Digging deeper into winter snow forecast/historical analysis as contest draws to close
Our near-term weather in Southwest Virginia is fairly simple, as the nor’easter pulls away along the Northeast coast (several inches of snow from New Jersey to Maine). We’ll have several dry, mostly sunny days through the weekend, gradually warming — 50s on Thursday, some 60s by Friday-Sunday, wouldn’t rule out a few low 70s. Then a cold front arrives near the middle of next week with a chance of rain and some cooler temperatures again. Some chance of a larger storm system beyond that, but we’ll leave that for the future now. I will focus on a few other even longer-term things today.
The time to submit entries for the snowfall prediction contest closes out Thursday at midnight — I must have your entry emailed to weather@roanoke.com by then for it to count. IMPORTANT NOTE: I screwed up on Wednesday’s column in the paper, the period of the contest runs from Nov. 15 to March 31 — 16 days longer than I said in Wednesday’s column. This column from October 17 has the correct dates, entry guidelines listed at the bottom of the column.
I want to dig a little deeper into the historical winter analysis I conducted in Wednesday’s column, linked here (contest closing date information also now corrected). The analysis was based entirely on Roanoke’s snowfall history during winters in which there was either a weak El Nino (warming of equatorial Pacific sea surface temperatures) or neutral conditions leaning a little warm but not enough to be considered an El Nino. This winter appears likely to be on the cusp between those two as of now. If you’ve read here before, you know that I consider El Nino highly overrated as a singular factor in predicting a winter — however, it does have the advantage of being a constant, slowly changing factor, unlike the whims and fancies of the North Atlantic Oscillation and Pacific-North America pattern that can change week to week, even within a few days, whatever the overall trend of a season may be. So I thought it was worth taking a look to see if there was a discernible pattern for our winters based on similar El Nino phases in the past.
The weak El Nino winters I studied, with total snowfall in parentheses, were 1953-54 (10.7 inches), 1969-70 (26.8 inches), 1976-77 (19.2 inches), 1977-78 (37.3 inches) and 2004-05 (16.1 inches). The “almost El Nino” winters were 1979-80 (31 inches), 1989-90 (16. 1 inches), 1990-91 (1.2 inch), 1992-93 (28 inches), 1993-94 (16.3 inches) and 2003-04 (21.9 inches). As you can see, 1990-91 was the only one of these winters under 10 inches of snowfall, and it and 1953-54 were the only two under 16 inches. That seems to be a fairly significant pattern leaning strongly to near-normal and above-normal snowfall winters, if we consider 17 inches or so the norm for Roanoke (which I do, not the old 22-24 inch figures you may have seen or heard, for 3 major reasons I explain in the column).
A few other things I noted:
* Four winters of the 11 studied also had a similar pattern to this year of predominant North Atlantic Oscillation-positive pattern (no blocking high near Greenland) switching to predominantly NAO-negative (blocking high near Greenland, forcing the jet stream south, bringing cooler air) from the first half of the year to the latter part of the year — 1969-70, 1976-77, 1977-98, and 2004-05. Those winters averaged nearly 25 inches of snow. My pick for Roanoke snowfall this winter was 26 inches (31 for Blacksburg).
* Only 2 of the 11 winters studied included a snowstorm of more than 12 inches: Christmas Day 1969 and the March 1993 Superstorm.
* The one low-snowfall exception on the list, 1990-91, seems to be well explained by its being the only one of the 11 winters to exhibit an extremely strong positive phase of the NAO. All of the almost-El Nino winters went predominantly positive on the NAO, however, while all but one of the weak-El Nino winters tilted NAO-negative.
* Total precipitation was within an inch of normal in 19 of the 33 months, and rarely extreme in the above or below-normal months. Temperatures skewed cold in 3 of the 5 weak-El Nino winters, while averaging near normal in the almost-El Nino winters.
