NittanyWx

Still expecting the inversion to hold for most north of the Island.  I'm a bit surprised Upton hasn't extended HWW further west as of this morning.  Think odds are pretty high of that verifying south shore and much of the Island at large.

13 minutes ago, MJO812 said:

So you are going with an op run that's definitely going to change  instead of a well thought post by a meteorologist?

Now you know how I feel.

47 minutes ago, IrishRob17 said:

And take a look at the snow accumulation map from that run…

 

I dk how many times this week I said that wasn't gonna be snow...

2 minutes ago, jm1220 said:

Inland that can work. Here as soon as the SE wind starts that hope dies.

*Far* Inland.

Would need a major (and it should be said quite unlikely) error with the northern stream to have much impact around the major cities like he's suggesting.

I dont want to speak for the guys at Mt. Holly or OKX, but I think they're waiting to see the northern stream piece sampled by our upper air network first given its importance to how far inland the low tracks.  That's the only thing I can think of at this point.

35 minutes ago, USCG RS said:

Sounds like they need a good Emergency Manager....

They need to be broken up and sold for parts.  As does PURA up here in CT.

10 minutes ago, sussexcountyobs said:

JCP&L is never ready. They're the worst.

I'll raise you one with Eversource up here in Connecticut.

1 hour ago, bluewave said:

You can see why the models have such strong wind gusts. The NAM forecast soundings have winds over 70 mph just a few hundred feet above the surface near the coast. Even stronger winds above that. 

 

I'm thinking the inversion holds north of the Island but I don't feel great about it.

This isn't good for LI.

14 minutes ago, Irishmick9 said:

Winter Storm Watch up for us in Sussex County. 5-7 inches of snow before changing to mixed precip. Pretty bullish by My Holly.

Think I'd be taking the unders there given trends today.  I know what they're thinking with the easterly fetch, but the mid levels always seem to warm quicker than progged.

I also don't get the 7" in Monticello, seems very high. 

13 hours ago, NJwx85 said:

Yes we're all aware of the strong LLJ but that CAD signature over the Hudson Valley is no joke. Perhaps 15 miles inland was a little bullish, but I think a lot of areas North of 287 and west of the GSP have a better chance of just drying up due to the proximity of the mid level lows rather than flip to rain. NYC South and East is a completely different ballgame unless things change drastically. 

Unless things change drastically everyone is changing over within 3 hours of precip onset.  It is a very, very brief window it can snow here before the column warms.  GFS this AM has the 0C 850 isotherm north of 287 by between 11pm and 12 AM Monday. 

You'd need the entire mid-level low structure shifted about 150-200 miles to make this work.

I am very interested in the timing of high tide vs LLJ cranking as this storm develop for Jersey.  Thankfully I believe that has the worst of the winds are in between high tide cycles, but subtle differences in timing could make for a pretty rough coastal flooding situation.

57 minutes ago, eduggs said:

Between I-287 and I-80... maybe even I-78 I definitely think there could be a few hours of snow before any flip. Decent cold in place with a slight upglide into terrain with that wind direction should be sufficient. A relatively early occlusion in VA might actually help us blunt the warm surge slightly. I also think north of the City into Rockland, and parts of Westchester could put down a little snow as well. I agree the duration is likely to be relatively brief. But it could be intense for however long it lasts.

A small period is fine.  I'd take the under on snow duration even up by 287/80 if thats the setup we get, you'll warm the 900-700 column very quickly with that setup.

That's not to say the GFS is even right on the the track or occlusion timing, but that 700mb low track is no good.  This ain't it.  

Just now, NJwx85 said:

I'm not saying that the warm air and eventual dry slot don't work out in the end but you're going to have several hours of snow inland before this happens. Look at those dew points over SNE on Sunday. Yes it's departing but you have a solid cold, dry airmass in place ahead of the storm.

I know what I'm looking at.  And that is not snow 15 miles inland for any appreciable length of time with those mid levels.   That is a screaming SE wind.

5 minutes ago, NJwx85 said:

For who? Not for Long Island or most of NYC but it's snow once you get 15 miles inland. Check the soundings. Doesn't flip over till the end.

I know exactly what I'm looking at and that's flipping over to sleet regardless of whether you're 15 miles inland or not.  You have a screaming SE fetch at the surface and mid-levels.  That type of track is not producing 12 hours of 'snow' 15 miles inland.

