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Overnight runs looked impressive for Sussex. Even into northern Morris and Orange. ECM, RGEM, GFS, HRDPS...

Could be some surprised people up there if they wake up to saggy snow covered branches with some still leaf-covered trees. NWS Mt Holly is finally talking about the banding potential. If it sets up, someone is going to get pounded.

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1 hour ago, Allsnow said:

Nw jersey with elevation might get a surprise 

If it happens, it shouldn't be a surprise since even us amateurs have been talking about potential snow in that area for days. And multi-model guidance has been steadfastedly highlighting the potential. But it's been so long since we've had rain, much less snow, it will seem like a surprise no matter what.

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Great satellite presentation this morning.

https://www.meteo.psu.edu/ewall/PSUGOES_NE/loop30v.html

Synoptic setup with this event next 24-36 hours is really unique surface and aloft.  Really interesting setup.

Track of upper level low means some surprises are certainly possible in terms of snowfall.

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46 minutes ago, eduggs said:

Overnight runs looked impressive for Sussex. Even into northern Morris and Orange. ECM, RGEM, GFS, HRDPS...

Could be some surprised people up there if they wake up to saggy snow covered branches with some still leaf-covered trees. NWS Mt Holly is finally talking about the banding potential. If it sets up, someone is going to get pounded.

Areas aoa 750’ up here in Orange are def in for a nice surprise. 6”+ might not be out of the question. Above 1000’ I think might be a lock for those amounts 

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15 minutes ago, snywx said:

Areas aoa 750’ up here in Orange are def in for a nice surprise. 6”+ might not be out of the question. Above 1000’ I think might be a lock for those amounts 

Seems like a good call.

I worry a little about locking anything in these scenarios. The SLP and associated vorticity and precipitation shield is going to make a loop-de-loop of some sort with the radius of that loop dependent on how quickly the mid/ULL take on a negative tilt and cut off. Exactly where any stalled or retrograding banding sets up will determine who cashes in. My fear is that it pushes too far NW and then weakens by the time it rotates back in. Some ensemble members give almost nothing outside of PA and the Catskills. Others spread the wealth to Passaic, Putnam, Westchester etc...

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25 minutes ago, eduggs said:

Seems like a good call.

I worry a little about locking anything in these scenarios. The SLP and associated vorticity and precipitation shield is going to make a loop-de-loop of some sort with the radius of that loop dependent on how quickly the mid/ULL take on a negative tilt and cut off. Exactly where any stalled or retrograding banding sets up will determine who cashes in. My fear is that it pushes too far NW and then weakens by the time it rotates back in. Some ensemble members give almost nothing outside of PA and the Catskills. Others spread the wealth to Passaic, Putnam, Westchester etc...

I was strictly referring to orange W of the walkill River. Areas like Otisville, Mount Hope, Port Jervis, Greenville Mtn area are mostly above 750’ and far enough W to benefit 

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Upton’s thoughts, A section of their AFD

CAMs and regional models have diverged somewhat on the position of the movement of the low tonight. Some of the CAMs bring the center of the low just north of our area and a little to the east into the early night before having it retrograde to our west in Upstate New York while other just stick with tracking the low to our northwest. The more northeasterly track, regardless will only occur this evening into early tonight before bumping west. With the low tracking north of us this evening, cooler air will take over this evening with temperatures near or below freezing in interior locations north and west of NYC. Prior to this, temperatures will be in the 40s. A transition from rain to snow is expected this evening for interior areas north and west of NYC, but given the warm temperatures prior, snowfall may struggle to accumulate. Its possible we could see a few heavy bands of snow with snowfall rates around 1-2"/hr this evening into early tonight indicated by the 00Z HREF and a saturated dendritic growth zone before the precip gets cut off by a dry pocket of air that moves in when the low retrogrades westward into upstate New York. This dry air is easiest to see when looking at model soundings or at model 700 mb relative humidity. Higher elevations in interior locations northwest of NYC will most likely see accumulations of 1-4 inches. Western Passaic, Orange and Putnam Counties are now highlighted in the HWO for this potential. However, most of the interior northwest of NYC is at lower elevation and only a trace to 0.5" is expected due to warmer ground melting the snow and a short window for snow banding before the precip becomes much lighter from dry air intrusion. Snow ratios are also expected to be on the low side, further contributing to lower snow accumulations compared to what some of the CAMs are producing with 10:1 Snowfall.

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18 minutes ago, snywx said:

I was strictly referring to orange W of the walkill River. Areas like Otisville, Mount Hope, Port Jervis, Greenville Mtn area are mostly above 750’ and far enough W to benefit 

Agreed. One thing though, Port Jervis/Matamoras itself is below 500' but you don't have to go far, in nearly any direction, to gain elevation quickly. 

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Although it's early in the year, next week's setup is a good one, as there is a potent ridge over AK that's reaching all the way into Siberia, promoting cross polar flow. Perhaps most notably, there is a developing Greenland block that forces a 50/50 ULL (ULL over Nova Scotia, basically). As a vort gets ejected from the Rockies, the confluence from the 50/50 ULL may push colder, drier air into the flow and can prevent the main energy from shooting north. This is more of an overrunning to coastal or SWFE type event rather than a potent Nor'easter, to be clear.

This is a favorable setup for snowfall, even down to the Mason-Dixon line. If it was late Dec instead of late Nov, I would be more open to workable coastal snowfall, though that is a difficult ask given how warm waters are. The main points of contention are: 1) how quickly does the vort get ejected? 2) how much of the vort gets ejected? and 3) how strong is the confluence? I would argue that the confluence is the most important part of the setup... if it vanishes, there is not enough press from the cold air and the setup is DOA. However, if the vort comes out too early, it won't matter. This is unlikely, though... if anything, the vort would come out of the Rockies too late or too sheared rather than before confluence forms. How the 50/50 ULL trends is crucial to this setup and I will be watching that closely.

These cross polar flow patterns are pretty much the only ones cold enough to allow for snow at this time of year, and there is very high confidence in one developing. We are still at the range where the vort can get sheared to nothing, so the storm can still "disappear." Just don't write the threat off due to the time of year.

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1 hour ago, snywx said:

I was strictly referring to orange W of the walkill River. Areas like Otisville, Mount Hope, Port Jervis, Greenville Mtn area are mostly above 750’ and far enough W to benefit 

I think those places are in a great spot for this.

The caveat for me is that this looks like a localized event as opposed to a widespread snowfall. Mesoscale banding and terrain effects will likely play a role. I wouldn't be too confident anywhere until later tonight as the radar presentation evolves.

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As per yesterdays conversation pertaining to "Wrap around moisture".  Originally last week I thought this was progged to be a cutter (Upper level low over the Great Lakes)?  Then a secondary (Low level) storm developed over NJ?  Then some predicted ample wrap around precipitation on Friday?  Is this true wraparound moisture, or just the upper level low moving across and not weakening ,as usually does cry out?  As I said, Most wraparound precipitation and/or back end moisture rarely make it to the greater NYC metro area.  Do all the other models/ outputs still support the HRRR?

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1 hour ago, bluewave said:

Could see some heavy convection tonight over LI and CT with the low backing in off the Atlantic which would enhance the much needed rainfall.

 

IMG_1989.thumb.png.76d08c9eef6845c34340ee55135f82f9.png

 

 

The beginnings of this deformation axis are starting now over NJ and will expand NE over time. 18z HRRR has 1-2” more precip especially I-80 and N. It could be quite heavy for a while especially northern areas. 

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