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How to get a cold winter in DC


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I was talking to Will last night about 2002-03...tied for DCA's 3rd coldest winter since 1950....And so I did a little investigating..certainly the PNA and NAO/AO are important, but the EPO might be the clincher...get that +anomaly north of AK/cross-polar flow and game on...I guess the source regions have to be cold since it will get modified so much...I suppose that is why we pay so much attention to Siberian snowcover....

post-66-0-43952700-1344448079_thumb.png

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The EPO has the biggest correlation with temps in the CONUS as a whole if I'm not mistaken. When you get the -EPO/-NAO/+PNA combo, its just a straight pipeline of cold air into the northeast.

Pretty much every single memorable frigid month had blocking up in the EPO region whether Feb '07, Jan '04, Jan '03, Jan '

94, Jan '85, Jan '77, Feb '79, Dec '89, Dec '00, Dec '83, etc...the common theme. The Atlantic wasn't always great but the EPO region was. The most ideal is to get a -EPO with a +PNA out in the PAC...not all -EPO blocks end up good if the PNA and NAO both work hard against it.

Of course, for snow, you want some help on the Atlantic side.

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Nice graphic, a couple of those years ie. 1976-1977 and 1993-1994 were not particularly snowy though the latter was really close with the big sleet storm and a couple of ice storms. The former is the coldest I can remember and the only time I can remember people ice skating on the bay and Potomac.

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Nice graphic, a couple of those years ie. 1976-1977 and 1993-1994 were not particularly snowy though the latter was really close with the big sleet storm and a couple of ice storms. The former is the coldest I can remember and the only time I can remember people ice skating on the bay and Potomac.

I am too young to remember 76-77 well...I was in Atlanta for 93-94....as a kid my #1 recollection of cold was January 1982...I don't know about the bay or potomac, but the ponds in my neighborhood were all frozen rock solid for quite some time and there would be tons of us playing on them after school....I don't remember any other month that happened as a youngster...January 1988 for a brief period though I didn't care as much...DEC 1989 too, but I don't think as well because too early in the season

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The EPO has the biggest correlation with temps in the CONUS as a whole if I'm not mistaken. When you get the -EPO/-NAO/+PNA combo, its just a straight pipeline of cold air into the northeast.

Pretty much every single memorable frigid month had blocking up in the EPO region whether Feb '07, Jan '04, Jan '03, Jan '

94, Jan '85, Jan '77, Feb '79, Dec '89, Dec '00, Dec '83, etc...the common theme. The Atlantic wasn't always great but the EPO region was. The most ideal is to get a -EPO with a +PNA out in the PAC...not all -EPO blocks end up good if the PNA and NAO both work hard against it.

Of course, for snow, you want some help on the Atlantic side.

Nice graphic, a couple of those years ie. 1976-1977 and 1993-1994 were not particularly snowy though the latter was really close with the big sleet storm and a couple of ice storms. The former is the coldest I can remember and the only time I can remember people ice skating on the bay and Potomac.

It is no coincidence that our strongest hemispheric anomaly last winter was a -anomaly precisely over northern AK....combined with an awful AO/NAO, the good PNA periods were useless

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It is no coincidence that our strongest hemispheric anomaly last winter was a -anomaly precisely over northern AK....combined with an awful AO/NAO, the good PNA periods were useless

Absolutely...you may have read/remember some of us say over the last few years that the single pattern to fear the most in the winter if you are rooting for cold/snow is a big vortex right over AK...esp N/W AK...smack over the EPO region. It almost always spells disaster unless you can get a very good Atlantic/PNA...but that is a rare combo...and even then its usually marginal cold/snow that can be salvaged.

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Absolutely...you may have read/remember some of us say over the last few years that the single pattern to fear the most in the winter if you are rooting for cold/snow is a big vortex right over AK...esp N/W AK...smack over the EPO region. It almost always spells disaster unless you can get a very good Atlantic/PNA...but that is a rare combo...and even then its usually marginal cold/snow that can be salvaged.

yep...note of the 8 winters...they are all ninos or neutrals during/following a warm/flat ENSO...now that PDO has flipped it is probably hard to get that kind of winter that has no cold water influence over a long duration..1976-77 is kind of a weird anomaly, but you have said lots of cold air was bottled up and we were undergoing a momentous PDO regime shift...I think our 2 most recent coldest before 1950...35-36 and 47-48 happened under similar cirumstances....fwarm/flat enso...

if we could get a 3 year warm/neutral period following this nino it would be pretty likely one of the subsequent winters would be frigid...

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yep...note of the 8 winters...they are all ninos or neutrals during/following a warm/flat ENSO...now that PDO has flipped it is probably hard to get that kind of winter that has no cold water influence over a long duration..1976-77 is kind of a weird anomaly, but you have said lots of cold air was bottled up and we were undergoing a momentous PDO regime shift...I think our 2 most recent coldest before 1950...35-36 and 47-48 happened under similar cirumstances....fwarm/flat enso...

if we could get a 3 year warm/neutral period following this nino it would be pretty likely one of the subsequent winters would be frigid...

