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Posted at 2:30 PM ET, 02/ 7/2010

Measuring Snowmaggedon's snow depth

By Kevin Ambrose

*** More snow Tues/Wed, are you kidding?: Full Forecast ***

* Detailed look at next snow threat: SLCB | Watch out ice dams *
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My final snow total at 5:31 PM Saturday near Oakton, VA.

What weather topic is more debated now in Washington than global warming? The answer is measuring snow at Reagan National Airport. National Airport is almost always on the low-end for snow reports in our area. Their snowfall totals do not compare well to nearby locations, and this has been consistent for many years.

My theory is that the low snowfall numbers result from the airport being located near sea level and surrounded by the warmer waters of the Potomac River. Basically, Reagan National Airport has a relatively warm micro-climate that does not favor heavy snow accumulations, particularly compared to nearby, elevated locations.

Keep reading for the photos of snow measurements...

I live not far from Dulles Airport (between Reston and Oakon, VA), in an area that does fairly well with snow totals. When I heard about the historic snowstorm in the forecast, I decided to do a photo shoot of measuring snow, showing the time line of snow depths during the storm with photos.

7:46 PM Friday.

I shoveled an area of my backyard to remove the previous snow cover then mounted a yardstick against the ground by attaching a spike. My plan was to photograph the snow depth relative to the yard stick as the storm progressed and the snow piled up. While this is not the best method for measuring snow, it provides a good point of reference for showing snow depths during the storm. It also removes any temptation to find the deepest snow to take measurements.

9:46 PM Friday.

11:44 PM Friday.

1:55 AM Saturday

9:10 AM Saturday.

1:40 PM Saturday.

5:31 PM Saturday.

My final measurement on the yard stick was about 24 inches. On the road surface, I measured 23". The total snow cover on the ground, combined with snow from previous storms, was between 28 and 29 inches. This current snow cover is truly remarkable, the deepest snow I ever remember, and I've lived through the storms of '79, '83, '96, and '03.

Regarding the snow totals at the airports for the storm, with their seasonal snowfall totals, see below:

DCA: 17.8"/45.1"
BWI: 24.8"/60.4"
IAD: 32.4"/63.5"

By Kevin Ambrose  | February 7, 2010; 2:30 PM ET
Categories:  Photography, Snowmageddon, Winter Storms  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: Watch out for those ice dams!
Next: Not again: Winter Storm Watch for Tues/Wed


@Kevin: I nominate that 5:31pm shot for the January picture in your 2011 calendar.

Posted by: --sg | February 7, 2010 2:33 PM | Report abuse

What is the current prognosis for Tuesday night? Any probability of additional accumulating snow? The Weather Channel at the moment is calling for snow showers.

Posted by: MillPond2 | February 7, 2010 2:35 PM | Report abuse

National Airport totals have always been lower and are thus unrepresentative. Sixteenth Street in Columbia Heights had snow levels of about 26 inches. They should not use National as the official count.

Posted by: robertwriter | February 7, 2010 2:38 PM | Report abuse

I don't know where half these snowfall totals are coming from. Some are just goofy. Ballston 24" and Rosslyn 18"? We're talking less than 3 miles there.

Posted by: tristesse27 | February 7, 2010 2:45 PM | Report abuse

On the flipside to this whole debate over where to measure, the DCA reading provides as consistent a reading as any other. I understand that there is some discrepancy as to how representative DCA is of the entire DC snowfall, but it IS representative of how much snow fell at DCA. And across the river here in SW DC and along the National Mall, we had similar numbers (18-19").

If we go changing it to elsewhere in the District, we'd then have to have two measurements - one that can be compared to past storms after, say, the 1940s, that were all recorded at DCA, and the "new" DC measurement. Might get even more confusing...

Posted by: SWester2010 | February 7, 2010 2:49 PM | Report abuse

As a native of Western NY, where we get lots of lake effect snow, it is interesting to see these measurement discussions. In Rochester, we actually had the opposite issue, the airport would report much higher totals than what was measured the next day. Part of the reason for this, I found out, was that they would measure every hour and clean off the measuring table so that the very light and fluffy lake effect would not get compacted. Thus when you add up the totals for each hour, they could be 6 or 7 inches and there would only be 4 on the ground due to compaction.
On a side note, I'd like to know where they get a higher snowfall rate than we had during the storm as at times it was coming down faster than I've ever seen before. I don't think that you all needed to qualify that 3 inches/hr is the most you'll see around here, it is the most you'll see anywhere even in the snow belt.

Posted by: JM222 | February 7, 2010 2:57 PM | Report abuse

3pm Fed Meeting... I guess we'll see in the next hour or 2...

Posted by: jrodfoo | February 7, 2010 2:58 PM | Report abuse

The Caps and the Capital Weather Gang. This town is ALL CAPS!!

