OceanStWx

I think we're looking at beam attenuation due to a wet radome. The ZDR is spiked for no good reason in that zone, and that will hurt other products.

This observed snowfall map is going be a piece of work.

"Friend"

N/NE winds just do so well. You can advect cooler air from the N to steepen those low level lapse rates and more efficiently mix.

Disastah

It's not not a supercell.

Took our first power hit just a few minutes ago.

Trying to interpret this CC loop, as the low values become uniformly high over the Gulf of Maine again. I'm thinking it's a sharpening rain/snow line becoming more upright over time. So the radar beam shoots through it quicker.

We definitely still have time. I think the surprise here is just how much of this is being driven by precip rates, so we're getting very little accumulation outside of the main band. It's actually hurting me not to be in the grids on this event though. This always felt like a 8-14" to me, but I definitely had an eye on spot 20 potential. I still think 8-14" could play but may be a lot narrower than originally thought.

36 on 95 and 34 out by the mall.

If I had to guess, I would say the NH jackpot is going to be east of you. But you should do well regardless.

The higher res stuff had a window between like now and 03z for the best rates locally.

It's about to get a whole lot more consistent. That WCB is ready to slam into the mid level front.

MHT pulled off 0.05 in their 15 minutes between top of the hour and SPECI, so similar in S NH.

1"/hr stuff outside right now and definitely sticking to the road (despite the warm ground cc: Scooter).

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.