eduggs

14 minutes ago, snywx said:

18z GFS is a big time event for all of Sussex county, NEPA, most of Orange County. The retrograding & stalling aspect of this event is giving me Snowicane vibes. Snow W of the Hudson w/ rain in New England 

That's a good analog for this kind of yin yang wrapped up low. FWIW, archived snowfall for the Snowicane event is wrong in Putnam County, NY, presumably due to sparse reporting in that area. Above about 500ft there was 12"+ with widespread 18-24" up a little higher back as far east as about Fahnestock State Park. East of there it dropped off rapidly. All maps and records I can find seem to indicate that the Hudson River was the dividing line, even though I know from first hand observation that that wasn't the case.

I'm starting to think a winter storm watch isn't out of the question for Sussex and Orange tonight or tomorrow. Probably not since temps below 1000ft are marginal and the localized nature of the event makes it susceptible to small model shifts. But you can't ignore what the data is showing. There are several indications for an impactful winter storm event.

GFS follows suit with heavy snow for Sussex and Orange as well as some for Putnam, Passaic, Westchester etc. Very good agreement now for a fairly localized snow event.

16 minutes ago, brooklynwx99 said:

RGEM is advertising a highly anomalous ~522dm ULL E of LI... would bring heavy snow to NNJ verbatim even with marginal surface temps

this is about as dynamic of a setup as you'll see regardless of the time of year

 

Yeah the 18z RGEM is eye catching. Could be snow anywhere those high UVVs set up just southwest of the SLP. Some slight model disagreement about placement, so it will be interesting to see how radar and satellite evolve on Thursday.

To me this looks like widespread first flakes, but very localized heavy snow. NEPA seems to win regardless of model but hopefully NNJ and the Hudson Valley cash in some too.

8 minutes ago, snywx said:

As of right now if im in Sussex county, Western Orange, Pike, Sullivan I would be preparing for a heavy wet snow event. Most of those areas are elevated as well. 

Absolutely agree. As modeled in those areas it's bigger than anything I saw last winter. Quite a way to end a drought and herald in a more active period.

9 minutes ago, sussexcountyobs said:

I'll take that 13-14" at my house on that map!

Realistically that's probably a coating to 1" at 500ft, 2-4" at 1000ft, and 4-6" at 1500ft. 10:1 is only going to work out in extreme NEPA or the higher peaks of the Catskills. Banding is a wild card.

10 minutes ago, snywx said:

Damn 12z Euro is a full fledge snowstorm up here after 1" of rain.. Almost every piece of guidance has measurable snowfall in these parts

Yup. And it's not a random model blip. We have multi-run and multi-model continuity. Sure there are some important differences between the GFS, EC, CMC, Ikon etc that affect distribution of potential snow accumulations, but everything is pointing in the same general direction. I also think snow accumulations could be pretty localized Thurs night into Fri morning before precip. tapers off, the SLP fills, boundary layer temps warm slightly, and elevation/upslope influence takes over. Where does any banding sets up and what's the trajectory of the pivot?

Euro is a major snowstorm for Sussex County NJ above about 800ft. At this point considering model consensus you'd have to forecast snow for at least Sussex, western Orange, Ulster, Pike and Wayne PA and add snow possible, particularly above 500ft in Warren, Morris, Bergen, Passaic, Putnam, all of Orange and Westchester.

Any potential accumulations outside of elevated areas will probably be a nowcast determination. But thermal profiles certainly look cold enough above 1000ft and briefly below that, depending on intensity.

12 minutes ago, Dark Star said:

Wrap around moisture is usually a fail, more times than not?

Well sure. Locally it's difficult to get snow on the backside of a storm. That's primarily due to regional topography and the timing and placement of mesoscale features. The Catskills and Taconics do better due to the upsloping component instead of downsloping.

Chances are low by default in our part of the world. But we have a slow moving, mature mid and upper level low with strong moisture transport, excellent PVA, vertical accent etc. These are the prerequisites for a "wraparound" event, particularly in a marginal column. Whether the 500mb low and associated vorticity swings up into New England, northwest into CNY, or stays put in CT could determine if anybody locally whitens the ground.

This has positive bust potential written all over it. Soundings show 35-38F with rain/snow or wet snow on the southwest side of wherever the SLP tracks. But dynamic cooling in any intense banding could easily bring that to 33 or 34 and pounding parachutes. The cold air delivery has worsened slightly in recent runs unfortunately.

I think a few places could get a surprise coating to maybe an inch or two that were not expecting anything wintry. Still looks like the NJ-NY-PA border area up into the western Catskills is the place to be for a plowable event. but it's definitely worth watching even across Morris, Passaic, Putnam, Westchester etc.

Lots of people sleeping on this end of week event. Certainly most are focusing on the drought busting potential but also squinting into the distant future for a more perfect snow threat.

12z CMC and GFS look pretty wild for the immediate NW suburbs. Rapidly developing and stalling SLP wrapping moisture back into a marginally snow-supporting column. Any distinct banding could be fun. Modeling has been very consistent and if it holds this could be a fun nowcast. Highly trackable event!

33 minutes ago, Dark Star said:

All I see are cutters?

   Put on your glasses then.

Or more likely you're looking too far out into the future. THIS thursday-Friday is an I-84 elevation snow threat. The kind that Walt D is often all over.

We've got a Walt D. I-84 special modeled for Thurs - Sat morning but no Walt thread, which is unfortunate.

Most modeling now has first snowflakes of the winter for a lot of areas sometime during this period. Could also be a significant elevation snowstorm for at least a narrow area.

Red flags for snow for most of us are a downsloping wind trajectory and the brunt of cold air going south of us into the mid-Atl and only slowly oozing in. But there is plenty of model support for wet snowflakes even outside of the hill towns.

