09-10 analogy Posted February 17, 2015 Share Posted February 17, 2015 Not really disappointed in this -- several measures all between 3.7 and 4.5 so I'll just round it to 4, which was the low end of my expectations -- because I consider it part of a serial event that kicked off with the Little Blizzard That Could and the follow-on frigid wind chills, and which holds in the future tomorrow's squall, Thursday's ridiculous (forecast) cold, and then the weekend mixer. If the cold is as advertised and we can pull a good (all-frozen) 0.75" or so qpf this weekend,that would make for one hell of a winter week. A taste of what normal winter conditions are like in Bismarck. All of a piece. OTOH if this had just been a one-off storm, yeah, it would have been a let down. I read somewhere our area's monthly departures are around -5.5 or so? And heading down ... Link to comment Share on other sites More sharing options...
psuhoffman Posted February 17, 2015 Share Posted February 17, 2015 My postmortem for DC proper https://www.facebook.com/HeadfulOfSnow/posts/404329553068436?notif_t=like So, 4.1" fell in my backyard, 4.7" at DCA, and a general 4-5" across DC. A trained spotter at the zoo measured 5.3", but he always seems to be high. I would call this a mini-bust. I missed my forecast range (5-8"), but only by an inch or less. The reason we got a bit less than I forecast was not because we didn't get enough precipitation. We got reasonably close to what I was expecting. Maybe a little less. But because snow ratios were so bad. You all probably noticed how small the flakes were. To my credit, I was not quite as gung-ho about snow to liquid ratios as some were including the National Weather Service. But I did expect to do better than we did which was about 10:1. I think a lot of us thought there would be higher ratios because it was so cold not just at the surface but in the mid and upper levels of the atmosphere. Indications were favorable for the formation of dendrites (big flakes) which would pile up more easily. More fluff factor. My guess is we were too dry in the snow growth layers and/or temperatures where we were moist enough were not ideal for dendrite formation. I hope everyone enjoys what fell. It is a wetter snow than it might appear, which is great because it will take longer to melt. your forecast was excellent. Missing by 1" is a win! I was an inch low up here (Westminster 3.5" vs my 2.5 call) and an inch or two too high down south. As for ratios, I agree it's overrated. It's nice for a few hours but the next day the fluff snow sublimates, blows around, and ends up no different if not worse then denser snow. Link to comment Share on other sites More sharing options...
Bob Chill Posted February 17, 2015 Share Posted February 17, 2015 Obviously ratios failed but if we have another similar storm with arctic hp it could easily be high ratio but we'll all predict low ratios. lol One thing crossed my mind last night is that we really had no hp to the north. If we had a hp to the north and the same type of evolution precip wise I would think it would add lift and help with snow growth. It's more typical (especially during the banding part of a storm) to have good snow growth. Either way, it looks pretty awesome outside. Link to comment Share on other sites More sharing options...
psuhoffman Posted February 17, 2015 Share Posted February 17, 2015 Thanks for the analysis. This was our best storm of the season, even though we only got about 3". Great sledding snow, and turning into great snowball snow. I'm surprised that we don't have better models for predicting ratios. Both the Cobb and Evan Kuchera methods seemed to greatly overpredict ratios in this storm. too many moving parts. You have to predict so many factors correctly, snow growth level, vvs, saturation, temperature. Any of those things are off a small bit and the whole calculation is wrong. Link to comment Share on other sites More sharing options...
Kay Posted February 17, 2015 Share Posted February 17, 2015 3.5" Link to comment Share on other sites More sharing options...
ThePhotoGuy Posted February 17, 2015 Share Posted February 17, 2015 I took this last night at about 1130. The flakes reminded me of sleet. You could hear it hit the glove. Link to comment Share on other sites More sharing options...
