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Posted at 9:00 AM ET, 11/19/2008

2008-09 Capital Weather Gang Winter Outlook

By Capital Weather Gang

Does D.C. snow continue its decline?

* Q&A Transcript: Matt Ross, Outlook Lead Forecaster | Near-term Forecast *

For local snow lovers, it's the sorry truth: average seasonal snowfall has been dropping and dropping fast over the past 120 years. Around the turn of the 20th century, Washingtonians would typically shovel about 23" of snow (averaged over a 15-year period) per season. In the last 15 years, we've averaged a paltry 14" a year. The long-term trend is to drop about 1" every 15 years. At the current rate of decline, single-digit seasonal snow totals will become the norm in many of our lifetimes when they used to be the exception.

Keep reading for more on our snow starvation, and our outlook for snow and cold this winter. Stay with us all winter long for the latest forecast -- rain, snow or shine -- including accumulation maps, storm timelines, SchoolCast and more.

Jump to 2008-09 Winter Outlook


Annual snowfall averaged over the last eight 15-year periods in Washington, D.C. Linear trend line in black.

The decline in snow hasn't been entirely smooth. The 15-year average spanning 1919-1933 (of 13.7") was actually lower than the last 15 years. But in those 15 years, snowfall exceeded 15" seven times compared to just three times in the past 15 years.

Our recent snow drought becomes more depressing for snow enthusiasts when we remove the blockbuster snow seasons of 1995-1996 and 2002-2003 (when 46" and 40" fell, respectively) from the 15-year average. In the remaining 13 years, we've averaged a lowly 8". And not once in those 13 years did we exceed 18" -- the 120-year average. The graph below shows the feast or famine situation with snow in recent years, with a heavy bias towards famine.

snow-last15.jpg
Annual snowfall since the winter of 1993-1994 at Reagan National Airport.

In stark contrast to recent times, our grandparents and great grandparents feasted on the white stuff from 1904-1918 with a 15-year average of 25" (the highest analyzed). Even taking away the two snowiest seasons from that period, Washington still averaged about 20" a year and in 10 of those remaining 13 years, snowfall exceeded the long-term mean of 18".


Annual snowfall for the winters ending in the years 1904-1918 in Washington, D.C.

The diminishing snow totals of late could be attributed to a number of factors: the urban heat island effect (i.e. the warming effects due urbanization), global warming, natural climate swings, and/or changes in observing locations (the official observing location at Reagan National Airport moved several times prior to 1941). It's difficult to say which of these is most important. But one thing is sure for D.C. snow lovers (myself included), the trend is not our friend.

Will we buck the trend this coming season? More than half of you who voted in our poll think we will. What does Capital Weather Gang think?...

CAPITAL WEATHER GANG'S WINTER OUTLOOK

While significant advances have been made in seasonal forecasting, there is still a great deal of uncertainty. So please keep in mind this is a low-confidence forecast, especially the overall snowfall estimate, where one big storm can make or break the forecast.

We expect this winter to be colder and snowier than last winter, and perhaps our coldest in several years. Though a historic winter, in terms of cold and snow, is unlikely. Here's how we see it:

Snowfall: Slightly below normal, but around the median

*National Airport (DCA): 12-14" (avg: 15.2"; median: 12.1")
*Dulles Airport (IAD): 18-20" (avg: 21.5"; median: 17.6")
*Baltimore-Washington Airport (BWI): 16-18" (avg: 19.2"; median: 15.5")
*Fairfax/Loudoun/Montgomery counties: 16-22" (avg: ~20-26")
*D.C./Arlington/Alexandria/Prince George's County: 12-18" (avg: ~15-20")

Overall 2008-09 Winter Temperatures: Normal to +1°F above normal

*December: -2°F to -4°F (below normal)
*January: Normal to +2°F
*February: +2°F to +4°F

Note: We did not include March in the temperature forecast, as here in the D.C. area the month tends to be more like spring than winter. Nevertheless, we do occasionally see snow events in March and even April, and thus the snow forecast is for the entire season (November-April).

