Dec 8th - 9th (2nd wave/winter storm discussion)

[Isotherm]

Why would you say that the "cold air is going to hang TOUGH"? How do you know that? I would say it's unlikely, possible but unlikely. Heights are near 570 screaming upper level winds out of the sw and you're dealing shallow cold air that isn't that cold. And, there's really not much high lattitude blocking, maybe some, but minimal at best!

WX/PT

 

 

Strongly disagree. I assume you meant high latitude blocking on the Atlantic side, because in general, you'd be incorrect. We have a significant -4 to -5 standard deviation negative EPO block in progress for the next week on the NPAC side.

 

Additionally, the following 2m temp map illustrates temperatures that are far from what I'd call shallow cold, especially given it's the first week of December.

 

I'm not arguing anything pertaining to the precipitation type of next week's events, but your comment about little high latitude blocking and shallow cold is wrong in my view.

 

[SnoSki14]

It's early, but the way these maps look, I would not think we'd get much frozen if any. Perhaps a little at the start or end of the event. But I'm really not impressed at all. Generally, in order to get accumulating snow (there's no rule on this), but 564-570 heights are too high.  If they come down, then there's a chance for more frozen here. As of now, the frozen looks more like central and northern New England and central PA, Poconos, parts of the Hudson Valley, Catskills, central NY State, maybe. But the maps can change and we shall see how things trend as we get closer.

WX/PT

 

Understandable, too much SE ridging then given those high heights.

[Snow_Miser]

This is an instance where we have normal to above normal height anomalies, but we are colder below because of the poleward -EPO.

 

 

 

[Wxoutlooksblog]

Understandable, too much SE ridging then given those high heights.

Not only that, somebody mistakenly commented that the high is in a perfect position! NO WAY. It is in a HORRIBLE position. It's perfect BEFORE the event. It moves quickly out east over the Canadian Maritimes and out into the northern Atlantic. Screaming se winds around that and the incoming system off of a 50 degree ocean. The more I look at this, the less frozen it looks.

WX/PT

[Isotherm]

It's early, but the way these maps look, I would not think we'd get much frozen if any. Perhaps a little at the start or end of the event. But I'm really not impressed at all. Generally, in order to get accumulating snow (there's no rule on this), but 564-570 heights are too high.  If they come down, then there's a chance for more frozen here. As of now, the frozen looks more like central and northern New England and central PA, Poconos, parts of the Hudson Valley, Catskills, central NY State, maybe. But the maps can change and we shall see how things trend as we get closer.

WX/PT

 

 

 

I generally agree on the height comment. 560dm is about the maximum for snow in this area.

 

 

Here's an example from Jan 7-8 of 1994, tight thermal gradient, heights around 558-560dm

 

[jm1220]

GGEM accumulated precipitation maps from Meteocentre have around 5 or so mm of sleet, and 10-15 mm of snow, FWIW.

Models notoriously underestimate warm air at mid levels (750-800mb especially). This setup strongly favors maybe a small area of snow but a lot more sleet/freezing rain, and that probably inland. For us it could be a quick transition to rain if we have east winds.

[Snow_Miser]

Models notoriously underestimate warm air at mid levels (750-800mb especially). This setup strongly favors maybe a small area of snow but a lot more sleet/freezing rain, and that probably inland. For us it could be a quick transition to rain if we have east winds.

 

It should be interesting to see how models trend over the next few days or so with the mid level warming.

[IsentropicLift]

I don't see this as favorable for frozen for this area. Maybe some freezing rain but that's questionable. I see this threat going one of two ways. Either the high trends stronger and this mess is all suppressed to the south or we start as very brief frozen before we torch and we end up in the 50's with rain by Monday afternoon. I would be more excited if I lived Philly south.

[Isotherm]

Models notoriously underestimate warm air at mid levels (750-800mb especially). This setup strongly favors maybe a small area of snow but a lot more sleet/freezing rain, and that probably inland. For us it could be a quick transition to rain if we have east winds.

 

 

Depends upon the track of the 850 and 700mb lows as well, but yes in general mid level warmth is understated. However, it's too early to know where exactly the baroclinic zone will set-up and the magnitude of the SE-ridge. If our starting point is colder than currently progged, we'd see a longer period of snow. And vice versa.

