DCA Snowfall Total Controversy

[Deck Pic]

Ya know what... egg on my face.  There is a screwup.  Frig.  Dangit.  My bad guys.  My deepest apologies. 

 

No worries.  I apologize for coming at you so hard. I get really defensive of the crew here when "outsiders" come in and "tell it like it is". You're one of us now anyway .  A lot of us have been here a long time, and there is a history of people from 40N coming in here and being condescending like we are morons.  So I am unusually on edge about that stuff. 

[Deck Pic]

I noticed an issue today going over the observations as well beyond what I was monitoring with the obs on Saturday.

 

This is the 4:52PM and 5:52PM METARs with the SPECIs between:

 

METAR KDCA 232152Z 34023G32KT 1/16SM R01/1800V2000FT SN BLSN FG VV006 M03/M05 A2966 RMK AO2 PK WND 34036/2118 SLP044 SNINCR 1/18 P0002 T10331050 $                      

SPECI KDCA 232218Z 34025G37KT 1/8SM R01/1800V2400FT SN BLSN FG VV006 M03/M04 A2968 RMK AO2 PK WND 34037/2216 P0001 T10331044 $                            

SPECI KDCA 232239Z 34022G29KT 1/2SM R01/3000V4500FT SN BLSN FG VV008 M03/M04 A2969 RMK AO2 PK WND 34037/2216 P0003 T10281044 $                            

METAR KDCA 232252Z 34023KT 1/2SM R01/3500V5000FT SN BLSN FG VV008 M03/M04 A2969 RMK AO2 PK WND 34037/2216 SLP054 SNINCR 1/18 P0003 T10281044 $

 

First off the 1/16SM and 1/8SM obs should be +SN and all should be FZFG but the other issue is how do you gain an inch in an hour both hours but still remain 18" on the ground. This right here is a clear discrepancy in the observing. You can't lose and then gain an inch of snow within an hour even in a blizzard, it just doesn't happen. Based upon what I have read, my conclusion is the measuring they did was snow depth and not snowfall as snowfall would have been a higher total as you'd have compaction with depth consider the storm was over 24 hours and a heavier snow ratio at that.

 

second-hand - from conversations with the observer at DCA, I think DCA was 17.0" at 3:52, 17.5" at 4:52 and 17.8" at 5:52.  And somehow they picked up another 0.05" liquid (which we know was probably like 0.08") and recorded no additional snow because they gave up...I have video from several miles away at 5:38 pm showing 1"/hr type snow.  

[Stebo]

second-hand - from conversations with the observer at DCA, I think DCA was 17.0" at 3:52, 17.5" at 4:52 and 17.8" at 5:52.  And somehow they picked up another 0.05" liquid (which we know was probably like 0.08") and recorded no additional snow because they gave up...I have video from several miles away at 5:38 pm showing 1"/hr type snow.  

That would be the only way that it could have happened. That being said based upon the visibility and snow intensity, I have a hard time believing 0.3" of snow fell between 4:52PM and 5:52PM and considering your first hand experience at the time, the 0.3" gain in an hour is garbage. 1.3" would have made more sense.

[zenmsav6810]

Rachel Maddow had this on her show tonight (can't find link). I emailed her hoping she would cease her use of the TWC winter storm naming practice. Also this thread was the second on the google search page for "dc snowfall controversy"

 

Other NBC coverage: http://www.msnbc.com/way-too-early/watch/dc-snowfall-totals-now-in-question-608178755572

 

CNN: http://www.cnn.com/2016/01/25/us/dc-snow-measure-gate/

 

Fox: http://www.fox5dc.com/news/81940399-story

 

other links: http://www.wunderground.com/blog/JeffMasters/colossal-noreaster-dumps-record-snow-from-maryland-to-new-york

[blizznd]

Anthony has been banging this drum for years. I admire his effort and have tried to assist him by calling AKQ, leaving comments on their FB page, sending emails, etc.