So, boiling down all of this down, and considering the tendency for northern latitude blocking patterns we’ve seen forcing the jet stream south (possibly linked to record summer Arctic ice melt, according to some studies) and the rapid growth of snowfall over Eurasia and Canada, I’m leaning to a winter of frequent periods of cold — interrupted by some unseasonable warmth in between — and occasional light to moderate snow events, with perhaps one event of the 6-12-inch nature. I’m leaning against a “big’un” type snow of 12-plus, but would give it perhaps 1 in 3 odds of occurring — much better odds than a year ago. I think there may be 2 or 3 setups this winter that could develop into that if the details line up right.
I said 26 inches for Roanoke, 31 for Blacksburg and Dec. 15 for first 1-inch snow at each site.
So there’s one idea of how things will go. Somewhat educated guesswork at best.
November 7, 2012 - 8:40 PM
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26″ of snow is a respectable winter and slightly above normal. I want about 100″ of the white stuff…hahahaha….JUST KIDDING! I’ll be happy if we eke out 15″ or more. Last winter was record warmth and a bust, except for that one moderate snow we had in February, in which it was warm the day before and the day after. Was gone in a flash. I hope winter doesn’t wear itself out early in the east like with Hurricane Sandy deep snows in West Virginia, that we almost could have got a piece and now an early Noreaster. Temps have been very chilly lately too and October was cool. Like others have said, I’d rather it be mild now and then when December -February arrive, Arctic blasts mixed with moisture. If winter breaks it’s back early when it’s generally too warm to snow, we will miss out!
I don’t think Sandy changes much. Sandy was quickly absorbed into the polar jet stream and carried inland. She didn’t wander into the North Atlantic and endlessly stir up the ocean, upwelling colder waters to the surface. In the battle between tundra and tropics that was Superstorm Sandy, the tundra rolled to a thunderous victory.
Sandy did cool the waters right of the Atlantic coast, but that hasn’t stopped a nor’easter from forming along there just a week later.
I just did some adjustments to your very thorough, detailed analysis, KM. I would toss out the weak El Nino years, because I feel that we will not have even close to an El Nino, and I would toss out years from 1980 and before, when SW Virginia and the U.S. in general were much, much colder and snowier, plus they are now more than 30 years ago. Still, that leaves 5 “almost El Nino winters” starting in 1989-90, and they averaged somewhere in the upper teens. If one says, wait, the 1993 total is bumped way up by one storm, another person can say, well, that winter that was almost snowless is a real outlier, too, and leaving out those two winters STILL leaves an average in the upper teens, almost 20.
I may have to awaken Sam O and get him to work doing his magic.
Originally I thought that we were overdue for an “average” winter, but with alternating spells of warmth and cold. I am now leaning toward a sort of first half / 2nd half approach, with only one major flip of the oscillations, but the “halves’ may not be halves at all. Could be snowy/cold for 3/4 of the winter, then a late flip, or 1/4 cold/snowy and an early flip.
I am going to hold off saying more until I see how the rest of November and perhaps the first half of DEC play out.
I just looked at today’s NAO outlooks, both the GFS ones and the ensemble ones. The GFS graphs have not changed in any real way from yesterday’s. Warm-up to neutral by the end of each multi-day graph.
But I just noticed something startling on the ensemble graph. Perhaps they looked like this yesterday, but I do not think so. Shows a consensus ABRUPT warm-up of the NAO all the way to positive +1.0 or even a bit warmer than that by Sunday or Monday. Then a close-to-consensus small descent back toward neutral, then disagreement after the 16th. A very few take the NAO back up over +1, while others take it down more, even slightly past zero. The links are in a comment I posted last night on the previous thread.
For the record, last year I started at 12 for Roanoke and 18 for Blacksburg. Ended up at 6 and 10, respectively.
Here are some snow totals around New York City tonight. And this is wet snow caking power lines.
http://forecast.weather.gov/product.php?site=NWS&issuedby=OKX&product=PNS
2″ FOR ROANOKE. 3″ FOR BLACKSBURG. SNOWHSHOE: 239,402,834,902,384,902,830,423″ these are my “unofficial parody snowfall predictions” haha
Wow, we only ended up with 6″ of the white stuff the entire 2011-2012 season? It was that balmy February snow wasn’t it? The snow gods must have been hibernating last year!
