DCA Snowfall Total Controversy

[Stebo]

I think that at some point there was a NWS Airport Office at DCA, but it was closed and the current FAA Contract Weather Observing station was established in its place.  I couldn't tell you when, maybe the 80s?

Could have even been as late as the early 90s, we used to have a NWS office here at DTW until 1992 when DTX was build to help centralize the NWS offices. Before then there were offices in Saginaw, Flint, Ann Arbor and at DTW.

[famartin]

OK, I looked and it looks like it became a CWO on 11/29/1979.

[BillB]

Could have even been as late as the early 90s, we used to have a NWS office here at DTW until 1992 when DTX was build to help centralize the NWS offices. Before then there were offices in Saginaw, Flint, Ann Arbor and at DTW.

 

The big draw-down in NWS observing offices (WSOs) was in the mid (and late?) 90s as ASOS was deployed.  The NWS staff at the WSOs were consolidated at the Forecast Offices (early 90s = WSFO, late 90s = WFO)  In Michigan, Ann Arbor was the Forecast Office up until Election Day 1992, then White Lake (DTX) took over.  Detroit Metro (DTW) and Flint (FNT) were the two WSOs in Southeast Michigan until late 1993 or 1994. Similar conversions took place elsewhere in the nation, including VA and MD, in the mid 90s.  

[famartin]

The big draw-down in NWS observing offices (WSOs) was in the mid (and late?) 90s as ASOS was deployed.  The NWS staff at the WSOs were consolidated at the Forecast Offices (early 90s = WSFO, late 90s = WFO)  In Michigan, Ann Arbor was the Forecast Office up until Election Day 1992, then White Lake (DTX) took over.  Detroit Metro (DTW) and Flint (FNT) were the two WSOs in Southeast Michigan until late 1993 or 1994. Similar conversions took place elsewhere in the nation, including VA and MD, in the mid 90s.  

Yes, but Reagan was much earlier.

 

 

IPS-98BB0BD7-824E-44EB-A252-885345E99426.pdf

[GramaxRefugee]

I think that at some point there was a NWS Airport Office at DCA, but it was closed and the current FAA Contract Weather Observing station was established in its place.  I couldn't tell you when, maybe the 80s?

I vaguely remember visiting (very briefly) the DCA NWS office somewhere around 1990. Had to be before 91. Maybe late 80s.

[famartin]

I vaguely remember visiting (very briefly) the DCA NWS office somewhere around 1990. Had to be before 91. Maybe late 80s.

It was contracted by then

[BillB]

Yes, but Reagan was much earlier.

 

Untitled.png

 

IPS-98BB0BD7-824E-44EB-A252-885345E99426.pdf

 

"Station type changed from WSO to WSCMO to 11/29/79"  1979 was Jimmy Carter.

[The Dude]

"Station type changed from WSO to WSCMO to 11/29/79"  1979 was Jimmy Carter.

 

He's referring to DCA, which has been re-named Reagan National Airport.

[PCT_ATC]

Inverted_Trough, on 28 Jan 2016 - 1:13 PM, said:Inverted_Trough, on 28 Jan 2016 - 1:13 PM, said:Inverted_Trough, on 28 Jan 2016 - 1:13 PM, said:

Has it always been the FAA that measures snow at DCA (i.e., for the past 40 years at least?).  Or have those responsibilities changed hands over the years?  And if those responsibilities have changed - then who used to measure it?

 

Of course all measurements have errors.  You can use spatial statistical methods to identify anomalies and adjust for them.  It's done all the time in any engineering or scientific field.  Weather has strong spatial and temporal autocorrelation, i.e., if everyone within a 1-mile radius is reporting 20% more snow than you, then your measurement is suspect.  

 

 

I was an Air Traffic Controller at DCA (no Reagan in my vocabulary.  Never called in Reagan Tower.. never will. They still call it National Tower today)  from 1998-2008 and we never ever took weather measurements.  All we ever did was put out the ATIS once an hour or when a speci came out.  The only facility I was ever a certified weather observer was at a little VFR  tower in Caldwell, NJ.

[MN Transplant]

I know we've touched on snow depth vs DCA's measurement some, but I thought I would throw a little more gas on the fire.

