impressive. Looks like I may be able to use on of my tables that I prepared earlier this summer in an article later next week or more likely the week after turkey day.

How much does your winter forecast change/or at all if the warming continues and we're able to get solidly into weak Nino territory?

[WinterWxLuvr]

I went back to 1948...all events over 5.5"

1/23-24/48 - 6.0"

1/31/49 - 5.7"

11/6-7/53 - 6.6"

1/22/54 - 6.4"

12/3-4/57 - 11.4"

2/15-16/58 - 14.4"

2/13-14/60 - 6.2"

3/2-3/60 - 7.9"

3/9-10/60 - 5.8"

12/11-12/60 - 8.5"

1/19-20/61 - 7.8"

1/26/61 - 5.9"

2/3-4/61 - 8.3"

2/8/61 - 8.4"

12/23/63 - 5.6"

1/12-13/64 - 8.5"

2/10-11/64 - 8.2"

3/30-4/1/64 - 6.2"

1/26-27/66 - 7.5"

1/29-30/66 - 13.8"

12/13/66 - 6.7"

12/23-24/66 - 7.0"

2/6-7/67 - 10.3"

2/17-18/67 - 6.7"

11/30/67 - 6.9"

12/31/70 - 1/1/71 - 9.3"

2/19/72 - 5.5"

12/16-17/73 - 10.2"

2/7/79 - 5.6"

2/12/79 - 5.6"

2/18-19/79 - 18.7"

1/4-5/80 - 6.9"

1/13-14/82 - 7.1"

12/12/82 - 6.6"

2/10-11/83 - 16.6"

1/22/87 - 10.8"

1/25-26/87 - 9.2"

2/22-23/87 - 10.3"

11/11/87 - 11.5"

1/7-8/88 - 8.0"

3/12-13/93 - 6.6"

1/6-8/96 - 17.1"

2/2-3/96 - 8.4"

2/16/96 - 6.8"

3/9/99 - 8.4"

1/25/00 - 9.3"

12/5/02 - 6.1"

2/6-7/03 - 6.6"

2/15-18/03 - 16.7"

1/25-27/04 - 5.7"

2/11-12/06 - 8.8"

3/1-2/09 - 5.5"

12/18-19/09 - 16.4"

1/30/10 - 6.4"

2/5-6/10 - 17.8"

2/9-10/10 - 10.8"

What was the total in the Jan 2011 storm? I thought it was a good one down there??

[Fozz]

What was the total in the Jan 2011 storm? I thought it was a good one down there??

5" at DCA. It was much better in the colder burbs (8-12"+).

[Bob Chill]

I went back to 1948...all events over 5.5"

Oh man, thank you! I'm going to have some fun this weekend for sure. Look for a long post full of diced and sliced data coming up. I'll probably toss in daily pna/nao/ao stuff as well. I have the daily data downloaded in excel so it will be easy to put together.

I'm interested in the week prior data. Hopefully I find a decent signal a week out. I want to get better at not buying big (but flawed) solutions with the models when the threat is 7+ days. Wes is really good at keeping us under control when obvious pieces are missing even though were getting pasted with virtual snow.

Works both ways too. Sometimes the models tease us with whiffs before locking in to something decent @ day 4 on in. It would be nice to have some data on hand when the upper air and indices are pointing at more potential than what is being shown.

[ORH_wxman]

Oh man, thank you! I'm going to have some fun this weekend for sure. Look for a long post full of diced and sliced data coming up. I'll probably toss in daily pna/nao/ao stuff as well. I have the daily data downloaded in excel so it will be easy to put together.

I'm interested in the week prior data. Hopefully I find a decent signal a week out. I want to get better at not buying big (but flawed) solutions with the models when the threat is 7+ days. Wes is really good at keeping us under control when obvious pieces are missing even though were getting pasted with virtual snow.

Works both ways too. Sometimes the models tease us with whiffs before locking in to something decent @ day 4 on in. It would be nice to have some data on hand when the upper air and indices are pointing at more potential than what is being shown.

I imagine 1 week out will not provide a ton of answers...you can probably create a composite for what it looked like 1 week out, but it might not be predictive since probably countless other times had similar setups 1 week out but the key synoptic players didn't solidify until a couple days before. Sometimes 1 week out you can see the writing on the wall with very stable features...ala Feb 5-6, 2010. That was about as much a slam dunk as you can have in the world of forecasting 6-7 days out for DC snow...the question was merely how much snow would there be. Those are usually the exception rather than the rule.