1 minute ago, NJwx85 said:

Quick dry slot this run.

About 12 hours of front end snow followed by dry slot as the low jumps from near DC to the benchmark.

It almost looks like a late developing miller B.

Need the mid level centers to pass offshore to have a chance at the back end CCB.

That ain't snow bud.

The kicker is annoying me.  Lotta potential here but it's too many little vorts and a displaced baroclinic zone.

May have to wait until next week.

20 minutes ago, MJO812 said:

If the models start showing 1 low then the amounts will go up.

There's very little point in looking at anything other than very short term stuff right now in the model space.  Looking for frontogenic forcing.

I bumped up an inch to 3-6 today and flagged higher east end and eastern CT.  2-5" west of 287

15 minutes ago, forkyfork said:

we're in a great spot with regard to the fgen circulation and the dendritic growth zone. i don't care about qpf output <3 

I'm using 2-5" right now and think I'll stay there unless the meso's really start going en mass towards a clean fronto band.  I see the potential I'm just not willing to commit to it yet.

Low side of range for those in jersey and lower Hudson valley, higher side potential for the south shore/east end.

Think a good O/U for the city is like 2.5" for those of you betting types.

I'm still more interested in that mid month period.

The deformation banding much more a function of timing of the deepening low.

Seems like a late bloomer that has upside potential, but most likely scenario still a light/moderate event.

12Z NAM is a good example of what happene if it deepens even just slightly on the later side.

Just now, bluewave said:

Yeah, overdoing precipitation and underestimating surface temperatures in strong WAA are a few if it’s biases. But changing over to a FV3 CAM based version may introduce whole new set of strengths and weaknesses. I know forecasters struggled through the recent GFS upgrades when the new model kept showing so many long range snowfall false alarms.  

I've long felt the consistent tinkering of these models is becoming a fools errand on several fronts and leading to more significant forecaster error.

A lot of these billed upgrades lead to only minor skill improvements and the yearly updates in an attempt to bias correct make it exceedingly difficult to figure out what those biases are from year to year.  Bybthe time you get the bias down it changes. 

That said, the one constant bias has been Euro massively overdoing low level cold after a snowfall.

32 minutes ago, bluewave said:

The NAM usually does a pretty good job from around 24hrs out. That’s why I am not a big fan of replacing it with some FV3 based CAM. Not sure why they don’t just stick with the NAM and upgrade it regularly like Canada does with the RGEM. The NAM does a great job when dry air is involved like yesterday. It excels when there is a warm tongue between 900 and 750 mb. And when there is a legit very heavy snow threat like January 2016 it’s a strong performer also. 

Its useful in those very specific situations but it really struggles with overdoing its QPF fairly often too.  

Trying to thread the needle, but I'd say accumulation chances are >50% for 2" or more in NYC Metro at this stage.

Agree that there are still over amp risks, but this is a decent spot to be inside 60 hours.

3 hours ago, EasternLI said:

It's a really tricky time period. How that jet extension interacts with the Pacific Ridge will determine a lot. Not really straightforward but maybe we can grab a progressive wave there. 

Essentially trying to thread the needle...any small piece goes wrong and the whole system is a dud for the immediate local area. 

Some interesting mid month trends, though I'd like to see this roll out of the 11-15 before getting too confident in this temporary relaxing of standing wave.

1 hour ago, snowman19 said:

This La Niña and -PDO mean business, very well coupled. As you pointed out that Niña standing wave is one of the strongest in history. If we don’t see a major SSW and we follow Niña climo, we are probably going to torch starting by late January and February…..

It's well correlated with this impressive warm pool in the WPac.  The problem isn't just the standing wave as it's also generating Rossby waves that are continuing to cause wave breaking and amping this Aleutian ridge.  It's a tough cycle to break out of right now.

It can snow, but it is significantly more difficult with this background state and it continues to be conducive to causing this PNA to dip and a lack of appreciable HP in Eastern Canada, especially with the Atlantic side looking as it does.

I think there are sub seasonal periods where you might be able to hit the sweet spot if you can eject a KW and/or get some westward propagation from an ERW timed with that.  Breaks the cycle of wave breaking for a few days and may allow the Aleutian ridge to roll over and dump some of this further east.

But right now this remains a challenge.