ORH_wxman

I think I’d hedge mostly sleet there based on guidance trends overnight. It’ll change to snow but I think the meat of the QPF is going to be a lot of sleet and mixed crud.

18z Euro seems kind of flaccid on QPF compared to other guidance. Really nothing over about an inch and a half for the frozen zones with lots of 1.2ish totals.

Yeah and I think we’ll have a decent idea by tomorrow afternoon if it’s likely or not. I am assuming the differences in model guidance right now will try to converge a little more…or we’ll either see one last bump south or north in these next couple cycles. If it bumps south, then it’s easily game-on for you, if it bumps north, game over. Status quo? You might be nowcasting.

18z GFS is just bonkers between 06z and 12z for extreme NE MA and SE NH. Like 3 hourly QPF of around an inch between 06z and 09z in Essex county and Rockingham county. That’s one way to overcome elevation deficiency.

You might get two 20-burger storms inside of 2 weeks after the equinox. Not bad.

Man what a pelting the NAM is over a lot of MA. Wish we could keep that mid-level warm front south longer but it doesn’t seem to want to happen except on a few rogue model runs. Western Maine is going to get crushed. Doesn’t really seem to matter the exact solution, they are getting 18-30” every run. Some a little close to 30 and others closer to 18 but always crushed.

Was also snowier N of pike. Esp up by Rt 2 and over to Ray's hood.

Yes. It’s subtle but we really need the height field to try and “open up” south of New England. That trend started yesterday after most guidance had relegated the system pretty much a total non-event south of monadnocks from the tempest they showed 2-3 days prior…but it’s a precarious trend that could easily snap back. And it’s possible we may not even know the fate of that idea until very close to go-time. As both of us know, convection can wreak havoc on those subtle height field differences and cause the mid-level warm front to stay further south than modeled. Or the reverse might happen and it goes further north than progged.

As soon as I looped H5 (I usually do that first) I knew it was going to be slightly worse since it wasn’t bulging out the H5 heights quite as well to the east as 06z was. That, in turn, pushes the midlevel warmth and dryslot further north. It’s crucial we keep the H7 front south of us through 12z Thursday if we want warning criteria snowfall.

12z euro looks a bit warmer than 06z. Took a step back. Gonna have to sweat it out apparently in the N MA/S NH zone.

That sounding honestly looks like it would be in the upper 20s range at the sfc if you have heavy lift. You’re pulling -5C not very far off the deck there. But the million dollar question remains is how organized can we keep the heavy lift? Given the relatively late nature of the secondary development and the ULL remaining very strong to our west, I worry about conveyor mechanics getting out of sync. But this subtle trend of “bulging” out the H5 low to the east and lowering heights there is helping over the past few cycles.

I think omega/lift will have a lot to do with it too. If we get a very good area of consolidated strong lift, the soundings are going to want to flash colder. But if we keep things a little more banded and slightly less organized or the lift just isn’t quite as intense, it’s prob a lot more sleet.

Yes. It’s pretty cold in the 925 layer around -3ish Heres the sounding at 06z tomorrow night near you while GFS is pounding…you can see how once off the immediate surface, you’re comfortably below freezing so this isn’t going to be a scenario where you have slush balls falling through an isothermal layer 3000 feet thick and not sticking well. If the rate are good, accumulations will easily be 10:1 on that type of sounding…you might even pull 15:1 for a while with that cross hair sig, but I’d want to see all the models agree on that before taking it too seriously.

Yeah it doesn't need much to get BOS into legit snow. What a tease.

12z GFS is pretty interesting too for areas like BED over to 495 belt near Westford/Ayer where Tip is.

Ray crushed on 12z GFS....really smoked that NH border region overnight tomorrow night and early Thu.

12z ICON is being run from Ray's computer. NE MA/SE NH jackpot.

There's a ton of sleet initially up in the border region so it's still a huge question of when that can flip to snow. It's plausible it ends up as mostly sleet and then some nuisance snow after that. IF we cool it one more tick, then I think it's gung ho near MA/NH border, but there's reason to stay cautious at the moment. I do think it won't be zero snow....there will likely at least be a few inches of crud at minimum.

I think it can accumulate during the day ok with these soundings....but the key is keeping H6-7 saturated and getting decent rates. If it goes slotty with light rates, then it won't matter. But if you're going moderate to heavy snow at noontime with 850 temps in the -9C range and 925s in the -4C range, it's pretty hard to not accumulate. But the key is not slotting aloft....we want to keep that H7 WF to the south of us. Those 0.15 to 0.2" QPF in 3 hours won't cut it...need over 0.25" every 3 hours.

Shows ORH hills sub-freezing at the sfc after midnight tomorrow night through Thu morning. Pretty good lapse rates from Sfc to 850ish, so any heavy precip is gonna prob get even lower elevations close to freezing from latent cooling....esp if we can replace the sleet with more snow, then latent cooling is even more efficient.

There's no such thing as 33-34F in the DGZ.....gotta be more like -10C to get ice crystals, though as we've talked about before, in New England we can often get away with something like -6C or -7C because of all the salt nuclei in the air here being surrounded by the Atlantic on two sides and onshore flow.

Loop the control run of the NMB and you can see how a bit further south with H7 makes a massive difference....that run prob gives Ray 20"+ of snow. http://www.meteo.psu.edu/ewall/ETAEAST_12z/etaloop.html

If we can trend that H7 warm front a little south, then it gets way more interesting. Right now, still mostly a sleet bomb for a chunk of SNE with maybe some crappy snow up near Rt 2 and border region.

Definitely continuing to trend colder.

I’m pretty surprised there’s no watch for N ORH county. Guess they think it’s below 50% chance for 6”+ there. Might not be a large enough area too, but they may have to issue one if 12z stays on the colder side.