 

You are correct about the Sandston override. Brian Hurley has confirmed that this was the policy when he left AKQ a few years ago. The lead met has informed me that the totals were too close (11.4 vs. 12.4) to do anything this time around though.

 

This still begs the question: why does ORF have an NWS observer and RIC does not? I understand the points about cost savings etc. But why not have all airports in an NWSFO area doing the same thing?

I am with NWS Grand Forks ND.     In our area....  for Fargo climate station...  we use the ASOS temps and liquid precip for the long term climate records.   When the NWS moved out of Fargo and ASOS installed...to keep snowfall records we had a long standing coop observer in N Moorhead MN  a couple miles east of the airport.  NCDC determines with the coop observer is within a certain distance and can be used for that site in regards to snowfall.   I dont recall what the standards are...  you must be 3 miles or 5 miles maybe from the climate station.    Our coop has been a snow pay observer and is paid per snowfall observations, which he does every 6 hours.  The FAA wants no part of snow measuring from tower personnel.....and Fargo isnt staffed 24 hrs anyhow.   It is a miracle if they augment the ASOS there.     I dont know what would happen if the paid snow pay observer moved.   Would have to see if interest is there for someone to take over that the NCDC finds acceptable.     If not no more snowfall records for Fargo.

 

For Grand Forks....the official coop station was the University of North Dakota and when we moved into town we took over as the official coop station as our office is close by campus.   Now for some reason,  the Grand Forks airport , which is 5 miles west of town and 5 miles away from our office,   is a Contract Weather Observer site and there is someone in building QC the ASOS obs and taking snow measurements from about 530 am to 1130 pm.   There obs go into the system as the Grand Forks airport climate data..... and our obs taken at the office go into the Grand Forks city climate data which runs back farther than the airport.  

 

We have many other cooperative observers that send in their snowfall/depth and they try  but about half are not the most trustworthy.   They are close....but often many are quite elderly and really have a hard time moving around outside in the winter.   We take what we can and we can always correct an RR3  if we think data is really bad.   Otherwise  corrections are made by NCDC as needed.

 

Snowfall measurements are quite subjective in many locations.....  snow depths even more so.   Snow depths are going to vary greatly once place to another esp out here in the Plains where in town you will have often double snow on your house lawn than in the open fields .   

 

I mention all  of this,   as it is possible there is no coop acceptable near the Richmond airport that can be used to supplement RIC climate records.    While at ORF  there may well be a long standing coop there nearby.

 

Dan

[MN Transplant]

second-hand - from conversations with the observer at DCA, I think DCA was 17.0" at 3:52, 17.5" at 4:52 and 17.8" at 5:52. And somehow they picked up another 0.05" liquid (which we know was probably like 0.08") and recorded no additional snow because they gave up...I have video from several miles away at 5:38 pm showing 1"/hr type snow.

So, it is confirmed that they gave up? I could alternatively see a situation where they had cleared whatever spot they used, but the snow all blew away from it. Then they would have had to make an educated guess and just punted.

[WinterWxLuvr]

Measuring snowfall can't possibly be this complicated.

[CAPE]

Measuring snowfall can't possibly be this complicated.

Apparently its like rocket science.

 

If the folks at DCA would just let RR show em how to do it, there would be no controversy .

[WinterWxLuvr]

Apparently its like rocket science.

If the folks at DCA would just let RR show em how to do it, there would be no controversy .

Evidently it's on par with the Manhattan project.

On a related issue, in every extreme weather event, my local station KOKV completely craps out. If the temp goes below 10, no obs. This weekend, 3 obs of heavy snow and down she goes. No obs for about 18 hours. I don't know if these are automated obs or what, but it happens every time.

[Deck Pic]

So, it is confirmed that they gave up? I could alternatively see a situation where they had cleared whatever spot they used, but the snow all blew away from it. Then they would have had to make an educated guess and just punted.

