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Mikethemanatee

DCA Snowfall Total Controversy

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So it seems there is some controversy over DCA's snowfall total's from this blizzard, and it was clogging up the obs thread so I decided to make a thread here.

 

Here's some links and info

 

DCA's snowfall total as of 8 pm: 17.8" (tied for number 4 in the record books)

 

CWG's take on the issue: https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/01/23/washington-d-c-snowfall-total-called-into-question-after-improper-measurement/

 

NWS obs at DCA chart: http://w1.weather.gov/obhistory/KDCA.html

 

 

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So it seems there is some controversy over DCA's snowfall total's from this blizzard, and it was clogging up the obs thread so I decided to make a thread here.

 

Here's some links and info

 

DCA's snowfall total as of 8 pm: 17.8" (tied for number 4 in the record books)

 

CWG's take on the issue: https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/01/23/washington-d-c-snowfall-total-called-into-question-after-improper-measurement/

 

NWS obs at DCA chart: http://w1.weather.gov/obhistory/KDCA.html

 

Yeah..there's something wrong at DCA. The fact they screwed this up is embarrassing.

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I sort of spoke my piece in the Obs thread, but I'll just say this: Having consistently incompetent and bogus measurements coming out the "official" measuring station for a major metropolitan area is a disservice to the region.  The fact that I can mention the DCA 25% rule and EVERYONE who cares about weather in this area knows what I'm talking about is a real shame. 

 

If these errors really did occur, I hope there are consequences here that lead to the establishment of a proper and REPRESENTATIVE official measuring location for DC.  Here's an crazy idea.... *gasp*...let's put it in DC.

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Tweet from Angela - CWG 

 

People in Arlington measuring, 16, 17, 18 inches, and DCA is at 14.8 and "highly estimated." Losing my mind.

 

I can say that by 1 pm, in N Arlington I had 17". Of course, I'm a few hundred feet higher in elevation than DCA, but there was no mixing or temperature issues this storm. And the difference between us became almost 7" with this report. DCA actually looked like it was getting pounded during the deathbands, even more than me, but apparently it wasn't! The whole thing seems very fishy.

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Yeah, it seems DCA's problem was during the 1-7 period. Here's a report from CWG comments:

 

I live 1.6 NM WSW of the DCA ASOS and can literally see where the snowboard was located. At this time I have 20.25" on my snowboard. I picked up 4.5" between 18Z and 00Z. Needless to say something went wrong with the DCA measurement during that timeframe.

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Why didn't they use a snowboard?  Why do they have such systemic quality control issues like this?  I mean, they had 17 consecutive months with a thermometer that was reading a few degrees too high, and it was only fixed because CWG finally called them out on it.  CWG shouldn't be their quality control auditor

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I really wish I could have measured better so I would have something to compare to DCA's #....

 

At 1pm, DCA had 14.9", and I had 14.5" - Mine was a low confidence reading and suffered from compaction, but even after walking all over my neighborhood and measuring a ton of places, the best case I could credibly make was 15.5".  So I believe DCA's # was at least in the range of credibility.

 

I do think the fact that they got 0.3" in a 2 hour period from 5pm to 7 pm is not credible given conditions.  I think it takes a lot of effort and expertise to get it right, and I wonder if the FAA contractors tried.  If you simply put a snowboard out or measured snow on snow in the same area, it explains the paltry amounts.

 

I don't think people quite realize how bad we do down here in UHI, low elevation hell.  There is going to be a big difference simply based on elevation and nothing else.  DCA is a horrible place to measure snow.  I knew this, but it is even more apparent after living near downtown DC the last 3 winters. I was last or 2nd to last in seasonal snow totals in this forum.  Typically I thought DCA's totals were credible in 2013-14, 2014-15.  I measured every event.

 

My guess is had they measured carefully and properly, and did the best they could, around 19" would be the result.  So not sure this whole "investigation" is going to yield a much different result.  It may end up over 18" anyway after adding everything that fell after 7.

 

But "highly estimated" and not using proper procedure is not good enough.

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I really wish I could have measured better so I would have something to compare to DCA's #....

 

At 1pm, DCA had 14.9", and I had 14.5" - Mine was a low confidence reading and suffered from compaction, but even after walking all over my neighborhood and measuring a ton of places, the best case I could credibly make was 15.5".  So I believe DCA's # was at least in the range of credibility.

 

I do think the fact that they got 0.3" in a 2 hour period from 5pm to 7 pm is not credible given conditions.  I think it takes a lot of effort and expertise to get it right, and I wonder if the FAA contractors tried.  If you simply put a snowboard out or measured snow on snow in the same area, it explains the paltry amounts.