Yes, we were coming off basically 4 consecutive years of a huge +AO up there that bottled up arctic air with 1975 and early 1976 especially enhanced.

The shift in the north PAC in 1976 was the most abrupt and drastic we've seen. Definitely a unique set of circumstances leading up to that winter.

You theories about the winter or winters prior to the cold winters is definitely interesting and may lend some significant weight. The lack of sample size is always an issue when trying to dissect these variables though.

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Yes, we were coming off basically 4 consecutive years of a huge +AO up there that bottled up arctic air with 1975 and early 1976 especially enhanced.

The shift in the north PAC in 1976 was the most abrupt and drastic we've seen. Definitely a unique set of circumstances leading up to that winter.

You theories about the winter or winters prior to the cold winters is definitely interesting and may lend some significant weight. The lack of sample size is always an issue when trying to dissect these variables though.

certainly no rule, but the cold winters and I think you can include 35-36, 47-48 as well as 81-82, 03-04 didn't have any lingering nina stink anywhere remotely close to them except for 76-77

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Good point about 76-77 and the same thing can be expressed for 02-03. For 02-03, we suddenly switched regimes both with ENSO and PDO (a relative max in the PDO occurred 02-03 through 05-06) after following an extensive -PDO/La Nina/+AO period (98-99 through 01-02). The key is knowing when to look for these type of years.

I don't think 12-13 is going to qualify in this caliber as I'm sure you guys agree but it still could pull something off on a smaller scale if certain things were to fall into place.

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Good point about 76-77 and the same thing can be expressed for 02-03. For 02-03, we suddenly switched regimes both with ENSO and PDO (a relative max in the PDO occurred 02-03 through 05-06) after following an extensive -PDO/La Nina/+AO period (98-99 through 01-02). The key is knowing when to look for these type of years.

I don't think 12-13 is going to qualify in this caliber as I'm sure you guys agree but it still could pull something off on a smaller scale if certain things were to fall into place.

i'm pretty unethusiastic about this winter down here....we could still pull off something half decent in the 1/25 to 3/5 period...like a 2/4/95 or 2/7/03 or 2/24/05...I am not anticipating any kind of moisture laden system with a good track....If we are lucky enough to get something juicy the low will probably go to Pittsburgh like 2/14/07..lol

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I'm ever so slightly optimistic about a decent event this winter and a couple modest ones as well. By decent I mean a 4-8". Not a big one unless the stars align.

I'm starting to go back to thinking that we're in an overall -ao-nao period with last winter being an oddball.

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I know HGR did well because I drove out there a number of times to see decent snow

Gettysburg as well for that matter

There were a couple solid storms with more NW/SE gradients that winter despite the majority being more N/S....the 3/3/94 storm comes to mind and also the 1/4/94 system.

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There were a couple solid storms with more NW/SE gradients that winter despite the majority being more N/S....the 3/3/94 storm comes to mind and also the 1/4/94 system.

That was a fun winter for my freshman year in college in central PA. Seems like it snowed constantly for a good stretch of that winter.

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There were a couple solid storms with more NW/SE gradients that winter despite the majority being more N/S....the 3/3/94 storm comes to mind and also the 1/4/94 system.

I'm pretty sure it was the 1/94 storm when I drove through HGR and then cut NE to Gettysburg and Gettysburg had 10"+, if not a foot, w/HGR similar

I still remember whining to my wife and kids all the way home to our 2" sleet/zr fest

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yep...note of the 8 winters...they are all ninos or neutrals during/following a warm/flat ENSO...now that PDO has flipped it is probably hard to get that kind of winter that has no cold water influence over a long duration..1976-77 is kind of a weird anomaly, but you have said lots of cold air was bottled up and we were undergoing a momentous PDO regime shift...I think our 2 most recent coldest before 1950...35-36 and 47-48 happened under similar cirumstances....fwarm/flat enso...

if we could get a 3 year warm/neutral period following this nino it would be pretty likely one of the subsequent winters would be frigid...

Matt, I wonder what your thoughts on precip analogs would be. This will be my fifth winter in Winchester and the problems have almost always been lack of precip as opposed to lack of cold. I know it's a bit of a different story down in the Wash/Balt areas with no elevation, and occasionally we miss snow out here due to temps, but I'm really sold on the idea that precip is the biggest worry. Just wondered if your research had uncovered a link between precip seen in past years and the conditions that we've had the past couple of winters and those we are looking at having heading into this one.

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i'm pretty unethusiastic about this winter down here....we could still pull off something half decent in the 1/25 to 3/5 period...like a 2/4/95 or 2/7/03 or 2/24/05...I am not anticipating any kind of moisture laden system with a good track....If we are lucky enough to get something juicy the low will probably go to Pittsburgh like 2/14/07..lol

What do you make of the latest MEI reading? It would seem to indicate moderate strength in progress/on the way for this winter. It's interesting because the general consensus / expectation is for a weak El Nino trimonthly peak or close to moderate strength (+0.8 to +1.2 type of thing).

