My Winter Outlook 2010-11

[OKpowdah]

Excellent read, and an excellent forecast thus far

[JBG]

Iso, if your forecast verifies, you might need to bring another rare analog into the equation-- the first pair of back to back 50" snowfall seasons at NYC since 1916-17 and 1917-18..... and the only time it's happened so far. And interestingly enough, two of the analogs being used once solar is factored into the equation.

To me those analogs are looking better and better.

[Isotherm]

my theory is if we don't get the January thaw the second half of the month it will come in February...Last year we had a good thaw (50 on this date last year) and February resumed the snowy cold pattern we had before the thaw...We are getting the coldest temperatures of the winter and a few snowfalls ( I hope ) when we should be getting the January thaw...We could get a long February thaw like we saw in 1961 or one like we had in 1994...1947 also had their thaw in February...1996 had two thaws...One the end of January and the other the end of February...1957-58 also...

Uncle W, I agree. We should have at least 1-2 week period of mild temperatures, probably early February based on the way things are looking right now. +AO/+NAO/+PNA combination for a bit, before we head back into the negative phase of the AO/NAO once again (probably mid Feb).

[Isotherm]

I think there's a good chance March comes in colder than normal, as do you. Your forecast has been among the best on this board so far, really great work! We are having another historic winter, and the next two weeks looks to be particularly snowy and bitterly cold now that we've gotten this slop storm out of the way.

Thanks Nate! Yeah I'm really liking the period second half of Feb-first half of March for wintry potential, as the Nina begins to decay and blocking resumes.

[Isotherm]

Excellent read, and an excellent forecast thus far

Thanks for the kind words!

[Isotherm]

I'm also going to ask you to look at some of our really good backloaded winters, since la ninas seem to produce big late season snowfalls. Specifically, looking at 1955-56, 1966-67, 1995-96 and 2005-06.

Alex, you can throw March 2001 in there as well. Big storm for New England and a massive blocking pattern. A bit further SW and that would've been a HECS for us. Late season definitely has some serious potential this year.

[VAwxman]

Pretty good so far man. You were definitely among those concerned we'd see more blocking. That definitely worked out, even moreso than almost anyone would have ever thought. With a solid nina, no one would have ever forecasted an anomaly pattern like this one for almost the whole first two months of winter. Wild.

Map courtesy of MDA:

[usedtobe]

Certainly a much better call than mine. I was pretty good for dec but didn't forsee this much blocking in January.

[Bob Chill]

VAwxman, can you post the link to generate those maps? I've been interested to see the departures this winter and that map is perfect. It really shows how other factors can vastly change what is expected in a Nina pattern. When I lived in CO in the 90's, Nina's were great for the northern Rockies where I lived. This years precip is spot on because the northern resorts are getting substantial snowfall but the temps have been above average. Nina's are usually pretty damn cold in the CO rockies and that is not the case this year.

[VAwxman]

VAwxman, can you post the link to generate those maps?

Unfortunately those maps come from a pay site (MDA - EarthSat site). We pay for their services here in the energy sector. They typically have not cared if I post maps like this occasionally, and it's kinda like free advertising for them anyway.

[A-L-E-X]

Hey Brian, can you compare that to last winter's map? I see some similarities with the temp gradients.

[VAwxman]

Hey Brian, can you compare that to last winter's map? I see some similarities with the temp gradients.

Here is the map for the same dates last winter... there are similarities with the gradient.

[Ellinwood]

Unfortunately those maps come from a pay site (MDA - EarthSat site). We pay for their services here in the energy sector. They typically have not cared if I post maps like this occasionally, and it's kinda like free advertising for them anyway.

It's all good

We're also getting ready to launch some new developments with the Dynacast system (still beta testing it last time I checked), and it's quite awesome.

[Isotherm]

Pretty good so far man. You were definitely among those concerned we'd see more blocking. That definitely worked out, even moreso than almost anyone would have ever thought. With a solid nina, no one would have ever forecasted an anomaly pattern like this one for almost the whole first two months of winter. Wild.

Map courtesy of MDA:

Certainly a much better call than mine. I was pretty good for dec but didn't forsee this much blocking in January.

Thanks for the nice comments Brian and Wes! My main regret is not going colder in the SE US, with a more expansive Eastern trough. The blocking has been so severe that any semblance of a strong nina induced SE ridge was crushed.

[Isotherm]

Verification:

Here are my last couple paragraphs from my winter outlook issued in October (I've bolded the calls within it).