 

My understanding is that at some point ( I think 5:52) they threw their hands up and said the depth wasn't changing, so they finalized the number. I am reasonably confident they were at 17.5" at 5pm.  after 5pm 0.08" of liquid fell (which we know was more)., and somehow they mustered another 0.3". In fact 0.04" fell between 5:52 and 6:52 and they had zero snow increase...

[famartin]

Anyway, what I noticed was this:

 

12Z depth was 14 inches

18Z depth was 13 inches

0Z depth was 18 inches

Reported total was 17.8"

 

There's an obvious missing 1.5 inches, minimum (assuming that depth was down to 13.4 and then increased to 17.8, that's 4.4" after 18Z, but the total reported was only an increase of 2.9". )

 

I think there is fear that changing it now may cause an uproar.

[Jersey Andrew]

For purposes of historical integrity, this reported total of 17.8 inches at DCA cannot stand.  The uproar will be if they do nothing about it, not if they make the proper change.  In the world of sports, perfect example is Secretariat's performance at Preakness when the timer malfunctioned and subsequently the race was re-timed and adjusted to show he had actually set the track record.  In the future, the official measuring location needs to be moved into D.C. proper because the error keeps happening and is getting to be a joke.

[donsutherland1]

From reading the initial CWG piece and this thread, I'll only state that it is a sad state of affairs at DCA. IMO, the point Jersey Andrew raises above is important: the integrity of the climate record should easily take precedence over any uproar related to making the necessary change. Any criticism DCA's snow measuring team receives in the recent national coverage of this issue is the result of its own lack of attention to quality/detail. As DCA's snow measurements have drawn attention previously, one would reasonably expect that DCA's team would devote sufficient effort to avoid the kind of issue that appears to have occurred. Unfortunately, it seems that such effort was lacking.

 

I am confident that the NWS will make any adjustment that might be necessary. For example, last winter, several adjustments were made to Central Park's figures when those figures were clearly dissimilar from those reported nearby. The same held true for BWI during winter 2009-10 when it was found that the Airport was incorrectly measuring snow on an hourly basis.

[RodneyS]

Thanks for your work on this. More uproar than there is now? It was the talk of the office this morning among people who don't even care about weather. If you found an error, fixing it is the right thing to do. People would mind more if NWS knowingly certified a bad record IMO.

 

I'm confident that the record will be corrected because two years ago I pointed out in an e-mail to Jim Lee an error in the DCA daily precipitation report for January 10, 2014.  Here was his response:

 

The correct amount of precipitation for Friday, January 10, 2014 was 0.57 inches. Our daily climate reports have been corrected.

 

Thanks for letting me know of the error.  I'm reviewing our operations procedures to reduce the risk of this type of error again.

Sincerely,

Jim Lee

[Deck Pic]

Anyway, what I noticed was this:

 

12Z depth was 14 inches

18Z depth was 13 inches

0Z depth was 18 inches

Reported total was 17.8"

 

There's an obvious missing 1.5 inches, minimum (assuming that depth was down to 13.4 and then increased to 17.8, that's 4.4" after 18Z, but the total reported was only an increase of 2.9". )

 

I think there is fear that changing it now may cause an uproar.

 

Thanks, Ray.  Can you inform Jim Lee?  

 

More analysis. These are additional potential issues that have already been discussed to some extent.  Feel free to correct me if I got something wrong.  The exact amounts came from the observer at DCA - I got them secondhand.  I think I have them right.

 

 

 

- If Snow increased ~ 1” between 4:52 and 5:52 how did the total only go up 0.3”?

 

- The 5:52 OB was 0.5/Mod Snow, and 0.04” fell in the bucket over the next hour (which we know was more because the bucket undermeasures). How did the total of 17.8” stay the same? It stands to reason at least a few tenths accumulated during that hour, and maybe more.

 

- 0.01” fell between 6:52 and 7:52.  That might have tacked on a couple more tenths. And perhaps even some after that.   

 

[winterymix]

Anyway, what I noticed was this:

12Z depth was 14 inches

18Z depth was 13 inches

0Z depth was 18 inches

Reported total was 17.8"

There's an obvious missing 1.5 inches, minimum (assuming that depth was down to 13.4 and then increased to 17.8, that's 4.4" after 18Z, but the total reported was only an increase of 2.9". )

I think there is fear that changing it now may cause an uproar.