Hopefully the Penguins will find a bus to take them to The Burgh (and a Burger King where they had to eat last night on their way from Newark airport).

Posted by: JerryFloyd1 | February 7, 2010 3:07 PM | Report abuse

It is hard to believe that just 10 miles north here in upper NW DC American University reported 27.5 inches while DCA only reported 17-18. I mean that is a difference of 10 inches in just 10 miles. I guess either it is DCA's low elevation, proximity to the river or it is the difference elevation of 400 plus feet up here as opposed to sea level for the airport. However I do think there was a sharp gradient of snow amounts the gradually increased from South to North through the city.

Posted by: ajmupitt | February 7, 2010 3:12 PM | Report abuse

Kevin, that cracks me up. As a fellow photog, I do exactly the same thing! I could go all geek and ask what camera/lens you use, but let's avoid that. :)

We ended up with 22" on our back deck and 24" in the yard here in north Arlington, but the difference is that I didn't shovel an area of the yard, so it still had snow.

Posted by: levyj4131 | February 7, 2010 3:15 PM | Report abuse

Fed should close or enact COOP and have as many as can work from home do so. It's just not safe to put all those people on the roads and trains yet.

Posted by: Alexandria2009 | February 7, 2010 3:20 PM | Report abuse

Winter Storm Watch in effect for metro area for Tues/Weds.







Posted by: JTF- | February 7, 2010 3:21 PM | Report abuse

Update from a 911 dispatcher who's been stuck at work since Friday -- we're tired, we're cranky and ready to attempt to go home tonight! And we are so not looking forward to any more frackin' snow.....

Posted by: natsncats | February 7, 2010 3:22 PM | Report abuse


Where did you hear they were meeting at 3?

Posted by: 300_sq_ft | February 7, 2010 3:24 PM | Report abuse

@300_sq_ft second post down

Posted by: megamuphen | February 7, 2010 3:27 PM | Report abuse

Great photos and enjoying the coverage along with everyone else. Beyond the Tuesday/Wednesday threat I've been hearing some rumors of another potential event next weekend. Is this just the delirium of snow-weary housebound neighbors or is there something to this?

Posted by: caryn74 | February 7, 2010 3:28 PM | Report abuse

@ 300_sq_ft

Posted at 6:17 PM ET, 02/ 5/2010
Berry: Decision about Monday by Super Bowl kickoff

Office of Personnel Management Director John Berry said he plans to convene a conference call with local, state and federal officials on Sunday around 3 p.m. and hopes to announce his decision about Monday's operating status before the Super Bowl's kickoff.

Posted by: jrodfoo | February 7, 2010 3:28 PM | Report abuse

Ironically, the folks in DC, Maryland, and Virginia WISH they had the 18" of snow measured at National!

Posted by: singleseatbiggermeat | February 7, 2010 3:28 PM | Report abuse


I bet you all are exhausted! Thanks for working so hard to get us through the storm. I hope everyone can get home safe today and get some rest.

Posted by: Alexandria2009 | February 7, 2010 3:29 PM | Report abuse

mega and jrod -

Thanks - I saw that yesterday and was hoping for a more "official" source. Ha. I'm sure we'll find out soon enough anyway.

Posted by: 300_sq_ft | February 7, 2010 3:42 PM | Report abuse

Feds will shut down tomorrow and open Tuesday

Posted by: Bious | February 7, 2010 3:49 PM | Report abuse

I always wondered if the official reporting stations periodically clear the snow and add up the amounts to minimize compaction impacts. While that may be more reflective of total snow that falls, I think what most people care about is how deep the snow is when it stops snowing (which is what I measure).

I'm now at just under six feet of snow for the season east of Front Royal. Details...

Posted by: spgass1 | February 7, 2010 3:51 PM | Report abuse

Thanks to the volunteer network of weather observers with CoCoRaHS, we now have some eye-popping storm totals to report. Keep in mind that these volunteers use NWS-approved precip gauges, and are trained to ensure accuracy. The data below cover the entire two-day storm event.

Highest Snow Total: 39.0" (3.11" liquid) at New Market, MD. Runner-up was Elkridge, MD with 38.3" snow (3.34" liquid). There was a report of 42" at Jarrettsville, MD but without corresponding snow water equivalent (i.e., melted snow), it was discounted pending further verification.

Highest Liquid Precip Total: 5.08" (24.3" snow) at St. Michaels, MD, with 2.16" on Feb 6, and 2.92 on Feb 7. Fredericksburg, VA was runner-up with 4.53" liquid, but only 16.5" snow.