"An interesting pattern may unfold this winter, with the potential high for the NAO averaging on the negative side for DJF, and the AO not as positive as it normally would with the present ENSO regime. However, we have a strong La Nina event in place, and that will undoubtedly play a significant role in the temperature/precipitation distribution across the United States. It’s going to be a bit difficult to analog this winter, or compare it to previous years, as there aren’t many similarities. We have an unprecedented solar set-up with record low geomagnetic activity; we have a –QBO shifting slightly positive in the means, a strong La Nina, and a relatively favorable Atlantic SSTA pattern. Big time conflicts between the Pacific and Atlantic signal fighting for dominance may be the name of the game this winter. The Pacific trying to torch much of the nation, which will surely happen at times, and the NAO overwhelming parts of the US with colder than normal temps and snowfall. 1954-55, 1955-56 are probably the best overall analogs for 2010-2011 IMO. Both occurred in a relative geomagnetic minimum with negative NAO values, both were at a similar place PDO/AMO wise, and both were mod-strong La Nina events (1955-56 was very strong like this one may be). 1973-74 would be up near the top if the solar/NAO fit with this year, but it doesn’t. 1970-71 is pretty good but the La Nina this year will be quite a bit stronger, thus warmer than that winter.

December should be the coldest month relative to normal in the Northeast, with colder anomalies continuing to hold on in January with a favorable NAO pattern. February should be the warm month with the Nina induced SE-ridge going wild, pushing above normal temps further west. Overall, DJF temp departures probably won’t be as warm as most strong La Nina’s, with the more favorable Atlantic regime expected. As for precipitation and storm tracks – there’s likely to be a mixture this winter. We’ll see a good amount of lakes-cutters and inland runners producing Ohio Valley and Northern New England snow, but in times of –NAO, we could see northern stream Miller B clippers dive southward and produce snow in the I-95 corridor. I anticipate December 15th-January 15th to be the snowiest relative to normal for most of the Eastern I-95 corridor, Richmond to Boston. The biggest snows for interior/NNE may be in February with warmer temps but also plentiful precipitation."

Temp departure forecast for DJF in NYC versus actual:

Temps

December: -1 to -2 / Actual: -4.5 Grade: C

January: 0 to -1 / Actual: -2.4 Grade: B

February: +1 to +2 / Actual: +1.4 Grade: A

Overall: 0 to -1 / Actual: -1.8 Grade: B

Snowfall: 25-32”

Updated call in mid Jan: 50-57"

Grade: C+

Overall grade for winter 2010-11: B

My assessment of this winter's forecast -- I thought both the temp departure values and trend throughout the winter (coldest in December, still cold Jan, warm Feb) worked out very well. I was happy to get the period of heaviest snowfall correct, Dec 15-Jan 15, in conjunction w/ the best greenland blocking. However I'm disappointed I didn't see the historic snow totals coming for the NYC area. Was hard to make a call that far above normal given other factors, and I wasn't sure whether the -NAO/AO pattern would be a very snowy one. Either way, snowfall is the most difficult aspect to predict long range, so it is not weighted as much as the temperature calls, which were good overall. What I'm most happy about is my NAO/geomag connection theory working out well, as NAO values were low most of the winter until February.

Biggest regrets -- not going colder in the SE US in December, and not going snowier in NYC. I had the idea correct for a poor winter in the mid atlantic and a great one for Boston, but was not bullish enough in our region (NYC/NJ/PHL).

Bonus cities snowfall:

Philly: 15-22”

Washington DC: 8-15”

Boston: 50-57”

[NJwinter23]

Really nicely done. My greatest concern going in (though I did not put the time into a full winter outlook) was always that the blocking would continue, considering the streak we were on. Just based off skeptical persistence and attributing it to the continued solar min...Actually in hindsight, a lot of people had the blocking through December and then it breaking down by Jan/Feb for Nina to take over. The true blocking really only continued through the first half of Jan and then shut down for good. So maybe an extra 2 weeks off? That really isnt terrible for a long range seasonal call if you think about it. But the real wild card in this winter was the timely MJO influence at that exact mid-month moment that brought the +PNA and ensured the 2nd half of Jan would be below average and snow-filled as well. February was more or less a raging Nina pattern of course and it pretty much continues to the present.

All in all through the pre-winter discussions and analogs, I liked the chances of this winter being the snowiest mod/strong La Nina at least in my lifetime (since 1987) here in central NJ. I thought an avg 20-25" was reasonable, but wow, woulda have never ever thought 60" was possible even if you told me the NAO would avg negative before hand. I mean, even through December..we were getting shutout through Christmas! Despite a -5 departure and a raging -AO/NAO!..Incredible winter

[A-L-E-X]

Really nicely done. My greatest concern going in (though I did not put the time into a full winter outlook) was always that the blocking would continue, considering the streak we were on. Just based off skeptical persistence and attributing it to the continued solar min...Actually in hindsight, a lot of people had the blocking through December and then it breaking down by Jan/Feb for Nina to take over. The true blocking really only continued through the first half of Jan and then shut down for good. So maybe an extra 2 weeks off? That really isnt terrible for a long range seasonal call if you think about it. But the real wild card in this winter was the timely MJO influence at that exact mid-month moment that brought the +PNA and ensured the 2nd half of Jan would be below average and snow-filled as well. February was more or less a raging Nina pattern of course and it pretty much continues to the present.

