psuhoffman

The ridge is slightly better oriented imo. It’s getting closer to what we want to see

Through 90 it’s better. Might not do it but it’s heading the right way

For me the big thing is keep seeing that NS wave digging south of us and amplifying. If that’s true we have ways to win that don’t require unusual and unlikely model adjustments.

We need the same adjustment. If the longwave features adjust west the same way they did last week that energy diving into the Midwest that becomes the storm will trend west also. Right now it’s coming in too far east for what we need. Shift that west and watch. Do I know it will no. A trend can reverse anytime. But this isn’t significantly more complicated. There is going to be a major wave amplification off the east coast. The pattern argues for it. It’s been identified as a period to watch for a long time. The question is where exactly. We don’t need some crazy adjustment in the phasing being shown. We juts need to shift the whole thing west. Some are applying the typical miller b thing here but the reason miller bs always fail for us is rarely does the NS dig south enough. That isn’t the issue on guidance right now.

Adjust the AIFS exactly the same way and…well

This is what it ended up actually looking like

BTW everyone is praising the AIFS and it did do really well but it was southeast at day 5-6 also juts not by as much adjust what it shows now the same way this adjusted and we’re good

Not grading my last minute adjustment as the storm started for many by then. This is the one I put out 2 days before. I think 90% ended up within the ranges. BWI busted high by 1”. I was too high along the southeast fringes. I’m ok with this.

Btw a super non scientific thing to keep an eye on. I’m way more ok with guidance being a miss to the southeast than if it’s to the east or worst northeast. If the axis of snow is to our south or southeast we have the best chance of a positive trend. East is more iffy. Northeast and don’t waste your time. It’s next. There are scientific reasons behind this regarding which model errors we need to correct each of those and which are more likely but I’m not in the mood to write 5 pages so for now I’m ok with the fact the major ensembles are all showing the snow max to our south. That’s not a typical miller b representation and one that’s more likely to adjust in a positive way.

Yea people don’t realize that the difference between 6” and 12” in your yard doesn’t impact the verification scores of a global model. Missing a mid level warm layer by a few hours and 30 miles might effect our ground truth but it’s an insignificant error in the global scheme.

Depends. If the longwave ridge trough axis stays where the guidance projects right now it’s likely a miss east. But it’s been trending west and last week it did the same thing right up to the end. If you apply the same idea that NS wave will dig in further west. Into the MS valley instead of the TN valley. Usually with a miller b our issue is the NS wave doesn’t dig south enough. Without some serious -AO help it’s rare to get a NS wave south enough for a major amplification to work for us. We need the upper low to track across southern VA really. Getting the NS to do that is hard. But this setup that actually doesn’t seem to be the issue. Damn some of the runs dig too much and cut off into a NC storm. The bigger issue I see now is the NS is diving in too far east to capture whatever STJ wave there is in time for us. Adjust the whole evolution west 200 miles and we would be in amazing shape! Keep an eye on two things. 1) the whole longer ridge/trough axis. Is the western ridge keeps adjusting west watch the NS wave dive in further west and boom. If it doesn’t then missing southeast (like the AIFS) is the likely outcome. 2) the depth of the NS trough. If we start to see if not dig as deep then a more typical miss to the northeast where Boston is happy and we smoke cirrus becomes a more likely outcome. if the depth of the trough remains the same and we get the westward trend of the longwave pattern to continue as it has the last 10 days then we will get a snowstorm.

the guidance was too slow on retrograding the longwave pattern last week which lead to this past storm going from a TN Valley/NC blizzard to eventually a OH Valley to New England blizzard. And the same trend is continuing right now, if it does continue the same exact error….well we’re all thinking it! The whole pattern is retrograding and reloading. Just as the current block is retrograding into the west and dissipating the next Scandinavian ridge is about to retro into Greenland next week! Think the last 9 years when we were often stuck in a feedback loop of never ending suck. This time we’re stuck in the feedback loop we want with the consistent being a permanently weak AO all winter that looks to continue frankly likely the whole cold season. We’ve slightly underperformed to this point but we have a whole half (and the snowier half) of snow climo left to correct that!

Oh I’m paying attention. I’m just exhausted.

RRFS held from its previous run showing a general 6-8" across most of the area before the flip

I posted a forecast 2 days ago...it's likely going to bust a little high...this was just a last minute update on what I am thinking...I won't grade this. And it hasn't started for me yet lol

Final Thoughts, these totals include sleet accumulation. Things really started to tighten up the snow/ice gradient the last 24 hours. I see a path for this to bust low...if we do have really heavy precip in the morning between 10-16Z like the RGEM/Euro/GFS/UK show

Naw DCA will report 3.8” no matter what

I’ll put a final map out in a min but some over unders in my head right now DC: 5” IAD: 6.5” BWI: 6.5” Winchester 10” leesburg 8” Frederick 9” Westminster 9” Owings Mills 8”

DC is just…I dunno it’s like they have some snow dome right there. And even when we get southern sliders they often end up missing the real big totals on those to the south.

Yea if we toss the NAM because it’s in its own universe. (Not saying it might not be right but it’s hard to bet on it v everything else) all other guidance is starting to tighten things up right through our area. Somewhere near us is going to be a very sharp gradient with 8-12” on one side of the line and 10 miles the other side only 3-5”. Right now my best guess is somewhere near you to Baltimore ends up near that line and tiny factors will decide if it’s a few miles one way or the other

UKMET is in the big thump camp. .7 qpf in DC before the flip. About .9 Winchester to Westminster before mix

I was trying to be nice but he forced me to say it. The heavy banding is just north of them on the rrfs during that time. It’s more extreme north VA and northern MD nw of 95 that was directed at

Sorry up here it was higher up at 16z. Assumed it was similar further south. it’s super close 70 north. DC not so much. Unfortunately I think DC south is cooked for the bigger snow totals. Things are tightening up and the gradient looks to end up somewhere near a Leesburg to Baltimore line with snow totals going from 3-5” south of that to 10” north or there pretty quick.

The better argument is that the rgem/euro and other guidance that gives us 8-12” does so by sticking an incredibly intense band over us from 10-16z. It’s a lot easier for WAA to win in light to moderate precip than it will be to advance if there is a band of .1 qpf/hr+ stuff over the area. It’s all going to come down to that really imo. The NAM doesn’t have that. It shifts the heavy banding way up into central PA and the WAA routes us because there is no dynamic cooling to slow it down. Basically if this is what’s going on from 10-16z the snow will hold on longer north of about 66 and definitely north of a Winchester to Baltimore line this on the other hand, ain’t gonna get it done Everyone is focused on the temps on the NAM, the real issue is why is the NAM missing the heavy banding tomorrow morning that all other guidance has. That’s why the mid level warmth surges north from 10-15z there is nothing to slow it down on the NAM.

Forget the NAM. It’s 50 miles off everything else even the other cams. But I Caught something on the RRFS. Verbatim it’s meh with 4-5” across the area. But it has an intense band of precip from 16-19z across the area as sleet but it’s super close. It’s only +1 at about 750 mb. Every other layer is fine. This is 700 which is the closest layer I can get represented but it’s close to the warmest layer. If it’s 1* colder across this area from 16-19z it would be 10” instead of 4” This trend has been on the last 2 runs and now it’s super close to a better result