ORH_wxman

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.

If you get one more tick colder, then you’ll be in big snows I think…right now it’s still a lot of sleet contamination.

06z Euro cooled. That’s pretty interesting now for N MA.

Funny how euro might be the the warmest model now. Maybe the NAM is with it. Both are razor close though for northern SNE near rt 2 and NH border.

Looks a bit warmer though through 54 compared to 18z.

That’s a hell of a sleet storm for a good chunk of SNE on that run.

Def Coming in colder at least through 51h

NAM def is the warmest and sometimes it’s right. But other times it can be on crack when it’s the warm outlier. I think it was pretty horrific in the March 23rd event up north. If the warmth is being caused by convection on the NAM, then it all depends on whether it sees that convection better than other guidance and that’s where the NAM can sometimes have an advantage. I did think it was strange that the RGEM wasn’t biting and instead has been on the colder side of guidance.

The low levels are pretty cold on GFS. The concern is between 700-800mb with the warm layer. The sfc might be 32-33 but you have like -4C at 925 over that MA/NH border region so you’re not dropping slush balls from that boundary layer.

Euro was a little better with the secondary. Hits S NH and maybe extreme N MA near the border decently Thursday AM whereas the 12z run really didn’t do much in those areas.

18z GFS is actually pretty interesting for the 128 crew just NW of BOS. Lot of sleet but it does flash to heavy snow during the latter stages. Warm layer is pretty thin too for a while even before that.