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

[uncle W]

Just now, mulen said:

Tough forecast haven’t been here for a while living in s. Florida now the one overlooked fly in the ointment is sst temp and how far the low is off the coast .watch buoy readings it’s fun and could give a good indicator on the coast for mixing issues .

hey buddy...hows it going...

[MJO812]

I cant believe how different the GEFS is from the EPS.  One is going to bust badly and I hope it's the EPS.

[SnoSki14]

1 minute ago, MJO812 said:

I cant believe how different the GEFS is from the EPS.  One is going to bust badly and I hope it's the EPS.

What does the EPS show?

[BxEngine]

1 minute ago, SnoSki14 said:

What does the EPS show?

Why? You declared the storm dead already. Sit this one out and wait for the next one.

[SnoSki14]

1 minute ago, BxEngine said:

Why? You declared the storm dead already. Sit this one out and wait for the next one.

I expect a few inches, that's not dead and I agreed with the 6" thump as long as models don't trend further inland.

[mulen]

Hey unc many moons remember the old original forum on the weather channel we got kicked off then eastern weather wow time flies.Feeling the storm though even if it doesn’t effect me anymore I remember the anticipation I’m kinda jealous lol hope you all get walloped keep those snow googles on stay well.

[uncle W]

Just now, mulen said:

Hey unc many moons remember the old original forum on the weather channel we got kicked off then eastern weather wow time flies.Feeling the storm though even if it doesn’t effect me anymore I remember the anticipation I’m kinda jealous lol hope you all get walloped keep those snow googles on stay well.

I remember being in Florida in Jan 2009 when a heavy snow warning for NYC busted and I was glad I was down there...

[crossbowftw3]

2 hours ago, wdrag said:

Good Tuesday morning, Dec 15.  I have no change in my previously expressed opinions regarding what I think is coming. Not the worst ever, by far, but this will alter pandemic normal lives.  If you have plans Wednesday and Thursday across parts of WV, western VA, PA, NJ along and northwest of I95 as well as NYS and all of southern New England, I would think twice (and probably change plans) about traveling there (especially 4PM Wednesday to 10AM Thursday).  Follow local NWS Warnings/Statements/ forecasts and that of local government officials. 

Other than e LI and portions of coastal NJ near and s of Toms River,  where an uncertain less than 6" of snow-sleet should occur, this will be a widespread 6"+ snow storm with a period of sleet possible in the overnight hours up to I80. The 45-50 MPH wind gusts are still expected on the coasts 9P Wednesday to 6A Thursday, This with the periods of heavy wet snow changing to sleet and/or rain should  result in extensive power outages, somewhere near or just east of the NJT, or on LI.  

Moderate coastal flooding is probable along the coasts-inlets for the Thursday morning high tide (follow local NWS guidance).

With a likely 10-20" of powdery snow from I80 (or I78?)  northward through the I84 corridor, it will be time to sit back and sip hot cocoa and get into the Holiday Spirit. 

Those with heart conditions, be careful...the snow will be wetter and heavier as you get close to NYC.  Otherwise removing a batch of snow around 9PM Wednesday will make it easier not to break overwhelmed with snow removal Thursday morning. 

My guess for CP is 6-10"--it will be wetter snow there and I think sleet mixes in and I could see 2-4" of snow on the ground there by 7PM. 

Top 20 snowfall potential exists for MPO, POU, BDR.  

Banding will be big and may overcome some slightly above freezing layers aloft to keep snow going over w LI and I80. The banding could yield isolated 2 foot snowfall somewhere near I84. These storms have suppressed areas and enhanced areas of snowfall and I've no way to predict where. So while you see the base snow amounts in the EC ensemble graphic... snow ratios will possibly add 10" to this in a few spots of ne PA or NYS, CT?  Then there are snow measuring guidelines, and the 30 MPH gusty wind fracture of dendrites overnight Wednesday as well as drifting that will make it a bit more difficult to figure out the amounts. You may want to regionalize your post-storm assessment (the mean of multiple snowfall abs within a 15 mile radius?)

