famartin Posted January 25, 2016 Share Posted January 25, 2016 This is a hard region to forecast for. Many a met has come in to Sterling and blown forecasts that they should have known better. Study and leave this stuff to the people who have lived here for decades. Just stop. And what's with all this "blown forecast" garbage? Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 Why did that spotter call change from 20" to 17"? I couldn't get less than 18" on any measurement in Old Town after the storm, but whatever. Was it that exact spotter call? We only include finals in the PNS. If that particular spotter never called back later, it would get ignored. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 Just stop. And what's with all this "blown forecast" garbage? We've been here for years, Ray. Perhaps better to read and post less on subjects you know little about. Link to comment Share on other sites More sharing options...
gymengineer Posted January 25, 2016 Share Posted January 25, 2016 Just stop. And what's with all this "blown forecast" garbage? No one's going to stop discussing this. This is a weather board. Good grief-- there was a great discussion going in here in good faith. Then, you come in first with your 29" IAD snow depth when the snow depth we were all talking about was at 12Z Sunday, when IAD reported 28". At least use the right comparison if you're going to post like a jerk. Link to comment Share on other sites More sharing options...
haudidoody Posted January 25, 2016 Share Posted January 25, 2016 Was it that exact spotter call? We only include finals in the PNS. If that particular spotter never called back later, it would get ignored. It was the same spotter according to the coordinates. I was just wondering if they had screwed up the earlier measurement for some reason, and changed their report later in the evening. 0510 PM SNOW 1 WNW NATIONAL HARBOR 38.80N 77.05W 01/23/2016 M20.0 INCH CITY OF ALEXANDRIA VA TRAINED SPOTTER 0755 PM SNOW 1 WNW NATIONAL HARBOR 38.80N 77.05W 01/23/2016 M17.0 INCH CITY OF ALEXANDRIA VA TRAINED SPOTTER Edit: And then I saw this number today for snow on ground from a different spotter, so I don't know. ...CITY OF ALEXANDRIA... 1 SSW ALEXANDRIA 23.0 800 AM 1/24 TRAINED SPOTTER Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 I'm still waiting for someone to explain to me why its a big controversy that DCA's total, which matches their depth, is a problem, but IAD's, which also matches their depth, is not. The meteorological explanation is easy: DCA got dry slotted. The evidence besides the observer measurements is abundant: Nearby spotter reports in the range of DCA's total. Lets take a look at ASOS precip totals, perhaps: DCA with 17.8" reported 1.48" liquid (raw ASOS, since observers don't melt it for us). IAD with 29.3" reported 2.23" liquid (that's raw ASOS, not what we melted, which was more). The only reason this is an issue is because people forecast big totals and DCA didn't deliver for them. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 It was the same spotter according to the coordinates. I was just wondering if they had screwed up the earlier measurement for some reason, and changed their report later in the evening. 0510 PM SNOW 1 WNW NATIONAL HARBOR 38.80N 77.05W 01/23/2016 M20.0 INCH CITY OF ALEXANDRIA VA TRAINED SPOTTER 0755 PM SNOW 1 WNW NATIONAL HARBOR 38.80N 77.05W 01/23/2016 M17.0 INCH CITY OF ALEXANDRIA VA TRAINED SPOTTER Not sure. It could be two spotters lived close enough. The program unfortunately is not very precise with only two decimal places. Of course we know exact street addresses for our spotters, but I coudn't give them out. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 I sent this in an email to several people but might as well post it here. These are potential issues with the DCA measurement - Losing the snow board so relying on depth in a very drifty storm. - Using depth instead of sweeping. Compaction and settling very likely in storm of this size. Perhaps up to 10-15% in compaction alone. Plus how did they have ~18” snow depth yesterday morning after a storm of 17.8”? - Pretty much saying they were estimating - Not caring after 7pm even though some snow fell. 2 obs of 1.75 viz and 1.5 viz and 0.01” in bucket supports perhaps an additional couple tenths. Said they figured they wouldn’t get a higher total and gave up? Or maybe they said that earlier. - Only recording 0.8” in an 8 hour period from 4-midnight, which included 3 straight obs of low viz snow. - Recording 0.10” liquid during 4-midnight period even in their crappy bucket (Do we really think they only got 1.48” liquid? -also see 2/5/10). Even at the 12:1 ratios for the storm (could have been higher in deform), 0.10” would produce 1.2” of snow and not 0.8”. White House Cocorahs guy got 21.9 on 1.82” liquid. Same ratio - 12:1. - Crystal City trained spotter 1.5 mi NW at similar elevation got 19.4” (not sure if he used board). - Using the same spot to measure at 7pm as 4pm is risky as snow could have blown off or skimmed across. I noticed little change in snow depth during some heavy periods as I watched snow skim across and fly off the pile as my enormous drifts got bigger. I think assuming Crystal city spotter was legit, 19.4” is good total. Even splitting the difference and calling it 18.6” would be better. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 Not sure. It could be two spotters lived close enough. The program unfortunately is not very precise with only two decimal places. Of course we know exact street addresses for our spotters, but I coudn't give them out. lol..your map has exact locations Link to comment Share on other sites More sharing options...
gymengineer Posted January 25, 2016 Share Posted January 25, 2016 lol..your map has exact locations Is he just going to keep on ignoring that IAD's depth at 12Z yesterday didn't actually match the IAD total like DCA's did? And seriously, using the precip total at DCA? Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 lol..your map has exact locations It must pull from the database directly. We record more decimal places than it puts out in the text product. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 Is he just going to keep on ignoring that IAD's depth at 12Z yesterday didn't actually match the IAD total like DCA's did? And seriously, using the precip total at DCA? We lost an inch. Big whoop. It was 29" at 1AM. As far as the precip, two ASOS's during a windy snow storm with the exact same equipment and exposure should be comparable. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 Is he just going to keep on ignoring that IAD's depth at 12Z yesterday didn't actually match the IAD total like DCA's did? And seriously, using the precip total at DCA? Plus let's not assume the IAD and BWI folks are stellar either. As we know there have been some very questionable and lazy readings in both directions at IAD, and a bunch of inflated readings at BWI. There is plenty of history of totals being adjusted. Having DCA's total adjusted, if the evidence supports it, is far from unprecedented. Link to comment Share on other sites More sharing options...
Ian Posted January 25, 2016 Share Posted January 25, 2016 I'll look at the radar closer today but I seriously doubt DCA only got half of what I did after 12z on 23rd. Their report was 14" cover and I measured 16" at 645. I don't think DCA got a ton more than reported but 17.8 seems low regardless. Link to comment Share on other sites More sharing options...
MacintoshPro Posted January 25, 2016 Author Share Posted January 25, 2016 famartin, what was the point of your original post? I created this thread to discuss the wapo articles and evidence that DCA's totals were sketchy and so far, we've had a lot of interesting viewpoints and eveidence about that subject. I don't think that your post was helpful or professional in any way - this is a weather forum and you can't expect people to not discuss weather related events like this. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 I'll look at the radar closer today but I seriously doubt DCA only got half of what I did after 12z on 23rd. Their report was 14" cover and I measured 16" at 645. I don't think DCA got a ton more than reported but 17.8 seems low regardless. The factual and anecdotal evidence is quite convincing that 17.8" is too low by 1-2" Link to comment Share on other sites More sharing options...
