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

[wdrag]

626A/16: Not much. 00z/16 EC op and 06z/gfs v16 (para) are best chance of a little snow this afternoon-night, mainly n of I80.  Doubt if NYC/LI can do more than T of snow-sleet if those elements occur. nw NJ might see spotty freezing rain showers tonight. Thread now converted to OBS-NOWCAST if and as needed. 

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543A/15: Below is my mental mesh of  modeling (lower than usual confidence) on what happens late Tuesday-early Wednesday. 

I78-I84 corridors-periods of light snow, sleet or freezing rain likely begin Tuesday afternoon or evening and ends as rain Wednesday morning. Modeling uncertain-so my confidence on how much ice/snow is less than usual. There is a pretty good chance of at least spotty icing in PA/NJ that may require treatments. If it's snow, just a slightest covering to maybe an inch or 2 but can't promise all snow except CT/MA. I can see the need for some caution traveling untreated surfaces Tuesday night-early Wednesday.  One model group: The GFS v15/16 have been hitting the snow harder along w the GEFS, for se NYS/extreme nw NJ/extreme ne PA with potential for 4" high terrain, if no ice.  One of my concerns is ice in ne PA/nw NJ. 

For NYC-LI: Even with snow snow or sleet in the air, NYC may not measure anything more than T if it's light.  If it manages the 00z/15 GFS scenarios, then yes, minor amount there. Better chance spotty minor amounts LI (under 1"). Follow the models.  I'd like to see models, other than the GFS, become more robust. For now, the GFS solutions are outlier heavier outcomes.  I don't know what to believe but the uncertainty on qpf volume, as well as thermal profiles suggest conservative expectations. 

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707A/14: 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. 

 

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554A/13:  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 as cold dry aloft sweeps south through New England) seem possible in much of the forum Sunday (14th), with scattered dustings in ne PA, CT, se NYS. 

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648A/12: Whittled down the days from 14-16 to just 16th. 

 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. 

 

604A/11: will  post additional impressions around 745A. Running a little late. 

As I see it... game on... if these models can finally hold serve as intended when the thread started. Even NYC might see a bit of snow.  IF, in the future, all this fritters to minuscule under 1" amounts of snow and only n and w of NYC, then this thread will hold for OBS/NOWCAST.  That's me thinking downside.

As of now, 00z/11 UK/EC ops trying for a hazardous snow event n of I80 (hills best for road acc at this mid March sun angle). I just haven't caught up yet with ensembles etc. At least now, the models are agreeing on an event of sorts directly NYC subforum, with a period of extensive ice/snow potential interior NC- New England, mainly nw of I95.  604A/11

 

Appended at 755A, with the GEFS ensemble maps later in the thread. 

Monday - Wednesday (15-early 17): Snow-ice probably ending as rain for a large chunk of the northeast USA.  Snow develops sometime Tuesday and ends by sunrise Wednesday either as ice or rain. Too early to lock in snowfall but my guess:  I84 anywhere from 1" minimum to a low chance of a much as 7" for a few high terrain locations. Models still uncertain on developments but something wintry is coming. EPS is the only ensemble less than 1/4" w.e. qpf now, and this was followed by WPC on the their overnight shift which has basically nothing for I84.  So uncertainty continues but from my perspective snow to ice is an 80-90% chance of occurrence for the suburbs w-n NYC, in part by the -NAO.  NYC, barring BL warming, I see a pretty good chance of snow or sleet to start on the 16th.  Please see attached 06z/11 GEFS ensemble 500MB for 18z/Tue-16 and 06z/Wed-17 with confluence to our north and nice short wave heading into the mid Atlantic.  I like this look and presuming it holds (still spaghetti uncertainty in the members- tho I don't think south bears the brunt of there snowfall anymore except VA's highest terrain). 