 

I don't think people quite realize how bad we do down here in UHI, low elevation hell.  There is going to be a big difference simply based on elevation and nothing else.  DCA is a horrible place to measure snow.  I knew this, but it is even more apparent after living near downtown DC the last 3 winters. I was last or 2nd to last in seasonal snow totals in this forum.  Typically I thought DCA's totals were credible in 2013-14, 2014-15.  I measured every event.

 

My guess is had they measured carefully and properly, and did the best they could, around 19" would be the result.  So not sure this whole "investigation" is going to yield a much different result.  It may end up over 18" anyway after adding everything that fell after 7.

 

But "highly estimated" and not using proper procedure is not good enough.

 

I think they had at least 20"+...19" seems a little low.

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One of the other big problems with DCA is that they are windier than pretty much everyone else with the river as an unobstructed funnel.  It is just really, really hard to get good measurements in wind.  If they tried to just take a point measurement, I might believe how they ended up with 0.3".

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I'm about three miles west of DCA, and and I got about 3.5" from 2 to 7; I didn't measure 20 anywhere IMBY

 

 

Is it really good testimonial support when the lowest identified nearby total measured 30% more snow between 2-7 pm than DCA did between 1-8 pm?  (And I'll bet that guy didn't receive under half an inch total between 7 am and 1 pm like DCA also reported.)

 

Bottom line:  At 7am, DCA reported 14".  Featuring pretty ideal conditions for snow accumulation, it snowed for 13 hours thereafter, including multiple heavy bands that ranked the areas immediately north, south, east, and west of DCA with heavy snow, and yet DCA got 3.8 inches out of it.  Does anyone believe this is plausible? 

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I can say that by 1 pm, in N Arlington I had 17". Of course, I'm a few hundred feet higher in elevation than DCA, but there was no mixing or temperature issues this storm. And the difference between us became almost 7" with this report. DCA actually looked like it was getting pounded during the deathbands, even more than me, but apparently it wasn't! The whole thing seems very fishy.

 

That makes a gigantic difference regardless of temps and mixing.  Here are my totals from the last 2 winters.  I'm at 90', and often I measure on a roof (huge roof).  I measure every event and even though I am not a spotter, I take measuring very seriously.  People are sometimes stunned at how "bad" I do being only a few miles away from them.  Even when I walk down the hill a few blocks the difference can sometimes be stark. DCA needs to follow protocol, but part of the solution is simply moving the station.

 

2014-15 - 20.0"

 

11/26: 0.25"

1/6: 3.25"

1/21: 0.5"

1/26-27: 1.25"

2/16-17: 4.0"

2/21: 3.5"

2/26: 2.0"

3/5: 5.25"

 

2013-14: 36.5"

12/8: 1.0", 12/10: 0.5", 1/2-3: 2.5", 1/21: 4.5", 1/28-29: 1.0", 2/9: 0.25", 2/12-13: 8.75", 2/18: 0.5", 2/25: 2.25", 2/26: 1.25", 3/3: 4.0",

3/16-17: 7.75", 3/25: 2.25"

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Ok, tinfoil hats on now. A CWG commenter found this which is the rate for plowing at DCA:

 

"The contractor shall be paid for Events requiring Snow removal/melting, and/or Ice control in accordance with the Base Services Contract Schedule. Pricing for Snow removal and Snow melting base services is based upon accumulated Snow fall between November 1 and April 30 of the next year."

 

 

 

:whistle:

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*Some* of the snow reports remind me how *some* people keep score

while playing golf.

 

---air whiff swing not counted---  ---kick the ball 3 inches from the base of a tree---

 

"Geoff, what was your score on hole #3?"   "Eh...give me a four."

 

Perhaps people shouldn't compare their report to spotters near them until after they submit their number.

Take it properly and scientifically, report it and then compare.

 

Kudos to Matt; disappointed that he can't pin down his reports with greater scientific precision.  He did his

best and I bet those numbers are representative.  Integrity!

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Ok, tinfoil hats on now. A CWG commenter found this which is the rate for plowing at DCA:

 

"The contractor shall be paid for Events requiring Snow removal/melting, and/or Ice control in accordance with the Base Services Contract Schedule. Pricing for Snow removal and Snow melting base services is based upon accumulated Snow fall between November 1 and April 30 of the next year."

 

 

 

:whistle:

 

That wouldn't surprise me.

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One of the other big problems with DCA is that they are windier than pretty much everyone else with the river as an unobstructed funnel.  It is just really, really hard to get good measurements in wind.  If they tried to just take a point measurement, I might believe how they ended up with 0.3".