I think this is just like "forward progress" in NFL football.

We can see that snow depth increased 5 inches from 18Z to 0Z.

Add that 5" to the 12Z depth of 14 inches and the forward progress to 0Z is 19".

Add whatever accumulated after 0Z and the minimum correct snowfall is

19+".

[famartin]

Alright, so I got some additional info. Supposedly, the 0Z depth was measured "differently" from the 18Z depth, so comparing the two is incompatible. meh

[winterymix]

Alright, so I got some additional info. Supposedly, the 0Z depth was measured "differently" from the 18Z depth, so comparing the two is incompatible. meh

At first, I thought Mr. Lee's choice of "perishable" was curious.

Now it makes perfect sense.

[Kat]

Bottom line is nothing will be done. The record will stand, like the many flawed measurements of the past. Need a new official station in DC along with DCA.

[Deck Pic]

2 trained spotters (Woodley Park and 4th and L NE) picked up 6.2 and 6.3" respectively after 1pm, when DCA picked up 2.9".  I trust that Jim Lee will prioritize the integrity of the historic record and scientific process over politics.  

[zenmsav6810]

For purposes of historical integrity I think it would be favorable to have no record than to have a record we know is incorrect.

[famartin]

2 trained spotters (Woodley Park and 4th and L NE) picked up 6.2 and 6.3" respectively after 1pm, when DCA picked up 2.9".  I trust that Jim Lee will prioritize the integrity of the historic record and scientific process over politics.  

For purposes of historical integrity I think it would be favorable to have no record than to have a record we know is incorrect.

Given that my original premise about the snow depth mis-match was flawed, there is no longer undeniable proof that the observation is bad.  So, I think it will stand.  Obviously I don't have the final say on that.  Since there is inherent error with all observations, and snowfall much more so than others, I don't think it should be left missing.

[Deck Pic]

[famartin]

I know the "official" airport records matter to a lot of you guys... but if I might make a suggestion which could help you feel better.... sign up for CoCoRaHS.  Your own data then gets into NCDC.  Here's mine (there's a few days lag usually, so its only up thru the 23rd at NCDC)

https://www.ncdc.noaa.gov/cdo-web/datasets/GHCND/stations/GHCND:US1VAFX0072/detail

[famartin]

I noticed an issue today going over the observations as well beyond what I was monitoring with the obs on Saturday.

 

This is the 4:52PM and 5:52PM METARs with the SPECIs between:

 

METAR KDCA 232152Z 34023G32KT 1/16SM R01/1800V2000FT SN BLSN FG VV006 M03/M05 A2966 RMK AO2 PK WND 34036/2118 SLP044 SNINCR 1/18 P0002 T10331050 $                      

SPECI KDCA 232218Z 34025G37KT 1/8SM R01/1800V2400FT SN BLSN FG VV006 M03/M04 A2968 RMK AO2 PK WND 34037/2216 P0001 T10331044 $                            

SPECI KDCA 232239Z 34022G29KT 1/2SM R01/3000V4500FT SN BLSN FG VV008 M03/M04 A2969 RMK AO2 PK WND 34037/2216 P0003 T10281044 $                            

METAR KDCA 232252Z 34023KT 1/2SM R01/3500V5000FT SN BLSN FG VV008 M03/M04 A2969 RMK AO2 PK WND 34037/2216 SLP054 SNINCR 1/18 P0003 T10281044 $

 

First off the 1/16SM and 1/8SM obs should be +SN and all should be FZFG but the other issue is how do you gain an inch in an hour both hours but still remain 18" on the ground. This right here is a clear discrepancy in the observing. You can't lose and then gain an inch of snow within an hour even in a blizzard, it just doesn't happen. Based upon what I have read, my conclusion is the measuring they did was snow depth and not snowfall as snowfall would have been a higher total as you'd have compaction with depth consider the storm was over 24 hours and a heavier snow ratio at that.

