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RU848789

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Everything posted by RU848789

  1. RU848789
    I didn't say NYC would get 2-3" as a forecast - I was only talking about the 12Z GFS verbatim likely leading to 2-3" OTG in Central Park.
  2. RU848789
    I know, I said that. I included the 10:1 map, as that shows how much snow is "falling" to illustrate that it's not "mostly rain." Kuchera shows about 2" and I think that's underdone on the model verbatim, as column temps are below 32F on the model until the surface and given decent intensity (once snow starts accumulating, subsequent snow is not affected much by above 32F surface temps, as the actual surface is now 32F snow/slush), even NYC will accumulate maybe 2-3" from that 4.3" of snow falling. That's my informed opinion. I'm not a met, but I guarantee you a PhD in chem eng'g and 30+ years of doing hard science including a lot of work in heat transfer and physical chemistry phase transitions (crystallizations and melting - with several patents in the field for organic molecules) and a lifetime of observing high intensity snow accumulating when people said it wouldn't (think most March/April storms), means a little bit. This is not really a "meteorology" question (assuming the model is correct and no warm nose aloft, just above 32F at the surface), but a physical chemistry/rate question.
  3. RU848789
    Could be at least partly elevation, as 10 miles W of CPK is still only ~50' in elevation, while 10 miles W of Boston is more like 150'.
  4. RU848789
    That's incorrect. Plenty of snow "falling" - it's just not clear how much of it will accumulate with 34-35F surface temps; during the thump part, NYC looks to be below 32F (barely) for the whole column, which is good. So verbatim there will be snow and if we can avoid a warm nose aloft (who knows?) I think a few inches (not the 4.3" on the 10:1 map below) is likely - as per the GFS, not a forecast.
  5. RU848789
    6Z NAM not good. Do we call it NAM'd?
  6. RU848789
    The EPS mean was still good for 95...
  7. RU848789
    Remember, verbatim, the NAM is putting down 6-9" of snow in much of the region including the 95 corridor NE of about Trenton from about 6 pm Sat to 2 am Sunday in the initial thump, which translates to about 3/4-1" per hour rates and even if the surface temps are 33-34F (likely for 95), at that intensity melting will be minimal once the accumulation starts (as subsequent snow will be falling on 32F snow), so 10:1 is quite possible unless there is some significant melting going on in the column, which the model doesn't imply as soundings look to be below 32F for the whole column for this entire time even in places like Edison, NJ. In fact, with good dendritic growth likely with good saturation levels due to excellent lift, we could even exceed 10:1, IMO, especially inland. If the model is correct...
  8. RU848789
    NAM'd again...
  9. RU848789
    I assume you've seen the latest WPC graphic on QPF from now through Wednesday. 3-6" for most of the EPA-NJ-SENY region would likely put many streams and river basins into major flood stage.
  10. RU848789
    No, look at the NWS office maps side by side. One can't have a discontinuity of <1" on the NWS-Philly side of the Morris/Somerset borders next to 3-4" on the NWS-NYC side of that same border. Same thing with Middlesex adjacent to Union/SI (0" next to 1-2" in SI and <1" next to 2-3" in Union). There was no collaboration, clearly.
  11. RU848789
    No, or at least it's nuts to have MMU getting ~1", while5 miles east of there the NWS-NYC has areas of Essex County in a 3-4" swath.
  12. RU848789
    SIAP, but this cracked me up from Tomer Burg on being NAM'd...
  13. RU848789
    Lots of NWS office inconsistency issues. The NWS has issued winter storm watches for a general 4-8" of snow for the Poconos, Lehigh Valley, Sussex, Warren, Morris, Passaic and NW Bergen, plus the Hudson Valley N of the Tappan Zee, but the discussions from the Philly and NYC offices are somewhat at odds, with the Philly office focusing on the warmth of the ocean and easterly winds keeping accumulations <1" for 95 from Philly to Woodbridge and SE of there, while the NYC office is saying things are trending cooler and now have 2-3" for places along 95 in NENJ (Union/Hudson) and NYC. I think they're all scrambling, so it's not worth focusing on their discussions, but their maps with inconsistencies are worth discussing - just look at the boundaries along Morris/Somerset where the Philly office has <1", while magically across the border into Essex/Union, the NWS-NYC has 3-6" of snow. Also, the NWS-NYC map has 8-12" amounts for their northern counties, but the watches only mention 5-8" so I think they have some work to do to get their forecast straight.