HOW DID WE MAKE OUR FORECAST?

Analog Method Explained

There are several popular methods used to craft a seasonal outlook. The prevailing one for this outlook is the analog method. This entails looking at conditions leading up to and expected during this winter, and then finding past years, or analog years, that featured similar conditions. The idea being that winter 2008 will be similar to past winters that saw similar conditions leading up to and during the season.

The analog method is far from scientific. First, one has to determine which conditions are important and which are not, which is no easy task and very subjective. Second, even when you do come up with analog years, the associated winters may be quite different from each other. Therefore, analogs should be viewed collectively as general guidance for the upcoming winter and nothing more.

The following factors were among those that we deemed most important in identifying analog years...

Equatorial Pacific Ocean

Although many factors go into a seasonal outlook, the state of the equatorial Pacific is perhaps the most important. Last winter we had a classic moderate to strong La Nina event. A La Nina -- the opposite of El Nino -- is characterized by sea-surface temperatures in the Pacific Ocean along the equator that are colder than normal for an extended period of time.

The tell-tale signs of a meaningful La Nina event were evident throughout last winter, including a strong area of high pressure off the southeast Atlantic coast, which frequently put the D.C. metro area in the warm sector of clashing air masses. This, combined with a lack of high-latitude high-pressure systems, forced the predominant storm track to our west. And there was a volatile but progressive weather pattern. As a result, while we saw frequent shifts from warm to cold and back again, the warmth dominated, leaving us with our warmest and least snowiest winter since 2001-02.

As we approach this winter, the equatorial Pacific is in a neutral state, meaning we are neither in a La Nina nor an El Nino event, though some leftover effects of the La Nina event earlier this year have been apparent in the pattern this autumn. Future El Nino/La Nina (ENSO) state is hard to predict. Signs point toward a neutral winter, though very weak La Nina conditions may develop later in the winter. Winters where ENSO is neutral are especially hard to forecast for, as factors other than the Pacific can often carry greater significance. However, we did pay particular attention to past years in which neutral or weak La Nina conditions followed a moderate/strong La Nina.

Summer/Fall Pattern

This summer was another hot one for D.C., averaging almost two degrees above normal, thanks to a very hot June. However, this wasn't the case for the continental U.S.; outside the coasts, it was a cool summer for much of the heart of the country.

This fall started out quite warm with a hot September followed by a warm first half of October. However, a major shift in the pattern occurred in mid October, leaving most of the country, absent the west coast, with normal to below-normal temperatures for the month. We are seeing a similar pattern in November, as a very warm start for much of the country looks to be followed by a significantly colder-than-normal second half of the month, particularly in the East.

Analog Years

Based on the above factors, the following winters emerged as analogs for this upcoming winter, some carrying greater weight than others...

In chronological order (along with seasonal snowfall): 1934-35 (31.4"), 1943-44 (4.6"), 1945-46 (21.6"), 1974-75 (12.8"), 1985-86 (15.4"), 1989-90 (15.3"), 1996-97 (6.7") and 2000-01 (7.4")

The analog winters for this upcoming one tend to be quite volatile. While we don't expect the pattern to shift as frequently as last winter, winter 2008-09 may be defined by extended periods of significant warmth and cold. An extreme example of this type of winter is one of our analog years, 1989-90. That winter featured a late-November snowstorm, followed by one of our coldest Decembers on record. Snow was on the ground from Thanksgiving to Christmas. Then, a complete pattern flip led to a very warm and snowless January and February, followed by a record heat wave in mid- March. But winter wasn't quite done as we saw several accumulating snow events in late March and early April.

The extremes will be a bit more muted this winter, we think, but we are likely to see some dramatic pattern changes throughout the season.

Other Factors

Other factors considered include persistence (what have recent D.C.area winters been like?) and climatology (the long-term averages for winter temperatures and snowfall in the D.C. area). Over the past 15 winters in D.C., only five featured below-normal temperatures and only three finished with normal to above-normal snowfall (see snowfall graph of last 15 years above). The last winter to do both was 2002-03, and we have now had four consecutive winters with above-normal temperatures and below-normal snowfall.