Elsewhere around the region:
37.5" sn/3.60" liq - Friendsville, MD
34.0" sn/2.84" liq - Crofton, MD
33.8" sn/3.40" liq - Columbia, MD
33.8" sn/2.65" liq - Fairfax, VA
33.6" sn/2.87" liq - Perry Hall,MD
33.0" sn/3.24" liq - North Laurel
32.9" sn/3.10" liq - Laurel, MD
29.6" sn/2.97" liq - Rossmoor, MD
29.1" sn/3.21" liq - Eldersburg, MD
29.0" sn/2.23" liq - Colesville, MD
28.5" sn/3.16" liq - Mount Airy, MD
27.9" sn/2.79" liq - White Oak, MD
27.3" sn/2.74" liq - Herndon, VA
27.0" sn/3.30" liq - Winchester, VA
27.0" sn/2.47" liq - Gaithersburg, MD
26.0" sn/2.96" liq - Mount Vernon, VA
25.5" sn/2.90" liq - Takoma Park, MD

It's interesting to note that thanks to temp variances and, in some cases, sleet mixing in, the snow amounts and liquid equivalents varied quite a bit.
But still, all things considered, it was an epic sorm!

Posted by: mtpeaks | February 7, 2010 3:53 PM | Report abuse


Posted by: Alexandria2009 | February 7, 2010 3:57 PM | Report abuse

@natsncats: Been waiting to hear from you! If it helps at all, let all the people stuck with you know that we DO think of you and are so grateful you're there.

Posted by: --sg | February 7, 2010 4:15 PM | Report abuse

I live right off the Pentagon City metro (so very close to DCA) and my guess would be we got much closer to 2 ft (ad perhaps more than 2ft) than the 18 inches reported at DCA. How far does DCA's warm micro-climate extend?

Posted by: msegal2 | February 7, 2010 4:19 PM | Report abuse

mtpeaks thanks for that excellent post.
Such amazing numbers. That matches the scene here in our Centreville Va subdivision. It looks like ground zero of a billion megaton snow bomb.
Some inroads & paths have been painstakingly hand dug now that 24 hours have past since storm ended.
I suppose if there was a 5 alarm emergency we could drive out to the secondary road, but it would be treacherous with the DEEPLY rutted packed ice surface.
My hearts go out to those who still don't have their power back. It's so very cold out there.

Posted by: FIREDRAGON47 | February 7, 2010 4:49 PM | Report abuse

@msegal2, I thought last night a CWG member made a persuasive case about air flowing from the east uphill to partly explain the discrepancy between accumulations at DCA and more inland areas (this "upslope lift" is one reason that Amarillo, TX sometimes gets, for lack of a better term, "plains effect" snow).

If you live below Arlington Ridge Road and got 2 ft and maybe more, then there's very little uphill flow. Whether you're just far enough inland from the river to make a difference?

I can remember walking home from the Kennedy Center one evening. As I left the KenCen, there was a sleety/snow rain mixture. By the time I reached 24th and Penn, just a few blocks north, I started seeing accumulating snow. The further uphill and north I headed, the heavier the snow.

DCA just doesn't cut it as a representative place for official Washington, D.C. metro snow totals.

Posted by: JerryFloyd1 | February 7, 2010 4:50 PM | Report abuse

Funny to see a Franconia Hardware written on the ruler - I think that is where the Paradiso restaurant is now.

Posted by: spot599 | February 7, 2010 4:51 PM | Report abuse

@JerryFloyd1-I live just slightly below Arlington Ridge backyard is the hill. So that may explain things.

Posted by: msegal2 | February 7, 2010 6:07 PM | Report abuse

@ JM222, you have a good point about the snowfall rate, because even in the portions of Alaska where a seasonal accumulation of 110" is not out of the question, receiving 4" an hour is considered heavy.

As for the DCA snowfall measurement issue, thank you Kevin for issuing a detailed theory/analysis of this situation, I really appreciate it. I have simply been bugged by this "anomaly" for quite a while now, and I am truly not prone to believe in any sort of conspiracy relating to the matter, but I do have some feelings of incompetency relating to such an issue on the part of the officials there. I am glad that the IAD total was taken from the NWS office, and although I see a 28.4" accumulation total reported on this page, the NWS put out a bulletin claiming a new record of 32.4".

Btw, I would like to issue my very own finalized snowfall accumulation report. I measured a low of 25", and a high of 36" (All over one yard, mine). The winds created an immense amount of difference in the snowfall depths during this storm, and obviously there were drifts shifting about as well. I thus averaged the measurements, taken over multiple portions of my property (With measurements of 25", 27", and 36", all of which are reoccurring numbers), then combined them with my neighbor's confirmed measurement of 31", and I can now claim a grand total of 30.25"! (30.166" without pre-rounding, but I feel that .084" is utterly negligible). So basically we received an overall average of 30" of snowfall in my neighborhood in Reston, VA (This is give or take an Inch, considering the spread-out area, but for precise scientific purposes you can simply use either of the exact decimal numbers I calculated if you would prefer it).