WxMan1 Posted February 17, 2015 Share Posted February 17, 2015 4.0" here in Crofton, about .37 liquid. Once again we are reminded how, when the entire column is below freezing, how much the SLR depends on the lift and supersaturation within the max dendritic growth layer (-12 to -18C) than anything else -- including 'how cold' the lowest layers are. We had the bulk of our uvvs and moisture within a nearly isothermal layer between -10 to -12C early, which is fine, though not optimal. The problem is that the moist layer warmed quickly, causing more needles and plates and less dendrites. That's the issue often times with these w-e sheared, more Miller B vs. Miller A systems. Not as deep or broad of a warm conveyor belt shield (deep moisture well into the upper trop), which often provides the ice seeding we need for the big flakes. Link to comment Share on other sites More sharing options...
hosj III Posted February 17, 2015 Share Posted February 17, 2015 5" of snow out of .42" liquid, giving an average ratio of 12:1. Any corroboration? My call on my FB page was 4-8 DC and north and 6-10 south of DC, so it looks like it verified for my backyard at least. Tenman's .75" QPF did not materialize. Imo, the coolest part of the storm was watching the transition from the WAA snows to the coastal snows. I measured 0 new snow from 11 to midnight and even got questions as to what happened to the snow. I got about 2.5" from both phases. Link to comment Share on other sites More sharing options...
hosj III Posted February 17, 2015 Share Posted February 17, 2015 Obviously ratios failed but if we have another similar storm with arctic hp it could easily be high ratio but we'll all predict low ratios. lol One thing crossed my mind last night is that we really had no hp to the north. If we had a hp to the north and the same type of evolution precip wise I would think it would add lift and help with snow growth. It's more typical (especially during the banding part of a storm) to have good snow growth. Either way, it looks pretty awesome outside. One thing I noticed but no one seemed to discuss was that although soundings looked great for snow growth through 7 PM, after 7 PM we got a big warm push at 600 mb or so that pushed to -8 or so. Looking at the crude twister data maps of VV's, it seemed we had very little lift above it to around 500mb where the dendritic growth zone was. I sort of assumed this was no big deal but it probably messed things up pretty bad, unless my analysis here is totally off. Link to comment Share on other sites More sharing options...
gymengineer Posted February 17, 2015 Share Posted February 17, 2015 4.0" here in Crofton, about .37 liquid. Once again we are reminded how, when the entire column is below freezing, how much the SLR depends on the lift and supersaturation within the max dendritic growth layer (-12 to -18C) than anything else -- including 'how cold' the lowest layers are. We had the bulk of our uvvs and moisture within a nearly isothermal layer between -10 to -12C early, which is fine, though not optimal. The problem is that the moist layer warmed quickly, causing more needles and plates and less dendrites. That's the issue often times with these w-e sheared, more Miller B vs. Miller A systems. Not as deep or broad of a warm conveyor belt shield (deep moisture well into the upper trop), which often provides the ice seeding we need for the big flakes. You really did a nice job in laying down the caution flags yesterday in terms of going crazy with ratios. I think many were ready to jump all-in for 15:1 to 17:1 type ratios. Link to comment Share on other sites More sharing options...
EastCoast NPZ Posted February 17, 2015 Share Posted February 17, 2015 Feb sun is doing its dirty work. Sidewalks (shoveled) are already melted and almost dry. Already pushing 30F. Snow is going to take a beating today outside of the shaded areas. Link to comment Share on other sites More sharing options...
Kay Posted February 17, 2015 Share Posted February 17, 2015 4.0" here in Crofton, about .37 liquid. Once again we are reminded how, when the entire column is below freezing, how much the SLR depends on the lift and supersaturation within the max dendritic growth layer (-12 to -18C) than anything else -- including 'how cold' the lowest layers are. We had the bulk of our uvvs and moisture within a nearly isothermal layer between -10 to -12C early, which is fine, though not optimal. The problem is that the moist layer warmed quickly, causing more needles and plates and less dendrites. That's the issue often times with these w-e sheared, more Miller B vs. Miller A systems. Not as deep or broad of a warm conveyor belt shield (deep moisture well into the upper trop), which often provides the ice seeding we need for the big flakes. Good post, thanks. Link to comment Share on other sites More sharing options...
Ian Posted February 17, 2015 Share Posted February 17, 2015 Great post wxman. Committing to memory. Link to comment Share on other sites More sharing options...