[earthlight]

The EPO block is massive and so the cold air over the Northern tier or 1/3 of the US will inherently be a bit more substantial than usual. To say there is minimal blocking is silly considering how the modeling is handling the EPO.

That being said we still have a few problems with the set up that we will have to tackle before we start thinking snow. First of all, I think the quality cold air will be relegated to the northern suburbs and into New England. The eventual movement of the arctic front will have a big way in this as well. Second, the individual perturbations are unpredictable at this point and we can't expect the models to have a good handle at this range. So much of the potential is still heresay at this point.

Third, the big trough located to our west means that we will have to deal with mid level centers naturally tracking north and west of us with the vort max tracks over the Mississippi and Ohio Valleys. So we will need a mechanism to force those southward in order for us to keep whatever cold air we have in play, and not allow the mid level warmth to surge with the southeast ridge waiting to flex it's muscles.

It's good to see some wintry potential on the models -- and I'm glad we're back in the swing of things (this is my first post of any substance in 6 months). But I suggest we all exercise some caution and put things in perspective before we go claiming a good or bad set up just yet. Lots of time.

[Storm At Sea]

I'm in awe that we are talking about precip type 6 days out. Absolute awe.

[96blizz]

I grew up in Monmouth County,NJ and now live in Sussex County, NJ.  This set up is remarkably reminiscent of the many times in my youth I was irritated to get a quick switchover to rain while the N&W burbs hung onto snow/sleet/frz for a prolonged period of time due to strong CAD. 

 

Suffice it to say, I'm much more optimistic with a set up/potential storm like this at this time of year sitting up here in the hils of NJ...

[earthlight]

I'm in awe that we are talking about precip type 6 days out. Absolute awe.

You shouldn't be. This happens all of the time, and you've been here long enough to know it would be coming as long as we had a mixed precip event at this range.

The difference is that most people seem a bit more level headed as far as expectations are concerned this year. We'll see how long that lasts.

[Snow_Miser]

The EPO block is massive and so the cold air over the Northern tier or 1/3 of the US will inherently be a bit more substantial than usual. To say there is minimal blocking is silly considering how the modeling is handling the EPO. That being said we still have a few problems with the set up that we will have to tackle before we start thinking snow. First of all, I think the quality cold air will be relegated to the northern suburbs and into New England. The eventual movement of the arctic front will have a big way in this as well. Second, the individual perturbations are unpredictable at this point and we can't expect the models to have a good handle at this range. So much of the potential is still heresay at this point. Third, the big trough located to our west means that we will have to deal with mid level centers naturally tracking north and west of us with the vort max tracks over the Mississippi and Ohio Valleys. So we will need a mechanism to force those southward in order for us to keep whatever cold air we have in play, and not allow the mid level warmth to surge with the southeast ridge waiting to flex it's muscles. It's good to see some wintry potential on the models -- and I'm glad we're back in the swing of things (this is my first post of any substance in 6 months). But I suggest we all exercise some caution and put things in perspective before we go claiming a good or bad set up just yet. Lots of time.

 

Great post John. I think it's way too early to say how this storm will end up. Lots of time for this to change like you said. 

[SnoSki14]

You shouldn't be. This happens all of the time, and you've been here long enough to know it would be coming as long as we had a mixed precip event at this range. The difference is that most people seem a bit more level headed as far as expectations are concerned this year. We'll see how long that lasts.

 

The rather benign couple of years has calmed the snow weenie in many so expectations are far less than they were following the winters of 2009-2010 and 2010-2011. 

[PB GFI]

I think  you are are going see the models go to back and fourth over the next 3 to 5 days determining the position of the frontal boundary ,determining

the exact position of the PV and strength of the Ridge .

The source region of this air is thru Canada and is not Pacific air and the models sometimes warm low level cold air too fast .

But yes on an EAST wind in mid Jan you will rain on the coastal plain , so my issue isn't precip type 7 days out  that's just gona get sorted by path and circulation .

For me its which model has a better handle on the strength and position of the PV , because its goin to be that simple.

Since Mid OCT  the cold has won  this neg EPO means business , so if the boundary is going to get pushed to the Mason Dixon line , this is the type of

events it does it in .

