OceanStWx

Is it really out of nowhere though? It's been at least 24 hours of the Euro on board with a strong band, and I know I've been talking about the mid level banding signal for a couple days. I think it's key that you're tucking the deepening 700 mb low into Cape Cod and keeping that forcing pinned through the heart of the region.

Yep, there's a button on the top right that is two arrows pointing towards each other.

Just wait until we're in it and waiting for it to happen.

Gotta be a little wary of the model QPF in situations like this. If you dry out the DGZ, it may be hours racking up "T"s for precip. Models are pretty notorious for spitting out 0.10-0.20" QPF during periods without much support for snow growth.

I'm a meteorologist, and I support this statement.

We don't hold. We update the forecast so that it at least has likely PoP. With the Euro and EPS supporting a NAM-lite scenario I need to have some moderate snow accumulation Tuesday. Doesn't look like it because it has hourly enhancement all the way west to EEN or LEB. Maybe a weenie finger of f-gen.

It's actually a beautiful thing to watch the explicit modeled ratios blossom as the deformation band starts cranking after 12z Tue. The NAM goes from a general 8-10:1 to a nice stripe of 15:1.

No snow in PWM through 09z Tue then a foot by 00z Wed.

We've turned over half the forecast staff in the last 6 months (but generally speaking they aren't the problem, or involved in the forecast much yet ).

I don't pay too much attention to snow output, because models struggle with QPF, especially when dry slotting occurs. Confidence is definitely highest in the Monadnocks to potentially cash in on both parts of the storm, but otherwise I could see much of our watch not needing warnings, or I could see it expanding.

I'm full on at the moment because other shifts don't put any thought into the message we're putting out there. Just burn it all down.

I just think there's no real confidence to get excited in big totals, especially on the northern edge of the watches up here. Either the WAA or deformation could bust for us and leave it an advisory event.

You can really see the model rip some sort of vorticity or PV through Delmarva and back into SNE at the end of the run. That's when you really see precip rates increased across SNE/CNE.

There's a lot of bust potential on the NE side if that WAA washes out too soon.

No, but I also don't know any website that reproduce it for free. Or paid for that matter. So I've only ever seen it in AWIPS.

I definitely agree that was a real warm outlier, but I did want to highlight one nice thing about the 3km NAM. It explicitly forecasts snow ratios based on hydrometeor type. Snow ratios change according to the rime factor. The higher the rime factor the close to pure sleet you are getting. This example from the latest 3 km shows reflectivity and rime factor. Over NNE there is reflectivity but no rime factor (=pure snow). As you move SW you get more and more riming. > 5 rime factor (cyan into the warm colors) is typically graupel and sleet. The NAM will use snow ratios anywhere from 5:1 for graupel down to 2:1 for sleet. Between the no riming and factor of 5 you get ratios from 3:1 to 8:1. It definitely produces a more realistic looking snowfall map in situations where mixing is forecast to occur.

Depends on the office philosophy. Sometimes it's more convenient for headlines to use a 24 hour criteria, but GYX philosophy has always been that 6 inches of snow that is drawn out over 24 hours is maybe more impactful than 12 hours. Because the plows are out longer, removal takes longer, etc. Definitely a philosophy issue with me. The long lead time warnings are just a pet peeve of mine, nothing drives me crazier. Except maybe stealing my half and half. But I think of warnings as go time. That's when we make a final call on snow totals. And right now I can't tell you with any high confidence whether some of those zones are going to get 4-6" with a lot of mixing, or 12-18" and naked snow angels. In my mind issuing a warning for 8-12" of snow that ends up being 4" or 16" is not that great a forecast. And sure things look good now, but we still have a half a dozen model runs and several ensembles left before it starts. They'll probably end up working out for most of those zones, but in my opinion it's a false confidence.

I'm on the desk this evening and tomorrow evening. So I get the last update before flakes fly.

In my experience the NBM is typically too high on snow ratios and too low on max wet bulb temps aloft. So I usually don't like it because I get too much snow in the forecast relative to what I'm expecting. Here the issue seems to be surface temps (NBM has a cap above which it doesn't accumulate snow) and mid level drying. It actually has more QPF than NWS forecasts, so I would guess it's producing a lot of drizzle/freezing drizzle in those 6 hour periods and reducing snowfall as result.

Top 3 American model?

I mean this is how you draw it up in your dreams

SW ME ripping like 2"/hr in the last 3 hours of that run.

Ripping 12-15" in 6 hours. I'll pass on rip and reading that solution.

But reversing the flow at 250 mb is where it's at.

Not singling you out, but I thought this was a good post to highlight for everyone how those probabilities work. Since we have an addiction and track these things routinely at days 5-7+, often times we are discussing a storm before the NWS offices are putting out QPF/snow forecasts. So the probabilities that you are referencing here only captured part of the coming storm. We're required to have 72 hours of QPF/snow, so unless someone intentionally adds extra hours of those variables, our snow probabilities will be partial.