Our more recent history has been even more skewed toward warmth, as only six of the last 30 months have featured below-normal temperatures. The last was this past May. There are likely multiple causes for this phenomenon, but suffice to say, getting a cold month has not been an easy task. While this didn't factor into our selection of analog years, it was a factor in issuing our final forecast numbers.

More Snow Stats

Snowiest winters--

1898-99 (54.4")
1995-96 (46.0")
1921-22 (42.5")
1891-92 (41.7")
1904-05 (41.0")

Least snow winters--

1972-73 (0.1")
1997-98 (0.1")
1975-76 (2.2")
1926-27 (2.3")
1930-31 (2.5")

30-yr DC snow average (1979-2008): 15.3"
30-yr DC snow average (1949-1978): 16.7"
30-yr DC snow average (1919-1948): 16.3"
30-yr DC snow average (1889-1918): 23.7"

60-yr DC snow average (1949-2008): 16"
60-yr DC snow average (1889-1948): 20"

120-yr DC snow average: 18"

Capital Weather Gang's Matt Ross was the lead forecaster of this outlook. Snow history by Jason Samenow.

How'd we do with last year's winter outlook? See our recap here.

By Capital Weather Gang  | November 19, 2008; 9:00 AM ET
Categories:  Local Climate  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   Del.icio.us   StumbleUpon   Technorati   Google Buzz   Previous: Forecast: Winter Cold Coming on Strong
Next: PM Update: Winds Slacken, Chilly Air Remains

Comments

Figures! After far too many dismal snow totals I finally decided to take up scuba diving and sell all my ski gear.

Posted by: skipper7 | November 19, 2008 9:47 AM | Report abuse

Ok, this may be a bit silly, but... All over my Arlington neighborhood, and in other areas around DC (according to a very unscientific survey of my coworkers), the squirrels ate large portions of the jack-o-lanterns. This is the first time I've ever seen such behavior. Are they fattening up for a severe winter, perhaps???

Posted by: gpmega | November 19, 2008 9:56 AM | Report abuse

Single digits in most of our lifetimes? Um... if 14 inches now, and averaging a drop of one inch every 15 years. Hmmm... 5 x 15 (or even 4 x 15 if you want to be generous): We're either going to be long-lived or the Post has VERY young readers.

Posted by: WebHarmonyLLC | November 19, 2008 10:01 AM | Report abuse

My collies cant predict snowfall or rain totals this far out but my oldest boy can predict how cold the winter will be by the size of his rough around his head and neck. The thicker it is the colder it will be. It reaches its max by the first week in December and right now it looks like a mild winter but we will see.

I also check with my other friends with working dogs.

The squirells look especially big this year
and fat this year but acorn production was down.

I get back to you all if Kim doesnt have me banned!

Posted by: omarthetentmaker | November 19, 2008 10:03 AM | Report abuse

Good enough for me! I would have liked to hear more snow, snow, snow, but as long as we get more than last winter, I'm happy.
I didn't hear of the squirrels and pumpkins- interesting!

Posted by: Snowlover2 | November 19, 2008 10:05 AM | Report abuse

Welcome new readers and old. If you're new to Capital Weather Gang (or a regular who hasn't fully explored CWG), click the links above the CWG banner at the top of the page (About This Blog, Meet the Gang, etc.) to learn more about us, browse our previous posts as well as content along the left sidebar, and don't forget to check out our latest forecast through the weekend. Also, feel free to comment here on our winter outlook, and tell us what you think this winter will be like. We also welcome suggestions -- from new and old readers alike -- on how we can make Capital Weather Gang your No. 1 daily source of D.C. area weather information (if it isn't already).