WxMan1 Posted February 17, 2015 Share Posted February 17, 2015 You really did a nice job in laying down the caution flags yesterday in terms of going crazy with ratios. I think many were ready to jump all-in for 15:1 to 17:1 type ratios. Well, to be fair, I may have given into the 15-1 SLR hype, especially when you consider EVERY but of SLR guidance techniques were giving us greater than 13-1 ratios. Everything outside of climo of course. That includes the NAM and GFS Roebber techniques. The model soundings certainly provided caution to ratios above 10-12 to 1. Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted February 17, 2015 Share Posted February 17, 2015 Final tally (Chevy Chase area), 4.0" where I'm at. A bit disappointing because the ratios never picked up much and kind of under-performed here, but very pretty snow. Can't complain that much. And easy to clear! Link to comment Share on other sites More sharing options...
WEATHER53 Posted February 17, 2015 Share Posted February 17, 2015 4.5" total. Just never could get it moist enough. My 6-10" call mostly did not materialize. Link to comment Share on other sites More sharing options...
Ji Posted February 17, 2015 Share Posted February 17, 2015 4.5" total. Just never could get it moist enough. My 6-10" call mostly did not materialize. dont forget your 15 inch lolipop:) Link to comment Share on other sites More sharing options...
Ji Posted February 17, 2015 Share Posted February 17, 2015 9 or 10:1...DCA got 4.7" on 0.52", IAD got exactly 10:1. Others all seemed to measure 9/10:1...crappy ratio thats just amazing...in a bad way Link to comment Share on other sites More sharing options...
Deck Pic Posted February 17, 2015 Share Posted February 17, 2015 thats just amazing...in a bad way less of bust than 3/3/14 when we literally had to get dendrites at the end to reach 50% of forecast amounts...yet both storms were successful in my opinion...we underperform about twice as much as we overperform....models haven't helped the hobby when it comes to the end game....I mean who the hell would be upset with a 3-5" event for DC metro at 14 degrees in mid February...improved guidance has actually led to more disappointment than we would have with little or inferior guidance...It makes the chase more fun of course Link to comment Share on other sites More sharing options...
Ji Posted February 17, 2015 Share Posted February 17, 2015 less of bust than 3/3/14 when we literally had to get dendrites at the end to reach 50% of forecast amounts...yet both storms were successful in my opinion...we underperform about twice as much as we overperform....models haven't helped the hobby when it comes to the end game....I mean who the hell would be upset with a 3-5" event for DC metro at 14 degrees in mid February...improved guidance has actually led to more disappointment than we would have with little or inferior guidance...It makes the chase more fun of course .10, .12, .15, .11 dosent really do it for us per 6 hours it seems. Even when people were saying it was raking..it really wasnt. You need to have a .25 to .50 in a 6 hour period to rake. It was a nice storm but overall when .40 to .50 is forecasted with temps in the low teens...you just except more. It was nice to see snow falling...just stressful not seeing it accumulate Link to comment Share on other sites More sharing options...
87storms Posted February 17, 2015 Share Posted February 17, 2015 i'm too lazy to read this thread now, but i ended up with about 4". i wouldn't call it a bust, but i would say a slight underperformer. i had some concerns going in because the trajectory of the precip was positively tilted (i'm sure that makes no sense) and the speed of the system (not to mention the low was pretty far south). anyway, the temps kept this from being a bust. i think if the temps were warmer, it would have been a bust worthy storm in all honesty. the temps saved it and overall it was a solid event. and yes, good post by wxman. Link to comment Share on other sites More sharing options...
87storms Posted February 17, 2015 Share Posted February 17, 2015 Yeah, maybe. A slight shave in total liquid and the more typical ~10:1 ratios then what was expected. This is why you always forecast a range of snow totals...these type of details are just always very hard to predict. Region wide, I think the forecast was good. Totals verified on the lower end of ranges for the most part, but wasn't a huge bust in most cases. i felt going in that there was a bit too much confidence in the models being exactly right. we were very much on the fringe on most models. note, i consider the M/D line being the northern extent of a storm as being on the fringe here. i liked some of the more conservative calls not because i think they would be right but because it played more into the fact that, hey, maybe the ggem adds a little wrinkle to the forecast and that it shouldn't be completely disregarded. Link to comment Share on other sites More sharing options...