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What do you make of the latest MEI reading? It would seem to indicate moderate strength in progress/on the way for this winter. It's interesting because the general consensus / expectation is for a weak El Nino trimonthly peak or close to moderate strength (+0.8 to +1.2 type of thing).

I haven't paid much attention to the MEI but that is interesting. I think 06-07 had a high reading as well? I want to see a tri-monthly peak of at least 1.3-1.4 and hopefully higher to feel good about winter. Following a 2-year nina in an insane -PDO regime scares me. I can already envision a Vortex parked over the EPO region. I know you and Wes and will and others have talked about the stability of vortices in the EPO and AO region and how the models break the pattern down way too quickly. Plus the lack of a southern stream.

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Matt, I wonder what your thoughts on precip analogs would be. This will be my fifth winter in Winchester and the problems have almost always been lack of precip as opposed to lack of cold. I know it's a bit of a different story down in the Wash/Balt areas with no elevation, and occasionally we miss snow out here due to temps, but I'm really sold on the idea that precip is the biggest worry. Just wondered if your research had uncovered a link between precip seen in past years and the conditions that we've had the past couple of winters and those we are looking at having heading into this one.

keep ur fingers crossed the CFS2 is right on precip if nothing else

it's been pretty bullish on a classic mod NINO pattern similar to today's forecast (linked below) for a while

http://www.cpc.ncep.noaa.gov/products/CFSv2/htmls/usPrece3Sea.html

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What do you make of the latest MEI reading? It would seem to indicate moderate strength in progress/on the way for this winter. It's interesting because the general consensus / expectation is for a weak El Nino trimonthly peak or close to moderate strength (+0.8 to +1.2 type of thing).

The MEI reading was a surprise to me since a lot of other factors about this Nino seem to be floundering. I wonder what variables are making the reading fairly robust...I have a hard time believing its the SST/SLP component of the index that is doing it since the SOI and SSTs havent been that Nino-like (though the SOI recently had a nice drop).

I haven't looked that closely at the zonal wind anomalies, but I know for a while they had been struggling as well.

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Uncle W posted this in the ENSO thread on the main forum Monday:

June/July mei index is 1.139...well into el nino territory...It's the fifth highest J/J index of all the developing nino years...

1997...+2.756

1972...+1.886

1982...+1.620

1965...+1.395

2012...+1.139

....................................

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Matt, I wonder what your thoughts on precip analogs would be. This will be my fifth winter in Winchester and the problems have almost always been lack of precip as opposed to lack of cold. I know it's a bit of a different story down in the Wash/Balt areas with no elevation, and occasionally we miss snow out here due to temps, but I'm really sold on the idea that precip is the biggest worry. Just wondered if your research had uncovered a link between precip seen in past years and the conditions that we've had the past couple of winters and those we are looking at having heading into this one.

right now I'd lean toward 2 mean storm tracks...across 4-corners and then cutting to the lakes..those will be more common earlier in the season...and then storms traversing a little further south and usually cutting up the apps and redeveloping off Jersey...those will be more common in January....Hopefully later in the winter if we can get blocking the southern track storms will redevlop further south or miller A straight up the coast but be a bit moisture starved...I'd also lean toward anything needing a timed stream phase to screw us no matter what the models say 2-4 days out

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right now I'd lean toward 2 mean storm tracks...across 4-corners and then cutting to the lakes..those will be more common earlier in the season...and then storms traversing a little further south and usually cutting up the apps and redeveloping off Jersey...those will be more common in January....Hopefully later in the winter if we can get blocking the southern track storms will redevlop further south or miller A straight up the coast but be a bit moisture starved...I'd also lean toward anything needing a timed stream phase to screw us no matter what the models say 2-4 days out

I pretty much 100% agree here. Especially the early season stuff.

I would also think that we stand a chance at a modest event or 2 consisting of an h5 vort rounding an ec trough that can tap into some gulf moisture. Doesn't even have to be an organized system either. A simple overrunner that produces areawide.

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yep...note of the 8 winters...they are all ninos or neutrals during/following a warm/flat ENSO...now that PDO has flipped it is probably hard to get that kind of winter that has no cold water influence over a long duration..1976-77 is kind of a weird anomaly, but you have said lots of cold air was bottled up and we were undergoing a momentous PDO regime shift...I think our 2 most recent coldest before 1950...35-36 and 47-48 happened under similar cirumstances....fwarm/flat enso...

if we could get a 3 year warm/neutral period following this nino it would be pretty likely one of the subsequent winters would be frigid...

The 500h anomalies were very different those years, 1935-36 looks pretty classic with a negative epo, ao and nao. It's a really cold look for the conus.

post-70-0-90105600-1344527040_thumb.png

1947-1948 us a different animal with a positive epo look. and a positive ao. It's very anomalous with cold over new England that gets down into our area but the cold is more in new england than for the mid atlantic at least based on the maps I looked at.

post-70-0-12643600-1344527163_thumb.png

I think the cold was really due to the semi-permanent negative anomaly near and just south of Nova Scotia.

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