Posted by: CapitalWeatherGang | November 19, 2008 10:20 AM | Report abuse

I'm new to the gang; that was a good article. Finally, some in depth science. Maybe you guys could start running the science section as well. Now that Dems are back in the white house, while Science get its own section in the Post? Or will it remain relegated to a subheading under NATION? Perhaps it could be equal to Religion and have a presence on the post.com homepage. THe saddest thing about the post, to me, is the fact that Science has been brushed aside to a once a week installment. The Food section gets more attention. The Mystics get more attention, for Gods sake.

Posted by: oo7 | November 19, 2008 10:40 AM | Report abuse

This reall is interesting.

What I'm wondering is if anyone could easily toss in a correlation to the Potomac freezing over.

The last time I remember it for certain is roughly the winter of '90-'91 -- I distinctly remember some walking on the ice in front of the Kennedy Center.

Terrific article!

Posted by: Georgetwoner | November 19, 2008 10:55 AM | Report abuse

Matt and Jason:
Thanks for a very interesting and well reasoned D.C. winter outlook. I agree with the general thrust but believe the departure from recent years may be even more pronounced.

Regarding the snowfall trends. I have researched the 15 year averages for my area, 100 miles to your west and find nothing to suggest a decline in 15 year averages regarding the number of above or below average winters during any 15 year period since 1918.

The 100 year average annual snowfall for my area is 26 inches.

The longest consecutive stretch of below normal winters is not recent as many would suspect, but the 9 year period from 1948 to 1957. We witnessed a 9 year average of only 13.51 inches or very slightly more than half of normal snowfall during this 9 year period, more than 50 years ago. During the most recent 9 year period (99-07) we have been below normal at 17.43, but received approx. 4 inches more annually than the period 1948-1957.

During the late 40's and most of the 50's, folks were probably quite happy with the "easy" winters, but had no idea what awaited during the very late 50's and much of the 60's.

The one exception to the rule was the very snowy period from 1903-1918.

15 year data for the Central Shenandoah Valley:
1903-1918 2 winters below average, 13 above
1918-1933 9 winters below average, 6 above
1933-1948 9 winters below average, 6 above
1948-1963 10 winters below average,5 above
1963-1978 9 winters below average, 6 above
1978-1993 9 winters below average, 6 above
1993-2008 10 winters below average,5 above

Take heart folks, we are due a snowy winter, perhaps this will be a winner!!

Posted by: AugustaJim | November 19, 2008 11:10 AM | Report abuse

Think you just hexed us for a plow load of snow this winter!

Posted by: holditnow | November 19, 2008 11:34 AM | Report abuse

Nice write-up! I'm not sold on the global warming causing less snowfall around the local DC area seeing how there were other snow drought periods previously. Lets hope for a cold snowy winter in the Mid Atlantic...

Posted by: CarolinaMike | November 19, 2008 11:38 AM | Report abuse

@WebHarmonyLLC--

Yes. The statement about single digit snow totals mainly applies to the under 30 set :)

@gpmega--

I've never seen anything scientific about squirrel activity and harsh winters. But there are a lot of anecdotal reports to that effect.

@AugustaJim--

Interesting analysis. As a follow-up, I'm going to take a look at IAD and BWI (which have more of a homogeneous record), and look at the trends there.

Posted by: Jason-CapitalWeatherGang | November 19, 2008 11:46 AM | Report abuse

WebHarmonyLLC -- Note it does say "many" lifetimes, not "most." My calculations, based on the 2nd graph in the article, would put us at single-digit annual average snow totals starting in 2069. So yes, this stat mainly applies to an under-30 audience (someone who is 30 now would be turning 91 in 2069). But hopefully we have many in our audience who are under 30, in addition to those of us who crossed that threshold long ago. And hopefully we all live long, healthy, happy lives :)

Posted by: Dan-CapitalWeatherGang | November 19, 2008 11:50 AM | Report abuse

The gang's winter prediction is at odds with those of the National Climate Prediction Center. I'm betting on the NCPC prediction instead. I've been following them for the past 5-6 years and I think they have a pretty good batting average for short to mid-term predictions.