[ORH_wxman]

Even for 4 inch or greater snowstorms, the ao correlates a little better for dc. I think becuase the nao allows the blocking to be pretty far east since the index uses iceland in the calculation and we really want the blocking over greenland and canada with below normal heights to the south of the block.

Yeah I imagine using the CPC number for NAO will create that issue. Iceland blocks are generally not very good for snowstorms there. If we just looked at the Greenland/Davis Straight/Baffin Island area, I'd bet that would correlate the best to snow events there. The AO probably would still win for temperatures though since its hard to get very cold without some semblance of a -EPO.

[Bob Chill]

I imagine 1 week out will not provide a ton of answers...you can probably create a composite for what it looked like 1 week out, but it might not be predictive since probably countless other times had similar setups 1 week out but the key synoptic players didn't solidify until a couple days before. Sometimes 1 week out you can see the writing on the wall with very stable features...ala Feb 5-6, 2010. That was about as much a slam dunk as you can have in the world of forecasting 6-7 days out for DC snow...the question was merely how much snow would there be. Those are usually the exception rather than the rule.

You just saved me a lot of work. lol

I'll probably take the top 10 and look hard at those anyway. Big storms have to have many things go right for us. I would think the state of the ao/nao/pna a week out along with h5 anom map would show some insight. If I don't come up with anything interesting it will still be a fun exercise.

[usedtobe]

How much does your winter forecast change/or at all if the warming continues and we're able to get solidly into weak Nino territory?

Not an awful lot.

[ORH_wxman]

Not an awful lot.

It might mean better news for February on the Pacific side, but given it can't really get beyond weak, the effects would probably be muted. But I suppose a last second strengthening in the western reaches of the ENSO regions can't be a bad thing. A La Nina-ish February would stink...we can probably say that much. So anything that could give it a more El Nino look would be welcome to snow lovers.

[usedtobe]

It might mean better news for February on the Pacific side, but given it can't really get beyond weak, the effects would probably be muted. But I suppose a last second strengthening in the western reaches of the ENSO regions can't be a bad thing. A La Nina-ish February would stink...we can probably say that much. So anything that could give it a more El Nino look would be welcome to snow lovers.

Since 1950 there have been 13 seasons with the oni between plus 0.2 and plus 1 and the biggest year was 25 inches or so. The average was 12.6...about the same as the median for all years. about 1 in 3 produced more snow than normal. Matt (CWG) forecast near the median or maybe a tad below so I'd still got near his forecast even with a nino unless I knew for certain that the ao would be negative which still looks to be up in the air. 13 years certainly is not enough to be statistically significant so the stats might be misleading. Give me an oni above 1.0 and I'd be more excited. For all ninos, the probability of getting above normal snowfall is right at 50%, the old flip of a coin but that's better than a normal year or a weak enso. Let's hope the GLAAM doesn't push us towards a nina like pattern in late Jan and early Feb, that would not be fun.

[griteater]

Interesting take from Paul Roundy on the winter Nino - http://blog.timesunion.com/weather/did-el-nino-die/2662/

"One of the leading forcing terms for changes in the state of El Niño is the Madden Julian oscillation, an eastward-moving region of organized thunderstorms and winds. the MJO produces alternating westerly and easterly wind signals over the Pacific Ocean. When El Niño itself has not yet fully coupled to atmospheric circulations (like right now), it is highly sensitive to forcing from the MJO, and the MJO in the right background conditions can change or amplify ENSO’s phase. Presently the western Pacific MJO is in its easterly phase. This phase is frequently followed by reduction of central Pacific sea surface temperatures. The westerly wind phase is likely to move over the Pacific during late November and early December. In consequence, I anticipate that the sea surface temperature pattern is likely to become less like El Niño into early December, followed by potential for dramatic sea surface temperature increases by late December or early January. Thus, although there is no guarantee of El Niño development across this season, I think it is a mistake to write it off. At least moderately strong El Niño conditions remain possible during January and February."

[Amped]

GFS 360. +10c 582 over western Greenland, Polar Vortex 50/50. Posted cause I'm tired of talking about Sandy.

