psuhoffman

If you look at the euro or 3k skew for the same time its surface temp is within 1 degree. The problem is the gfs cannot see the warm layer at 750mb. It’s not capable of it. This is a known problem. In cases where there is WAA and a mid level warm layer you have to adjust the snow/sleet line NW on the gfs. You can figure out where it should be a number of ways. Least technical is to look at the 3k or euro and say ok now if their Synoptics were identical to the gfs where would they have the snow/sleet line? Then make the adjustment. If you use the GFS snow line in wAA situations you’ll be wrong EVERY SINGLE TIME. It won’t ever see the mid level warming. Caveat…the only way we overcome the mid levels is if the precip is so heavy (death banded) that dynamic cooling can overcome a bit and the heavy precip can mix out the admittedly small warm layer all the better guidance has for our area. That’s not impossible but it wouldn’t be the gfs being correct it would a similar result for different reasons. like if you call a crossing route on 4th and goal from the 5 and the receiver falls down and the QB scrambles and breaks 2 tackles and dives into the end zone. Sure it ended up with a TD, same results, but when breaking it down in film study you wouldn’t say the play worked.

A shit ton of that accumulation along 95 is sleet. Like 3” of sleet! 6z brings in this ridiculous band and dumps close to an inch of qpf midday Sunday most of which is sleet but hey that counts! It also did beef up the snow before the flip by 1-3”.

Gfs has slowly shifted some towards other guidance if you account for the fact it can’t see mid level warm layers and adjust the snow/ice line 20-30 miles NW like you have to. Then it looks identical to the euro and rgem. The warmest guidance shifted colder. The coldest shifted warmer and they ended up converging on about what the euro has shown the last 24 hours. Shocking.

I think the top 3 are safe. Jan 96, Jan 2000, Feb 2006 After that the next tier for DC/Balt are 6-12” storms like 1965 and Jan 2011 which this could fall into or surpass.

I'm not weary of this solution because the NAM shows it...I'm weary of it because I had already decided days ago that this was what the only fail path was...seeing it on anything isn't good...but yea if something is going to show it rather be the NAM over anything else. Just saying...when I draw up my "please anything but that" solutions I don't want them showing up on anything. Way way way too often the last 9 years my "this is what could possibly go wrong" FKNG musings are exactly what ended up happening.

Yea but in this case what it did made sense...weaker wave initially, WAA runs out ahead of the main support, weaker...less Thump...GFS kind of has this...but its offset by a south enough second wave that we just snow for 24 hours... NAM we get the weaker initial thump but then flip anyways. That is the in between screw solution. And its not impossible...not likely...not with only the NAM showing it. But I've seen this kind of thing before...remmeber yesterday when I said "the only way MD doens't get a warning level event is if this splits and the WAA wave runs out ahead and then the second wave cuts...this was that disaster scenario I had made up in my head.

3k NAM is COLD

No it wasn't random, the snow gods hate you

We got stuck in between on the NAM but it was closer to a GFS type solutions...it was a step in that direction...the problem is...if you end up in between an amped up wave that thumps us with WAA and the GFS idea we get screwed.

The trough is amplifying way too far west of us

I was kicking this around when some of the 12z runs showed this trend...and now I am pretty sure... less amped is not necessarily what we want anymore. Unless it goes full on GFS, the other less amp solutions are just ending up warmer and dryer because there is less intense WAA precip, which cools the column and holds off the advance of the WAA for a time. So these slightly weaker solutions are actually worse...yea the track might be slightly better...but it fails to change the changeover time significantly and it just cuts down on the thump before we flip.

it continued to be better at h5

oh it is...you can really see it on the h5 trend gif I just posted

better at 51

its snourther

at 51 the whole flow is flatter out west also, this is less amped so far (NAM can go nuts in a hurry so not reading into what happens later yet), the initial WAA is directed in a better trajectory also.

on approach the high is a little south in the midwest, SLIGHTLY less confluence ahead but so minor I don't think that matters much, slightly flatter flow out west (good) but better organized system (also good IMO because we might get a thumpier thump before a flip).

The confluence over top of us is very important...in about 48 hours...not 12 or 24 hours...as whatever it is then will be gone by the time the storm is here...at those time ranges what is happening to our NW is more important actually than super tiny minor differences in the height fields over top of us way ahead of the storm.

The EPS 25-75% doesn't look far off from what @MillvilleWx has been saying all along ETA: Keep in mind this is pure 10-1 so in the NW zones these numbers would be underdone a little

I used the EPS to create this map using the 25% and 75% snowfall output

EPS did shift NW slightly overall, but there is some good under the hood. The 10 and 25% snowfall actually shifted southeast...the 10% snowfall is now 6" in DC, up from about 4.5" This would seem to indicate a floor of about 6". There are less disaster members with under 6". The 50% did drop from 11 to 9" and the 75% dropped from 14" to 11" so we are losing the upside potential as the jack zone is shifting further and further northwest the last several runs.

I'm not sure we want that... if you disregard the GFS pretty much everything else is about the same in terms of when we lose the mid level thermals...between 15-21z depending on where you are south to north. So we want as much precip before that as possible...

TT does also but won't have it updated for another 2 hours probably

it ends up speeding back up...in the end it simply trended further NW, primary hangs on longer...looks kinda like last nights GGEM