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high risk

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Everything posted by high risk

  1. high risk
    Lots of things obviously need to align, but that's certainly what we want to see if we're hunting derechos. We would be well within the hot, humid air mass, but also just barely within the faster flow aloft, giving organized convective systems the opportunity to race to the east-southeast.
  2. high risk
    Experience, for sure. I always look at as much available guidance as I can, and when they don't agree, I make mental notes on which ones did well and which didn't. It's not as tough to keep track of as it sounds. Or you can just cheat and use AI:
  3. high risk
    The NAM Nest is the gold standard. The HiresW ARW2 is decent. HRRR and especially the HiresW FV3 are the worst. When they both showed the warm front staying south of DC yesterday, I started writing off severe potential up our way.
  4. high risk
    But that's climatology. There are certain models that depict warm front movement very well, and none of them today had it getting nearly as far northeast as DC. The only model that had good UH tracks this far north was the 12Z HiResW ARW, but it showed DC at 80 degrees at the time the watch was issued. Guidance *and* observational trends were clear this was not the day when the front would move quickly northeast. In fairness, though, SPC's focus today was on the Southern Plains, so I can't really fault them for not working more to pinpoint the size of the Mid-Atlantic watch box.
  5. high risk
    Having the tornado watch cover as far northeast as the DC metro area was somewhat silly. The warm front was never going to make it this far.
  6. high risk
    I still don't know what to make of this setup. Few CAMs have a handle on the band of showers currently pushing southwest to northeast across the area. The ones that do have these showers don't really do a whole with convection lot later today. The HRRR looks more interesting, but it isn't handling the current stuff well, and while its reflectivity looks good later, there isn't much instability. The shear (both deep layer and low level) is intriguing for sure, but I wonder if it's just going to be too stable for much of the area to really have a threat. My best guess is that any severe threat stays south and west of a Winchester to Culpeper to Quantico line, but we'll see how temperatures evolve for the DC-Baltimore corridor.
  7. high risk
    That Euro run yesterday was on the right track with the best chance of rain today being during the late morning / early afternoon along the warm front boundary. That area of rain is there, but it's fairly splotchy and progressive, so while some localized areas will get soaked, it doesn't appear that widespread big totals are likely.
  8. high risk
    I think that the original meso occluded - you can see a northwest motion in loops. A new one has been trying to form over Columbia but has struggled to organize. The rain is legit, though. Incredible flooding in my neighborhood
  9. high risk
    I want to use the HRRR to figure out the evolution, but it has zero handle on the large batch of storms around Fredericksburg.
  10. high risk
    It’s definitely worth watching. Once the trough axis passes, winds just above the surface shift to northwest, and the speeds rocket up (50+ kt) just above the ground. The question always is whether those speeds can be mixed downward. Some of the guidance shows an additional round of showers after midnight with some very weak low-level instability. Can that get it done? Not sure, but it could.
  11. high risk
    The more northern track of the surface low likely reduces the flash flood threat for most of us, but it definitely increases the severe threat. Surface winds may end up too light, but if they’re not, some of the morning guidance does show enough turning in the low levels to generate favorable hodographs. The 12z HREF reflects this with a notable increase in the probabilities for good UH values into the DC/Baltimore region, relative to earlier guidance, and I would not be surprised if the 1630 outlook brings the 5% TOR further north.
  12. high risk
    I’m far from confident in this, as there will probably be a narrow corridor of big rainfall models that the models are struggling to place, but there seems to be a trend to place the heavy rain axis more up into northern MD and southern PA. This would reduce the flood threat in and around DC, but it would increase the severe threat.
  13. high risk
    Yeah, forecast soundings along the warm front certainly support at least transient supercell structures. The question is where the warm front will reside, as there isn't good model agreement. If there is a weak consensus, it's for the warm front to set up just south of DC. Saturday could be a hail threat throughout the area, as very cold temperatures aloft will be in place, and the secondary front looks to move through at a favorable time of day.
  14. high risk
    Based on the 00z CAMs, much of the area will have a flash flood risk Friday late afternoon through early Saturday, and at the least, areas along and south of I-66 in VA and Rt 50 in MD will have severe potential early Friday evening. The exact track of the surface low will determine the mesoscale corridors of threat, but a tornado or two certainly seems possible along the warm front.
  15. high risk
    The synoptic wind is near the end of and after the precip, but yeah, the 500 map is super impressive.
  16. high risk
    The simulated reflectivity on the 18z NAM Nest suggests a flash flood threat for the area Friday late afternoon into Saturday morning
  17. high risk
    I may have gotten the atmosphere's attention with my complaint... Friday is at least worth a look. We will have a deepening surface low track just to our north which is often a good setup. The instability might end up being too weak, but the HiResW FV3 gets my attention.
  18. high risk
    I'm super happy that we're putting a legit dent in our drought, but at the same time, I'm bummed that we're wasting our peak climo period for severe weather. Maybe by the end of next week?.......
  19. high risk
    You can see in the simulated reflectivity that the NAM Nest has way heavier cells moving through the area early Wednesday relative to most of the other CAMs. I'm not ready to say that it's wrong, but it's certainly an outlier.
  20. high risk
    I was expecting thunderstorms today, but I did not think we’d get a warning in the local area.
  21. high risk
    Some healthy convective cores shown by several CAMs tomorrow afternoon. They’ll be quick hitters, but they should be interesting.
  22. high risk
    Most guidance had the most widespread rain this morning. Certainly looks like an underperformer.
  23. high risk
    Yeah, consistent with what you noted in the mesoanalysis, the 00Z Dulles raob shows that the earlier convection really stabilized the atmosphere here. Surface-based instability is negligible, and the mid-level lapse rates are lousy. Perhaps some improvement advects in overnight, and I'm not ready to throw in the towel after one HRRR run goes to crap after several more interesting runs. That said, IF we do get an overnight round, I think it would likely be elevated and therefore non-severe. I won't discount some improvement in the low levels and a fast-moving convective system that is able to generate some wind, but I don't think that scenario is very likely.
  24. high risk
    Regarding the “failed” morning MCS, guidance overnight showed that the far southern flank might ignite after 8 or 9 am this morning in northern MD. A few showers are now indeed breaking out, so there is clearly at least some forcing. Model solutions vary between just isolated weak showers and actual robust storms, so I’m unsure how the next few hours will play out, but we clearly do have some sort of forcing mechanism.
  25. high risk
    Even if we lower the dew points, it's the lapse rates that are driving the huge instability. Some sort of remnant EML appears likely to advect into our area overnight Thursday - there is really good, continued model agreement this evening about that. (Toss the GFS/HiResW FV3 which are known to underdo lapse rates.) The impressive lapse rates will allow some sort of MCS to survive into our area early Friday and then enhance whatever severe threat exists Friday afternoon. I'm still not totally sold on a trigger (yeah, a leftover boundary from a morning MCS could help a lot), and we might have some downsloping subsidence to suppress convection, but the shear/instability profile would favor splitting supercells with a wind and very large hail threat if any storms can form. (The tornado shear profile shown in the forecast sounding above is not supported in this evening's guidance which generally shows more westerly surface winds.)
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