JonathanW Posted January 25, 2016 Share Posted January 25, 2016 Doesn't it follow, then, that both locations and their measurement practices should be looked into, rather than neither? I'm still waiting for someone to explain to me why its a big controversy that DCA's total, which matches their depth, is a problem, but IAD's, which also matches their depth, is not. The meteorological explanation is easy: DCA got dry slotted. The evidence besides the observer measurements is abundant: Nearby spotter reports in the range of DCA's total. Lets take a look at ASOS precip totals, perhaps: DCA with 17.8" reported 1.48" liquid (raw ASOS, since observers don't melt it for us). IAD with 29.3" reported 2.23" liquid (that's raw ASOS, not what we melted, which was more). The only reason this is an issue is because people forecast big totals and DCA didn't deliver for them. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 Plus let's not assume the IAD and BWI folks are stellar either. As we know there have been some very questionable and lazy readings in both directions at IAD, and a bunch of inflated readings at BWI. There is plenty of history of totals being adjusted. Having DCA's total adjusted, if the evidence supports it, is far from unprecedented. If very strong evidence supported it, then sure. I just don't see that evidence. Snowfall measuring is easy to screw up, and even easier in a windy mess like this past blizzard. You're probably more likely to get a lower total at a windy airport than you are in a sheltered suburban area. In fact, you might get inflation in a suburban area with all the drifting snow from roof tops, etc. In an urban area with even more rooves, its even more likely. I agree there have been funky measurements out of both IAD and BWI in the past. Right now we don't have the FAA doing either observation. We do IAD ourselves and we contracted a local office to do the BWI ones (not sure I can reveal what office). Link to comment Share on other sites More sharing options...
gymengineer Posted January 25, 2016 Share Posted January 25, 2016 Plus let's not assume the IAD and BWI folks are stellar either. As we know there have been some very questionable and lazy readings in both directions at IAD, and a bunch of inflated readings at BWI. There is plenty of history of totals being adjusted. Having DCA's total adjusted, if the evidence supports it, is far from unprecedented. Right-- we know that because we've been paying attention over the years. 2/5-6/10, LWX rejected BWI's total. Why? Because they concluded the observers did it wrong by measuring once an hour instead of the 6-hr standard. Then, they went ahead and dropped BWI's 12/09 21" total down to 18". Why? Because they knew the observers did the same thing in that storm. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 Doesn't it follow, then, that both locations and their measurement practices should be looked into, rather than neither? Well LWX did IAD's measurement. I'm pretty sure we did it right, though I surely didn't supervise them all. I think our people have an idea of what they are doing. Jim Lee wouldn't allow anything less than top notch for us. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 Right-- we know that because we've been paying attention over the years. 2/5-6/10, LWX rejected BWI's total. Why? Because they concluded the observers did it wrong by measuring once an hour instead of the 6-hr standard. Then, they went ahead and dropped BWI's 12/09 21" total down to 18". Why? Because they knew the observers did the same thing in that storm. Yes..and there are plenty of examples. The F-6 used to change quite a bit, even well after storms. I think DCA's measurements have been reasonably decent the last 2 winters. This one is very questionable. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 famartin, what was the point of your original post? I created this thread to discuss the wapo articles and evidence that DCA's totals were sketchy and so far, we've had a lot of interesting viewpoints and eveidence about that subject. I don't think that your post was helpful or professional in any way - this is a weather forum and you can't expect people to not discuss weather related events like this. Well, this is now a big national story and its highly annoying, quite frankly. Maybe, maybe they missed an inch, maybe, but is that *really* that big a deal? An inch? Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 Right-- we know that because we've been paying attention over the years. 2/5-6/10, LWX rejected BWI's total. Why? Because they concluded the observers did it wrong by measuring once an hour instead of the 6-hr standard. Then, they went ahead and dropped BWI's 12/09 21" total down to 18". Why? Because they knew the observers did the same thing in that storm. I am fully aware of the BWI issue. That's why we don't have the FAA doing measurements there anymore (at least, not the official ones). Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 Well LWX did IAD's measurement. I'm pretty sure we did it right, though I surely didn't supervise them all. I think our people have an idea of what they are doing. Jim Lee wouldn't allow anything less than top notch for us. He suggested that DCA's totals were potentially perishable. Would Jim Lee lose his snow board? Would Jim Lee use the exact words "Highly Estimated"? Would Jim Lee essentially say that he gave up because he didn't see the snow depth changing that much? Link to comment Share on other sites More sharing options...