 

One of the things that does not make sense about DCA's 17.8" is that the reported snow depth for the morning of the 24th was 18" and the reading on the morning of the 25th was 17".  Depth is rounded, so it could have been 17.5" and 16.5" respectively, but I wanted to see how that rate of settling/compaction/melting compared to the Cocorahs observers in the local area.  Below are the Cocorahs stations, the total storm snowfall, the depth on the 24th, and the depth on the 25th:

 

Falls Church 1.6W (me) - 24.0", 23", 21"

Franconia 1.3 SSE - 22.0", 20.5", 20"

McLean 1.5 S - 27.7", 23", 20"

McLean 2.4 SSE - 24.5", 22.5", 21.5"

Vienna 1.3 W - 27.3", 24", 21.5"

Greenbelt 1.6 WNW - 25.9", 24", 22"

 

Rounded compaction levels of 3, 2, 8, 3, 6, 4.  Even throwing out the high outliers, you get a 2-4" compaction from the total to the depth on the 25th.  That makes DCA's 17" on the 25th after a 17.8" snowfall even less believable.  

 

(methodology - all Cocorahs stations in Fairfax/Arlington/DC/close-in PG that recorded snowfall and snow depth for all three days - 23rd-25th.  Stations where the total storm snowfall equaled the snow depth on the 24th were thrown out, as was the Reston total which had a 10" drop in one day)

 

[wxdude64]

I know we've touched on snow depth vs DCA's measurement some, but I thought I would throw a little more gas on the fire.

 

One of the things that does not make sense about DCA's 17.8" is that the reported snow depth for the morning of the 24th was 18" and the reading on the morning of the 25th was 17".  Depth is rounded, so it could have been 17.5" and 16.5" respectively, but I wanted to see how that rate of settling/compaction/melting compared to the Cocorahs observers in the local area.  Below are the Cocorahs stations, the total storm snowfall, the depth on the 24th, and the depth on the 25th:

 

Falls Church 1.6W (me) - 24.0", 23", 21"

Franconia 1.3 SSE - 22.0", 20.5", 20"

McLean 1.5 S - 27.7", 23", 20"

McLean 2.4 SSE - 24.5", 22.5", 21.5"

Vienna 1.3 W - 27.3", 24", 21.5"

Greenbelt 1.6 WNW - 25.9", 24", 22"

 

Rounded compaction levels of 3, 2, 8, 3, 6, 4.  Even throwing out the high outliers, you get a 2-4" compaction from the total to the depth on the 25th.  That makes DCA's 17" on the 25th after a 17.8" snowfall even less believable.  

 

(methodology - all Cocorahs stations in Fairfax/Arlington/DC/close-in PG that recorded snowfall and snow depth for all three days - 23rd-25th.  Stations where the total storm snowfall equaled the snow depth on the 24th were thrown out, as was the Reston total which had a 10" drop in one day)

Interesting, and although not 'scientific' a good basis to work off of. I still say DCA was in the 19.5-20.0 range for snowfall considering depth was 18 after the storm.

I am a good distance away so hard to compare with types of snow and whatnot, but I had the EXACT amount of snowfall they reported, 17.8 though the 24th and had 15/13 for depths next days. 

[famartin]

Interesting, and although not 'scientific' a good basis to work off of. I still say DCA was in the 19.5-20.0 range for snowfall considering depth was 18 after the storm.

I am a good distance away so hard to compare with types of snow and whatnot, but I had the EXACT amount of snowfall they reported, 17.8 and had 16/15 for depths next days.

 

 

So you measured on a snow board which was raised back to the level of the snow after each measurement and was free of blowing, drifting and was twice the distance away from the height of all nearby obstructions?  Just checking.

[wxdude64]

So you measured on a snow board which was raised back to the level of the snow after each measurement and was free of blowing, drifting and was twice the distance away from the height of all nearby obstructions?  Just checking.

Yep, 6 hour measures on board, done the 'official' CoCoRaHS way.

Not much drifting up here, highest wind gust I had entire storm was 28 mph. Most time wind was in the 10-15 mph range.

I did have a 30 minute period of heavy sleet around 6 pm,  which likely hacked the depth on ground a bit.

 

EDIT, had to check my CoCoRaHS numbers, I was off, they are right now.

[famartin]

Yep, 6 hour measures on board, done the 'official' CoCoRaHS way.

Not much drifting up here, highest wind gust I had entire storm was 28 mph. Most time wind was in the 10-15 mph range.

I did have a 30 minute period of heavy sleet around 6 pm,  which likely hacked the depth on ground a bit.

 

EDIT, had to check my CoCoRaHS numbers, I was off, they are right now.

Not quite related, but just a note:  CoCoRaHS has removed references to 6-hour measurements from their training slides:

http://cocorahs.org/media/docs/measuringSnow2.1.pdf

[famartin]

I know we've touched on snow depth vs DCA's measurement some, but I thought I would throw a little more gas on the fire.

