OBS-NOWCAST any snow-ice-rain for the NYC sub forum Tuesday March 16, 2021

[NEG NAO]

This possible event is about thread the needle as you can get IMO . Too bad that HP and all the confluence / convergence involved would just relax a bit and get in a better position to allow the precip to reach here instead of being driven mainly south of us.........

[wdrag]

Two things:  V16 is not necessarily better than the GFS op.  I know it's going to be implemented on the 17th. It is another member. 

 

fwiw: modeling... a few times in the past 4 days, has been trying for back-backs snows in the forum (15-16, 18-19).  I know a lot of folks are down on 15-16, but just as the 18-19 (not threaded yet), think it good to check ENS and 500MB pattern.  -NAO is when best to go for snow here (thats the 16th with a possible last gasp snow the 19th as the NAO starts rising?).  So, on 15-16... and a possible future threaded 18-19 (that work will probably preclude being able to follow up very much-except evening),  ENS trends are helpful.  For the 15-16 event... watch the confluence zone and track of primary vort max. There will be pretty strong 850 inflow ahead of the 500MB vort, and into the confluence zone.  That's all I can say right now: I am monitoring confluence zone trends. 

 

[wdrag]

I think we need to focus on 3/15-16,  more qpf and sooner than some of modeling. GEPS 2m temps at 18z/15 and 16 look quite cold and certainly colder than any previous GEPS modeling.  This also fits the colder NAO phase.  GEFS has moved confluence north, at least temporarily,  so to me, there is no doubt about an event and the focus now is I78 northward, but just how much front end is wintry and how soon it arrives Tuesday are my uncertainties.  My last impressions on this til tomorrow morning, at the earliest.  Hopefully subsequent modeling comes together = snow/ice to rain for the forum on Tuesday the 16th, ending early 17th. 

[wdrag]

648A/12: Lots of words and uncertainty for a potential modest wintry event. This should be a bit simpler by now. 

00z-06z/12 GFS series is the only primary operational model holding onto a wintry event while most other operational models have dried up. That modeling disparity is not a good sign for an event as we draw closer to whatever transpires.  I do have some doubts about how this works out. 

By 430PM (2130z/12) this afternoon, you'll have a pretty good idea  via the 84 hour NAM whether the GFS is out to lunch by  checking the leading edge of whatever the NAM has against the predictions of the GFS.  For now, I think the 12z/12 84 hr NAM has to have leading edge close to CLE-PIT, and the 18z cycle something to BWI-AOO at 84 hours, and the RGEM has to pick it up as well.  If not, then prospects for the GFS solutions are probably evaporating and this c(w)ould be a wasted thread-busted expectation.  Of course the 12z/12 volatile EC will be available. 

 It's possible the dry air associated with cold surge Sunday-Monday will evaporate the oncoming warm front- vort max associated wintry precip,  as the decaying Midwest short wave shoots into the confluence zone here in the northeast.  

GEFS and even the EPS have a nice RRQ of the upper level jet pulling for us, with weak 850 WAA but lack a little punch on the LFQ of the upper level jet near 35N latitude. 

00z/12 GEPS and 00z-06z GEFS continue with modest qpf and relatively cold, so that 2-8 hours of snow-sleet is modeled coming for most of the NYC subforum Tuesday, including NYC-LI with a base snowfall near 1" (potential 4-5" highest elevations of I84 but that is completely qpf dependent).  It should begin ~6A western NJ/se NYS, maybe 8A-Noon NYC/CT.  It would then end as rain LI-NJ Tuesday night-early Wednesday along and s of I80 but possibly as freezing rain I84 corridor.

Again, my assessment is predicated on ensembles of GEFS/GEPS. It's not big but it appears to me to be the best wintry option for NYC the next week or so.  

The back-back (18-19 second event) is even more uncertain with respect to wintery elements and if there are back-back snow-ice events, I think best chance I84 corridor, which does not guide me to a thread, since 18-19 currently doesn't have big snow prospects for NYC metro. 

[LoboLeader1]

It might be time to give up on this storm and winter all together.  

[CPcantmeasuresnow]

8 hours ago, LoboLeader1 said:

It might be time to give up on this storm and winter all together.  

It depends on where in the forum you live. I’m sure people on the jersey shore gave up on winter two months ago. 

[wdrag]

Maybe WY/CO utilized too much of the energy,  so despite the short wave crossing our forum directly ~ Tuesday night, this thread will probably have been a waste of time.  Modeling has dried up.  Multiple 00z/13 ens and few models give us spotty light snow (or ice) Tuesday or Tuesday night but can't see this being a hazard now. In case it does the long odds minor snow measure in NYC, this might be the last decent chance of measurable snow in the city, associated with a -NAO?  So, while the door seems to have closed,  still worth a look once a while. 

