stormtracker Posted Tuesday at 10:23 PM Share Posted Tuesday at 10:23 PM 14 minutes ago, Terpeast said: QPF 0.3 for IAD and 0.46 for DCA. Apply your own snow ratios... I’d hit it. Seriously, if I could lock this in, I’d buy rn. 2 Link to comment Share on other sites More sharing options...
Alfoman Posted Tuesday at 10:24 PM Share Posted Tuesday at 10:24 PM GFS had that northern stream piece come down way more aggressively the last few runs (on the later side of the storm and not early). If only our southern stream wave wasn't sheared to shit... The storm continued to trend further OTS here - we still held QPF-wise by faster strengthening of the surface low (~5 mb lower at hour 96 than 12z) off the coast. You realllllyyy need that SS SW to play nicer if we want to get something larger than a couple of inches. It hasn't trended the right way with that piece on the GFS on a single run since yesterday, need to reverse than going into 0Z. Link to comment Share on other sites More sharing options...
high risk Posted Tuesday at 10:24 PM Share Posted Tuesday at 10:24 PM 1 minute ago, Scarlet Pimpernel said: Actually, in all seriousness, I don't even know what method is used to compute the Kuchera ratios. Maybe it's good in some situations, but I've heard so many mixed things about it. Seems almost better to show 10:1 and go from there, fudge as needed. It's driven by lower-atmosphere temperatures. It's great at chopping amounts in marginal temperature environments, and the premise that SLRs will be better than 10:1 in cold environments has some truth, but it's not as simple as colder=better SLR, so it goes nuts when the air mass is cold. 1 3 Link to comment Share on other sites More sharing options...
Eskimo Joe Posted Tuesday at 10:26 PM Share Posted Tuesday at 10:26 PM Regardless of how much snow we get this weekend, the Euro/EPS, GFE/GEFS, and GEPF all keep us at or below normal through at least Inauguration Day...possibly the end of the month. 12 Link to comment Share on other sites More sharing options...
wxdude64 Posted Tuesday at 10:30 PM Share Posted Tuesday at 10:30 PM 30 minutes ago, SnowenOutThere said: I have no idea what just happened with the GFS, but it does still snow. @Bob Chill jackpot! 2 Link to comment Share on other sites More sharing options...
midatlanticweather Posted Tuesday at 10:38 PM Share Posted Tuesday at 10:38 PM 15 minutes ago, Scarlet Pimpernel said: Actually, in all seriousness, I don't even know what method is used to compute the Kuchera ratios. Maybe it's good in some situations, but I've heard so many mixed things about it. Seems almost better to show 10:1 and go from there, fudge as needed. According to ChatGPT Kuchera ratios are used in meteorology to estimate snowfall amounts based on the temperature profile in the atmosphere. They provide a more accurate prediction of snow-to-liquid ratios compared to the standard 10:1 rule, which assumes 10 inches of snow for every inch of liquid water. Steps for Kuchera Ratio Calculations: Gather Atmospheric Data: Obtain vertical profiles of temperature and humidity from numerical weather models (e.g., GFS, ECMWF, NAM). This is often visualized in a Skew-T diagram. Identify Critical Layers: Look at the temperature profile throughout the atmosphere. Snowfall efficiency depends on whether temperatures are conducive to dendritic growth, typically between -12°C and -18°C. Check for layers above freezing, which could cause melting and affect snow ratios. Estimate Snow-to-Liquid Ratio: The Kuchera method calculates a dynamic snow-to-liquid ratio based on the temperature and saturation levels at various atmospheric layers. Ratios are higher (e.g., 15:1 or more) in colder, fluffier snow conditions and lower (e.g., 8:1 or less) in wetter snow. Calculate Liquid Precipitation Amount: Determine the total precipitation amount forecasted in liquid form (usually in inches). Apply Kuchera Ratios: Multiply the liquid precipitation forecast by the Kuchera snow ratio for each time or grid point to estimate total snowfall. Models often automate this step. Example: If a model predicts 1 inch of liquid equivalent precipitation: A Kuchera ratio of 12:1 gives 12 inches of snow. A ratio of 8:1 (wet snow) gives 8 inches. A ratio of 15:1 (light, fluffy snow) gives 15 inches. Kuchera ratios consider temperature dependencies, making them more reliable for variable snow conditions than static assumptions. 2 Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted Tuesday at 10:38 PM Share Posted Tuesday at 10:38 PM 11 minutes ago, high risk said: It's driven by lower-atmosphere temperatures. It's great at chopping amounts in marginal temperature environments, and the premise that SLRs will be better than 10:1 in cold environments has some truth, but it's not as simple as colder=better SLR, so it goes nuts when the air mass is cold. Yup...that kind of reminds me of an event in Feb. 2015. It was extremely cold that whole month, there was an event around mid-month that everyone "assumed" would be high ratio fluff (so lots of excitement). But it wasn't. The growth rates and growth zone weren't ideal. We still got a solid amount to be sure, but it was more like thin ice crystals or pixie dust, not the huge flakes like we saw last night. Link to comment Share on other sites More sharing options...
