eduggs

Not a lot of wiggle room on those GEFS for the metro area. The CMC looks quite a bit warmer.

The GFS has a really nice looking sounding for near interior areas. Really steep lapse rate in the lower boudary layer. That would probably be rain at 200ft and a winter wonderland at 500ft in NENJ and the Hudson Highlands. The NAM has an above freezing layer near 800 or 850mb that would probably mean mostly rain until you got near the Poconos, far northern NJ or western Orange County.

I still don't like the primary cutting off our "cold" air supply. This could be rain to pounding snow, ending as light rain or drizzle.

Two back to back ULLs are forecast to take basically the same track from northern Mexico/west Texas to near Chicago, separated by just over 24 hours. That's kind of funky. The second tracks slightly east of the first on most guidance, but the trough axis and airmass are little improved after the first. There is a forecasted weak high pressure center in eastern Quebec/Maine early Sunday and a slight hint of damning, but once again cold is really marginal until you get into interior SNE. Still I think any slug of heavy precipitation could bring the parachutes because the forecast soundings show mostly a boundary layer issue. Let's hike to our highest local hills and hunt for the snow line.

This looks like an elevation (800ft+) or intense banding deal for snow. 

It looks like the latest GFS still brings some wet snow to elevated areas N&W of the City, but I still don't like the ULL track heading up into NNY. The primary surface low holds on a little too long, keeping a southerly component to the flow through the low and mid-levels until late in the game. So the area appears to get dryslotted with backside precipitation limited to upstate NY and NE.

I'm glad there are at least a few wintry threats to track, and this event could still be salvaged, but it needs some work.

Just now, 40/70 Benchmark said:

I'll take your word for it......I took a quick look and it seemed warm with a track over the cape. Baby duty, though.

It's a little warm, especially early. But the rapidly deepening low makes up for it. A solution that intense is doubtful though. But that would be some seriously intense snow.

2 minutes ago, 40/70 Benchmark said:

Not me, which all I care about.

You look pretty snowy to me based on that CMC depiction. Isothermal column pounding pasty parachutes.

That's a ton of QPF on the CMC. Someone's getting a paste bomb if that's close to right.

5 minutes ago, HeadInTheClouds said:

I like a cmc/Euro/ukie blend. The GFS is out to lunch and is once again playing catch up. 

The op GFS is definitely on its own a little bit.  But I don't think it's as far off as it appears at the surface. I expect the GFS to shift slightly closer to the coast with the surface low in future cycles. I just hope the mid-level low doesn't track too far north. I'd like to see it a little further south before - hopefully - closing off several isobars. I think you're in a pretty decent spot up there in Dutchess if this thing does develop. 

The CMC looks like it drops a lot of QPF all across the area. That depiction probably dumps 6"+ across elevated parts of the NW interior.

A GFS CMC compromise solution for Sunday might look interesting for most of the area. In fact you could throw the EC, UK, and even ICON in there for good measure and the inter-model average is intriguing. Still plenty of spread on the ensembles.

The initial mid-level low track might be fairly far north.  But a late developing coastal low could crash the column at the last moment. Not a perfect snow setup. Maybe that's why this one feels like it's sliding under the radar.

The new CMC is much warmer than last night's run.  Still has some sleet or freezing rain to start, especially NW areas. But it's not nearly as interesting as yesterday. The follow up coastal is gone too. It looks like maybe the 0z was a blip. It's been so tough to get any momentum going lately.

The 12z GFS still looks really ugly for Jan 1st and 2nd. The might be some ice in that solution for favored northern locations, but the warm push is too strong. There does appear to be some room for a better phase for the follow up coastal system on the 3rd and 4th. This system doesn't have much cold air to work with either, but it could be enough with a slightly more wrapped up mid level low.

Just now, MJO812 said:

Big battle going on with the models now with the NAO and PNA.

Yeah you could describe it that way.

But models don't know or care what the NAO or PNA are. Models just represent the physics. Climate indices are a way of simplifying and quantifying complex atmospheric states for easier human understanding.  They aren't tangible things that have causal effects on anything.

Great CMC run. No deep cold, no major snow events, and complex shortwave interactions that will likely keep changing, but it's the best midrange run in a while!