I look at it from the stand point of the hair has to go with the hide. Guess up this weekend.
Scott: Winter 2011-12 was the second warmest on record in Roanoke’s weather history dating back a century, so it wasn’t just a balmy February. That said, the 6.1 inches that fell was more snow than occurred officially at Roanoke in the 2006-07, 07-08 or 08-09 winters (though the March 1, 2009 snow was bigger almost everywhere than it was at the WDBJ/Roanoke aiport area where it’s measured). I think snow lovers did very well squeezing the Feb. 19 snowfall (5-9 inches areawide) out of a winter like last year. Could have easily been a snow no-hitter. Some folks north of us, especially I-64 corridor near Charlottesville, did doubly well getting an overachieving 4-8 inch clipper about 2 weeks later. D.C. Reagan National got 2 inches for the season.
Interesting that the warmest winter on record — 1931-32, more than 3 degrees warmer in average temperature than last winter — also ended with 6 inches of snow at Roanoke due to one late snow, that one occurring in March. The mild 2011-12 winter, however, led into the hottest March on record, while the warm 1931-32 winter led into a colder than normal March.
A few spots in New Jersey and Connecticut went over a foot of snow in the nor’easter. New York-Central Park’s 4.7 inches is the earliest 4-plus snow on record dating deep into the 1800s.
http://www.hpc.ncep.noaa.gov/discussions/nfdscc1.html
So Kevin – how did the winter of 1932-33 go? Did it make up for the previous winter?
Nice and sunny up here on the ridge but the wind is blustery!
The tropics won’t die? Now, that’s pretty far out in the Atlantic for something to try and get started in November.
http://www.nhc.noaa.gov/
’32-’33 was a medium winter, Carol. 14.5 inches. So was 33-34, 17.5. Then came 3.4 in 34-35. 1930s weren’t a big snow era around here.
I’m planning to play golf, one way or another, this weekend. The weather is simply going to be too nice to pass up. If I had the time, and could still get free greens fees (by working at a golf course), I’d play all winter long. But, having to pay for rounds of golf, I pick and choose when I play to get the best weather, so I maximize the value for what I pay.
I have played in sub-freezing temperatures, in a nor’easter, and in 100+ degree sweltering heat and humidity (and all while walking the courses too…)…fun experience when it’s free, a horrible decision if it’s not!
Being as this will likely be the last winter I spend the majority of time in Roanoke, I would be more than pleased with a snow total as the one you are guessing, Kevin. Hopefully we are in for a fun few months!
wd, would you be nice enough to translate what your 8:28 AM sentences meant? I have no idea …..
I just looked at the CPC 6-10 and 8-14 day outlooks, and both show SW Virginia in or just out of the eastern edge of a warm bubble centered in the Midwest on both maps. Of course they could end up being wrong, but where is the big cooldown?
COLC Linkman worketh: http://www.cpc.ncep.noaa.gov/products/predictions/610day/index.php and http://www.cpc.ncep.noaa.gov/products/predictions/814/index.php
I don’t see a big cooldown — other than quickie cooldown for 2 days next week — til no earlier than Thanksgiving week and maybe later. Some discussion of that in new blog entry I posted a bit ago.
I just looked at the Ensemble outlooks for NAO and AO. They may be indicating when the cold weather will return. There is now consensus on the NAO Ensemble …. a big increase up to positive territory before the 15th, and then another “upside-down-cone” perhaps with a drop back to neutral and slightly negative country from the 14th to 20th, roughly. Sure looks like the start of another V into negative levels.
Mr. Griggs, I would have figgered you’ve lived down here long enough to have at least learned some of our talk and customs, but I guess not. Once a yankee, always a yankee. Ask some ole southern boys at work, they’ll fill you in.