gymengineer Posted January 25, 2016 Share Posted January 25, 2016 I am fully aware of the BWI issue. That's why we don't have the FAA doing measurements there anymore (at least, not the official ones). To your credit, you are discussing this issue now in good faith. You must have realized that your first post rubbed people completely the wrong way. And yes, did you notice that our collective guess about the actual DCA total was around 19"? So, yes, on a weatherboard, we care about 1 inch. Link to comment Share on other sites More sharing options...
Ian Posted January 25, 2016 Share Posted January 25, 2016 Is he just going to keep on ignoring that IAD's depth at 12Z yesterday didn't actually match the IAD total like DCA's did? And seriously, using the precip total at DCA? The precip is almost certainly too low. We've been here before with DCA in a big storm that's also windy of course. Other than the WH CoCoRaHS station all 2"+, mostly 2.5"+. Maybe not far off but I think most spots were probably close to 2" around here even with kissing the dry slot. They were running fine most of the storm.. the problems were when it was snowing hard while it was extremely windy. Comments made make it apparent tracking a record wasn't their top priority IMO. And understandable if it's not, but then let's be truthful about our 'records'. This is all a can of worms lol. Bucket the big storms more.. we'll be fine. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 He suggested that DCA's totals were potentially perishable. Would Jim Lee lose his snow board? Would Jim Lee use the exact words "Highly Estimated"? Would Jim Lee essentially say that he gave up because he didn't see the snow depth changing that much? He was responding to a question about potentially bad measuring at DCA. He wasn't there and we haven't reviewed all the evidence yet, so that's the best he can say. That said, with the BWI issue, when we found out they were sextuple dipping (swiping hourly), what did we do? We used the depth. DCA's total for this storm matches the depth. Just in case its not obvious, all these posts are my personal view, and not those of the NWS. Link to comment Share on other sites More sharing options...
Deck Pic Posted January 25, 2016 Share Posted January 25, 2016 Well, this is now a big national story and its highly annoying, quite frankly. Maybe, maybe they missed an inch, maybe, but is that *really* that big a deal? An inch? Huge. We are creating an important body of record that goes back 130 years. The difference between #8 all time and #4 all time is 1.4". Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 The precip is almost certainly too low. We've been here before with DCA in a big storm that's also windy of course. Other than the WH CoCoRaHS station all 2"+, mostly 2.5"+. Maybe not far off but I think most spots were probably close to 2" around here even with kissing the dry slot. They were running fine most of the storm.. the problems were when it was snowing hard while it was extremely windy. Comments made make it apparent tracking a record wasn't their top priority IMO. And understandable if it's not, but then let's be truthful about our 'records'. This is all a can of worms lol. Bucket the big storms more.. we'll be fine. Of course the ASOS was low. But that doesn't mean its not comparable to IAD (which was also low). The difference between the ASOS totals is comparable to the difference in snow totals. Link to comment Share on other sites More sharing options...
famartin Posted January 25, 2016 Share Posted January 25, 2016 Huge. We are creating an important body of record that goes back 130 years. The difference between #8 all time and #4 all time is 1.4". Let me quote one of the NWS's climatologists on this: "Snowfall data are riddled with issues like this. Everywhere, at some point or another, some observer has estimated instead of measured, or stuck their stick into a drift, or stuck their stick into a clearing. It is one of the many reasons that we don't put much stock in studies that investigate trends in climate based on snowfall data (except for the hope of offsetting penalties - that is, that the errors cause overestimation as often as they cause underestimation). Snowfall data are sausage - you definitely don't want to look too closely at what is in there, consume with caution, and make other things the staples of your diet." Link to comment Share on other sites More sharing options...
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