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Major Nor'easter snow storm (possible top 20) Noon Wednesday-Noon Thursday Dec 16-17, 2020

wdrag

By wdrag,
in New York City Metro

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Rjay
Rjay
RCNYILWX
RCNYILWX

Lurker on this thread, originally from College Point Queens, been working at NWS Chicago since 2010. Jealous of this storm, as it's been exceptionally boring out here and big snowstorms like Superstor

jbenedet
jbenedet

I think you’re going to see a correction back southeast today as the arctic airmass that’s building into the region throughout the day begins to get ingested into the models.  The temp drops thro

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BxEngine

BxEngine

Posted
Posted
1 minute ago, RCNYILWX said:

The current ECMWF is 9 or 10km resolution. The parent NAM is 12km and NAM nest is 3km. The HRWs (ARW, NMM and NSSL) are 4km.


Sent from my SM-G965U using Tapatalk
 

So yes, the euro has a higher resolution than the 12k nam. Thanks. Lol

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uncle W

uncle W

Posted
Posted
2 minutes ago, mikem81 said:

Strange how the HP is coming in stronger each run (1039 on latest EURO) and in similar position yet the relatively weak LP just shoves north so easily....

 

sfcmslp.conus.png

all the other Dec storms I posted did not have this strong a high to the north...lets see if it can withstand the SW onslought...

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wdrag

wdrag

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22 minutes ago, RCNYILWX said:

Lurker on this thread, originally from northeast Queens, been working at NWS Chicago since 2010. Jealous of this storm, as it's been exceptionally boring out here and big snowstorms like Superstorm 93, Blizzard of 96 etc drove my passion for the weather.

Anyway, certainly can't discount the depictions of the NAM and the RGEM in this timeframe. It was comforting to see the Euro with an all/mostly snow solution for the city. That said, think big picture old school meteorology before we had access to this firehose of data. The parent mid-level low has trended stronger and farther run over run (looks like we'll even get fringed by light snow out here which was very low probability just a few days ago). With the pretty far north and west mid-level low center tracks, this seems to be a setup that favors a very intense front end thump with very strong large scale and mesoscale ascent (low level f-gen and steep lapse rates) in the warm conveyor belt. Hopefully not like the March 2018(?) storm that got flooded with warm air and caused mix much quicker.

Recall the 93 Superstorm had a terrible track for the coast but we still got 10-14" on the front end because the warm advection thump was that intense. For the city and a good chunk of Long Island, you could see most of your liquid equivalent QPF as snow but then dry slot and mix with the 700 mb deformation zone displaced well to the north and northwest. Good luck to everyone that's been tracking this storm! Wish I was heading up to the Catskills to ski on Thursday lol.

Sent from my SM-G965U using Tapatalk
 

I  agree 100%  - for NYC this could be an 8 hr snow blitz, sleet/rain/freezing rain after midnight for a while then back to snow by sunrise with 25-0F air lurking in CT to swoop south during the morning as the low track and ppp falls shift e of ISP longitude.  Think its a heckuva a mess NYC.  

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psv88

psv88

Posted
Posted
Just now, David-LI said:

Isn't a "banana high" as depicted on the euro a textbook signal for a strong nor'easter? What's missing? 

This is not a banana high. A banana high is shaped like a banana in southern Canada, this high is to the NE, and is moving away. 

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L.I.Pete

L.I.Pete

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26 minutes ago, psv88 said:

Very tough call for north shore right now. Based on trends, i think 8-10" may be the ceiling, and the floor is 3-5". South shore ceiling is 6-8", floor is 1-3". This one will be fun to watch unfold

We usually end up OK in these...better than most. Agree it will be fun, great to have something to watch for a change.

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jbenedet

jbenedet

Posted
Posted
6 minutes ago, wdrag said:

I  agree 100%  - for NYC this could be an 8 hr snow blitz, sleet/rain/freezing rain after midnight for a while then back to snow by sunrise with 25-0F air lurking in CT to swoop south during the morning as the low track and ppp falls shift e of ISP longitude.  Think its a heckuva a mess NYC.  

Surface temps looks really cold in NYC throughout. Peak out in upper 20’s it looks like. If there’s ptype issues it’s the mid levels and sleet or freezing rain.

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wdrag

wdrag

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No changes for me  in expectations based on the 12z model cycle.  The sleet profile is marginal and strong VV at the time of it's impingement could keep it S+ til a mesoscale dry slot temporarily shifts ne along and e E of I95 later Wed night. I still think sleet up to I80. Power outages look like a big problem to me NYC-PHL NJT corridor wherever wind gusts 40-50 MPH and 6+ wet snow at 32-33F.  That's a challenge to forecast. I'll be curious.   Drifting to 4 feet I think is a possible problem wherever more than 18" of snow falls. (no rule of thumb for me on drifts). e LI might not exceed 4" snow??

