Re: 12/29 Potential Snowstorm Update #1

by **Frank_Wx** Tue Dec 27, 2016 10:37 am

Nothing too significant on the GFS aloft so far compared to 00z. The 00z GFS did not show anything spectacular for the area. 12z GFS should finish shortly.

by **Frank_Wx** Tue Dec 27, 2016 10:42 am

GFS aloft valid 12z THURS now looks better than 00z GFS. May want to transfer to coast sooner. Trough has more of a tilt to it. Not surprise given other guidance.

by **Frank_Wx** Tue Dec 27, 2016 10:43 am

by **amugs** Tue Dec 27, 2016 10:43 am

Remember a deepening low in this position as per NAM will have dynamics at play that should mix down to the surface. Could have Dec 2002 type storm dynamics at play for a majority of the area - Id say at this time South of I 78 not much - IF we can get a CCB forming which it looks like then we will cool the BL/Surface and it will stick and accumulate.

by **Frank_Wx** Tue Dec 27, 2016 10:44 am

Aha. The ridge is MUCH improved on the 12z GFS compared to 00z. There's your difference.

by **Frank_Wx** Tue Dec 27, 2016 10:45 am

Not really paying attention to what GFS shows at the surface. I think it took a step toward other guidance aloft. We know this game. It will catch on tomorrow. EURO will be a big run.

by **amugs** Tue Dec 27, 2016 10:47 am

Frank_Wx wrote:Not really paying attention to what GFS shows at the surface. I think it took a step toward other guidance aloft. We know this game. It will catch on tomorrow. EURO will be a big run.

RGEM will lead the way now - showing BL temps lower when the precip starts - no way we warm up that much IF this is correct!!

12/29 Potential Snowstorm Update #1 - Page 3 Rgem_T2m_neus_17

12/29 Potential Snowstorm Update #1 - Page 3 Rgem_T2m_neus_17

by **nutleyblizzard** Tue Dec 27, 2016 10:49 am

Frank_Wx wrote:Not really paying attention to what GFS shows at the surface. I think it took a step toward other guidance aloft. We know this game. It will catch on tomorrow. EURO will be a big run.

TREND IS YOUR FRIEND.

by **dsix85** Tue Dec 27, 2016 10:58 am

Is it possible this new information could lead to a mixing event for LI instead of the original all rain event?

by **jmanley32** Tue Dec 27, 2016 11:00 am

Been so busy just caught up.on past 2 days. So is there now some chance my area just north.of nyc may see some meaningful snow? It seems like storm is trending stronger and it will b colder from.the quick read I did. Here's hoping. Of course new England and Boston get hammered lol

by **algae888** Tue Dec 27, 2016 11:04 am

dsix85 wrote:Is it possible this new information could lead to a mixing event for LI instead of the original all rain event?

It all depends on how much precipitation is left as the low is deepening. I for one kind of like the eastern half of long island as precip maybe a little slower to depart and storm really deepening just east of Montauk.

by **Frank_Wx** Tue Dec 27, 2016 11:04 am

dsix85 wrote:Is it possible this new information could lead to a mixing event for LI instead of the original all rain event?

It is possible LI can be all snow for a period of time. The issue is getting it to stick. It could be a wet snow scenario.

jmanley32 wrote:Been so busy just caught up.on past 2 days. So is there now some chance my area just north.of nyc may see some meaningful snow? It seems like storm is trending stronger and it will b colder from.the quick read I did. Here's hoping. Of course new England and Boston get hammered lol

Maybe a couple of inches...depends where banding sets up and timing of the cyclogenesis that takes place off the coast. We'll know more tonight.

by **rb924119** Tue Dec 27, 2016 11:06 am

Throwing this out there, at quick glance it looks like we could be dealing with another slantwise convection/symmetric instability regime with this system, which means that if that is the case we will see all guidance lag with the dynamics that actually occur and they will bust low (the system will likely over-perform). I have to do a deeper analysis after all of today's 12z runs come in, but that' what it looks like to me.

by **Frank_Wx** Tue Dec 27, 2016 11:10 am

rb924119 wrote:Throwing this out there, at quick glance it looks like we could be dealing with another slantwise convection/symmetric instability regime with this system, which means that if that is the case we will see all guidance lag with the dynamics that actually occur and they will bust low (the system will likely over-perform). I have to do a deeper analysis after all of today's 12z runs come in, but that' what it looks like to me.