All in all through the pre-winter discussions and analogs, I liked the chances of this winter being the snowiest mod/strong La Nina at least in my lifetime (since 1987) here in central NJ. I thought an avg 20-25" was reasonable, but wow, woulda have never ever thought 60" was possible even if you told me the NAO would avg negative before hand. I mean, even through December..we were getting shutout through Christmas! Despite a -5 departure and a raging -AO/NAO!..Incredible winter

That was the greatest 5 week combo of snow and cold I have ever seen here. From Jan 6 through Feb 5 the highest positive mean anomaly was +1. 23/30 days were below normal. And from Jan 3 through Feb 5, a period of 33 days, every single mean was in the 30s or below. Getting the most sustained and coldest weather of the season when its supposed to be coldest was a big reason why the entire region saw well over 50 days of sustained snowcover. In some ways, it mimicked 2008-09 for having sustained cold at the climo favored coldest time of the year, but of course it was MUCH snowier.

[Isotherm]

Really nicely done. My greatest concern going in (though I did not put the time into a full winter outlook) was always that the blocking would continue, considering the streak we were on. Just based off skeptical persistence and attributing it to the continued solar min...Actually in hindsight, a lot of people had the blocking through December and then it breaking down by Jan/Feb for Nina to take over. The true blocking really only continued through the first half of Jan and then shut down for good. So maybe an extra 2 weeks off? That really isnt terrible for a long range seasonal call if you think about it. But the real wild card in this winter was the timely MJO influence at that exact mid-month moment that brought the +PNA and ensured the 2nd half of Jan would be below average and snow-filled as well. February was more or less a raging Nina pattern of course and it pretty much continues to the present.

All in all through the pre-winter discussions and analogs, I liked the chances of this winter being the snowiest mod/strong La Nina at least in my lifetime (since 1987) here in central NJ. I thought an avg 20-25" was reasonable, but wow, woulda have never ever thought 60" was possible even if you told me the NAO would avg negative before hand. I mean, even through December..we were getting shutout through Christmas! Despite a -5 departure and a raging -AO/NAO!..Incredible winter

Thanks man, and agree with your assessment. Although the blocking began to fade in late jan, we had that nice PNA surge to help sustain the eastern troughiness. Yeah I was pretty confident as well we'd be looking at the snowiest strong la nina based on the NAO prospects, but had no idea we'd end up this snowy. Which I'm glad we all busted low on snowfall rather than too high. Was a great winter.

[A-L-E-X]

Thanks man, and agree with your assessment. Although the blocking began to fade in late jan, we had that nice PNA surge to help sustain the eastern troughiness. Yeah I was pretty confident as well we'd be looking at the snowiest strong la nina based on the NAO prospects, but had no idea we'd end up this snowy. Which I'm glad we all busted low on snowfall rather than too high. Was a great winter.

Just imagine what kind of a winter it would have been if it was a weak la nina following an el nino-- 95-96 would have been eclipsed fairly easily.

[Isotherm]

Just imagine what kind of a winter it would have been if it was a weak la nina following an el nino-- 95-96 would have been eclipsed fairly easily.

Yeah agree Alex -- we probably wouldn't have seen such a quick death to winter in February. All NYC needed was a couple more SECS events to get to the total.

Maybe next winter we can pull a 95-96 w/ a weak nina and strong blocking.

[nzucker]

Yeah agree Alex -- we probably wouldn't have seen such a quick death to winter in February. All NYC needed was a couple more SECS events to get to the total.

Maybe next winter we can pull a 95-96 w/ a weak nina and strong blocking.

I think you did an excellent job with the forecast, I would grade it an A-. No one is going to call for 60" of snow in NYC in a strong La Niña. We both had similar ideas with a powerful trough in December due to the low solar causing a -NAO/-AO, January as a transition month, and then a milder February with the ENSO being the main pattern driver. Although we didn't see a February 1976 type torch, the winter did follow this general progression, a pattern we saw in 54-55 and 88-89 with the mean trough moving to the West Coast late in the winter. I think the only aspect you and I missed was the MJO wave in January that sent the PNA into positive territory and substituted for the gradual breakdown of the arctic blocking.

Do you think we see one more period of blocking in mid-late March? I don't like what I see on the models right now, but some La Niñas did get very blocky late like 1956 and 1967. I have to wonder, however, with Region 3.4 still being at -1.2C, if the La Niña is just too strong for us at this juncture.

