psuhoffman

to be fair his observation about the mid level low tracking too far NW for what we typically want is not wrong. But there are more variables than just that. The depth of the cold in front makes this a situation where a further NW track than typically ideal might not hurt us as much. Remember February 2015 when a storm tracking into OHIO gave us 8-14" across our area before mixing with sleet/freezing rain, because there was arctic air in front...and there was absolutely no 50/50 or blocking with that setup...it was simple that a departing arctic high had left a shit ton (borrowing this from Randy) of cold air in place in front of it and the WAA needed to scour it out produced a ton of snow before we lost thermals. And that would be kind of a worst case scenario here given the setup is even better. So on the one hand I get what he is saying...he isn't wrong about that one thing being an "issue" but I think on the whole there are factors that offset that. Hopefully I don't get schooled by a legend here.

but day drinking is the best

This could end up being the bigger story when it's all over

I was in Herndon VA for that, got about 18" of snow followed by several inches of sleet.

I definitely am more worried about over amped than suppressed BUT that seems a bit of an exaggeration. Chicago has a 1045 high right over it as the system is organizing to the south in just 60 hours...that would take a pretty freaking radical failure (models are much better inside 100 hours than they used to be) for this to end up THAT much further NW than say the GGEM run this morning. The mid level track is troubling...but we've seen things offset that before...look at last February when the upper level trough was back over OHIO and the VA capes got a big snowstorm. There is an arctic high in the way here and a 50/50 with a TPV lobe right over us as the system starts to develop, that does change the equation somewhat.

Moderate snow moves into the Annapolis area around 6z and mixing doesn't really become an issue until 15z. That is 9 hours of snow before you lose mid level thermals.

I don’t think the ec P type output is correct. The freezing rain along 95 should be sleet This is toward the end of the thump period and the biggest risk of losing qpf to non snow. surface is plenty cold and so is 925. The warm layer is somewhere around 850 and slightly above. That depth would indicate sleet imo along 95 not freezing rain. During the dry slot it looks like freezing drizzle. Surface 925 850 700

is that a technical term?

It did come on board though for one day...then backed off, but it was less enthusiastic for as long as other guidance. I don't have time to watch squirrels, but please feel free to let us know

My take: It's actually been the best op model in terms of verification scores over the last 6 months or so...and it was the one model to never tease us with that disaster last February. It's new but so far its been impressive. Having it on our side here is a big deal.

GEFS is better than the GFS op but still pretty far down on the list of things I care about I would rank importance in terms of what I weight this way 1)EPS 2)EC AIFS 3)Euro Op 4)UKMET 5)GEPS 6)GEFS 7)GGEM 8) tea leaves 9) wooly bear caterpillars 10) the almanac 11) Op GFS

I won't tell anyone what they should think. But what I think when presented with a scenario like this is that the potential is there for an HECS level event... but there are 3 caveats we have to acknowledge. 1) the setup here does support the possibility of a major event...the key components we need are all in place, blocking, 50/50, arctic high. But those things don't guarantee a max potential outcome...we sometimes have all that and the details don't fall our way and an event fails to reach HECS level. I am not talking about a total fail but plenty of times we have the potential for an HECS and only get a SECS or MECS because some minor details didn't work out 2) the guidance has never universally shown HECS results, not like 2016 when across the board EVERY DAMN THING showed 20" totals. This time each run we've had 1 or 2 peices of data showing that...but we've also had some less enthusiastic output. The GFS showing some deamplified wave, the UK or GGEM with some over amplified mixed event. We have not had run after run of across the board uniformity agreement on a HECS. That indicates there is still variability to this and an HECS is not necessarily the most likely outcome 3) Even if the guidance did show 100% agreement on an HECS at 100 hours out...we have to acknowledge the limitations and faults in this guidance. Yes our models are flawed, we don't yet have the scientific ability to model the atmosphere accurately at 100 hours. It's possible the guidance is wrong in some way and things will shift by this weekend. It's ok to admit this. But it's also important to also admit without the models we would have no freaking idea there was a big storm even possible on Sunday. So there is a benefit...that benefit is not that we can know for sure what is coming 4 days out though.