In the meantime, a few flurries (unstable lapse rates associated the cold core aloft sweeping south through New England) seem possible in much of the forum Sunday (14th), with scattered dustings in ne PA, CT, se NYS. 

 

[wdrag]

707A EDT:Looked back on the original post of the 7th...  seems like we may be onto something, but considerable model uncertainty, which tells me nothing big and impact minor, as always intended, but at least, I think, targeting the NYC subforum with a wintry event. In checking back the snow snow shower threat for the 14th was introduced on the 9th. 

Wind driven dustings of flurries I84 corridor  with maybe a spotty half inch or so? (far N CT & Pocs). Wind gusts midday-this afternoon similar to those of early Saturday, maybe a touch higher with isolated power outages---generally 40-50 MPH. (I missed forecasting the gusts of early Friday where we in Wantage had 43MPH-320A).  No OBS thread anticipated since trees not leaved. Can post obs in March 2021, unless you wish an obs thread for the midday-afternoon wind. Just let me know.

 

Tuesday evening-Noon Wednesday:  I78 northward to I84 (Tuesday night-Wednesday morning). Looks like (not guaranteed) a period of snow and possibly ice. If snow, generally an inch or less (spotty 2" possible high terrain?). iI ice, it would be minor but hazardous for untreated surfaces during the Tuesday night hours.  For NYC-LI: same old uncertainty. EC for at least 3 cycles continues to insist on light snow with potential for a few tenths? I don't know.  I am aware the the EC overall was always driest well in advance and also much slower to arrive (apparently handling the Rockies closed low much better than the GEFS/GEPS).  Now am seeing some "possible" minor intensification of the short wave crossing our area early Wednesday.  Anyway, road impacts should be negeligible except high terrain untreated's at night. 

 

[wdrag]

We'll see what future modeling brings, but seems like the heavier trends are coming to the forum via 12z/14 guidance.  If the 12z/14 GFSv16 is right, there will be an OBS thread for measurable NYC/LI and up to 5" nw of the city (even the ICON is hitting the Catskills decently)..  Modeling for the mid Atlantic on this coming event has been highly variable...disconcerting and so I am unsure of the ultimate solution.  Will be interesting to see everything late this afternoon tomorrow as we draw closer. 

[hudsonvalley21]

15 minutes ago, wdrag said:

We'll see what future modeling brings, but seems like the heavier trends are coming to the forum via 12z/14 guidance.  If the 12z/14 GFSv16 is right, there will be an OBS thread for measurable NYC/LI and up to 5" nw of the city (even the ICON is hitting the Catskills decently)..  Modeling for the mid Atlantic on this coming event has been highly variable...disconcerting and so I am unsure of the ultimate solution.  Will be interesting to see everything late this afternoon tomorrow as we draw closer. 

To me it seems that the events at this time of the year (late winter early spring) can give some late 23rd hour surprises.

[crossbowftw3]

If this does become something, are we looking at uniform 10:1 or higher wrt ratios? I understand it's late season but also looking to fall at night.

Also looks like it generates a lake response for our friends upstate.

[snowman19]

3 minutes ago, crossbowftw3 said:

If this does become something, are we looking at uniform 10:1 or higher wrt ratios? I understand it's late season but also looking to fall at night.

Also looks like it generates a lake response for our friends upstate.

The GFS/Para is the only model showing this. It is an extreme outlier

[MJO812]

Looks like suppression to me

[wdrag]

26 minutes ago, hudsonvalley21 said:

To me it seems that the events at this time of the year (late winter early spring) can give some late 23rd hour surprises.

I am unsure what will happen,  but the pattern from then 7th on said, something wintry would occur here.  Modeling can't get a consistent grasp.  I sometimes wonder about sensitivity to different interactions and that at least in the ensembles and LR ops beyond 5 days, that some sort of dampening needs to be applied to the physics or the chaos is too much.  Again,  I don't know and this still could be a bust. The uncertainty is the flag not top lock in on anything. 

[NEG NAO]

27 minutes ago, crossbowftw3 said:

If this does become something, are we looking at uniform 10:1 or higher wrt ratios? I understand it's late season but also looking to fall at night.

Also looks like it generates a lake response for our friends upstate.

Only model showing significant accumulations in immediate metro are is GFSv16 - the new kid in town - taking over for the old sometimes unreliable GFSv15 - can't get onboard for anything more then a few snow showers until other guidance shows significant precip - I would keep an eye on the late week system - big strong 1042 HP in southeast Canada and a couple of systems passing just to the south

 

[wdrag]

21 minutes ago, snowman19 said:

The GFS/Para is the only model showing this. It is an extreme outlier

12z ICON?  12z UKMET T-2" nw NJ se NYS-CT.  12z EC?  Have no idea what it will say but suspect it will be close to prior 3 cycles.  