Posted by: fmschiav | November 19, 2008 12:23 PM | Report abuse

Hi all -- so it would appear that the next six weeks could be "as good as it gets" for us snow folk. Was nice to see the flakes yesterday.

Interesting note on the freezing of the Potomac -- we did have it "sort of" freeze, I think back in early 2004 (my first winter here), and it took a couple weeks of extremely cold weather to do it. But often, these cold spells don't translate into a lot of snow -- you frequently get a storm track that is south of here, leaving us with a boring pattern of 30s for highs, teens for lows, and no moisture. So I'd be surprised if the correlation between Potomac freezes and snow is high (and you'd have to figure out how to measure what a freeze means, and whether the freeze point is by the Key Bridge or somewhere else along the river, et cetera). A lot of methodological assumptions would need to be made on this one.

Posted by: JamieYPotomac | November 19, 2008 12:50 PM | Report abuse

fmschiav -- which CPC products are you referring to. These? ... they actually don't look all that different from our outlook. CPC has the metro area at equal chances for above-normal, normal, or below-normal for both temps and precipitation. But right on the edge of the 33% probability for above-normal temps and not far from the edge of the 33% probability for below-normal precip (that could be rain or snow or ice), which actually seems to correlate rather well with our outlook above. Though CPC doesn't say anything about snowfall per say, at least not in this product.

Posted by: Dan-CapitalWeatherGang | November 19, 2008 12:52 PM | Report abuse

i'm excited for any snow we get - and the squirrels ate our pumpkins too!

Posted by: madisondc | November 19, 2008 2:08 PM | Report abuse

My winter outlook: Temps will range between -1 to +1 for Dec-Feb., with 13-18" of snow. Dec temps below, Jan temps average & Feb temps above.
The last time the Potomac froze over was Jan 04, it was also the last yr that striper fishing was great at the 301 power plant. I was the manager at Fountainhead Park from 78-93 & the Occoqun Res. froze over almost every year until the late 80's.

Posted by: VaTechBob | November 19, 2008 2:29 PM | Report abuse

In an earlier life (not all that long ago) I was a researcher and operational forecaster at the NWS Climate Prediction Center (CPC) and since then have kept up with the science and practice of long range forecasting.

Matt rightly and quite justifiably acknowledges that seasonal outlooks (better term than forecasts) are by nature extremely uncertain and are of low confidence - especially for a particular location such as DC. It's unlikely this will ever change for scientific reasons

Perhaps the best way to appreciate this is the following:

The likelihood that ANY seasonal outlook has skill (correctly predicting departures from "normal" (e.g., more or less snow or temperatures above or below average) is like the toss of dice rigged to favor one outcome (e.g., "snake eyes") ever so slightly more than any other.

For any given toss the odds are that something other than snake eyes, i.e., something other than what is forecast, will result because there are more possibilities than the single snake eye outcome.

But, over a very large number of die tosses, snake eyes should occur more frequently. (If this were a toss of a coin sightly weighted in favor of heads, tails could turn up on any toss but over a large number of flips, heads will win out)

So, all things being equal in this analogy, over the long term (maybe as many as 50 - 100 winters) the forecast be will be right more often than not.

All things, though, are not always equal. For example, if we know it's an El Nino year, the odds in favor of snake eyes - or a specific winter outlook being correct - are increased relative to, for example, an neutral year (neither El Nino or La Nina) as Matt rightly said characterizes current conditions.

Posted by: SteveT-CapitalWeatherGang | November 19, 2008 3:06 PM | Report abuse

AJim:
thanks for the hope!!

Posted by: manassasmissy | November 19, 2008 3:17 PM | Report abuse

Thanks for the depression. Heh. I'm still hoping that we get a few good storms this winter.

I'll be 78 in 2069 when DC starts seeing those single-digit snow totals, so hopefully I'll be way away from this area when that happens.

Posted by: weatherdudeVA | November 19, 2008 3:23 PM | Report abuse


In my Bethesda neighborhood the pumpkins
have been seriously munched by squirrels or other critters-in recent years they've hardly touched 'em...