Odd change to the mean... didn't trend north or south...just "less"...but we are in the midst of an amplification trend across all guidance...so I find it hard to believe the decrease is due to a less amplified system. I would have to look under the hood but that change is just odd given when else we've seen from 12z data.

We tend to get a lot of our snow in epic runs that happen sporadically once in a blue moon. This pattern has that kind of upside potential. I wouldn't put any qualifiers on it. Sure we need to get some luck, it could go sideways if things don't fall our way...(but by sideways I mean we just get some snow not epic totals) but this is the type of pattern we could score multiple big hits.

The flow that drives the surface low up to our west is happening at the mid levels in response to what is happening to our west, the surface and the strength of the MSLP isn't really the issue. Take a look at the mid level wind flow as the trough is phasing to our west...that is the issue on the runs that drive the primary further north.

This UKMET run is somewhat similar to the Feb 2014 storm...but colder and without that upper low part 2. Big heavy thump up front before a huge dry slot. And the thump wouldn't end with temps in the upper 30s and melting...temps would stay well below freezing...the dry slot would be light sleet and freezing rain.

I don't think this pattern is one and done. But I'd sure love to get the big hit out of the way right up front.

The wall of high pressure is still there. The difference is the trend has been towards more energy ejecting and a more phased amplified system which will attack that thermal boundary with WAA and press it north more...how far is the question. Before guidance was showing a less energetic phased system which wasn't going to really move the thermal boundary much and just slide along it. This has more upside but more fail potential also.

What did the UKMET show last night?

Not sure it will...but on that particular GGEM run the 50/50 exits a little too quickly allowing more ridging to penetrate further north head of the trough axis, with more phasing to "flip" the whole thermal profile on its axis, pinwheel effect so to speak. The greenland block is north of perfect, the 50/50 isn't locked in like we see in true suppressive patterns, but there is a crazy EPO ridge and crazy blocking with a 50/50 and an arctic high in place, there is plenty good here...but is it technically possible if we get a full phase like the GGEM for this to over amp a little and the HECS snow ends up NW of us...yes. But there are plenty of ways for us to win...slightly less phasing, the 50/50 hangs on 12 hours longer, the phasing happens but is centered a little further southeast...there are more win paths than fail ones here, and even the fail path is not a full fail just a failure to maximize potential.

ratios will be slightly higher NW of 95, and that zone that gets a little less snow also gets more sleet after the flip, in the end it evens out...everyone ends up with like 8-10" OTG probably...area's NW do it with more sleet, along 95 with a quick heavy snow thump before a flip and more dryslot.

I know this is anecdotal but might be relevant, at about this range ahead of the 2016 storm, the GGEM was the most amped consistently showing crazy ridiculous snowfall totals further north than the other models. It has also been over amped a few times over the last few years when I was rooting for a more amped solution in systems where I was getting fringed...and I got fringed so... All of that to say, if the GGEM ends up on its own with an over amped solution I would not worry too much...if other guidance ends up going that way...then I would worry some.

It's a 6-12" snowstorm across our area followed by sleet. What adjective people use to describe that is up to them. It is pretty close to the worst case scenario given the setup, so to be fair in that way it is a disaster because we would underachieve in a rare big potential setup. But by most objective standards that kind of storm affecting our whole area would still be very rare, a once every 5 years type event, so calling it a disaster is kinda harsh...but depends by what lens you're viewing it.

This GGEM run is pretty close to what I see as the worst case scenario, but yes it's a realistic option...it's also showing 6"+ of snow followed by a lot of sleet which is not a bad event, if we don't start expecting HECS level snow when were still 4 days away.

BTW I wonder if it's not a coincadence that all the major guidance systems come out in inverse of their verification scores ICON, GFS, GGEM, UKMET, EC I know there used to be something to the delay in the euro and its accuracy, they used an initialization process that took longer but was significantly better. I have not kept up to date with the details of the various guidance over the last 10 years so I can't say for sure this is still true, but it seems odd that basically the longer the model takes to generate, the more accurate it is. ETA: Odd meaning maybe not a coincidence