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high risk

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Everything posted by high risk

  1. The NAM definitely tracks the vort extremely favorably for the area. Both the parent and the nest end up with a healthy mesoscale band; it's obviously better defined in the nest. We'll have to see exactly where that vort ends up.
  2. Something isn't quite right. If you look over Lake Superior, there is clearly some of the "3rd level of green" which corresponds to 12+ dbz, and the second plot then should have echoes there if it really starts at 12 dbz. I wonder if the listed scale on the second plot is wrong. On the other hand, I think it's more likely that the developer of that page is doing some processing of the original reflectivity field in order to convert the reflectivity to a precip type-based reflectivity plot; whatever remapping is being done could be wiping out some detail. The details of the features on the bottom map just don't quite match up with the features on the top plot.
  3. I wouldn't worry too much about "the NAM @ 60". Guidance seems to be locked in on the synoptic details, so it's worth looking here at a simulation that tries to resolve the mesoscale details. Maybe that band would fall apart as it comes east if the run went another 6 hours, but the overall look there is encouraging for those who want to see a quick burst of snow. As for those plots, the scales are different, but it still looks to me like the labels aren't right. Almost seems like the second plot really starts at 20 and not 12.
  4. NAM nest at the end of its integration (00z Wednesday) does show a band of snow showers on the front in the simulated reflectivity field.
  5. no. The parallel GFS is not yet being run by NCEP Central Operations, so it won't show up on that page. It's still being run by EMC, as code handoff to NCO is not for several more weeks, but files are being distributed so that various sites can make graphics. It's part of the NCEP effort to lengthen the evaluation period for major upgrades.
  6. too much deep southwest flow with this event to do a whole lot here. best case scenario is probably a strongly-forced line of quick snow squalls right on the front, and getting shut out is certainly in play.
  7. April is probably the best case scenario. Code still has to be turned over to NCEP Central Operations, and then a TON of testing needs to be done, as many NCEP systems use the GFS either for initial conditions, boundary conditions, or forcing. You can also get graphics at mageval.ncep.noaa.gov
  8. NAM says we're 60 early Sunday afternoon falling to 40 by evening and then dropping more during the night. The problem is that the low-level flow here goes strong westerly late in the day which should dry us out good. It will only be cold enough for flakes well after dark, and the NAM says that precip isn't anywhere near here by then. I think we have a better shot at thunder Saturday night than we do of snowflakes on Sunday
  9. Don't like seeing an impressive sfc low going well north of us like that. The low-level winds here usually end up southwesterly which causes some downsloping. Looking at the NAM at 84, you can see strong SW flow even up at 700 mb which can assist with dry slot formation. With a strong vort in the right place and an intense arctic front, you can still certainly create a band of healthy snow showers (that can accumulate. hell, look at what the band in North Dakota did Wednesday night), but some things will be working against us.
  10. absolutely true that diurnal heating in December has little influence. I figured that someone would make the "wrong time of day" argument and tried to dismiss it but didn't really do a very good job of explaining myself.
  11. Yeah, the NAM nest has been consistent with one of the lines that develops in the Ohio Valley later today maintaining itself through the night and coming through here early tomorrow morning. That timing would usually be very unfavorable for us, but the NAM has something like 72/67 here by that time, leading to 500-1000 j/kg of cape. The shear will be pretty ridiculous, so *if* that scenario were to play out, you could certainly have an early morning severe threat here.
  12. The model hasn't changed, but the NCEP site last Tuesday started using the 0.25 degree output grids to generate their GFS graphics. They had previously been using a much lower resolution grid.
  13. thunder here in southern Howard County too. Congrats DC!
  14. I'm going with us getting a mesoscale discussion for either round 1 or round 2 and a box being issued later tonight for DE/NJ/NYC metro.
  15. indeed. several of the recent HRRR cycles show embedded cells with the batch that will come through between 22 and 00z. the last couple of HRRR cycles have also ramped up the 04-05z line.
  16. you forgot "and spectacularly wrong". but you are too kind - thanks! With this event, the problem is two-fold: there is some sort of lead shortwave (not totally sure - haven't looked closely enough) that is going to fire widespread showers (and maybe TRW) in the very early evening, and then the front is actually slower than it had looked. The mid-level cooling will help the cape a lot, but that only slowly arrives during the evening. Without that lead wave and a slightly faster front, we could have had a nice window in the late evening for a strong line. Instead, the 22-00z stuff is the main show, with lesser threat of a line along the front at 1AM. Overall, that 22-00z threat will have crummy lapse rates and overall limited instability, so the severe threat is low. That said, there is strong shear and *some* cape, and the HRRR has a nice lightning signal, so it has to be watched. Hell, I got the weak EFO go through my backyard a few weeks ago in an event with strong shear, very little cape, and no lightning.