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Eduardo

Eduardo

Posted
Posted
27 minutes ago, mikem81 said:

Strange how the HP is coming in stronger each run (1039 on latest EURO) and in similar position yet the relatively weak LP just shoves north so easily....

 

I think it's all about the 50/50 low, right?  If that slips east, then the high (no matter how robust) will follow.

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jm1220

jm1220

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20 minutes ago, David-LI said:

As someone mentioned, the 12z NMM is a cold and snowy run. Don't ask me if that model is reliable or not, maybe someone else can answer that. Here are the totals, for whatever is worth...

 

wrf-nmm_asnow_neus_48.png

Can’t speak much to it but I’d rather see models like the Rgem and Nam correct SE. 

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Stormlover74

Stormlover74

Posted
Posted
2 minutes ago, SnoSki14 said:

Are there any similarities to this with the November storm a couple years back?

I remember that one taking everyone by surprise. 

Euro threw a life raft in a fleeting situation but could just be a fluke. If the next set of runs doesn't tick SE then you'll probably see the Euro correct NW tonight. 

Pretty sure that was a rain vs snow event with surface temps expected to rise into the mid and upper 30s and instead we stayed around freezing and never flipped. This storm seems more complicated with mid-level warming being a bigger issue

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wdrag

wdrag

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16 minutes ago, jbenedet said:

Surface temps looks really cold in NYC throughout. Peak out in upper 20’s it looks like. If there’s ptype issues it’s the mid levels and sleet or freezing rain.

Hope you're right. Wind may be 050 degrees but it's still off LI sound. I'll go for 31-33F by midnight Wed night. I see wind damage here and there for LI and coastal NJ. 

When the wind changes to 020 toward sunrise, should drop into the 20s NYC BUT, i stand to be corrected. Let me know tomorrow night (If I can stay awake). 

No one should be surprised by the mesoscale modulation of snowfall... I can see one spot 8" say NYC, 2" MTK, 16" HPN or POU or BDR...but with large variations as the bands set up. I'm definitely good for tow 25" bullseyes...one in PA and the other somewhere near ALB or even back to n of BGM. 

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SnowGoose69

SnowGoose69

Posted
Posted
4 minutes ago, SnoSki14 said:

Are there any similarities to this with the November storm a couple years back?

I remember that one taking everyone by surprise. 

Euro threw a life raft in a fleeting situation but could just be a fluke. If the next set of runs doesn't tick SE then you'll probably see the Euro correct NW tonight. 

The high position and the approach of the shortwave/low aren't as good.  I've posted a few times the high center near PWM and the system riding north along the immediate coast is the setup to watch.  The high in this case is centered more NW and the system is riding more NE or NNE from a point inland.  A place like Harrisburg would be the spot to watch for a surprising front end blast as they sit roughly in the same correlated spot NYC was in November 18

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gravitylover

gravitylover

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1 minute ago, wdrag said:

Hope you're right. Wind may be 050 degrees but it's still off LI sound. I'll go for 31-33F by midnight Wed night. I see wind damage here and there for LI and coastal NJ. 

When the wind changes to 020 toward sunrise, should drop into the 20s NYC BUT, i stand to be corrected. Let me know tomorrow night (If I can stay awake). 

No one should be surprised by the mesoscale modulation of snowfall... I can see one spot 8" say NYC, 2" MTK, 16" HPN or POU or BDR...but with large variations as the bands set up. I'm definitely good for tow 25" bullseyes...one in PA and the other somewhere near ALB or even back to n of BGM. 

You really think that far N or W?

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wdrag

wdrag

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32 minutes ago, gravitylover said:

You really think that far N or W?

Multiple models near 2" qpf near ALB... take a look.  That tells me big banding.  Usually does shift unexpectedly far nw...  There could be two or 3 bands of 1"+ /hr snow at 4AM Thursday from NYS and ne PA across into SNE...  I think our lurker friend from LOT might confirm how unexpectedly far nw these bands can go.  Then SHARP SHARP drop off to nearly nil in possibly 60-80 miles north of that 25" IF it occurs as I can see this somewhere near ALY.  Idea...most of the Adirondacks may have nothing for less than 2".

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Jeff Grann

Jeff Grann

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1 hour ago, weatherpruf said:

It has happened; in December. I've seen it. Just need the right set up. This doesn't appear to be it.

Yes. It has happen and can still happen. But everything has to be perfect this time of year for NYC /coast to get these types of snows. There really is a tight window on December 15th from being fringed and having  mixing/changeover. Once you have most models tucking a low along the NJ coast, for people to still disregard the low placement because of clown maps is just pages of teenage wishcasting. Can everything shift SE in next 24 hrs and give the city a big dump? Sure. But until that happens, sticking to the reality instead of begging for the extreme in one's backyard makes the forum much more interesting... Like the New England forum. 

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