[wdrag]

2 minutes ago, NEG NAO said:

Only model showing significant accumulations in immediate metro are is GFSv16 - the new kid in town - taking over for the old sometimes unreliable GFSv15 - can't get onboard for anything more then a few snow showers until other guidance shows significant precip - I would keep an eye on the late week system - big strong 1042 HP in southeast Canada and a couple of systems passing just to the south

 

My eye is on it...   still too early for me...too much positive tilt.  But definitely worthy of further look.

[crossbowftw3]

12 minutes ago, NEG NAO said:

Only model showing significant accumulations in immediate metro are is GFSv16 - the new kid in town - taking over for the old sometimes unreliable GFSv15 - can't get onboard for anything more then a few snow showers until other guidance shows significant precip - I would keep an eye on the late week system - big strong 1042 HP in southeast Canada and a couple of systems passing just to the south

 

I admit that this whole week's potential for some wintry events has been rather hard to follow in part because of the v16's inbound implementation. I don't think this would be more than a minor event regardless.

[NEG NAO]

I think the Euro is a good compromise right now compared to the snowy GFSv16 and the other models showing nothing in the  immediate NYC metro

[MJO812]

7 minutes ago, NEG NAO said:

I think the Euro is a good compromise right now compared to the snowy GFSv16 and the other models showing nothing in the  immediate NYC metro

I dont see it being suppressive. The blocking doesn't look strong for a brief period. I think this has a chance but rain is more likely.

[NEG NAO]

Looking further down the road to later this week IMO if the 03/15 0Z models  such as the Euro show the system to the south similar to this 12Z out - its time to start a storm thread for it

[NEG NAO]

1 minute ago, MJO812 said:

I dont see it being suppressive. The blocking doesn't look strong for a brief period. I think this has a chance but rain is more likely.

with the EURO showing snow all the way down into Delaware  ??????

[snowman19]

9 minutes ago, NEG NAO said:

Looking further down the road to later this week IMO if the 03/15 0Z models  such as the Euro show the system to the south similar to this 12Z out - its time to start a storm thread for it

A storm thread for less than an inch of snow in NYC?

[MJO812]

12 minutes ago, NEG NAO said:

with the EURO showing snow all the way down into Delaware  ??????

What is going to suppress this ?

[MJO812]

4 minutes ago, snowman19 said:

A storm thread for less than an inch of snow in NYC?

It is possible the storm comes further north 

[JustWeatherWx]

 

35 minutes ago, MJO812 said:

It is possible the storm comes further north 

If it did verbatim it'd be rain. There is a very fine line to walk there.

Even so - have to look deeper than just the ptype maps in one snapshot now. The Euro is solidly above freezing at the surface, and it's falling at 18z on March 19th at light rates...sounds more like white rain to me more than anything - as modeled. One step at a time. 

[snowman19]

40 minutes ago, JustWeatherWx said:

 

If it did verbatim it'd be rain. There is a very fine line to walk there.

Even so - have to look deeper than just the ptype maps in one snapshot now. The Euro is solidly above freezing at the surface, and it's falling at 18z on March 19th at light rates...sounds more like white rain to me more than anything - as modeled. One step at a time. 

Agree. It’s time to let the snowstorm dreams go at this point. A 1001mb low on 3/19 isn’t going to get it done in the NYC metro area

[wdrag]

3 hours ago, NEG NAO said:

Looking further down the road to later this week IMO if the 03/15 0Z models  such as the Euro show the system to the south similar to this 12Z out - its time to start a storm thread for it

I agree: Will get it done tomorrow morning, once I'm a little more comfortable w it.  I think this is fitting the back-back concept in the 16 thread.  The modeling has seen many hiccups and so am not convinced of anything yet but can see equal amounts in the forum for both 16-early 17 and 19. 

[wdrag]

btw...NAM is starting to join the fray, need the GGEM/RGEM coming up. GFS v15 and 16 now in for NYC-LI potential measurable. I sort of expect the EC to come back tomorrow. What ultimately happens, unclear, but some sort of wintry qpf is coming to a fairly large part of the forum Tuesday and probably again Fri. Late season:  tougher accums but this thread continues in the game with a new one probable tomorrow morning if the EC/GFS can keep it lively. 

[winterwx21]

3 hours ago, snowman19 said:

Agree. It’s time to let the snowstorm dreams go at this point. A 1001mb low on 3/19 isn’t going to get it done in the NYC metro area

This is March. It's a wild, volatile month. Snow threats can pop up very quickly this time of year. We have to watch both threats for this coming week. It's most likely that NYC will see little to no snow accumulation this week, but it would be foolish to completely rule out something more significant. March is known for wild swings and snow events that are difficult to predict. And we can dream all we want. Most of us enjoyed the 70 degree weather, but it would be nice to get one last snow event to finish off the season. Especially since NYC is just shy of the 40 inch mark. It would be nice to see NYC get to 40 inches. We just need a small 2 inch snow event to do it.