1609 replies to this topic

[ORH_wxman]

I decided to create a separate thread for the 12/23 potential as we are close enough now that it looks like someone will get something out of that...whether its CNE or SNE still remains to be seen...or maybe both.

The Christmas potential can stay in the other thread. This will be discussion on the 12/23 threat.


Right now the BL is going to be marginal so the higher terrain in the interior will be favored...esp N of the MA/CT border as the colder air is a bit deeper the further north you go. Most likely it will be a 1-3" event but I suppose there is a small threat at a 4" jackpot somewhere....the GFS, NAM, and Euro are all in fairly good agreement on these ideas.

We will still have to watch for some inverted trough lighter snows on Christmas Eve lingering as another shortwave moves over the region from the west.

[HubbDave]

Anyone want to hazard a start/end time for this?

I thought it looked pretty drawn out on the nutty GFS

[weatherMA]

2am start, over by 8am by most models...I'll be sleeping.

[HubbDave]

weatherMA, on 20 December 2011 - 07:42 PM, said:

2am start, over by 8am by most models...I'll be sleeping.

I'll be driving to work

My students will be so much smarter

[H2Otown_WX]

weatherMA, on 20 December 2011 - 07:42 PM, said:

2am start, over by 8am by most models...I'll be sleeping.

Nah, the rain will wake you up.

[CT Blizz]

• Why are you not including all high terrain?

[MarkO]

Skiing Friday up north, so hoping, hoping, hoping the trend continues.

[ORH_wxman]

CT Blizz, on 20 December 2011 - 07:50 PM, said:

• Why are you not including all high terrain?

It might be everyone in the high terrain, but there's a chance that the southern hills in RI/NE CT struggle a bit...especially early in the event as the BL warmth will be strongest down there initially. It might not be a big deal either, but we won't know until we get closer.

[H2Otown_WX]

Wow, I didn't realize how much colder the GFS was compared to the NAM. The NAM doesn't even have snow in SNE on the twisterdata snow maps with the exception of areas around ORH and surface temps. look to be close to 40F south of the Pike.

[CT Blizz]

ORH_wxman, on 20 December 2011 - 07:55 PM, said:

It might be everyone in the high terrain, but there's a chance that the southern hills in RI/NE CT struggle a bit...especially early in the event as the BL warmth will be strongest down there initially. It might not be a big deal either, but we won't know until we get closer.

Ok that makes me feel better lol.. If the NAM is right in thermal profile I think all the hills see a couple inches and hopefully most of SNE can grab some with the heavier vv's. Euro was very close here and if you factor in it's warm 2m temps bias would prob be a 32 wet snow..The GFS quite honestly I always factor out whether it's cold or warm

No matter what happens we've got something to track and it sure as hell is nice to have a couple shots at a White Xmas since when we talked at the GTG we were thinking less than 20% chance.

[ORH_wxman]

CT Blizz, on 20 December 2011 - 07:57 PM, said:

Ok that makes me feel better lol.. If the NAM is right in thermal profile I think all the hills see a couple inches and hopefully most of SNE can grab some with the heavier vv's. Euro was very close here and if you factor in it's warm 2m temps bias would prob be a 32 wet snow..The GFS quite honestly I always factor out whether it's cold or warm

No matter what happens we've got something to track and it sure as hell is nice to have a couple shots at a White Xmas since when we talked at the GTG we were thinking less than 20% chance.

Well even the GFS gave you like an inch. The northern hills probably have the best shot with the deeper cold, but the BL warmth could be overplayed a bit...not sure. We'll have a much better idea probably by tomorrow night.

[CoastalWx]

GFS is pretty juiced up and warm for now. It might have the idea of ticking north, but maybe a little too aggressive on this run. It's pretty bad south of the Pike.

[CoastalWx]

CT Blizz, on 20 December 2011 - 07:57 PM, said:

Ok that makes me feel better lol.. If the NAM is right in thermal profile I think all the hills see a couple inches and hopefully most of SNE can grab some with the heavier vv's. Euro was very close here and if you factor in it's warm 2m temps bias would prob be a 32 wet snow..The GFS quite honestly I always factor out whether it's cold or warm

No matter what happens we've got something to track and it sure as hell is nice to have a couple shots at a White Xmas since when we talked at the GTG we were thinking less than 20% chance.

LOL, you are such a Nervous Nelly. You'll probably see some snow.

[H2Otown_WX]

CoastalWx, on 20 December 2011 - 08:02 PM, said:

GFS is pretty juiced up and warm for now. It might have the idea of ticking north, but maybe a little too aggressive on this run. It's pretty bad south of the Pike.

Hmm, twisterdata must be flat out wrong then:

NAM  18z NAM 2m temps.jpg   263.05K   3 downloads

GFS  18z GFS 2m temps.jpg   248.68K   2 downloads

[CoastalWx]

I guess the concern I have in general..and not just imby..is if this does tick a little north. If that were to occur, we probably would shot the precip down before it gets cold enough for anything meaningful. I can't totally toss the GFS solution right now, but hopefully it's a little too far north.

[CoastalWx]

H2Otown_WX, on 20 December 2011 - 08:06 PM, said:

Hmm, twisterdata must be flat out wrong then:

NAM 18z NAM 2m temps.jpg

GFS 18z GFS 2m temps.jpg

??