 

One of the things that does not make sense about DCA's 17.8" is that the reported snow depth for the morning of the 24th was 18" and the reading on the morning of the 25th was 17".  Depth is rounded, so it could have been 17.5" and 16.5" respectively, but I wanted to see how that rate of settling/compaction/melting compared to the Cocorahs observers in the local area.  Below are the Cocorahs stations, the total storm snowfall, the depth on the 24th, and the depth on the 25th:

 

Falls Church 1.6W (me) - 24.0", 23", 21"

Franconia 1.3 SSE - 22.0", 20.5", 20"

McLean 1.5 S - 27.7", 23", 20"

McLean 2.4 SSE - 24.5", 22.5", 21.5"

Vienna 1.3 W - 27.3", 24", 21.5"

Greenbelt 1.6 WNW - 25.9", 24", 22"

 

Rounded compaction levels of 3, 2, 8, 3, 6, 4.  Even throwing out the high outliers, you get a 2-4" compaction from the total to the depth on the 25th.  That makes DCA's 17" on the 25th after a 17.8" snowfall even less believable.  

 

(methodology - all Cocorahs stations in Fairfax/Arlington/DC/close-in PG that recorded snowfall and snow depth for all three days - 23rd-25th.  Stations where the total storm snowfall equaled the snow depth on the 24th were thrown out, as was the Reston total which had a 10" drop in one day)

I don't think it was necessary to remove the sites where depth matched fall from your analysis. 

 

Also, the lower total at DCA means less compaction may occur at various points. 

 

Finally, I can't find stations which match DCA's current snow depth of 3" nearby.  I'm sure the next comment will be "well they are low", but I went to DCA last night and took a few measurements.  They're 3" depth is legit. 

[wxdude64]

Not quite related, but just a note:  CoCoRaHS has removed references to 6-hour measurements from their training slides:

http://cocorahs.org/media/docs/measuringSnow2.1.pdf

Well, isn't that dandy, well, I have been measuring in the 6 hour adds for 24 hour totals since I started in '79, I'll keep my method for 'preservation of records'. Anyway that is what I had, 16.6 first day, 15 on ground at 7 am (23rd), 1.2 next day for storm total of 17.8, 15 on ground that day (24th), 13 on ground following day (25th). SWE went 1.55, 1.55, 1.47.

[famartin]

Well, isn't that dandy, well, I have been measuring in the 6 hour adds for 24 hour totals since I started in '79, I'll keep my method for 'preservation of records'. Anyway that is what I had, 16.6 first day, 15 on ground at 7 am (23rd), 1.2 next day for storm total of 17.8, 15 on ground that day (24th), 13 on ground following day (25th). SWE went 1.55, 1.55, 1.47.

 

When possible, my parents still are doing 6-hourly too.  Its all they've done.  NWS HQ has "encouraged" all non-airport snow reporters (spotter and coop) to cease 6-hour measurements, though not all WFO's are on board. 

[wxdude64]

When possible, my parents still are doing 6-hourly too.  Its all they've done.  NWS HQ has "encouraged" all non-airport snow reporters (spotter and coop) to cease 6-hour measurements, though not all WFO's are on board. 

I'll keep my method. I have had to * a few storms in past 2 years since son is in Colorado and wife passed, they were my 'helpers' when I was at work. I remember NWS causing the firestorm about only measuring at 7 am for CO-OPs. I sent a few choice remarks about that then. So it snows 4 inches  in a 6 hour period, sun comes out and melts it down to 2 inches and it settles to 1.5 overnight so at 7 am when the CO-OP reports he has 1.5 inches of snow on 0.55 liquid.....quite a heavy wet snow, wouldn't you say. I think they came back with "measure when it is deepest" or something to that effect. All that is doing is measuring depth.

[famartin]

I'll keep my method. I have had to * a few storms in past 2 years since son is in Colorado and wife passed, they were my 'helpers' when I was at work. I remember NWS causing the firestorm about only measuring at 7 am for CO-OPs. I sent a few choice remarks about that then. So it snows 4 inches  in a 6 hour period, sun comes out and melts it down to 2 inches and it settles to 1.5 overnight so at 7 am when the CO-OP reports he has 1.5 inches of snow on 0.55 liquid.....quite a heavy wet snow, wouldn't you say. I think they came back with "measure when it is deepest" or something to that effect. All that is doing is measuring depth.

 

New depth, yes.  The idea behind the change is that over the history of the COOP program (which is of course well over 100 years old), most observers probably measured peak depth during the 24 hour period, if that.  Otherwise, they just measured new depth at 7AM and called it "fall".  Certainly, the 6-hour clearing method is new to the program, and it was decided by a powwow of state climatologists in concert with NWS to eliminate that method, for the sake of consistency with historic records. 

