MN Transplant
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There's no mystery here on where we are headed. Rewinding back to one of our great runs from earlier this week. You've got a neutral trough right at our longitude and you've got a backside vort that is going to help dig and stall even more. This is a great look for a big storm. Then you have the NAM this morning. Positively-tilted trough, not much help on the backside. This is just a run-of-the-mill storm look around here.
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Another model run with a positively-tilted trough. Looks like the CCB is up in Long Island and NJ. We get snow showers on the backside from the 500 low passage, but it is not really the the beatdown that we are looking for.
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This is the first time that the NAM nest has run through the WAA period, and it is certainly drier than the 12km NAM. Still ~0.4" around DC, but that is actually somewhat of a jackpot zone.
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NAM 12km is just fine on the front side. No p-type concerns in DC until 00z. At that point, ~0.6" precip has fallen.
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I'm sure that is has been stated in the many pages back, but the big problem we have with the backside/stall scenario right now is that the trough is still a bit positively tilted at our longitude. Prior runs were showing it neutral. That results in the shove off the coast.
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Everybody hating the Euro and I'm just sitting here in the DC area...
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Especially if the sleet is during the lull after the WAA anyway. You aren’t “wasting” much precip.
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In a perfect scenario I think we’d like to see a bit more of a surface reflection at 84, but you can start to see it and it will stall as the 500 comes close. That 500 track looks good. Better than the open wave GFS at that point.
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Looks great for us on the front, with the usually caveat of the NAM being too juicy. Questionable low position at 84, but the 500 low is on track.
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It is a deeper 500 low than the Euro, interestingly. But, NAM.
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NAM is also cold at the surface and 925. 850 is another story, but it is all sleet, no rain like the GfS or even Euro.
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NAM is juicy on the front end, as it usually is. Over 0.5” qpf by Sunday evening in DC when the column gets too warm.
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Total snow 10:1 at DCA - 10” hooray! Total depth change - 3” argh!
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GFS torches again overnight Sun into Monday. 38 at the surface at DCA. we are going to have some takers for the 93 hour panel, though.
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Hard to argue against this
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Stacked right under the 500 low at that point (Tuesday, 12z)
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500 low on the IN/OH border at 84. Backstream vort in Alberta. Same as 00z.
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I'm not seeing any dramatic changes at 500mb.
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It doesn't look quite as bad if you squint and don't worry about the specific low location, I think. The good part of the GFSv16 is that while we lose the column at some point late Sunday into Monday, the temps don't spike. DCA peaks at about 34, vs 39 on the GFS. Those looking for a good backside on the para should avert their eyes.
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Para GFS is a nice 3-5" front end.
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I'm not sure whether this is predictive or not, but it looks like one of the reasons why the GFS is a bit further north for longer is that it retains a connection to the upper level low/trough in central Canada. 12z GFS above, 00z Euro below, both for Sunday morning. You can see that the Euro is more divorced from the low/trough than the GFS is (also shown in the slight wind streak north of MN on the Euro that is less impressive on the GFS).
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Simply put, the storms ahead and behind our system are helping to "buckle" the setup which digs our trough into a good spot for us. The GFS just has it happening a touch too late, allowing the warm air to come in early. PSU is right that it may be how the GFS is handling the thermal structure overall. I can also squint and maybe make the case that the GFS has a slightly more pronounced connection to the trough in northern Canada that keeps it from diving southeast as quickly.
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Even with the mid-storm torch, it is very generally a 3" storm with the WAA and then a 0" (to the SW) to 5" (to the N and NE) backside event. So, a region-wide 3-8" storm, which isn't bad for the model that doesn't look quite right.
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Torch
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DC is losing the surface at 18z Sunday. The upside is that it has the precip coming in earlier than the other models so there is still snow on the front side.
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