Graphics are: NWS office collaborated impact product-please use as an experimental guidance.  WPC 304AM  QPF assessment. The EC EPS ensemble baseline 10 to 1 snow ratio snowfall (be careful southeast edge where sleet is treated as snow), the WPC probability of 6"+ and 18+". This gives a feel for confidence by the NWS and axis of concern. Added SPC Short Range Ensemble Forecast (SREF) plumes for snowfall amounts at LGA, AVP, POU, IJD. We see the spread in the members and mean (Bold line).  Then close with the two day top 20 snow accumulations - Note the shorter Period Of Record (POR) at some stations.  Sussex is in there to show that we have quite a hurdle to exceed here, but MPO, POU (valley shadow lower amounts??) and BDR are vulnerable for top 20. Follow local NWS products and the advice of officials. My posts do not represent the NWS, only utilizing all the available models-tools to the public including NWS generated products. I may be off-line many hours today and probably won't have a comment on whether I overdid this, until about 6PM tonight or 6AM Wednesday.  Have at it and do the downside checks to help keep perception of future reality, realistic, with hopefully few disappointments Thursday. 533A/15

 

I'

Walt,

What's your best guess on ratios inland? Still between 12-14:1 or even up to 16?

[lee59]

The Philly area has not had an inch of snow in some 650 days. The models are showing areas some 15 miles south of Philly getting almost nothing with this storm and some 15 miles NW of Philly getting near a foot.

[the_other_guy]

5 minutes ago, lee59 said:

The Philly area has not had an inch of snow in some 650 days. The models are showing areas some 15 miles south of Philly getting almost nothing with this storm and some 15 miles NW of Philly getting near a foot.

That is a staggering statistic. Has it happened before? Was 72-73 that long of a stretch?

[Brian5671]

Just now, jfklganyc said:

That is a staggering statistic. Has it happened before?

In 72-73 PHL had a trace of snow for the winter so if it has, I would bet it's in that time frame.   No other year other than last year recorded less than an inch. (.3 last year)

[wdrag]

4 minutes ago, lee59 said:

The Philly area has not had an inch of snow in some 650 days. The models are showing areas some 15 miles south of Philly getting almost nothing with this storm and some 15 miles NW of Philly getting near a foot.

Wow... TOUGH forecast.  I do think they will see sleet and rain after maybe 2" of snow to start. This based on 00z and 06z guidance.  Could be wrong but thats a quick guess. 

[lee59]

2 minutes ago, wdrag said:

Wow... TOUGH forecast.  I do think they will see sleet and rain after maybe 2" of snow to start. This based on 00z and 06z guidance.  Could be wrong but thats a quick guess. 

Snow lovers in that area are going to be real happy or real mad. Would not want to make that forecast.

[SnowGoose69]

1 hour ago, jm1220 said:

Certainly hope you're right. We definitely could see a tick back SE today hopefully for the reasons you mention. 

But even the amped models aren't all that bad for the NYC area especially. 6z NAM is about 12" in NYC (which actually is more snow than 0z run had), but the 700mb low goes north which means a huge initial thump to a dryslot. Much of the period that would coincide with mixing would be light precip in the dryslot, and then some snow as the low leaves. 6z RGEM also about a foot in NYC, 6z Euro about the same? The cold dry air should be our savior for at least that heavy initial thump, and the mid levels don't look horrible unless the WAA there is being underdone (which is possible). 

The big winner though is shaping up to be central PA to perhaps the I-84 corridor where that 700 low track means a heavy high ratio snow band forms and pivots there. Trying to think of the last time State College PA had over 20" in a storm-may have been March 3, 1994. 

The problem is on the NAM runs you have several hours where it’s snow but the layer from like 720-820 is 0C with a 60kt SSE wind.  If indeed that came to fruition I can guarantee you that layer verifies 1-2C easily and those periods are sleet 

[wdrag]

20 minutes ago, crossbowftw3 said:

Walt,

What's your best guess on ratios inland? Still between 12-14:1 or even up to 16?