Ian Posted February 17, 2015 Share Posted February 17, 2015 .10, .12, .15, .11 dosent really do it for us per 6 hours it seems. Even when people were saying it was raking..it really wasnt. You need to have a .25 to .50 in a 6 hour period to rake. It was a nice storm but overall when .40 to .50 is forecasted with temps in the low teens...you just except more. It was nice to see snow falling...just stressful not seeing it accumulate Around 1 am it was thumping for a bit but it was mainly still like a heavy mist of plates. Outside the rogue band north there wasn't much pure yellow goodness etc. It was definitely a slow pile for much of the time.. but painless and no dripping. I think 75% of my snow events feature moderate to major dripping at some point.. so no dripping is a win. This cold was/is the real deal.. we've been focused on snow but Balt broke some long standing records. Link to comment Share on other sites More sharing options...
87storms Posted February 17, 2015 Share Posted February 17, 2015 ...also was surprised to see the roads in such good shape this morning. was out at about 1am last night and it was like driving on a colorado ski slope. all roads completely snow covered. Link to comment Share on other sites More sharing options...
gymengineer Posted February 17, 2015 Share Posted February 17, 2015 i felt going in that there was a bit too much confidence in the models being exactly right. we were very much on the fringe on most models. note, i consider the M/D line being the northern extent of a storm as being on the fringe here. i liked some of the more conservative calls not because i think they would be right but because it played more into the fact that, hey, maybe the ggem adds a little wrinkle to the forecast and that it shouldn't be completely disregarded. But it wasn't the model-blend QPF that was the issue-- it was the predicted ratios. The GGEM (and last run of the RGEM) was quite a bit off on its QPF until you got well south of DC. Link to comment Share on other sites More sharing options...
Ian Posted February 17, 2015 Share Posted February 17, 2015 ...also was surprised to see the roads in such good shape this morning. was out at about 1am last night and it was like driving on a colorado ski slope. all roads completely snow covered.I wasn't. Kinda felt OPM might look silly but same thing with St. Patricks day mostly. Main roads largely clear shortly by after sunrise. Of course plenty of side streets still have at least some etc. Link to comment Share on other sites More sharing options...
ravensrule Posted February 17, 2015 Share Posted February 17, 2015 ...also was surprised to see the roads in such good shape this morning. was out at about 1am last night and it was like driving on a colorado ski slope. all roads completely snow covered.This. The difference in road conditions from 2 am to 8 am were astounding. Link to comment Share on other sites More sharing options...
mattie g Posted February 17, 2015 Share Posted February 17, 2015 .10, .12, .15, .11 dosent really do it for us per 6 hours it seems. Even when people were saying it was raking..it really wasnt. You need to have a .25 to .50 in a 6 hour period to rake. It was a nice storm but overall when .40 to .50 is forecasted with temps in the low teens...you just except more. It was nice to see snow falling...just stressful not seeing it accumulate Overstating snowfall rates is standard practice around here. People are excited to see snow, so the reality of how the snow is falling is often clouded by that. With the number of people who were saying it was "pouring snow" or "ripping," you'd have expected to see much higher totals. You just have to account for it when reading peoples' reports. Link to comment Share on other sites More sharing options...
87storms Posted February 17, 2015 Share Posted February 17, 2015 I wasn't. Kinda felt OPM might look silly but same thing with St. Patricks day mostly. Main roads largely clear shortly by after sunrise. Of course plenty of side streets still have at least some etc. did they just go into a full-on salt mode after 2am or something? it was kind of impressive given the temps. or maybe the sun helped. i slept in so i didn't see the road conditions at 7am to judge. Link to comment Share on other sites More sharing options...
87storms Posted February 17, 2015 Share Posted February 17, 2015 Overstating snowfall rates is standard practice around here. People are excited to see snow, so the reality of how the snow is falling is often clouded by that. With the number of people who were saying it was "pouring snow" or "ripping," you'd have expected to see much higher totals. You just have to account for it when reading peoples' reports. it was a steady snowfall with maybe occasional moderate. i think ripping was a great term to use saturday, but not for this one. satuday was a ripping snowsquall. Link to comment Share on other sites More sharing options...
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