Kevin Reilly Posted Tuesday at 10:39 PM Share Posted Tuesday at 10:39 PM 1 hour ago, soadforecasterx said: Alot of west leaning members. 1 jog to the west and its Folks time! 2 Link to comment Share on other sites More sharing options...
MillvilleWx Posted Tuesday at 10:42 PM Share Posted Tuesday at 10:42 PM 17 minutes ago, Scarlet Pimpernel said: Actually, in all seriousness, I don't even know what method is used to compute the Kuchera ratios. Maybe it's good in some situations, but I've heard so many mixed things about it. Seems almost better to show 10:1 and go from there, fudge as needed. Kuchera is useful in some cases, but you really have to be mindful of the algo. Last storm was a case that it differed from model to model and if you didn’t account for that (Hello, it’s me), then you could be a little too high on the forecast. HRRR corrected inside 12 hrs with the last forecast and that’s why totals dropped and became more realistic. RAP and a lot of the other CAMs did not and it inflated everything. This is a 10:1 type storm with MAYBE slightly higher for areas that get banded, like the eastern shore. EVEN THEN, 10:1 might still be the preference here. This is something I will be mindful of in the future, for sure. 2 2 Link to comment Share on other sites More sharing options...
Kevin Reilly Posted Tuesday at 10:42 PM Share Posted Tuesday at 10:42 PM 41 minutes ago, SnowenOutThere said: I have no idea what just happened with the GFS, but it does still snow. That snow map looks like the result of a difluent flow aloft. A few tweaks and it’s close. Link to comment Share on other sites More sharing options...
Interstate Posted Tuesday at 10:45 PM Share Posted Tuesday at 10:45 PM 29 minutes ago, high risk said: Thank you. The Kuchera drives me nuts. It always feels like this is 10:1 and this is the same case with Kuchera: Yes. Kuchera should be banned 1 1 Link to comment Share on other sites More sharing options...
CAPE Posted Tuesday at 10:48 PM Share Posted Tuesday at 10:48 PM 39 minutes ago, SnowenOutThere said: I have no idea what just happened with the GFS, but it does still snow. You need to look at more than a snow map to understand why the modeled snowfall looks this way. Plus this is a total snow map. 1 Link to comment Share on other sites More sharing options...
SnowenOutThere Posted Tuesday at 10:50 PM Share Posted Tuesday at 10:50 PM Just now, CAPE said: You need to look at more than a snow map to understand why the modeled snowfall looks this way. Plus this is a total snow map. Oh I was looking at the H5 map and the vort map I just had no idea what would actually lead to a better storm after comparing runs. I can tell setups like the one we just had on an H5 level but not this mess of phases. 1 Link to comment Share on other sites More sharing options...
Ji Posted Tuesday at 10:54 PM Share Posted Tuesday at 10:54 PM 18z ensembles took a step back though but it looks like it shows a stronger storm but the track is worse 1 1 Link to comment Share on other sites More sharing options...
IronTy Posted Tuesday at 11:01 PM Share Posted Tuesday at 11:01 PM GFS looks like a jack the same places that got it for this last storm. "It snows where it wants to snow" Link to comment Share on other sites More sharing options...
mitchnick Posted Tuesday at 11:01 PM Share Posted Tuesday at 11:01 PM 18z Gem https://meteocentre.com/numerical-weather-prediction/map-explorer.php?mod=cmc_gdps&run=18&stn=QQ500&hh=084&map=na&stn2=PT&run2=18&mod2=cmc_gdps&hh2=084&comp=1&fixhh=1&lang=en&yyyy=latest&mm=latest&dd=latest&mode=latest&stn2_type=prog&date_type=dateo Link to comment Share on other sites More sharing options...
Bob Chill Posted Tuesday at 11:07 PM Share Posted Tuesday at 11:07 PM 33 minutes ago, wxdude64 said: @Bob Chill jackpot! Been liking this one a lot. A fairly uncomplicated 3-6 deal all snow falling on frozen ground. First event in 3 years to do that here. You're in a decent spot too. I never felt like this one had the pieces for a big event so I'm getting pretty excited. Gfs is prob a top end solution. 3-4" would look amazing around here. I'll take a ton of pics cuz it may never happen again 5 Link to comment Share on other sites More sharing options...
Scraff Posted Tuesday at 11:07 PM Share Posted Tuesday at 11:07 PM 4 minutes ago, mitchnick said: 18z Gem https://meteocentre.com/numerical-weather-prediction/map-explorer.php?mod=cmc_gdps&run=18&stn=QQ500&hh=084&map=na&stn2=PT&run2=18&mod2=cmc_gdps&hh2=084&comp=1&fixhh=1&lang=en&yyyy=latest&mm=latest&dd=latest&mode=latest&stn2_type=prog&date_type=dateo Unless I am reading that wrong, but that looks promising! Link to comment Share on other sites More sharing options...