 

Lately, I have looked much harder at fall vs. depth.  Usually, with the historic storms of the past that we like to compare to, depth was fairly close to fall, even at airports.  Lately this has been less common.

[wxdude64]

New depth, yes.  The idea behind the change is that over the history of the COOP program (which is of course well over 100 years old), most observers probably measured peak depth during the 24 hour period, if that.  Otherwise, they just measured new depth at 7AM and called it "fall".  Certainly, the 6-hour clearing method is new to the program, and it was decided by a powwow of state climatologists in concert with NWS to eliminate that method, for the sake of consistency with historic records. 

 

Lately, I have looked much harder at fall vs. depth.  Usually, with the historic storms of the past that we like to compare to, depth was fairly close to fall, even at airports.  Lately this has been less common.

To me it is 6 of one half a dozen of another. Yes, snow settles over time, melts too (as in my example). So if a 70 year CO-OP has always measured at 7 am and still does it, fine. If a new one has started since the change and he is told to stop that messes with the consistency of record. I have always done the 6 hour, and will keep for records unless told not to.

[famartin]

Lately, I have looked much harder at fall vs. depth.  Usually, with the historic storms of the past that we like to compare to, depth was fairly close to fall, even at airports.  Lately this has been less common.

 

To expand on this, here are some notable storms at DCA and how depth compared to fall

(Note:  These are all the climo depths, i.e. 7AM during the airport era, though before that I think it was actually more like 7PM).

 

2/5-6/2010

Fall 17.8.  Max depth 18

 

12/18-19/2009

Fall 16.4. Max depth 16

 

2/16-18/2003

Fall 16.3. Max depth 16

 

1/6-8/1996

Fall 17.1.  Max depth 17

 

2/10-11/1983

Fall 16.6.  Max depth 17

 

2/18-19/1979

Fall 18.7.  Max new depth 16 (6 on ground at start, 22 at end)

 

1/29-30/1966

Fall 13.8.  Max new depth 12 (4 on ground at start, 16 at end)

 

2/15-16/1958

Fall 14.4.  Max depth 14

 

(obviously these below are before DCA existed; they are from downtown)

 

2/7-9/1936

Fall 14.4.  Max depth 14

 

1/27-29/1922

Fall 28.0.  Max depth 26

 

2/16-18/1900

Fall 14.3.  Max depth 14

 

2/12-14/1899

Fall 20.0. Max new depth 20 (14 at start, 34 at end)

[rgwp96]

When possible, my parents still are doing 6-hourly too.  Its all they've done.  NWS HQ has "encouraged" all non-airport snow reporters (spotter and coop) to cease 6-hour measurements, though not all WFO's are on board. 

depth is a more accurate method and and would eliminate the inflated numbers. majority of the public sees of what is on the ground as how much fell. i want to see how these people wipe these boards clear and where do they start again?  example do they clear the area and leave it in a the ground still? or do u have it on top of a table ect?

[gymengineer]

depth is a more accurate method and and would eliminate the inflated numbers. majority of the public sees of what is on the ground as how much fell. i want to see how these people wipe these boards clear and where do they start again?  example do they clear the area and leave it in a the ground still? or do u have it on top of a table ect?

What, you don't like Central Park's 26.8" total vs. a 22" snow depth ~6 hours after the snow stops falling?  

[Deck Pic]

I know we've touched on snow depth vs DCA's measurement some, but I thought I would throw a little more gas on the fire.

 

One of the things that does not make sense about DCA's 17.8" is that the reported snow depth for the morning of the 24th was 18" and the reading on the morning of the 25th was 17".  Depth is rounded, so it could have been 17.5" and 16.5" respectively, but I wanted to see how that rate of settling/compaction/melting compared to the Cocorahs observers in the local area.  Below are the Cocorahs stations, the total storm snowfall, the depth on the 24th, and the depth on the 25th:

 

Falls Church 1.6W (me) - 24.0", 23", 21"

Franconia 1.3 SSE - 22.0", 20.5", 20"

McLean 1.5 S - 27.7", 23", 20"

McLean 2.4 SSE - 24.5", 22.5", 21.5"

Vienna 1.3 W - 27.3", 24", 21.5"

Greenbelt 1.6 WNW - 25.9", 24", 22"

 

Rounded compaction levels of 3, 2, 8, 3, 6, 4.  Even throwing out the high outliers, you get a 2-4" compaction from the total to the depth on the 25th.  That makes DCA's 17" on the 25th after a 17.8" snowfall even less believable.  