That seems reasonable... Maybe some of the office AFD's will talk about snow ratios. If you have BUFLIT, I think you can look at ratio's there.  Also, there may be some blended 6 hourly atio product out there, but for now... ??? You've got it

[wdrag]

3 minutes ago, lee59 said:

Snow lovers in that area are going to be real happy or real mad. Would not want to make that forecast.

comes the territory--- they are paid and I know they like the challenge and reward. I did. 

[jm1220]

3 minutes ago, SnowGoose69 said:

The problem is on the NAM runs you have several hours where it’s snow but the layer from like 720-820 is 0C with a 60kt SSE wind.  If indeed that came to fruition I can guarantee you that layer verifies 1-2C easily and those periods are sleet 

Yep hopefully that’s wrong. The mid level low tracks are concerning. 

[crossbowftw3]

3 minutes ago, wdrag said:

That seems reasonable... Maybe some of the office AFD's will talk about snow ratios. If you have BUFLIT, I think you can look at ratio's there.  Also, there may be some blended 6 hourly atio product out there, but for now... ??? You've got it

BGM has kept pretty steady between 12:1-14:1 with their discussions so that makes sense. Temperatures don't break 30 Wednesday daytime and fall to between 17-20 nighttime. All I need to know--good work as always.

[SnowGoose69]

4 minutes ago, jm1220 said:

Yep hopefully that’s wrong. The mid level low tracks are concerning. 

At this stage anything after 03Z for long island as well as southern Brooklyn and queens might be sleet.  I won’t get into the possible change back to snow yet but I think that most areas wouldn’t see much.  The CCB would primarily  remain north and it’s usually hard to clean up the mess that gets made in the mid levels.  We sort of saw that on 1/25/00 after the dry slot 

[NJwx85]

Good morning and good luck to everyone.

While we're waiting for the 12z NAM to finish running, the 09z SREF mean has the heaviest axis of snow falling in Southern/Central PA up into SE NY and NW NJ with a swath of 12-18" in those areas. For most of NE NJ, NYC and the LHV the mean has 10-12" with lesser amounts as you travel South and East. I can only post the zoomed out low quality image.

[NJwx85]

12z NAM is more amped up through hr 25.

[sferic]

19 minutes ago, crossbowftw3 said:

BGM has kept pretty steady between 12:1-14:1 with their discussions so that makes sense. Temperatures don't break 30 Wednesday daytime and fall to between 17-20 nighttime. All I need to know--good work as always.

looking good for me. you, me and @snywx

[Edubbs83]

The earlier solutions of all snow for the coast seemed too good to be true. Always felt to early in winter climatologically to have a big storm like this be all snow for LI. Hoping for a solid 6” that isn’t washed away. 

[snywx]

3 minutes ago, sferic said:

looking good for me. you, me and @snywx

Interior bomb incoming. Should be widespread 12-24” throughout our area up here. We will have ratios on our side as well 

[sferic]

Just now, snywx said:

Interior bomb incoming. Should be widespread 12-24” throughout our area up here. We will have ratios on our side as well 

Is this a solid 12 hour or 12-18 hour event?

Do you see Blizzard warnings being hoisted later today or tomorrow?

[Northof78]

NAM quite cold, still odd precip shield, but 850s dont get above 0F down to Toms River area...and I have to say with this strong of a block/confluence, the heaviest precip that far from the low seens suspect to me

[NJsnow89]

Tons of mixing issues for the metro area 

[jm1220]

2 minutes ago, Edubbs83 said:

The earlier solutions of all snow for the coast seemed too good to be true. Always felt to early in winter climatologically to have a big storm like this be all snow for LI. Hoping for a solid 6” that isn’t washed away. 

In the long run it’s good to have sleet pounded into the snow pack anyway, it freezes into cement and takes forever to melt. 

[jm1220]

Just now, Northof78 said:

NAM quite cold, still odd precip shield, but 850s dont get above 0F down to Toms River area...

The high looks a little stronger which undoes some of the more amped tendency of the trough. Really want that to be as stout as possible. 

[Northof78]

2 minutes ago, NJsnow89 said:

Tons of mixing issues for the metro area 

Any mixing issues seem to be due to progged dryslot, lack of lift, very light precip...not overall warming