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659A/10 update added here at 746A.  00z-06z/10 modeling continues all over the place. In essence, I've no significant change to this thread.  Something wintry is coming.  EC looks too slow and both EPS/GEFS 500mb patterns shoot the decaying Midwest short wave across the area later on the 16th.  I expect that snow-sleet will overspread from the west, much of the I95 corridor  from Baltimore to New Brunswick, then on the 16th while changing to rain south of I78, overspreads the remainder of the forum by late in the day. How long the snow-sleet before a change to rain (except ice se NYS/CT/extreme nw NJ)? 

This should be the first of two or three foreseeable wintry events opportunities for the subforum though the last two should be mostly I84 corridor (18-19, 22-23).  My guess, if NYC is to get some snow, it has to be with this first opportunity (Tuesday the 16th).  

00z-06z/10 ensembles used to modify the op cycles which would say, forget it for the subforum on the 15th-16th.  This could be my mistake.  I tend to use ensemble patterns in the longer range and focus on the ops inside of 4 days.  659A/10

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251-3P/9: Graphics added on with the originating post at the end of this page.

Multiple 12z/9 ensembles are producing snow and ice for the NYC subforum beginning with possible scattered southeast moving cold shot snow shower dustings late Saturday or Sunday,  and then a widespread light-possibly moderate wintry event 15-16.  This one may even try to bridge back to another oncoming wintry event late 18-19, though with a 24 hour break later 17-18.  

Staying with the 15th-16th: Whether this wintry system goes the route of the most depressed GEFS, or the closer to LI, EPS and GGEM/GEPS?  Something wintry continues to keep coming and while the EC had its 1-4" north of I80 on the 00z/9 cycle it now had it south of I80.  This will be the first widespread wintry event of the second half of March,  and as Bluewave implied,  quite possibly more... this too signaled by the CFS for a few days (multiple NYC subforum snow-rain events). 

Graphics are the 12z/9 EPS snow (10-1), GEFS snow, GEPS snow depth returning south of I80 with a 00z-3/15 view and a 06z 3/17 view of SD 251P/9

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655A/9: Lot's of words follow, for the modeled proposed wintry mix solution early next week.

So, the door continues open for a small wintry weather event, snow-ice to rain with very low confidence for any snow accumulation - NJ coast-NYC. Modeling continues vacillating but it appears to me it's gathering a bit of a trend for a well defined warm frontal wave e of Cape May/s of LI. (not so the 00z/9 GGEM,). It's a WAA situation over the remaining cold influx of this weekend. The weakening short wave out of the Midwest, is delayed a day so will remove (early) on the 16th from the title and drop the 14th. Whatever might have occurred the 14th might still occur, but more so late Saturday the 13th but that is a very low chance and negligible.  Otherwise,  ensembles are less than 2" on snow acc.  Operationally the 00z/9 GFSv15-16 continue with minor ice/snow interior, while the 00z/9 EC... probably can't hold it's operational 00z/9 offering in subsequent cycles, but the EC just tells me, that that heavier single member option is still on table, as proposed a couple of days ago by multiple GFS cycles. In short: there is still a chance for snow-ice, but this is probably just your typical probably only minor event, destined mainly for the interior. This barring a reinvigoration and deepening eastward moving short wave out of the Midwest as the following short wave hurls the ridge northward behind it. Right now, 06z/9 WPC has spotty 10% chance of .25" frozen w.e. precip in the nw part of our subforum.  Another way to look at this, it's a 90% chance of non-occurrence.

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607A/8 Update: Closed low departure into midwest seems a little slower, so overall arrival may be delayed til late 15? Still looks favorable for a period of wintry qpf event anywhere in our subforum, with possibly something near the reinforcing CAA short wave Sunday, and then most likely the large scale event late Monday 15-early Tuesday 16. Think it's best to smooth out all the modeling lows and highs and see if this potential is still valid come this Wednesday morning (00/10 cycle). All ensembles (EPS, GEFS, GEPS) continue to give us some wintry qpf but just light nuisance  amounts. Will revisit this on Tuesday.

