nj2va Posted January 7 Share Posted January 7 1 minute ago, yoda said: I'd take the 18z GFS and run Yep, snow on snow. Nice 3-4" refresh. 1 Link to comment Share on other sites More sharing options...
midatlanticweather Posted January 7 Share Posted January 7 With this kind of setup, a correction north --- or south (more possible) could be seen! This looked pretty good! It gets all VA some love (except maybe far SE VA)! Link to comment Share on other sites More sharing options...
SomeguyfromTakomaPark Posted January 7 Share Posted January 7 Just now, jgentworth said: untrained eye, comparing to 12z, it looks like 18z heights out front are slightly steeper and the trough is slightly more neutral allowing the surface to be slightly (just a tick NW). 18z Precip shield seems a bit broader Your username just got a jingle stuck in my head. I approve of your analysis though. 1 2 Link to comment Share on other sites More sharing options...
yoda Posted January 7 Share Posted January 7 16 Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted January 7 Share Posted January 7 16 minutes ago, stormtracker said: At the gym. Yinz on your own for the gfs. Good luck Damn. Was hoping you'd be at the bar drinking complimentary tequila shots again, while doing the PBP! Link to comment Share on other sites More sharing options...
stormtracker Posted January 7 Share Posted January 7 4 minutes ago, jgentworth said: untrained eye, comparing to 12z, it looks like 18z heights out front are slightly steeper and the trough is slightly more neutral allowing the surface to be slightly (just a tick NW). 18z Precip shield seems a bit broader I need a cash settlement. 3 7 Link to comment Share on other sites More sharing options...
yoda Posted January 7 Share Posted January 7 Just now, stormtracker said: I need a cash settlement. Only if you bring snow now 1 2 Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted January 7 Share Posted January 7 1 minute ago, yoda said: Can't hate that, really! Though I though the use of Kuchera ratios was perhaps not the best. Still, that is a nice advisory-level event in these parts (warning level in some others). Link to comment Share on other sites More sharing options...
Terpeast Posted January 7 Share Posted January 7 2 minutes ago, Scarlet Pimpernel said: Can't hate that, really! Though I though the use of Kuchera ratios was perhaps not the best. Still, that is a nice advisory-level event in these parts (warning level in some others). QPF 0.3 for IAD and 0.46 for DCA. Apply your own snow ratios... 3 2 Link to comment Share on other sites More sharing options...
rjvanals Posted January 7 Share Posted January 7 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 Link to comment Share on other sites More sharing options...
CAPE Posted January 7 Share Posted January 7 Euro made a step towards the GFS with phasing in that last piece of NS energy earlier on the 12z run, and it was closer to something decent at the surface, but discombobulated. It takes a bigger step this run I believe. 3 Link to comment Share on other sites More sharing options...
Terpeast Posted January 7 Share Posted January 7 Just now, CAPE said: Euro made a step towards the GFS with phasing in that last piece of NS energy earlier on the 12z run, and it was closer to something decent at the surface, but discombobulated. It takes a bigger step this run I believe. 12z, right? 18z hasn't run yet Link to comment Share on other sites More sharing options...
Paleocene Posted January 7 Share Posted January 7 Temps look good at surface, 850, and 700. Cold on cold, snow on snow. 1 Link to comment Share on other sites More sharing options...
Maestrobjwa Posted January 7 Share Posted January 7 7 minutes ago, Scarlet Pimpernel said: Damn. Was hoping you'd be at the bar drinking complimentary tequila shots again, while doing the PBP! We probably wouldn't have gotten any pbp at all 1 Link to comment Share on other sites More sharing options...
high risk Posted January 7 Share Posted January 7 6 minutes ago, Scarlet Pimpernel said: Can't hate that, really! Though I though the use of Kuchera ratios was perhaps not the best. Still, that is a nice advisory-level event in these parts (warning level in some others). Thank you. The Kuchera drives me nuts. It always feels like this is 10:1 and this is the same case with Kuchera: 2 19 1 Link to comment Share on other sites More sharing options...
CAPE Posted January 7 Share Posted January 7 8 minutes ago, Terpeast said: 12z, right? 18z hasn't run yet Yes 12z. I think that's what I said lol. Link to comment Share on other sites More sharing options...
Ji Posted January 7 Share Posted January 7 12 minutes ago, Terpeast said: QPF 0.3 for IAD and 0.46 for DCA. Apply your own snow ratios... done 20:1 2 Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted January 7 Share Posted January 7 5 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: 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. Link to comment Share on other sites More sharing options...
stormtracker Posted January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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 January 7 Share Posted January 7 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...
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