  17. I think we're starting to see consensus on this. Between a lot of HRRRs, the newest NAM nest, last night's hi-res windows, the LWX hi-res run, and the NCAR ensemble, they point to the 22-01z timeframe for a batch of heavy rain approaching from the south-southwest, possibly with some embedded thunderstorms. This is probably our best chance for an embedded rotational cell, but the chances may not be too great. The 04-05z threat along the front is still there, but some the guidance really downplays this now.
  18. yes, I had been thinking 00-04z with a severe threat in a band just ahead of the front, but as the models have now started to converge on the timing, I think I have to modify things a bit. Based on several consecutive runs of the HRRR, there may be two distinct threats here: 1) The HRRR has a wide band of heavy rain moving through the area between roughly 6 and 8PM. It's probably mostly just lots of rain, but it's in an environment with good shear and some instability. The 13z HRRR reflectivity prog looks somewhat cellular, and I saw a nice updraft helicity track in the 12z cycle along with a modest lightning signal. 2) Then after a break, the front approaches around midnight or so, and the HRRR at the end of its run has a band approaching with a surge of cape ahead of it. I thought this would be the player, and it still might, but the best forcing may be just north of our area.
  19. this is a good point, and it must be noted that the NAM warms us up a lot during Wednesday morning during a time of showers. It's often hard to get the warm front to move through quickly here when it's raining, but it looks like there is decent agreement on the winds veeing around to southeast quickly tomorrow morning and strengthening. And the NAM and GFS don't really have a ton of QPF for us tomorrow either which may limit the chance of a big rain shield hindering the progress of the warm front.
  20. as I'm sure some of you have seen, the SPC day 2 has us in a marginal risk. definitely looks like the best threat period is roughly 8PM-midnight or so, with a lot of guidance depicting a band or broken band of storms along the cold front. NAM take us to around 70 during Wednesday afternoon and keeps us there until the front passes. CAPE increases ahead of the front into the ~750 j/kg range, as some modest mid-level cooling occurs. Strong shear is also in place during the afternoon, so that has to be watched too, but right now I'm thinking that it will be more widespread showers in an area of strong forcing and very limited cape, but if a discrete strong updraft can occur, that would need to be watched too
  21. I think that this does indeed warrant some watching. One nice thing is that at this time of year, time of day is often not a big issue. Whereas a late evening timing might hurt us in May or June, sfc heating often plays a lesser role in the fall, being trumped by advection. In fact, the NAM shows us rising to near 70 Wednesday afternoon and then rising into the low 70's during the evening and staying there. The NAM (and it seems like the GFS too) right now has an early evening break in the rain, followed by a late evening frontal band moving into our area with 500-1000 sfc-based cape and fairly healthy shear. Even the afternoon stuff, even though it may be too widespread for discrete updrafts, still has cape and a ton of shear and needs to be watched. Ultimately, I've seen WAY too many fall events here have buckets of shear but fail on instability and not get the job done, and the progged lapse rates for this event right now are terrible, but maybe this ends up being one of the rare fall events here that works out.
  22. CPC's new 3-month outlook is out, and for us in November through January, it leans modestly towards us having above average precip with slightly better chances of above average temps.
  23. not sure if this is better in here or in general discussion, but the line now coming into northern MD is pretty healthy, with warnings just across the border into PA. The mesoanalysis suggests that the parameters here are not much worse than those where SPC issued the box to our northeast.
  24. Tomorrow is quiet for much of the country, so LWX asked for the NAM fire wx nest to be placed over the Mid-Atlantic: http://www.emc.ncep.noaa.gov/mmb/mmbpll/firewx/firewx_18z_refc_animate_1h.html it has a healthy line rolling through the area around 00z tomorrow evening
  25. First, I agree with the idea that we're going to have a wet winter here, and that is always half of the battle. But in the details hypothesized below, the idea of lows tracking into the Great Lakes or the Ohio Valley probably isn't a scenario we'll see much of. That is the storm track for La Nina years. El Ninos usually don't have lows tracking west of DC, and the CFS precip map posted by mitchnick sure supports that idea. From what I can recall in 1997-98, there were lots of lows taking nice tracks up the coast; there just wasn't any cold air in place to avoid rain or a change to rain after 45 minutes of slop. It's always possible that blocking does somehow set up, and it could easily work out where it's overall warm but we time cold air with the active stormtrack once or twice and hit the jackpot, but seeing that CFS map with torching north and northeast of here makes me worry about the same type of pattern this winter as we had in 1998.
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