  14. RU848789
    NAMed! Most of this falls in part 2 on Sunday afternoon...
  15. RU848789
    Fascinating that every model has 6+ inches for Boston and the NWS has a forecast for 1". I understand models are not everything, but that seems a bit out of whack to me...
  16. RU848789
    zoomed in - such steep gradients make for easy forecasts, lol...
  17. RU848789
    Looking very similar to the 18Z euro...maybe a touch warmer/wetter; below is 18Z and 0Z Euro runs through 12Z Sunday for comparison.
  18. RU848789
    No it does not. It only takes into account the max air temp in the column and does a crude subtraction from a 10:1 ratio based on that. I've posted deeply and extensively on Kuchera. It does not address snow crystal formation/habit, aggregation while falling due to partial melting, intensity or the degree of melting at the surface due to ground temps or solar insolation, all of which can be important.
  19. RU848789
    Yes, but I dislike Kuchera, as it's a lousy algorithm and while it's probably more realistic for this scenario, I prefer knowing how much snow is actually falling (assuming 10:1 ratio) and will do my own analysis of how much of that will likely accumulate, given how many variables there are that Kuchera doesn't take into account, plus some that aren't known well, like intensity.
  20. RU848789
    Who do I have to pay to have this verify imby, lol? Incredible gradient from an inch or two (at the end of the storm) ~20 miles SE of me to about 8-10" at my house to over a foot 5 miles north of me. Insane.
  21. RU848789
    Ignore it, like the NAM, at this range - it's a regional/mesoscale model...
  22. RU848789
    Yep, he's fairly pessimistic on the 95 corridor and SE of there...
  23. RU848789
    Y'all are falling down on the job, lol. I've been away (playing disc golf) for several hours and I come back to a great GFS run that came out an hour ago and nobody posted this map? It's not the JMA or the Chilean model, c'mon. More seriously as many of us have been saying, let's see what we get at 18Z/0Z tonight after all the players are being well sampled by the RAOB network. Maybe the GFS will be an outlier, maybe not, but I'd rather have it in the snowier than before camp.
  24. RU848789
    Thanks, that's very nice of you to say.
  25. RU848789
    The Pivotal page is definitely well done, but they acknowledge that in marginal temp situations it's simply very difficult to translate the "snow that falls" to the "snow that accumulates." Also, as I've discussed many times over the years, Kuchera is very simplistic (it simply takes the warmest temp in the air column and has a simple algorithm reducing ratios based on that temp only) and doesn't account for snow crystal shape impact on accumulated depth nor snowfall intensity, which can easily overcome melting in some situations. IMO, as someone with significant expertise in crystallization, heat transfer and phase change dynamics, the biggest "miss" in that page is not accounting for intensity, nor the fact that once there is some accumulation on a warmer-than-32F surface, the "new" surface is now snow/slush, which, by definition is then 32F, meaning subsequent accumulation of snowfall will no longer be significantly impacted by melting on that surface, plus air temps a few degrees above 32F will have a very small melting effect, since heat transfer via air to the snow is far less than from a solid (the ground) or liquid (e.g., wet ground/puddles), due to the huge density difference, primarily (air is far less dense, which is why the heat transfer coefficient is about 20X less from air than water, for example - that's why one can kep one's hand in a -10F freezer for minutes, but can't keep one's hand in a 32F cooler filled with ice/water for more than a few seconds). This is why we can see snow accumulate quite well at high intensity in April during the day with ground and air temps well above 32F - and we're not going to have ground or air temps that far above 32F in this case, plus we're not going to have any solar insolation issues for most of the storm, at night and even during the day, as the sun angle is still quite low, so we're not going to need high intensity to accumulate well (just moderate intensity most likely, although high would be better, of course). I'm not saying we're going to see 10-15:1 snow to liquid ratios (which is what we'd likely get with good dendritic growth we're likely to see where the snow crystals are being formed, if that snow didn't encounter above 32F air in the column nor above 32F ground), but I am saying getting to 8-10: ratios shouldn't be that much of a stretch, as long as we have decent intensity.
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