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Thunder Road

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Everything posted by Thunder Road

  1. I *really* wouldn't be looking at TT accum maps that include sleet as snow. They ought to just pull those down, honestly. Like others have said, Pivotal's Kuchera maps are a big step in the right direction.
  2. Hey folks, long time no chat. How's it going? Since ZR is in the mix for most I just thought I'd pop in and share this paper with you all: https://journals.ametsoc.org/doi/full/10.1175/WAF-D-15-0118.1. This is the research behind the FRAM (Freezing Rain Accumulation Model) that the NWS uses. (Or at least, in Central Region we use. I can't speak to those living the Bohemia lifestyle 😉.) The gist is that ice-to-liquid-ratio, ILR, is often actually even less than 1:1. The FRAM is a function of 1) rain rate, 2) wind speed, and 3) surface Tw. Rain rate shows the most robust statistical relationship. And it might not be what you think. Higher rain rates decrease the ILR - see Figs. 10-12. Remember that there is latent heat released when liquid freezes on contact. More liquid freezing at a time means more latent heat release and thus more warming of the surface. Secondarily, a higher rain rate also means more splash-off and thus less of the liquid remaining as ice. As for the other factors... more wind helps to transport that heat away from the surface and thus increases the ILR. For Tw, the relationship is non-linear, but as you can see, the peak ILR occurs with a surface Tw of around -1 to -3 C. That means a surface temp of 32.0 F usually doesn't cut it. Even 30-31 F can be iffy for significant ice accrual. So if we were to believe the NAM (famous last words), in Philly you're getting most of your ZR in the optimal temp range, so that's a plus for significant ice accrual. You should also have a 10-15 knot wind, which helps. Buuut a big chunk of the precip is coming while rain rates are still pretty high. Looking at the NAM in BUFKIT, I'm seeing a rain rate around 0.1"/hr during the hours where the Bourgouin gives ZR. That may end up really limiting the ice accrual - the median ILR for that rain rate is 0.5, and the innerquartile range is ~0.3 to 0.65. So all in all I'm not ready to bite on a major ice storm just yet. Now that said, I was also really bearish on the November snow event, so... 🙃 P.S. We'll cross 100" on the season up here by the end of the weekend. Sitting at 99.1" right now, with 19" on the ground. Continuous snow cover since November 9th. And this is entirely normal!
  3. Thunder Road

    I have an announcement...

    Now that NOAA Workforce Management has (finally) cleared me, I can announce that in June I'll be starting at NWS Marquette, Michigan! That's right, I'll be a Yooper! As I move from Lawn Guyland to Da Yoop, I'm excited at all the new opportunities and blah blah blah but I'm most excited about adding a new hideous accent to my repertoire. Their snow depth for the season went to 0 on May 1st. Next +NAO/-PNA La Nina winter I'll mail you guys a cooler full of Lake Superior's Finest™.
  4. Mom has 11" in Bensalem. I don't think I can remember ever seeing the tree limbs sag this much before.
  5. Yeah I like this map. Am I missing something? Climo is an important part of a good forecast.
  6. Where are you finding these?
  7. Anyway fwiw here's the snowfall accumulation map from our in-house NAM-WRF: (Sorry for the bad acid trip colors; one of these days I'll get around to cleaning it up...)
  8. That's way low, imo. We have a strong cyclone rapidly deepening as it approaches (before pulling away later) and as precip begins to thin out. Anywhere that begins to deepen the PBL, even just to 1000 feet or so, could gust over 60 mph. The heavy rain + already wet February + gusts has been concerned for widespread trees down and power outages in eastern PA if I'm being honest. Hopefully others would agree but I don't think I'm generally one to hype.
  9. Not sure. I mean just from basic dynamics, yes it would be coincident with the greatest height gradient. And if you think about it, extratropical cyclones always have the maximum wind removed from their centers because the height gradient follows the temperature gradient pattern of a baroclinic wave (think hypsometric equation, thickness being proportional to temperature). So to have the maximum PBL-top wind over eastern PA rather than closer to the cyclone center isn't at all inconceivable.
  10. So uh, yeah, that's 90 kts at 925 mb showing up over the PHL area on our in-house WRF...
  11. Yup. I forget if it was PHI or OKX but one of the AFDs actually used the word you're thinking of here: Ekman Transport. Large water bodies are generally under Ekman Balance, which is the balance between wind stress forcing and Coriolis force, thus, water movement deflects to the right of the wind in the Northern Hemisphere.
  12. Have I just never paid attention to Coastal Flood Watches before (very possible) or is the extra table with MLLW and MHHW new in response to my complaining last night? Haha
  13. What still eludes me is how to relate MLLW (or MHHW) with the AHPS flood stages. Atlantic City's tide+surge gets to 8.29 ft above MLLW Saturday. The AHPS hydrograph says the datum is MLLW, so 8.29 ft would be major flood stage. But am I reading that right?
  14. Cool, thanks! I'm trying to provide some guidance for family with a house in Sea Isle. They're not in a particularly bad spot, but they did have water in the lower level with 1/23/2016.
  16. Keep in mind it's Spring with marginal temps. I know you know, but it never hurts to broadcast to the general public. These 10:1 maps are usually garbage, and in this case, it's very off from what the EuroWX algorithm produces, i.e., 2.7" at NYC vs 8", 2.1" at ABE vs 6", 2.5" at TTN vs 6", etc.
  17. 1/23/2016 was a full moon too. Without overreacting, I'm trying to get my family who has a shore house to take this one seriously. A cyclone in the mid 970s on the benchmark with a full moon is gonna cause problems...
  18. Thunder Road

    January (30th?) Ends With A Norlun Trof

    I disappear for a few weeks and people are micro-analyzing the JMA...
  19. Hi folks, Slowly but surely our research group at SBU has been transitioning our WRFs over to a new website (not my work) and Python graphics (my work). Someday over the rainbow this will become the operational page without /test at the end of the URL, but for now: http://itpa.somas.stonybrook.edu/sbuwrf/test/ Let me know if (when) you encounter any issues! I'm slowly picking off plots one day at a time to switch to Python. Sorry I didn't share it two days ago!
  20. Thunder Road

    1/3-1/4 Nor'easter OBS: Who will win ? Bus ?

    Best I could get was 4.4", but as I mentioned Saturday, no snow board so ehhhh I was gonna go up to Long Island this week and come back this weekend but for a number of reasons decided to stay here. Boy, did I misplay that. 15.8" at Islip
  21. Thunder Road

    January 4th 2018 Bomb Cyclone Discussion

    I wonder how effective the MSLP Low centers plot is when we're considering whether there will or won't be a double-barrel structure. It's conceivable to me that there could be some members with a secondary western SLP min that the plotting algorithm doesn't pick up because the primary min is still lower.
  22. Thunder Road

    January 4th 2018 Bomb Cyclone Discussion

    From the 06z GEFS, about 4 members give PHL and N&E >0.1" snow liquid equivalent, with much higher probs over New England: http://vortmax.somas.stonybrook.edu/WEB/models/GEFS/snowliq10prob/ (I'm still troubleshooting why the graphics are old until FHR 102, then abruptly become current...)