CAPE Posted Tuesday at 11:08 PM Share Posted Tuesday at 11:08 PM 15 minutes ago, SnowenOutThere said: Oh I was looking at the H5 map and the vort map I just had no idea what would actually lead to a better storm after comparing runs. I can tell setups like the one we just had on an H5 level but not this mess of phases. It is busy. Amplified pattern with plenty of vorticity in the flow, and intricate interactions determine the ultimate outcome for our period of interest. 2 Link to comment Share on other sites More sharing options...
mappy Posted Tuesday at 11:09 PM Author Share Posted Tuesday at 11:09 PM 26 minutes ago, MillvilleWx said: Kuchera is useful in some cases, but you really have to be mindful of the algo. Last storm was a case that it differed from model to model and if you didn’t account for that (Hello, it’s me), then you could be a little too high on the forecast. HRRR corrected inside 12 hrs with the last forecast and that’s why totals dropped and became more realistic. RAP and a lot of the other CAMs did not and it inflated everything. This is a 10:1 type storm with MAYBE slightly higher for areas that get banded, like the eastern shore. EVEN THEN, 10:1 might still be the preference here. This is something I will be mindful of in the future, for sure. Qpf I make my own adjustments in my head on possible totals based on the storm setup. Snow maps are lol 1 Link to comment Share on other sites More sharing options...
Bob Chill Posted Tuesday at 11:09 PM Share Posted Tuesday at 11:09 PM 8 minutes ago, IronTy said: GFS looks like a jack the same places that got it for this last storm. "It snows where it wants to snow" Train tracks 2 Link to comment Share on other sites More sharing options...
Kay Posted Tuesday at 11:12 PM Share Posted Tuesday at 11:12 PM 38 minutes ago, high risk said: It's driven by lower-atmosphere temperatures. It's great at chopping amounts in marginal temperature environments, and the premise that SLRs will be better than 10:1 in cold environments has some truth, but it's not as simple as colder=better SLR, so it goes nuts when the air mass is cold. Relatable. 18z GFS - take and run. Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted Tuesday at 11:22 PM Share Posted Tuesday at 11:22 PM 13 minutes ago, Scraff said: Unless I am reading that wrong, but that looks promising! Looks similar to the gfs. Low pressure over central Georgia. Link to comment Share on other sites More sharing options...
stormtracker Posted Tuesday at 11:27 PM Share Posted Tuesday at 11:27 PM 18z Euro has 0"-1" inch forum wide. Jackpot is Bob Chill! Congrats! Fucking thing won't budge 1 1 1 Link to comment Share on other sites More sharing options...
WesternFringe Posted Tuesday at 11:31 PM Share Posted Tuesday at 11:31 PM 6 minutes ago, stormtracker said: 18z Euro has 0"-1" inch forum wide. Jackpot is Bob Chill! Congrats! Fucking thing won't budge Last storm it had 12-16” for me and would not budge. I ended up with 8.5” after the 2” in the second round last night. I am not complaining, I’m just saying it is a model and stating the obvious that it is not infallible just bc it has the best verification scores. Link to comment Share on other sites More sharing options...
CAPE Posted Tuesday at 11:34 PM Share Posted Tuesday at 11:34 PM 6 minutes ago, stormtracker said: 18z Euro has 0"-1" inch forum wide. Jackpot is Bob Chill! Congrats! Fucking thing won't budge My hunch was wrong. Its worse. That NS vorticity comes right over the top like a wrecking ball. Link to comment Share on other sites More sharing options...
Jebman Posted Tuesday at 11:35 PM Share Posted Tuesday at 11:35 PM 1 hour ago, stormtracker said: I need a cash settlement. It's YOUR Money! Use it when YOU need it! 1 Link to comment Share on other sites More sharing options...
Maestrobjwa Posted Tuesday at 11:36 PM Share Posted Tuesday at 11:36 PM 1 minute ago, CAPE said: My hunch was wrong. Its worse. That NS vorticity comes right over the top like a wrecking ball. What was your original hunch? Lol Link to comment Share on other sites More sharing options...
Maestrobjwa Posted Tuesday at 11:37 PM Share Posted Tuesday at 11:37 PM 1 minute ago, Jebman said: It's YOUR Money! Use it when YOU need it! Call JG WENTWORTH, 877-CASH-NOWWWWWW! Call now! 2 2 Link to comment Share on other sites More sharing options...
Wonderdog Posted Tuesday at 11:37 PM Share Posted Tuesday at 11:37 PM 1 hour ago, rjvanals said: If the GFS is right we're only ~80 hours from the first flakes from this storm so it's getting late kinda early if we want big changes Not necessarily. Change is not a clock watcher. It's dependent on other things but not time. Link to comment Share on other sites More sharing options...
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