What are your thoughts on next winter? Will the -NAO/-AO continue even if we do see another Niña? Or will it take an El Niño to revive the blocking since the PV has been strengthened?

[Isotherm]

I think you did an excellent job with the forecast, I would grade it an A-. No one is going to call for 60" of snow in NYC in a strong La Niña. We both had similar ideas with a powerful trough in December due to the low solar causing a -NAO/-AO, January as a transition month, and then a milder February with the ENSO being the main pattern driver. Although we didn't see a February 1976 type torch, the winter did follow this general progression, a pattern we saw in 54-55 and 88-89 with the mean trough moving to the West Coast late in the winter. I think the only aspect you and I missed was the MJO wave in January that sent the PNA into positive territory and substituted for the gradual breakdown of the arctic blocking.

Do you think we see one more period of blocking in mid-late March? I don't like what I see on the models right now, but some La Niñas did get very blocky late like 1956 and 1967. I have to wonder, however, with Region 3.4 still being at -1.2C, if the La Niña is just too strong for us at this juncture.

What are your thoughts on next winter? Will the -NAO/-AO continue even if we do see another Niña? Or will it take an El Niño to revive the blocking since the PV has been strengthened?

Thanks man! Agree about the MJO wave, didn't see that +PNA period coming in the heart of winter, but that helped produce another 12"+ event out of the winter.

I do believe we'll see the NAO become more negative once the effects of the weakening nina begin to impact the atmosphere. Problem is when does that occur? Doesn't look like it happens before March 15th, but if a blocking episode sets in before the end of March, which is possible, I can see one more 4"+ event for the coast.

As for next winter, good questions. A lot depends upon how solar activity behaves over the coming months and whether the nina remains weak/moderate or dies off to neutral. My early guess would be another winter w/ a tendency for blockiness, especially if we've got weak ENSO and continued low solar forcing.

[NJwinter23]

A lot of good long range guys out there are suggesting a return to cold in the east for the last 10 days or so of March, some suggesting continuing into April. Late winter snow would be possible, but cold is obviously pretty useless by that time. We are over due for a lousy Spring I guess.

As for our 2 KU storms in NYC this winter, the +PNA was the most important piece to the puzzle in my opinion. The -NAO was omnipresent thru all of Dec but so was the lack of PNA ridging out west, not allowing any snowstorms really. We got a huge ridge for the couple days in late Dec. and boom.

[Isotherm]

A lot of good long range guys out there are suggesting a return to cold in the east for the last 10 days or so of March, some suggesting continuing into April. Late winter snow would be possible, but cold is obviously pretty useless by that time. We are over due for a lousy Spring I guess.

As for our 2 KU storms in NYC this winter, the +PNA was the most important piece to the puzzle in my opinion. The -NAO was omnipresent thru all of Dec but so was the lack of PNA ridging out west, not allowing any snowstorms really. We got a huge ridge for the couple days in late Dec. and boom.

Could be the case. Generally with -PNA/-NAO winters, NYC doesn't see more than 35" of snow. The PNA surge in late dec and again late jan definitely aided in amplifying the nern stream s/w as it rounded the base of the eastern trough.

As for late March, the AO and NAO look to be approaching neutral in the longer term, so I doubt we see any blowtorch in the coming weeks; however, I'm not yet convinced on a blocking episode for late march-early april. One would expect the NAO to trend negative based upon past performance, analogs, weakening nina, etc. 1956 and 1971, both very good analogs for this winter, featured -NAO development in mid march and maintainence through April. We'll see what happens but the odds certainly favor a cooler temp regime march 15th and beyond, probably a crappy early to mid spring as well.

[A-L-E-X]

Thanks man! Agree about the MJO wave, didn't see that +PNA period coming in the heart of winter, but that helped produce another 12"+ event out of the winter.

I do believe we'll see the NAO become more negative once the effects of the weakening nina begin to impact the atmosphere. Problem is when does that occur? Doesn't look like it happens before March 15th, but if a blocking episode sets in before the end of March, which is possible, I can see one more 4"+ event for the coast.

As for next winter, good questions. A lot depends upon how solar activity behaves over the coming months and whether the nina remains weak/moderate or dies off to neutral. My early guess would be another winter w/ a tendency for blockiness, especially if we've got weak ENSO and continued low solar forcing.

I would extend the chances for accumulating snow through the first ten days of April IF we can maintain a strong block-- this is just based on prior history of what strong blocks have done in the past in this timeframe. Of course, the biggest issue is getting the strong block in the first place.

As far as the rest of what you said-- I agree that solar forcing is the key to how much blocking we get next winter. What's the record for most consecutive winters with a strong block?

[uncle W]

March 2009 and 1993 had snowstorms with no blocking and probably many more...