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A wintry event has been on and off for our area the period of the 14th-16th (another to follow ~the 18th?).

The 00z/7 EPS is driest of the ensembles but at least operationally it has a chance of flurries or a period of snow.  The 00z-06z/7 GFS v15 and 16 both have snow and ice possibilities for our subforum, but primary target-duration-amounts unknown. The GEPS also has a decent qpf event coming but it's snow depth change is not enthusiastic about snow.

The primary teleconnection indices are not favorable so I cannot be confident of snow NYC-LI but I do think we will see a ~1/4" of freezing-frozen precip into at least a portion of the NYC subforum by Tuesday morning the 16th.  (that could be snow-ice combo or just 3" of snow).  

The primary event is centered on Monday the 15th.   Typical late season caveats apply including light precip during the daylight hours (spring forward 1 hour on Sunday 14th to EDT) being almost useless for road impacts except wet road slow downs. Alot of this will depend on strength of the high over Quebec and how cold the boundary layer. 

This is basically a D8 outlook: So I dont want to encourage diving deep into snow dreams but something wintry is coming. Whether it's only I84 high terrain or more encompassing is tbd.  This will probably garner some attention in the coming days.  One graphic to demonstrate the emerging low in the Midwest 12z/14 with the confluence zone. (649A/7)

[NEG NAO]

06 Gfsv16 - 0Z Euro Op Comparison

[hudsonvalley21]

[CIK62]

GFS is making a small portion of almost 2" of rain,  into some snow that is self-cleaned away by the storm itself.         Two days ago it was 15" on the 19th.         Now the 19th. has a high of 64*.        For  another laugh see below.

But at any rate:

An even better run here, but remember this is just 2 runs out of the last 5 with snow.       Give me two more snowy runs to become a believer.

[MJO812]

[NEG NAO]

12Z GFS

[NEG NAO]

12Z GFSv16

[MJO812]

No talk about the GFS? 

[NEG NAO]

39 minutes ago, MJO812 said:

No talk about the GFS? 

The circus is in town...........

[weatherfreeeeak]

15 minutes ago, NEG NAO said:

The circus is in town...........

Lol

Would be  where the heaviest snow was all year 

[hudsonvalley21]

25 minutes ago, NEG NAO said:

The circus is in town...........

The Circus is always in town, it never leaves. 

[snowman19]

5 hours ago, hudsonvalley21 said:

The Circus is always in town, it never leaves. 

Circus indeed the 0z GFS and the Para GFS both have absolutely nothing now

[snowman19]

5 hours ago, hudsonvalley21 said:

The Circus is always in town, it never leaves. 

The GFS is the worst model there is, thank God it’s gone for good on St. Patrick’s Day. The 18z run was a hoot, showing “snow” in greater than 540 thicknesses during the day in mid-March. Lmfaooooo 

[wdrag]

607A/8 Update: Closed low departure into midwest seems a little slower, so overall arrival may be delayed til late 15? Still looks favorable for a period of wintry qpf event anywhere in our subforum, with possibly something near the reinforcing CAA short wave Sunday, and then most likely the large scale event late Monday 15-early Tuesday 16. Think it's best to smooth out all the modeling lows and highs and see if this potential is still valid come this Wednesday morning (00/10 cycle). All ensembles (EPS/GEFS/GEPS) continue to give us some wintry qpf but just light nuisance  amounts. Will revisit this on Tuesday.

[NEG NAO]

I think as of now the EURO OP is the model of choice - meaning basically a non-event throughout most of metro maybe some light precip northern zones as of right now.....hopefully things will change....

[wdrag]

Lot's of words follow, for the modeled proposed wintry mix solution early next week.