[WVclimo]

Interesting take from Paul Roundy on the winter Nino - http://blog.timesuni...-nino-die/2662/

"One of the leading forcing terms for changes in the state of El Niño is the Madden Julian oscillation, an eastward-moving region of organized thunderstorms and winds. the MJO produces alternating westerly and easterly wind signals over the Pacific Ocean. When El Niño itself has not yet fully coupled to atmospheric circulations (like right now), it is highly sensitive to forcing from the MJO, and the MJO in the right background conditions can change or amplify ENSO’s phase. Presently the western Pacific MJO is in its easterly phase. This phase is frequently followed by reduction of central Pacific sea surface temperatures. The westerly wind phase is likely to move over the Pacific during late November and early December. In consequence, I anticipate that the sea surface temperature pattern is likely to become less like El Niño into early December, followed by potential for dramatic sea surface temperature increases by late December or early January. Thus, although there is no guarantee of El Niño development across this season, I think it is a mistake to write it off. At least moderately strong El Niño conditions remain possible during January and February."

That's good stuff. Thanks for sharing it.

[okie333]

Stratospheric vortex is also split.

[WxUSAF]

Overnight GFS ensembles very supportive of a signficant -NAO in the long range.

[Deck Pic]

The PAC in the OP map isn't very good. We definitely don't want a trough northwest of AK.

[Bob Chill]

Euro shows a strong 582dm ridge just off the cali coast and a pretty good cold outbreak breaking into the northern plains @ d10. -14 to -16 850's into MN. Ridging east of GL squeezing the flow. That type of setup would definitely let the cold and trough shift east. It's looking more and more likely that we end the month pretty chilly. Looks pretty dry but who cares. Better than warm rain.

[Deck Pic]

Euro shows a strong 582dm ridge just off the cali coast and a pretty good cold outbreak breaking into the northern plains @ d10. -14 to -16 850's into MN. Ridging east of GL squeezing the flow. That type of setup would definitely let the cold and trough shift east. It's looking more and more likely that we end the month pretty chilly. Looks pretty dry but who cares. Better than warm rain.

The front comes through next weekend. Seasonal til then with peak warmth around thanksgiving. GFS/Euro on same page with low 60s Thursday. GFS mos is 62.

[Bob Chill]

The front comes through next weekend. Seasonal til then with peak warmth around thanksgiving. GFS/Euro on same page with low 60s Thursday. GFS mos is 62.

I have a bunch of family staying at my house over tday weekend. The warmth will actually be nice. We can take the kids and cousins to the parks and let the dog run. It will make is easier on my wife because we won't be all cramped up in the house for days on end. I'm looking forward to the pleasant weather.

Looks like the local ski areas can fire the guns and open up in early Dec. Good for them.

[Deck Pic]

I have a bunch of family staying at my house over tday weekend. The warmth will actually be nice. We can take the kids and cousins to the parks and let the dog run. It will make is easier on my wife because we won't be all cramped up in the house for days on end. I'm looking forward to the pleasant weather.

Looks like the local ski areas can fire the guns and open up in early Dec. Good for them.

Yes. Nothing worse than a cold pattern 11/15/ 11/30 only to torch after. Maybe we get another shot on 12/5. We've had early to mid DEC events in 2002, 2003, 2005, 2007, 2008(minor), 2009, 2010. What was nice about the mid dec clipper in 2010 was how long it stuck around even though it was only 2".

[Deck Pic]

I'm living in Old Town at 10', 3 miles due south of DCA 100 yards from the river. And I have a perfect place to measure. Might even put a snow board out there. I will have a great opportunity to see how bad DCA measures.

[Bob Chill]

I'm living in Old Town at 10', 3 miles due south of DCA 100 yards from the river. And I have a perfect place to measure. Might even put a snow board out there. I will have a great opportunity to see how bad DCA measures.

You should absolutely do it. I hate their stats. It skews everything IMO. I would use yours over DCA's every single year.

Who knows about precip chances in early december. It impossible to say what happens after the first cold shot although odd seems to favor a more blocked vs progressive pattern. I really like the euro ridge out west. Hopefully we can get the hudson bay vort spinning if the atlantic cooperates. Then anything hitting pac nw and bc can ride up over and down. December 5th clipper ftw.

[Ji]

Euro has chilled us for Thanksgiving. 55 for the high?