Posted by: jws3 | November 19, 2008 3:33 PM | Report abuse

Snow events around here often seem to turn into ice events, which are infinitely more difficult to deal with. Any prognostications on that end of things?

Posted by: weathergrrl | November 19, 2008 4:22 PM | Report abuse

Thanks for the outlook Gang.

Honestly though... is winter that hard to predict here? For the past 20 years you would have been right saying that it would be warmer and less snowier than the "average." Long range forecasts are just for fun, like a shot in the dark. Last year was a relatively easy call because of the beastly La NiƱa.

All we need is one storm to bump up our numbers significantly, and I hope this will be the winter. Probably not... but you never know.

Posted by: LAWNMAN209 | November 19, 2008 6:51 PM | Report abuse

You say less snow like that's a bad thing... will we have correspondingly more or equal rain?

Also, what would happen if we went further back... DC had to have been warmer when the White House was built and there was a yellow fever epidemic. I guess records aren't reliable? What happens if you slide the 15-year period around? Do you get the same results? Why 15 years? Is that statistically relevant?

I ask these questions as a skeptic who seems to be raising another skeptic; I want him to understand climate analysis if he's going to be spouting off his mouth!

Posted by: dynagirl | November 19, 2008 7:09 PM | Report abuse

20 years from now the DC metro area will look like Florida, and Maine, Michigan, and Canada will look like DC. All thanks to the rethuglican idiots who say "global warming is not real," and continue to trust in coal and petroleum as are only energy sources.

Posted by: terp4life1 | November 19, 2008 7:19 PM | Report abuse

terp4life1,

You wanna make a bet?

Then again you have much better choices for alternative energies. But then please don't ask for electric cars because without coal that's impossible. =)

Posted by: LAWNMAN209 | November 19, 2008 7:38 PM | Report abuse

I don't know if global warming is true or not, but I know currently it is cold for the month of November with no major warm-up in the near future according to the models.

Posted by: CarolinaMike | November 19, 2008 8:04 PM | Report abuse

Well, terp4life1, if you like D.C.'s climate, and think that it's being changed by politics, then move north if you want to hold onto it. Then, you can have what you want, and we won't have to listen to your political whining and insults to the Republican party.

Have a nice day.

Posted by: MMCarhelp | November 19, 2008 8:39 PM | Report abuse

@dynagirl:

Good questions. Admittedly, the choice of the 15 year averaging periods was simply due to the fact I realized we had 120 years of snow records, and I could divide those into neat 15-year bins. I also looked at other multiples-- 30-year, 60-year, and the whole 120-yr record. Yes, if you slide the periods you average around, you'd probably get somewhat different results, but probably not different enough to change the story.

I can't say anything about snows prior to 1889 because we don't have good records. The presence of yellow fever I imagine had a lot to do with the state of the public health system at the time (or lackthereof) so I don't think you can use that as a snowfall or temperature indicator.

Posted by: CapitalWeatherGang | November 19, 2008 8:56 PM | Report abuse

The entire analysis questionable b/c it/s skewed by the period of record...which starts during a period where 5 of the 15 years were more than one standard deviation (STD = 11.4") above the mean of 17.8".

There were four +1 STD winters during the next 15-year period...adding still more weight / bias to the front-end of the historical record.

The third period...1918 - 1933...has one +1 STD winter and 5 winters where the annual snowfall was at least 1 STD below normal. This is the true anomalous period during the 120 year record. Since then...there has been and equal number (11) of years where the annual snowfall was more than one STD above normal and one STD below normal.

The 4th period...there were 3 +1 STD winters and 2 -1 STD winters.

During each of the 5th...6th...and 7th periods...there were 2 +1 STD winters and 2 -1 STD winters.

The last 15-year period ('04 - '08) saw 2 +1 STD winters and 3 -1 STD winters...which is hardly noteworthy nor does it provide significant to support the CapWx/s conclusion that "At the current rate of decline, single-digit seasonal snow totals will become the norm in many of our lifetimes..."

