psuhoffman

lol its pretty much a non event for our area. Even up here its about 1" of snow to rain to dryslot. It mixes almost to state college lol. Be honest...it does bother you just a little to see it go that far west lol. I am not overly concerned by an at range NAM run...but I would rather see it going the right way then the wrong way.

Can you just make 6-12 8-12. Sounds better You see where the lines are...your closer to the 12 than the 6...call it whatever helps you sleep

my best guess

One is avg precip rate over the previous 6 hours and the other is instantaneous rate (or like a radar depiction).

@osfan24 @Ji everytime in the last few years the GFS was significantly less qpf then the other globals it eventually caved. I’m way more worried about track then meso scale features that will determine 10 v 20”. Unless we see all guidance shift that way I’m just happy to have a solution that doesn’t go towards my fail scenario. And for me only getting 10” isn’t a fail.

So that’s why it suddenly gets colder right after...makes sense. Perfect correlation.

I don’t have a crystal ball on what the final track will be. My best guess is a 60/40 compromise between the most progressive gfs and most amplified euro leaning 60 euro. But I am fairly confident I would trust the colder thermals of all the other guidance. Not saying DC gets pummeled. If it tracks inside the colder thermal profile won’t matter as a warm layer blasts in. But if the low stays off the coast I think you will be colder then the gfs indicates.

GFS has been running warmer then all other guidance at the surface. I would bet if the gfs track verifies it would end up closer to the euros thermal depiction adjusted for track.

Plus I don’t see much of a difference with the SW coming onshore

But then it wouldn’t be so over amplified

Last 24 hours of EPS

@PhineasC not saying your wrong but the QPF didn’t actually match those crazy model output. I know the coop a couple miles from here recorded 19” in that 2009 Storm but on only 1.26”qpf. We actually had pretty good ratios in most of MD in those storms due to beautifully perfect mid and upper level low passes. ETA: BWI had 18” on 1.57qpf

Did models over estimate qpf more back then though. I know the high res models back then had horrible wet biases

Those maps.... the difference is if you are NW of 95 a lot more of that snow is REAL on the 18z and not some clown map fantasy. The thermal profile was 1-2 degrees colder and that makes a big difference when you are talking about these 1C warm layers at 850 during the height of the storm when a few hours one way or the other can be the difference between 5" and 10" of snow.

That really would be a "give me that and we're good the rest of winter" storm...40" lol We are in good shape I think. Even if this takes one of the more inside tracks like that one GFS or some of the euro runs, historically that track with a pretty stout high in southern Quebec would still produce a 8"+ snowfall up here. If this stays offshore we could do REALLY well. But for us I think it is more of a matter of how significant will the snow be not whether it will be significant. Assuming your bar for significant isn't Ji level. His zones are ok but somewhere in that 6-12 will be a 12+. I get that its too soon to nail down where though.

EPS is tightening the goalposts...as it should. But if you are from 95 NW odds have slightly improved each of the last several runs. trends mean more importantly odds of 3”/6”

That was just my snark

I have not dug into the members yet...might not for a while busy. But from previous runs the ens were always warmer on those mean plots because the handful of crazy cutters that run up the Piedmont were skewing the mean. The colder runs aren’t as much “colder” along the edges as the warm outliers are warmer. Plus I think the lower resolution of the ensembles makes them have a warmer representation in general. Not picking up the extreme meso features and CAD as well. I would focus more on track of the Eps and focus on the ops for meso details like exact thermal structure.

I’ll throw out a guess later today

I saw that...that warm pocket gets right to our door then stalls and sits there for 6 hours...I don't buy that. Some of that period we are getting .2 QPF per hour. I would adjust that. Even with that there we would likely be puking snow/sleet mix during that 6 hour period...low ratio but we would likely still go way over a foot...just not those stupid totals on the clown maps. But again, worrying about a little warm layer pocket like that and banding at this range is useless. I am analyzing for the DC/Baltimore area where most people in here are. Not only talking to the 3 people that live near me. But sorry. I will try to focus on my yard more.

If we were to assume this run verbatim looking at the 1 hour temps at all levels and the precip I would say about 3-6 before a change to sleet for people from 95 NW. Then it gets tricky...there is about 6 hours of crazy banding with pockets cold enough to support snow and pockets in the subsidence in between that are sleety. The odd thing is some of the warm pockets don't line up with the banding. Has a warm pocket over the NW burbs around 3z while they are getting smoked by the deform. But I am NOT sweating that kind of thing at this range. I actually think temps crash a little faster once the storm reaches our latitude and we probably mix out that warm layer better for the back end. But as is...it only flips back to pure snow for a couple hours at the end..but its puking snow so maybe another 2-3" on the back side after a crap ton of sleet. But again...that is not my forecast...I would adjust this slightly to the southeast and mix out some of those warm pockets a little better during the deform. Not a lot...but the euro is often SLIGHTLY overdone. Slightly makes a huge difference on the edges like we are.

I am mostly happy with this run. It was a much colder run, especially at the surface. Never gets places from 95 NW above freezing. Probably means more sleet then rain during the "mixy" period. Unfortunately a slightly more tucked in track mean't it did blast a warm layer pretty far west at 850...it gets right to my doorstep at its furthest NW. For big totalys into 95 we would want to see that surface track judge just a bit southeast...but the good news is if the euro and ggem are correct on the colder thermal structure of the storm we wouldn't need the track to adjust all the way to the GFS. That's good because in the end I expect a 60/40 compromise track between the usually progressive GFS and the usually amped euro, biased toward the euro, to be reality. That is going to cut it really close for getting big totals into 95. But if we adjust the euro just a slight bit southeast on the surface track it gets it done.

Colder so far through 72

Gem isn’t as awful as some are making it. It’s a LOT colder then the GFS even with a worse track. If you are N or W of DCA it’s a big time thump snow 6-10” with 12” up near PA. Reason it’s not more is it’s hauling A and lost the nice wrap around deform. I NEVER rely on that. Treat it like bonus. That’s why I was meh on last nights 0z euro because ALL the snow was back end. That’s living dangerous. Give me the gem idea of a really cold profile and a guaranteed front end thump then if the back happens we go big...if not we still have a very good snow for December. It’s got less upside but a safer way to roll then the warmer runs that rely on the wrap around to get big totals. Plus if you take the gem thermal representation and assume a Gfs track and speed it’s a big win. That option isn’t impossible still.

You’re correct in your analysis and pessimism wrt big totals 95se. The problem with his post is that he says the exact same things EVERY threat in this range. And because our climo sucks he is right most of the time. But when we eventually do get a hit he is wrong. His posts aren’t useful because they’re a generic canned response. He simply assumes the worst and says why the worst case scenario is likely everytime. Unfortunately that’s usually true.