[H2Otown_WX]

CoastalWx, on 20 December 2011 - 08:09 PM, said:

??

Well these would indicate the NAM is warmer than the GFS but you were saying the exact opposite.

[CapeCodWeather.net]

this is pretty funny.
the boundary layer is torched...then just crashes cold...and truly isothermal...18z nam hya:

 nam_18z_bufhya.jpg   252.8K   1 downloads

[ORH_wxman]

The GFS starts off a bit like a torch....but by 12z it cools off a lot.

[Ginx]

ORH_wxman, on 20 December 2011 - 08:13 PM, said:

The GFS starts off a bit like a torch....but by 12z it cools off a lot.

Clown maps

[dendrite]

H2Otown_WX, on 20 December 2011 - 08:10 PM, said:

Well these would indicate the NAM is warmer than the GFS but you were saying the exact opposite.

The NAM dynamically cools strongly in E MA during the height of the event. The GFS cools off toward the end.

[CapeCodWeather.net]

dendrite, on 20 December 2011 - 08:16 PM, said:

The NAM dynamically cools strongly in E MA during the height of the event. The GFS cools off toward the end.

yeah i thought maybe there was a dry layer...but there isn't...i guess it just rips enough VVs and maybe some downward drag to cool it off?

it's kinda strange how much it drops.

[H2Otown_WX]

dendrite, on 20 December 2011 - 08:16 PM, said:

The NAM dynamically cools strongly in E MA during the height of the event. The GFS cools off toward the end.

Yeah I see a little bubble of colder air there between ORH and BOS. Is that what you mean? At hr 66?

[ski MRG]

ORH_wxman, on 20 December 2011 - 08:13 PM, said:

The GFS starts off a bit like a torch....but by 12z it cools off a lot.

If someone lived at, let's say 1400' near the border of Hampshire/Berkshire county, what do you think the likely outcome will be? Just hypothetically speaking of course.

[CapeCodWeather.net]

ski MRG, on 20 December 2011 - 08:22 PM, said:

If someone lived at, let's say 1400' near the border of Hampshire/Berkshire county, what do you think the likely outcome will be? Just hypothetically speaking of course.

killed by jealous snow lovers

[CoastalWx]

H2Otown_WX, on 20 December 2011 - 08:10 PM, said:

Well these would indicate the NAM is warmer than the GFS but you were saying the exact opposite.

Like Phil and Brian said, the NAM is a product of dynamic cooling. But the GFS imo kind of stinks for people like Kevin. Here is why. This will be a system I think where closer to the actual low center, there will be a more compact, but intense area of lift, whereas further away..it may not be as intense, but a more broader area of light to moderate values of lift I think. Sorry for the run on sentence BTW.

Anyways, here is why you don't want the GFS. I know it can run warmer this time of year and I agree it can torch 850 a lot more than it should. However notice in this graphic, SNE has good lift overall, but it's probably just switching over to snow in nrn CT..maybe down to Kev. I'm also trying to take into account the warm bias.

 avn_63_vv.gif   65.94K   1 downloads




But look at 12z, the precip is just about gone with the mid level deformation and associated weak return way up in NNE. SO just when he is ready to rock, the precip is gone.

 avn_66_vv.gif   65.22K   0 downloads


The euro is further south with all this, and is much better for areas near and south of the Pike. However, I'm just showing why you don't want this much further north.

[Ginx]

Ride the Euro like a wild pony.

[ski MRG]

CapeCodWeather.net, on 20 December 2011 - 08:23 PM, said:

killed by jealous snow lovers

I'm reporting this post.

[CoastalWx]

This could be a classic case of CNE getting more than some think...despite what the QPF output is.

[ORH_wxman]

CoastalWx, on 20 December 2011 - 08:30 PM, said:

This could be a classic case of CNE getting more than some think...despite what the QPF output is.

That happens a lot in SWFE type events...I remember in 12/19/08 they did much better than anyone forecasted.

[messenger]

CoastalWx, on 20 December 2011 - 08:30 PM, said:

This could be a classic case of CNE getting more than some think...despite what the QPF output is.

More like a classic case of it being Tuesday and it'll change 3 times between now and Wednesday evening.

[ski MRG]

CoastalWx, on 20 December 2011 - 08:30 PM, said:

This could be a classic case of CNE getting more than some think...despite what the QPF output is.

Scott, thanks for continueing to make great posts. They are very helpful for those of us trying to learn more. Always illustrative and easy to comprehend.

[CoastalWx]

ORH_wxman, on 20 December 2011 - 08:32 PM, said:

That happens a lot in SWFE type events...I remember in 12/19/08 they did much better than anyone forecasted.

It has that look. Look how that deformation area hangs back. It doesn't mean that whole areas is like 15-20 DBZs, but I wonder of a stripe across central VT and NH do well relatively speaking.

The euro has this further to the south, but still encompassed a large part of New England.

[HubbDave]

ORH_wxman, on 20 December 2011 - 08:32 PM, said:

That happens a lot in SWFE type events...I remember in 12/19/08 they did much better than anyone forecasted.

That was a decent little event... I even had power back

edit: I had 11"

[CoastalWx]

messenger, on 20 December 2011 - 08:32 PM, said:

More like a classic case of it being Tuesday and it'll change 3 times between now and Wednesday evening.

Well I'm just saying and using that run as an example. I was trying to be careful with the wording.