 

(methodology - all Cocorahs stations in Fairfax/Arlington/DC/close-in PG that recorded snowfall and snow depth for all three days - 23rd-25th.  Stations where the total storm snowfall equaled the snow depth on the 24th were thrown out, as was the Reston total which had a 10" drop in one day)

 

Nice work.  Hopefully LWX holds FAA at DCA to the same standards as it did BWI and IAD.  Even if you throw out most of the mounting evidence, all you need is the fact that they threw in the towel while snow was still accumulating.  This isn't a murder trial. DCA was getting moderate snow at 5pm, picked up 0.04" the next hour which we know was more), but had already waved the white flag.  2 different downtown spotters picked up just over 6" in the finale.  DCA picked up 2.9".  

[famartin]

What, you don't like Central Park's 26.8" total vs. a 22" snow depth ~6 hours after the snow stops falling?

 

He probably doesn't actually

[gymengineer]

He probably doesn't actually

Right, that's exactly what my post meant-- and another point was to put the Central Park numbers here for those who didn't know about it.

The snow depth as better than snowfall posters have been consistent in their posts.

[rgwp96]

What, you don't like Central Park's 26.8" total vs. a 22" snow depth ~6 hours after the snow stops falling?

Nope bogus . the 2006 one was even worse , 26 plus total with a max depth of 16 .

[gymengineer]

He probably doesn't actually

And just as pure befuddlement to your post: If a conversation proceeds like this:

"I can't stand cats."

"What, you don't like my Fluffy who scratches your arm everytime you come over? :)"

And you reply: "He probably doesn't like Fluffy actually."

[famartin]

The more I think about this, the more of a feeling I get that everything before the final report was tossed by the last observer during the storm. So, we can't say anything about comparisons to earlier measurements.

Considering that, there is evidence that supports the storm total as reported. (See earlier post if you are still having trouble with the history of fall va depth matching at DCA). At this point I feel that the odds it remains intact are decent.

[Deck Pic]

The more I think about this, the more of a feeling I get that everything before the final report was tossed by the last observer during the storm. So, we can't say anything about comparisons to earlier measurements.

Considering that, there is evidence that supports the storm total as reported. (See earlier post if you are still having trouble with the history of fall va depth matching at DCA). At this point I feel that the odds it remains intact are decent.

 

You're invested in building a case against altering the record, and I am not entirely sure why.  Is this like a football challenge where we defer to the call on the field and the evidence has to be overwhelming?  Or is there some other standard that we are unaware of?  

 

I've been following snowfall data here religiously for 12 years now, and there have been a number of changes to preliminary totals for all 3 airports, and not just based on some data entry error, and not just moderate to major events.  I have a body of work here staunchly defending DCA's snow totals for most storms - - I can pull up the posts if needed - - especially the last 2 winters.  I am not gunning for anyone.  

 

IF, and someone in the know is free to correct the record if it needs to be corrected.  IF my understanding is correct, they had one snowboard, and it got buried in the snow at some point and they couldn't find it. So they had to improvise.  At 2:52 pm, 17" had fallen. I have video from 2:51 pm, and it is apocalyptic looking in downtown DC yet somehow only 0.8" fell the next 2 hours.  At 4:52 pm when it was still snowing hard, evidenced not only by the 4:52 OB, but also by the fact that 0.04" liquid was captured in the following hour (we know it is probably at least 0.06"), they measured 17.8", and quit measuring the storm.  So, just to be clear. They measured 17.8" at 4:52 PM - almost certainly a snow depth measurement - and finalized the total.  And then it snowed for another 7 hours.  Again.  If I am not getting the facts right, someone can please feel free to correct me.  I am not here to perpetuate something that isn't true or is misleading.

 

I hope the standard for correcting an error is nothing other than - let's do the best we can to get it right -  and not some "ruling on the field" standard.  If this is about not upsetting the FAA or not rocking the boat or not fracturing the relationship between LWX and the DC observers, then I think it is kind of a bummer. There are people in this forum who take measuring very seriously.  We have trained spotters who post here and Cocorahs folks and ACON folks, and skilled hobbyists.  Accuracy is a source of pride here.  Mapgirl has made professional maps the last 2 winters based on our reporting.  We are creating a body of work.  So, I'd hope folks who are the stewards of official historic records work their hardest to maintain the integrity of that record, if we are putting that much effort into an unofficial reference.  

 

If the FAA erred, so be it. Hopefully LWX will fix it if that is the case.  If it ends up being 17.8", so be it and it doesn't change the fact that LWX/FAA are still good people who do good work.  Agreeing to disagree is healthy. But it would be kind of a bummer if it is because some arbitrary standard got in the way of just trying to get it right.