This is the first interesting setup since last March or maybe February. Heck it might even be more interesting than anything we had all last winter.

9 hours ago, CPcantmeasuresnow said:

Any chance we're looking at some snow for Thursday night? Seems like the chances for at least a couple of inches in the towns above 500 feet are a realistic possibility. Above 1000 feet even better, maybe several inches. 

If the model consensus is right, I think we could be looking at 4-6" above 1000ft in Orange County or the near vicinity. Poconos, NNJ, Hudson Highlights, Taconics, and Catskills all have a good shot at snow. The GFS, ECM, and CMC are all homing in on a narrow area of significant wraparound precipitation into a sub 534 thickness field.

The upper level evolution is pretty impressive. The 18z ECM in particular was incredible. There's a banding signal as well as the potential for a stall and long duration precipitation pivot. Exactly where any banding sets up will probably be the difference between some slush and several inches of snow. I'd like to be in the western Catskills or extreme NEPA for this.

If you averaged the ECM's thermal profiles with the EC-AIFS surface and upper level low tracks you'd have a pretty significant elevation snowstorm for NNJ and possibly SENY. The AIFS is a great track but 925 temps are +1 to +2 whereas the regular ECM is 0 to -1F.

Remember these 3rd party snow maps simply convert modeled frozen precipitation to snow at a 10:1 ratio. So it's entirely possible the model itself is correct in showing a snow ptype for 12 hours at 33-36F that doesn't accumulate at all.

6 minutes ago, skillsweather said:

To be fair Reed Timmer was claiming 100mph sustained winds and gust 200mph with tons of downed radio/cell towers and flying small cars in his stream. Which he either knows what hes talking about and was falsifying the storm for views or he doesn't know what hes talking about. Supposedly hes a well known storm chaser and a meteorologist.

Timmer tends to combine both.  200 mph gusts and flying small cars, huh? Impressive.

5 minutes ago, Radtechwxman said:

I'm not but doesn't mean I'm not educated on hurricanes. I understand land friction and you don't see same winds as over water. But also typically with a cat 4 you will see higher sustained winds and much higher gusts. But also I don't think there's a lot of recording stations capturing that so could be missed. I just found it interesting pressure was dropping till LF but we did see clouds warm on satellite esp in NE quadrant and wonder if something meteorologically was going on. Not properly mixing down winds, something like that. 

It's likely winds would have been a little stronger had the NE eyewall been stronger, which would have been magnified by the storm's forward motion. But I suspect you're right that the lack of reports from the immediate coastal area explains the lack of extremely high wind measurements. I bet 100-120 gusts were widespread within a mile or so of the Ocean.

8 minutes ago, Radtechwxman said:

Not what we're saying at all. Not expecting 140mph winds at all. But one would expect sustained winds near or over 100mph with some gusts of 120+. Perry gusted to 99mph. I would have thought sustained winds would be closer to that. Just seems underwhelming. 

140 mph is the maximum sustained winds in a tiny localized region over the open ocean. If you move in any direction away from the maximum winds, they will decrease quickly. Then on top of that, the effect of land is much stronger than people realize. That's why extreme wind damage from hurricanes is usually very localized. The surge is typically far more dangerous and widespread. 100 mph gusts more than a few miles inland is uncommon in any hurricane - even a major hurricane.

6 minutes ago, CoastalWx said:

Airport is south of town. 

So 15 miles or so inland? Even a quarter mile inland significantly reduces surface wind speed.

17 minutes ago, ScottB said:

I'll second not looking anything like 120/130 mph winds anywhere out of Perry. Watched several streams and looked relatively tame compared to what I was expecting. 

Perry is way inland. Little chance of major hurricane sustained winds there.

We go through this every time with landfalling hurricanes... Where's my 140 mph winds!!?? Due to friction with the ground surface, surface wind speeds are significantly lower over land than over water. So unless someone is literally right on a wind-exposed beach, which is not advisable in a surge scenario, it is very unlikely to record a peak wind speed anywhere close to what would be observed on the open ocean.

12 minutes ago, donsutherland1 said:

The GFS figure is from 10:1 vendor maps, not the NOAA.

Soundings show sleet during the height of the precipitation in NYC with a warm layer at 850 mb +/- 25 or so mb. Just as other model output is low skill at the timeframe involved, the same applies to the soundings. However, the other guidance is warmer. Until there is consensus toward the GFS idea, I'm reluctant to embrace the GFS's outlier solution.

The temperature chart merely illustrates the range for past storms with specified temperatures. The point is that typically storms with above freezing temperatures tend to have lower snowfall amounts. Only a few have been moderate or larger. North and west of NYC, things would be more favorable. But we'll have to see where things stand in a few days when model skill begins to improve and when the synoptic picture itself becomes clearer.

It's premature for the posting of operational model maps showing a snowy outcome for NYC. Indeed, just one member of the GEFS and not a single EPS member shows anything like the GFS did. There are many arguments for caution, not to mention that such events have been infrequent for NYC following winters as warm as the one the region just had.

In sum, the base case is against the 12z GFS's significant snowfall for NYC (not necessarily well north and west of it). Something lighter is currently in play for NYC, JFK, and LGA. Until much changes (synoptic details, model/ensemble support, deeper cold farther south, etc.), there's little reason to depart from the base case.

I am also largely discounting the 12z GFS solution locally. I think there could be snow somewhere in the northeast next weekend, but I think it's a longshot for NYC and the immediate suburbs. That said, there is some decent in situ cold on the GFS run specifically.

I also want to try to dispel the myth that the GFS produces snowfall maps. A model output can be perfectly accurate and seem completely wrong in terms of forecasted snowfall if 3rd party vendors are used. So we should usually just ignore them and use model output and forecast soundings.