OceanStWx

Yeah I'm thinking our coastal areas up this way could do a rain-snow-rain-snow scenario.

Walked in the door, started reviewing things, saw that TAF and slapped the changeover at 22z without looking at any guidance.

GYX has flipped to snow.

JFC, I lost it when I saw what we had in there.

Okay, I'm back after trying to put out our local dumpster fire.

Run through some of those Bufkit soundings. You have a well mixed 500-1000 ft layer in the upper 30s that wipes out to isothermal around freezing in two hours as the rates go heavy.

It was a pretty tough event for our probabilistic snowfall (maybe they all are?). For a long time this looked like an all or nothing event, so you were either going to hug the 10th or 90th percentile. We thought snowy, so we went 90th. Now that models have come into better agreement (especially interior) on snow occurring our probabilities are settling into something between the goal posts.

In convection is most likely riming that is producing that, but in certain events actual sleet has been observed. OKX did in Feb 2013.

I can actually see what the 3km has for a rime factor (which is incorporated into its snowfall) in AWIPS. So in general it can be more realistic than your traditional 10:1 or Kuchera maps because it's trying to model microphysics. The reason lift below the DGZ is not great as Will is pointing out here is because lift from below is likely driving supercooled water into the DGZ. If there is supercooled water hanging around you'll rime your snowflakes and kill your ratios. If lift is smack in the middle of the DGZ you can produce pure dendrites and don't have to worry about riming as much on the way down.

Yeah, that's prime, but we can do better locally because our primary ice nucleus is sea salt. I tend to just expand it to -10 to -20 as a proxy, if it's low level junk even as warm as -6 to -8.

Probably how they are accumulating snow. Hourly accumulation on the 3km can time down those changeovers, while the 12km 3 hour chunk will average and can dump a lot of snow where it doesn't necessarily belong.

Yes, but more wiggle room than BOS. You've done the dance before, so you could stay just on the good side a la the Euro vs. the GFS.

In my experience that advisory level (3-4") snow if it all sticks to the limbs will do the trick.

Going to do the weather tonight with tear-away style pants?

I thought the Euro looked overall better on the bent back front aloft than the GFS. GFS brings it awfully far inland (which also explains the crap clown map).

That low level lift is no bueno for snow, it's either going to be precip rates too light for changeover or heavily rimed snow that has trouble stacking up.

Your snow growth procedure definitely has dry slot issues on the GFS/Euro for BOS.

BOX needs to stop feeding the trolls.

I'm disgusted.

Developing way too late to score that much to the SW.

I really have very little recollection of the storm itself because I was at school, but it is the reason I'm working for the NWS now. UML wanted me to do a research project on it using an old Weather Event Simulator from BOX. So I was going to collaborate with them. The WES died, but I turned that into an internship for the summer, which turned into a thesis, which got me over the hump and into a met intern spot at DVN. And now you're all stuck with me.

There's a pretty good TROWAL signal, even on the regional Canadian. It's essentially in the same position as this GFS version but 3 hours delayed.

I love the HRRR depiction of 1 hr snow totals, because it's only going to give you a number where it thinks it's snowing. So you can see the pytpe changeover as the coverage expands. Starts in the higher elevations of the Berks and ORH Hills mid morning and then it's game on by midday into Metrowest.

I'm actually pretty excited for the toaster baths during the day tomorrow. "You said I was going to get snow!!1!@" ...right before they flip to 2"/hr.

Fall back on conceptual models and ignore the 2 m temp noise. Between 18 and 21z those winds go from NE to N in Essex Co and that should stop any warming potential for the rest of the event.