Hi-Res guidance may be best for this system. And using soundings. 950mb and lower looks warm. Anything above that is cold. So it's going to be interesting for sure.

by **CPcantmeasuresnow** Tue Dec 27, 2016 11:15 am

jmanley32 wrote:Been so busy just caught up.on past 2 days. So is there now some chance my area just north.of nyc may see some meaningful snow? It seems like storm is trending stronger and it will b colder from.the quick read I did. Here's hoping. Of course new England and Boston get hammered lol

It still rains in Boston through most of the event so that's not true.

by **sroc4** Tue Dec 27, 2016 11:38 am

One of the keys for coastal sections will be at 850mb. CMC and GFS don't close it off until way up in NE. NAM and Euro close it off just SE or over of LI. The implications of this are HUGE. esp for E LI. The faster it closes off the quicker the cold air in the mid levels comes rushing back in. Even the GFS has both 925 and 850 below freezing with decent heavy precip still over much of eastern sections on the GFS. I have seen this movie before. I agree with rb here I think models, esp the global ones are missing the true dynamics here. It will interesting to see when the rgem gets in closer because at 500mb it looks a lot more like the Euro that it does the CMC at 500mb by 12z 29th. very potent energy associated with this trough.

12/29 Potential Snowstorm Update #1 - Page 3 Rgem_510

12/29 Potential Snowstorm Update #1 - Page 3 Rgem_510

by **Frank_Wx** Tue Dec 27, 2016 11:40 am

This will be fun to nowcast. FINALLY!!!!

by **sroc4** Tue Dec 27, 2016 11:47 am

For the record IMBY I have seen snow accumulate with surface temps above between 35-40*F. As long as it comes down hard enough it will accumulate. There will likely be areas that bust low and High with this system.

by **amugs** Tue Dec 27, 2016 11:54 am

sroc4 wrote:For the record IMBY I have seen snow accumulate with surface temps above between 35-40*F. As long as it comes down hard enough it will accumulate. There will likely be areas that bust low and High with this system.

Scott in line with my post on the ccb that will be forming and will be west of slp and as it bombs the precip shield will expand as this dynamic unfilds. Again a Dec 25th 2002 type set up here dynamically.
Hi red models such as nam Hi Res showing this.
Think N&W I 80 and up can see 3-6" possibly at this time.
Trend has been for s depper colder storm as Ray said.

by **rb924119** Tue Dec 27, 2016 11:54 am

I stand corrected, this is NOT going to be a slantwise convection/symmetric instability driven system. The coast redevelopment screws that up. I'm also now worried about that zone of subsidence Frank mentioned the other day (yesterday?) playing a large role, especially for the northern and western folks. This may end up being an I-95 special here.

by **rb924119** Tue Dec 27, 2016 12:00 pm

Well the latest Ukie is on board lmfao

by **sroc4** Tue Dec 27, 2016 12:10 pm

rb924119 wrote:I stand corrected, this is NOT going to be a slantwise convection/symmetric instability driven system. The coast redevelopment screws that up. I'm also now worried about that zone of subsidence Frank mentioned the other day (yesterday?) playing a large role, especially for the northern and western folks. This may end up being an I-95 special here.

Exactly Ray. Miller B set ups always have the dreaded subsidence zone between the original and the new hence the bust low bust high statement above. Many will likely think it will be too warm at the surface to snow on or near the coast, but if the mid levels behave and close off sooner rather than later, and the surface Low is undergoing bombogensis the dynamics take over and eastern sections will be surprised. Here is the UKIE FYI

12/29 Potential Snowstorm Update #1 - Page 3 GZ_D5_PN_072_0000

12/29 Potential Snowstorm Update #1 - Page 3 GZ_D5_PN_072_0000

by **sroc4** Tue Dec 27, 2016 12:12 pm

Sorry the image above was 00z. Here is 12z: LP stronger and HP to the NE slt stronger..import ingredient

12/29 Potential Snowstorm Update #1 - Page 3 GZ_D5_PN_060_0000

12/29 Potential Snowstorm Update #1 - Page 3 GZ_D5_PN_060_0000

by **amugs** Tue Dec 27, 2016 12:12 pm

Ukie wow looks great

12/29 Potential Snowstorm Update #1 - Page 3 P1_GZ_D5_PN_060_0000.jpg.bd930cad82eaaa0952937598f46d6924

by **amugs** Tue Dec 27, 2016 12:13 pm

Precip holy smokes UKIE!!

12/29 Potential Snowstorm Update #1 - Page 3 PA_000-072_0000.jpg.6b9e5164c4888279ef8c11e3f6adf226

by **lglickman1** Tue Dec 27, 2016 12:14 pm

is that ukie all snow?

by **sroc4** Tue Dec 27, 2016 12:15 pm

lglickman1 wrote:is that ukie all snow?

No

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