 

yes, my biggest issue is the 0.8" measured between 4pm and 7pm.  I actually found the best spot I could, cleared a table, and also used another table with the snow still on it.  After 30 minutes of ripping snow, there was 0.0" on the cleared table, and 0.0 additional inches on the table with snow on it. The snow was blowing sideways skimming the surfaces and drifting.  I can see why DCA measured only 0.8"  Probably quite a bit more fell.  They got 0.09" liquid during that period and we know it is underrepresented, and probably significantly so.  Probably more like 0.15+.  Even if the 17" 4pm measurement is legit, they probably picked up 1.5 - 2" between then and 7 pm

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yes, my biggest issue is the 0.8" measured between 4pm and 7pm.  I actually found the best spot I could, cleared a table, and also used another table with the snow still on it.  After 30 minutes of ripping snow, there was 0.0" on the cleared table, and 0.0 additional inches on the table with snow on it. The snow was blowing sideways skimming the surfaces and drifting.  I can see why DCA measured only 0.8"  Probably quite a bit more fell.  They got 0.09" liquid during that period and we know it is underrepresented, and probably significantly so.  Probably more like 0.15+.  Even if the 17" 4pm measurement is legit, they probably picked up 1.5 - 2" between then and 7 pm

 

I've found that cleaning the snow board isn't always the best way to measure.  I gave up on this one and I still think my total is solid.

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I don't think people quite realize how bad we do down here in UHI, low elevation hell.  There is going to be a big difference simply based on elevation and nothing else.  DCA is a horrible place to measure snow.  I knew this, but it is even more apparent after living near downtown DC the last 3 winters. I was last or 2nd to last in seasonal snow totals in this forum.  Typically I thought DCA's totals were credible in 2013-14, 2014-15.  I measured every event.

 

My guess is had they measured carefully and properly, and did the best they could, around 19" would be the result.  So not sure this whole "investigation" is going to yield a much different result.  It may end up over 18" anyway after adding everything that fell after 7.

 

I don't post much but I agree with "I don't think people quite realize how bad we do down here in UHI, low elevation hell" for sure as someone who has lived between Old Town and Potomac Yard since 2003.

 

Especially in the marginal temperature events, the DCA effect is real and terrible. People would sometimes imply I was lying with my observations they were so divergent. I've defended DCA measurements in the past when I was more active on the forums.

 

That all said, they have completely blown a few storms IMO including Feb 2010 where I diverged terribly. It doesn't appear to be as bad for this storm, but we'll see what the final measurement is. I must say it was almost impossible to measure for about three hours this afternoon, especially in the urban environment where wind speed was enhanced at ground level by the density of structures in my neighborhood.

 

I can't be certain, but the times I've differed from DCA, it's been in a "cold" storm.

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I've found that cleaning the snow board isn't always the best way to measure.  I gave up on this one and I still think my total is solid.

 

I agree with you, but even snow on snow didn't work during that period...It was really really windy here. I think the 17.8" + whatever fell after 6:52 is probably close to legit.  I doubt DCA got over 20" .  Those spotters who measure low, I never really trust their totals either.  I imagine them walking outside after 3 hours, plunking a ruler into the ground, and running back in because it is cold and windy.  

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Perhaps a way to fix this is to take the closest five observations to DCA, that has measurements at the time the DCA 14.9" was taken, and also has measurements at the end of the storm. 

 

For each of the five, get the difference between the final total and the ~1 pm total. Perhaps better to use LWE rather than snowfall due to drifting. 

 

Then take the average these five "deltas" and add it to the 14.9" to get the final total. 

 

For example, if five observing stations got an additional 6" (or 0.6" liquid) between 1 pm and now, add that 6" to the 14.9" to get 20.9". 

 

My 2 cents. However, it wouldn't be in line with past numbers in 2010, 2003, 1996, etc. A simpler solution might be to just change the official location.

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I had this in the other thread, copying to here since a thread was opened-

jacindc, on 23 Jan 2016 - 9:01 PM, said:snapback.png

I am very much surprised that CWG has never set up a measuring station at 24th and M when a large storm is looming.

Even better, how about somewhere on Thomas Ave down towards the end of the south runway in one of the parking lots?

That would definitely be comparable for the DCA numbers.

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Interestingly I'll end within small zone of Snowmageddon too. Had 23.75" earlier. Kinda doubt I'll get a measurement higher. Had 24" then.

But it was much colder and dCA was running well early.

Honestly I think a bunch of obs are like this most just don't get the same kind of scrutiny. I believe they are probably not doing it right tho most public reports aren't with a snowboard and many are inflated.

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I agree with you, but even snow on snow didn't work during that period...It was really really windy here. I think the 17.8" + whatever fell after 6:52 is probably close to legit. I doubt DCA got over 20" . Those spotters who measure low, I never really trust their totals either. I imagine them walking outside after 3 hours, plunking a ruler into the ground, and running back in because it is cold and windy.

In a case like this I think you have to make a ton of measurements in places that do not seem disturbed. Obviously they aren't doing that at DCA.

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