I am looking thru the obs now, and I see that the 2252Z ob was corrected later, removing the SNINCR remark

 

KDCA 231752Z COR 35019G28KT 1SM R01/3500V5000FT -SN BLSN FEW013 OVC021 M02/M04 A2956 RMK AO2 PK WND 35036/1658 SLP008 4/013 933022 P0000 60013 T10221039 11022 21039 58012=

KDCA 231852Z 35022KT 1/2SM R01/2600V3000FT -SN BLSN VV014 M03/M04 A2956 RMK AO2 PK WND 35030/1842 SLP008 P0000 T10281044=

KDCA 231952Z 35025G31KT 1/8SM R01/1200V1400FT +SN BLSN VV006 M03/M04 A2957 RMK AO2 PK WND 35033/1940 SLP012 P0003 T10331044 $=

KDCA 232052Z 34024G34KT 1/4SM R01/1600V2000FT +SN BLSN FG VV007 M03/M05 A2962 RMK AO2 PRESRR SLP029 SNINCR 2/17 P0002 60005 T10331050 53021 $=

KDCA 232152Z 34023G32KT 1/16SM R01/1800V2000FT SN BLSN FG VV006 M03/M05 A2966 RMK AO2 PK WND 34036/2118 SLP044 SNINCR 1/18 P0002 T10331050 $=

KDCA 232252Z COR 34023KT 1/2SM R01/3500V5000FT SN BLSN FG VV008 M03/M04 A2969 RMK AO2 PK WND 34037/2216 SLP054 P0003 T10281044 $=

KDCA 232352Z COR 34020G27KT 1 3/4SM -SN BR VV010 M03/M04 A2973 RMK AO2 PK WND 34030/2257 SLP066 P0004 4/018 60014 T10281044 11022 21033 51037 $=

 

[wxdude64]

I know the "official" airport records matter to a lot of you guys... but if I might make a suggestion which could help you feel better.... sign up for CoCoRaHS.  Your own data then gets into NCDC.  Here's mine (there's a few days lag usually, so its only up thru the 23rd at NCDC)

https://www.ncdc.noaa.gov/cdo-web/datasets/GHCND/stations/GHCND:US1VAFX0072/detail

Agree, and it is easy, been doing CoCoRaHS since 2007 when I first learned about it.  Kept my own records back to 1979 when I was only 15, first writing on paper until I got a computer in late 80's.

[Deck Pic]

I am looking thru the obs now, and I see that the 2252Z ob was corrected later, removing the SNINCR remark

 

 

right..because they quit measuring at 2152z and threw their hands up.  This was conveyed from DCA to CWG.  The 0.04" that fell the next hour (we know it is more) just evaporated into thin air.  Maybe they can correct the metars to show it never happened.

[famartin]

right..because they quit measuring at 2152z and threw their hands up.  This was conveyed from DCA to CWG.  The 0.04" that fell the next hour (we know it is more) just evaporated into thin air.  Maybe they can correct the metars to show it never happened.

Sometimes a remark might get copied into the next one inadvertently, so they really might not have meant to send that in the ob twice.  Its uncertain.  Like all of this.

[Deck Pic]

Has anyone here ever recorded 0.04" from moderate snow in an undermeasuring bucket at 27 degrees with 17.8" depth and the snow didn't stick?

[famartin]

Agree, and it is easy, been doing CoCoRaHS since 2007 when I first learned about it.  Kept my own records back to 1979 when I was only 15, first writing on paper until I got a computer in late 80's.

Of course they really only want the 4-inch rain gauge readings for precip, but if you have snow data further back, you can add that in back to 1998.  I did that with my parents, check it:

https://www.ncdc.noaa.gov/cdo-web/datasets/GHCND/stations/GHCND:US1NJMC0017/detail

I just left precip missing.  If you have a standard rain gauge (not a tipping bucket) you could probably include precip too.