December 9th Storm - Snow Map

Good Morning,

We have been mentioning December 6th pattern change for some time now, and even called out December 9th as a date that may feature our first snowstorm. Alas, here we are and our first winter storm of the season is upon us.



What was originally looking like a glancing blow with little snow totals has changed drastically in the last 24 hours to a significant storm event for many. My original thinking was this would be a minor event because of the transient blocking in the NAO region and lack of HP or 50/50 Low to our north. However, things changed when models began showing a partial phase between the northern and southern branches of energy in response to the very positive PNA (western ridge) - which you can clearly see on this graph.





On the 500mb vorticity map valid for 1pm and 7pm Saturday, check out that piece of energy digging into the Midwest and toward the east coast. This energy was not always there on the models. But because of the extensive and strong western ridge, this piece of northern energy has no choice but to dig into the U.S. and try to phase with the southern energy. They never fully phase, but this northern energy is so strong is raises heights along the east coast which allows the low pressure that develops from the southern energy to track closer to the coast.



The low pressure takes a track to the 40/70 benchmark. The precipitation field is expansive in response to the partial phasing that is happening between each pieces of upper energy. It may not be a storm with the greatest frontogenesis, or lift, (mechanism that brings thick snow flakes, rates, and high snow totals), but it will be a moderate event for many.



Here is my snow map for this event. I am being mindful of dry air and a relatively quick moving system due to lack of blocking. Also, do not rule out mixing with rain along the Jersey Shore and southern/eastern parts of Long Island. This is why snow predictions may look lower than what some models are showing. Can't rule out isolated 6"+ amounts across parts of the area, mainly interior and southern NJ. Snow should start between 6-7am and end around 7-8pm.

Have fun

Frank, I am going to be grading you on this

Thank you Frank for the map and post you put up finally our first snowstorm of the season

Hey frank! What’s the start time for the north fork of LI specifically Orient point ,

Frank you and me paisan lock in step with this map - thanks for teh write up and work on this!!

Thanks Frank!! Excited!!!

Cool I'll take 3 to 6 bring it. I thought it was into Sunday morning so glad to know it should be clear by then.

Frank, can you clarify something... is Wilkes-Barre/Scranton area in C-2 or 2-4?

thanks for the map, i have some reservations with this storm so we'll see how it pans out for us north western peeps

I'm hearing snow growth issues area wide by the soundings anyone have any info

Frank's numbers look good to me. My thought is that the heaviest precipitation will be closer to the coast, but that being close to the still relatively warm ocean will keep coastal areas above freezing with two accumulations problems: 1. Possible mixing with rain and 2. warm surfaces where the snow will not stick as easily during the day. So I'm thinking in terms of actual accumulation the highest totals will be from about 10-15 miles inland from the coast back to the I-295/287 corridors just west of the Turnpike. Slightly less north and west of there (i.e. Sussex/Warren/NE PA) due to lighter snowfall from the storm still being maybe just a bit east of the BM, and slightly less south and east (i.e. coastal Monmouth/Ocean/Atlantic/Cape May) due to possible mixing and sticking issues.

billg315 wrote:Frank's numbers look good to me. My thought is that the heaviest precipitation will be closer to the coast, but that being close to the still relatively warm ocean will keep coastal areas above freezing with two accumulations problems: 1. Possible mixing with rain and 2. warm surfaces where the snow will not stick as easily during the day. So I'm thinking in terms of actual accumulation the highest totals will be from about 10-15 miles inland from the coast back to the I-295/287 corridors just west of the Turnpike. Slightly less north and west of there (i.e. Sussex/Warren/NE PA) due to lighter snowfall from the storm still being maybe just a bit east of the BM, and slightly less south and east (i.e. coastal Monmouth/Ocean/Atlantic/Cape May) due to possible mixing and sticking issues.

For those unfamiliar with Long Island, the northern half (generally north of the LIE) is very hilly and forested. 100-200' elevation is common. I'm at 181'. We are also 15 miles from the Atlantic Ocean so oftentimes we get much more snow then forecast due to the elevation and cooler temps. Tomorrow seems to be a classic set up for us.

So 3 to 6 good for brooklyn

I am not able to see the snow map which Frank has posted

Roger92 wrote:I am not able to see the snow map which Frank has posted

Are you able to see any of the images Frank Posted??

Yes, I seeing all images except the actual snow map.

Roger92 wrote:Yes, I  seeing all images except the actual snow map.

This work?

12z GFS snow map

Can anyone give me any idea how much snow in Wayne, NJ by noon? I teach at William Paterson on Saturday mornings and my students have their final paper due, evaluations of me to do, and a short lecture. Need to try to squeeze that in.

Ill be on my way down to LI tomorrow morning. Live updates will therefore occur from the Iannone residence lol

aiannone wrote:Ill be on my way down to LI tomorrow morning. Live updates will therefore occur from the Iannone residence lol

We all know St James usually ends up with at least 1-3" more than the rest of us LI'ers.

sroc4 wrote:

aiannone wrote:Ill be on my way down to LI tomorrow morning. Live updates will therefore occur from the Iannone residence lol

We all know St James usually ends up with at least 1-3" more than the rest of us LI'ers.  

Elevation and no ocean! It's a sweet spot!

sabamfa wrote:Can anyone give me any idea how much snow in Wayne, NJ by noon? I teach at William Paterson on Saturday mornings and my students have their final paper due, evaluations of me to do, and a short lecture. Need to try to squeeze that in.

1-3 inches

Frank_Wx wrote:

sabamfa wrote:Can anyone give me any idea how much snow in Wayne, NJ by noon? I teach at William Paterson on Saturday mornings and my students have their final paper due, evaluations of me to do, and a short lecture. Need to try to squeeze that in.

1-3 inches

How about me? Pittston, between Wilkes-Barre and Scranton.

mikeypizano wrote:

Frank_Wx wrote:

sabamfa wrote:Can anyone give me any idea how much snow in Wayne, NJ by noon? I teach at William Paterson on Saturday mornings and my students have their final paper due, evaluations of me to do, and a short lecture. Need to try to squeeze that in.

1-3 inches

How about me? Pittston, between Wilkes-Barre and Scranton.

By Noon? Not much, maybe a coating to an inch or 2