Posted by: TheAnalyst | February 7, 2010 7:27 PM | Report abuse

Out here in the boondocks-Lucketts to be specific- I think we got close to 30 inches. No formal measurements. Also, no landline phone service.
I am from Wisconsin and want to urge people to read the material on snow/ice damns on roofs, though all you can do is knock off the snow, which is very dangerous. It all depends on whether the temps go up and then drop, which doesn't seem to be what's going to happen.

Posted by: Liebestod | February 7, 2010 8:30 PM | Report abuse

Thanks to CWG for all of the wonderful coverage of this historic snow storm. I no longer live in the DC area, but grew up in Montgomery County and followed the weather avidly as a kid in the 70s and early 80s. I think it is fair to say that National Airport has always been an unrepresentative weather station for the metro area in many ways, but particularly when it comes to snowfall. Why are the official measurements for Washington's weather taken on the river at sea level when most people in the District do not experience the weather there. New Yorkers balked at the idea of La Guardia being the city's official weather station for the same reason--snowfall in NYC is always measured in Central Park--and New York is much more of a coastal city than Washington is. Seems to me that official measurements of precipitation and temperature for DC should be taken somewhere in the District proper. Perhaps not in upper Northwest at 400', but not by the river at sea level. How about somewhere in Rock Creek Park? National is also warmer at night than most areas of the region, overstating the length of the growing season and understating minimum winter temperatures for most DC area gardeners. Although there is no perfect spot to collect "official" weather data, whatever is reported should be representative of what at least a significant minority of the residents in the region have experienced. Perhaps a place where the snowfall totals are in the middle of the range of what has been reported, not at the bottom.

Thanks for this opportunity to vent! I have been waiting 30 years to do it!

Posted by: vdprouge | February 7, 2010 8:32 PM | Report abuse

levyj4131, I use a Sony A350. For the yardstick shots, a simple auto exposure with flash. No tripod this time.

SWester2010, I agree that DCA has been consistent and this storm's measurement can be used to compare past storms and winters in DC. Unfortunately, DCA does not represent most of the DC area with their totals.

spot599, I lived in Franconia until I was 12 years old so that yard stick is almost an antique!

One last note, the snow depth went down 2" today with compaction in the bright sunshine. It's not noticeable unless you look at the yard stick.

Posted by: Kevin-CapitalWeatherGang | February 7, 2010 8:40 PM | Report abuse

Heaviest DC snowfall rate. In around 1984, in March, there was continuous thunder and lightning where I lived (18th and Swann Sts, NW, a few blocks north of DuPont Circle) for 45 minutes. At the end of that time there was 4 inches of snow on the ground. You do the math, that's well over 5 inches per hour. I've never seen it snow remotely that hard anywhere before or since. Some people I knew who lived farther north ended up with 7 inches.

Posted by: doubtingdavid | February 7, 2010 8:59 PM | Report abuse

The variability in snowfall across the region doesn't surprise me at all. I lived in Houston for many years, and we got the same phenomena with rain. During a typical summer storm one area of the city could get 4" and another none at all. When I saw my first real summer storm there, it was pouring on one side of the office building and not the other. During a tropical storm in 2000, the heaviest hit area got 24" and 12 miles away we got 18". If you use the 8" of snow equals 1" of rain standard typically accepted, it's only an inch or 2 difference in moisture and the variability across the region seems quite reasonable.

Posted by: lawatson2002 | February 8, 2010 7:25 AM | Report abuse

In suburban Mclean just inside beltway not far from Churchill Road School, we used yardstick method measuring snow buildup on top of deck table that got fairly steady accumulation with little interference from drifting, etc. Measurements I got were 10" at about 11PM Friday night, 19.5" Saturday mid-morning and 24.5" about an hour before snowfall ceased Saturday afternon. Wasn't able to return to location until about hour after snowfall had stopped, and level was actually slightly lower than 24" probably as result of some compaction setting in. I reckon we may have topped out near 25" at highest point.

Posted by: mlmcronin | February 8, 2010 12:23 PM | Report abuse

Do we know where the other "records" were measured? Can we go there and measure also for an unofficial snowballs to snowballs comparison? I would be curious to see what the totals were.

Posted by: readerl | February 8, 2010 3:00 PM | Report abuse

Too much snow....

Posted by: acwarrate | February 8, 2010 10:14 PM | Report abuse

for the snow a great read...

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it all about true love is possible. From infatuation to heartache, love is the universal energy that binds the world. Panes of the Heart is an exploration of this enigmatic force.

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Go to to order.

Posted by: drmullings | February 9, 2010 4:38 AM | Report abuse

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