Finally, Dynagirl raises a good point b/c standard climatologies are 30 years long.

Using a standard 30-year time period...1889 - 1918 had 9 +1 STD winters and 1 -1 STD winter.

1819 - 1948 had 4 +1 STD and 7 -1 STD winters.

1949 - 1978 had 4 +1 STD and 4 -1 STD winters.

1979 - 2009 had 4 +1 STD and 5 -1 STD winters.

Again...the 30 year period between 1919 and 1948 (everything else being equal) is the real anomalous period for below normal snowfalls at DCA.

Posted by: toweringqs | November 19, 2008 9:37 PM | Report abuse

Very interesting information! I hope the storm tracks this year will be more conducive for snow in the region.

I think the Gang should also do a sort-of "mid-winter outlook" in January, with revisions to the Jan.-Feb. predictions if needed. Just a suggestion, though. :-)

Now, for all the snow lovers (me included), don't be disappointed with a prediction of slightly below-average snowfall. If we get that, it will be more than in recent years.

Also, as the CWG has said, one big storm can make or break the season. It is simply too early to tell what our actual totals will be- they could be skewed in either direction. (But for long-range forecasting, I think this is as good as it gets!)

Posted by: Sterlingva | November 19, 2008 11:52 PM | Report abuse

ToweringQS: Thanks for your comments. Very interesting analysis but I'm not entirely convinced that it fundamentally changes the story. I think if you analyze the snowfall between + and - 1 SD, that's where I think you're going to see the decreases. So while we haven't seen changes in the frequency/magnitude of the big ones or the little ones, it's the ones in the middle which have trended downwards. I can take a look at this, or if you want to take a shot, email us and I'll post the results.

Posted by: CapitalWeatherGang | November 20, 2008 8:57 AM | Report abuse

The thrust of my argument is annual snowfall within +/- 1 STD of the average is 'normal' snowfall. During the most recent 15 year period...the were 5 years where the annual snowfall was not 'normal.' Three years had below normal snows with STDs of -1.146, -1.295, and -1.566.

Two years had above normal snows with STDs +1.957 and +2.447...the latter occurring during the '95 /'96 winter which was second only to the station/s record season (54.4") in 1899.

Yes, the remaining years were all below the long-term average of 17.8" but within 1 STD of the average, therefore 'normal.'

The data do not suggest the post/s conclusion that "(a)t the current rate of decline, single-digit seasonal snow totals will become the norm in many of our lifetimes..." It didn/t happen following the 1919 - 1933 period and I/m skeptical it/s likely to happen now.

The 'Preview' ate my first draft.

Posted by: toweringqs | November 20, 2008 4:26 PM | Report abuse

You poor poor souls without snow. I live out in the mountains of western Colorado and if we get less than 80" in town and 300" up the mountain we are disappointed.

That being said it's been a pretty dry November out here so....

I recommend a prey for powder party to satisfy the snow gods. Just as idea but it worked for us last year

Posted by: boondoggle1 | November 21, 2008 11:30 PM | Report abuse

Jim in Blacksburg here:

I really don't think the "DCA effect" in all of this can be underestimated. As we all know, DCA as a reporting station is grossly unrepresentative of the vast majority of this area. In fact, it probably is only good for areas within a mile or so of the river. If you accept DCA's average as approximately 16" (it is listed as 15.5 - 16.2" depending on the source), realistically speaking, other areas inside the Beltway, including NW DC, Ballston, and so forth can more realistically expect 18" or so. This is a significant difference.

Given this, I really don't think data prior to DCA being the official reporting station can be considered as part of the same trend as post-DCA data.

That said, the trend still is not good, but it wouldn't take a whole lot to change that around either. This winter, I personally am going against the CapWeather forecast. I expect slightly above average snowfall, on the order of 17-18" at DCA, and generally near 20" elsewhere inside the beltway.

Posted by: jahutch | November 24, 2008 12:20 AM | Report abuse

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