The brutal stretch continues with virtually no trackable wintry threats for the foreseeable future. It's been almost 2 weeks of unfavorable model runs across the full suite since a few days before the December 17 event. Hopefully the wait will make it sweeter when the snow tracking resumes.

The problem with the 0z GFS is that after the likely near miss at day 6 there's nothing in the hopper for the rest of the run.

3 minutes ago, LibertyBell said:

It can actually be seen immediately after snowfalls when models start to correct to colder scenarios.  I distinctly remember this happening in 1993-94 and meteorologists talking about how snowcover was making airmasses colder than what the models had progged them to be before the snowstorm occurred.  It also affected the track of storms (they were tracking farther south than originally progged to) because of more than expected cold air pushing southward.

I wonder if the same might have been the case in 2010-11 which you might remember was forecast to be a mostly snowless winter, but it all turned on a dime on Boxing Day and then we had a very snowy stretch for about 5 weeks with long duration snowcover.  It makes me wonder if that completely unexpected snowstorm hadn't occurred, how the following 5 weeks would have turned out

 

 

I don't buy this. Local snowcover definitely decreases surface temperatures, especially during clear, windless nights. So weather models, especially back in the early 90s, might have over-estimated temperatures when there was snowcover.  It might also shift marginal wintry situations slightly colder, although this is questionable. But I believe that any significant impact of regional snowcover on synoptic scale track/features is anecdotal and not scientifically well supported.

Great run for northern half of NE.  Past few runs have been moving in that direction. I hope the trend continues. I love the lagging and separation of the s/w deep down in TX from the northern stream day 4.5.  But I'd like to see a little less phasing with the follow up trof swinging through the mountain west right behind it. I still think this is probably a Lakes cutter. But this makes it slightly more interesting to track.

2 minutes ago, LibertyBell said:

You dont buy the concept that a persistent snowcover from an early season snowstorm breeds more cold air and blocking resulting in a higher probability of more snowstorms in the next few weeks immediately after that initial storm?

 

No. I think any effect on synoptic level features is marginal. To the degree that snowcover affects large-scale patterns, it is hemispheric snow cover not regional snowcover that drives the influence.

Just now, NEG NAO said:

calculate the percentage from this:

monthlyseasonalsnowfall.pdf (weather.gov)

That's a nice compilation of the past. But it doesn't tell us a whole lot about the future. We can try to make inferences to correlate, for example, December with the entire season, but we'd be on really shaky statistical ground.

22 hours ago, donsutherland1 said:

The definition is qualitative, not quantitative. Measures such as the NAO and AO can provide related quantitative information.

https://glossary.ametsoc.org/wiki/Blocking

Exactly my point. If you want to make predictions regarding weather likelihoods based on climatological indices, you have to be precise about the locations of both the weather and the indices in question. A "blocky" pattern is a very broad statement that can have a wide range of implications for the northeast US.

5 hours ago, NEG NAO said:

In addition take a look at previous seasons when NYC received over 10 in. of snow in December and report back....

I don't think one December storm has much bearing on how the rest of the season will play out.  Places that are above average snowfall for this date probably have a better than 50% chance of finishing above average for the season.  But that's about all you can say.

3 hours ago, HeadInTheClouds said:

Tricky rain/snow lines are a part of many storms in this area. A lot of places just north and west of NYC got a foot or more. My point stands. You cant throw in the towel in early December or late December for that matter. Same posters do it all the time. Yawn. 

Past snowfalls cannot predict future snowfalls no matter what some wannabe statisticians say. So I agree nobody should be throwing in the towel. Snow events often come unexpectedly. And you're right that most of the area has already received a moderate to major snowfall event. I would just caution against using snowfall totals from any specific location to make general claims. It seems like you're saying the same thing. In parts of the mid-Hudson valley 12/17 was a major event.  And in some parts of C and NNJ it was barely a moderate event.

10 minutes ago, HeadInTheClouds said:

Funny how certain people are throwing in the towel again. Blah blah blah. Central park stands at 10.5( I got 16) and same prognosticators were throwing in the towel in early December, lol. Still a long way to go. 

The immediate NYC area got a little lucky in terms of snowfall on Dec 17.  Lots of areas surrounding the City received noticeably less.