But living here im never shocked if  I see it forecasted to be sitting over the MASS tpke either in 5 days .

[earthlight]

Strongly disagree. I assume you meant high latitude blocking on the Atlantic side, because in general, you'd be incorrect. We have a significant -4 to -5 standard deviation negative EPO block in progress for the next week on the NPAC side.

Additionally, the following 2m temp map illustrates temperatures that are far from what I'd call shallow cold, especially given it's the first week of December.

I'm not arguing anything pertaining to the precipitation type of next week's events, but your comment about little high latitude blocking and shallow cold is wrong in my view.

I'm really interested to see how far east the cold air can progress across the northern 1/3 of the US. The models have been waffling a bit on this and I have a feeling it'll have a huge impact on whether we get wintry precipitation at all.

Obviously the individual perturbations are extremely important...but on a large scale, in terms of where the cold will make it..I always get excited to see where the first real winter cold air sets up. Sometimes it ends up repeating and becoming a pattern throughout DJF.

[alwaysready126]

The rather benign couple of years has calmed the snow weenie in many so expectations are far less than they were following the winters of 2009-2010 and 2010-2011. 

LOL.  I was a snow weeny until I realized at the end of last winter that just because we haven't had a blizzard in a couple of years, doesnt mean we are going to get one on that premise alone.  If conditions are not favorable, they will not change because they feel like becoming favorable.  There is no rhyme or reason.  I've learned oyu have to look at the big picture.

[Weathergun]

The 925mb inland low causing SE winds at that level, was what gave us mostly rain last December, with the miller B coastal. This is what the 12z GFS is showing for this storm:

 

[IsentropicLift]

The 18z GFS has like 0.10"-0.25" before the surface freezing mark moves north of the city. The NW burbs stay locked in a bit more. Looks like 2-3" of rain spread out over 3 events in five days.

[Snow_Miser]

The 18z GFS is warmer than the 12z GFS because of a stronger surface reflection in the lakes when compared to the 12z GFS. This allows for more WAA to overcome the CAD quicker, and you get a warmer solution as a result. The 12z GFS transfers the low to the coast, and this lessens the WAA. Of course, this is no where even close to being resolved. The 18z GFS is the left panel at 159 hours, while the 12z GFS is the right panel at 165 hours. 

 

[MJO812]

Weenie run of the DGEX

[IsentropicLift]

Have a feeling that this trends more suppressed. Looks like a setup where Philly to DC gets hammered and up here in the northern burbs we're chocking on virga. I hope I'm wrong.

[SnoSki14]

Have a feeling that this trends more suppressed. Looks like a setup where Philly to DC gets hammered and up here in the northern burbs we're chocking on virga. I hope I'm wrong.

If anything it would trend further N&W given the SE ridging, why would it trend further south?

[MJO812]

If anything it would trend further N&W given the SE ridging, why would it trend further south?[/quote

The power of the high to our north. The epo has been doing wonders in our pattern.]

[IsentropicLift]

If anything it would trend further N&W given the SE ridging, why would it trend further south?

Right now the front is forecasted to drape right over the area but even on the 18z GFS Philly recieves quite a bit more precip than NYC. If that front ends up even 100 miles further south, we're high and dry. If it trends further north, we get torched. Just not an ideal setup for snow for us.

[IsentropicLift]

If the trough tilted a little more negative, those images look eerily similar to BDS, 2010. Hows that for weeny-ISH???

Look how sharp of a cutoff that is.

[MJO812]

Have a feeling that this trends more suppressed. Looks like a setup where Philly to DC gets hammered and up here in the northern burbs we're chocking on virga. I hope I'm wrong.

These types of events are so hard to pinpoint a week in advance.

[Heisy]

If the trough tilted a little more negative, those images look eerily similar to BDS, 2010.  Hows that for weeny-ISH???

 

Not really since the vortmax is over NW PA and not overseas, If that trough deepened it'd be a snowstorm, but anymore you're risking rain. 

[SnoSki14]

The pattern is more promising than one might think. At least it's not a full on coast to coast torch like in past Decembers. The pattern is pretty epic for the Pacific NW and the amount of cold coming down for the northern plains is nothing to sneeze at either. They'll be seeing downright dangerous wind chills of -30 to -40 or lower.