So, the door continues open for a small wintry weather event, snow-ice to rain with very low confidence for any snow accumulation - NJ coast-NYC. Modeling continues vacillating but it appears to me it's gathering a bit of a trend for a well defined warm frontal wave e of Cape May/s of LI. (not so the 00z/9 GGEM,). It's a WAA situation over the remaining cold influx of this weekend. The weakening short wave out of the Midwest, is delayed a day so will remove (early) on the 16th from the title and drop the 14th. Whatever might have occurred the 14th might still occur, but more so late Saturday the 13th but that is a very low chance and negligible.  Otherwise,  ensembles are less than 2" on snow acc.  Operationally the 00z/9 GFSv15-16 continue with minor ice/snow interior, while the 00z/9 EC... probably can't hold it's operational 00z/9 offering in subsequent cycles, but the EC just tells me, that that heavier single member option is still on table, as proposed a couple of days ago by multiple GFS cycles. In short: there is still a chance for snow-ice, but this is probably just your typical probably only minor event, destined mainly for the interior. This barring a reinvigoration and deepening eastward moving short wave out of the Midwest as the following short wave hurls the ridge northward behind it. Right now, 06z/9 WPC has spotty 10% chance of .25" frozen w.e. precip in the nw part of our subforum.  Another way to look at this, it's a 90% chance of non-occurrence.

[NEG NAO]

Now all of a sudden the EURO offers some hope for next week

[wdrag]

Multiple 12z/9 ensembles are producing snow and ice for the NYC subforum beginning with possible scattered southeast moving cold shot snow shower dustings late Saturday or Sunday,  and then a widespread light-possibly moderate wintry event 15-16.  This one may even try to bridge back to another oncoming wintry event late 18-19, though with a 24 hour break later 17-18. 

Staying with the 15th-16th: Whether this wintry system goes the route of the most depressed GEFS, or the closer to LI, EPS and GGEM/GEPS?  Something wintry continues to keep coming and while the EC had its 1-4" north of I80 on the 00z/9 cycle it now had it south of I80.  This will be the first widespread wintry event of the second half of March,  and as Bluewave implied,  quite possibly more... this too signaled by the CFS for a few days (multiple NYC subforum snow-rain events). 

Graphics are the 12z/9 EPS snow (10-1), GEFS snow, GEPS snow depth returning south of I80 with a 00z-3/15 view and a 06z 3/17 view of SD 251P/9

 

[wdrag]

00z-06z/10 modeling continues all over the place. In essence, I've no significant change to this thread.  Something wintry is coming.  EC looks too slow and both EPS/GEFS 500mb patterns shoot the decaying Midwest short wave across the area later on the 16th.  I expect that snow-sleet will overspread from the west, much of the I95 corridor  from Baltimore to New Brunswick, then on the 16th while changing to rain south of I78, overspreads the remainder of the forum by late in the day. How long the snow-sleet before a change to rain (except ice se NYS/CT/extreme nw NJ)? 

This should be the first of two or three foreseeable wintry events opportunities for the subforum though the last two should be mostly I84 corridor (18-19, 22-23).  My guess, if NYC is to get some snow, it has to be with this first opportunity (Tuesday the 16th).  

00z-06z/10 ensembles used to modify the op cycles which would say, forget it for the subforum on the 15th-16th.  This could be my mistake.  I tend to use ensemble patterns in the longer range and focus on the ops inside of 4 days.  659A/10

[LibertyBell]

1 hour ago, wdrag said:

00z-06z/10 modeling continues all over the place. In essence, I've no significant change to this thread.  Something wintry is coming.  EC looks too slow and both EPS/GEFS 500mb patterns shoot the decaying Midwest short wave across the area later on the 16th.  I expect that snow-sleet will overspread from the west, much of the I95 corridor  from Baltimore to New Brunswick, then on the 16th while changing to rain south of I78, overspreads the remainder of the forum by late in the day. How long the snow-sleet before a change to rain (except ice se NYS/CT/extreme nw NJ)? 

This should be the first of two or three foreseeable wintry events opportunities for the subforum though the last two should be mostly I84 corridor (18-19, 22-23).  My guess, if NYC is to get some snow, it has to be with this first opportunity (Tuesday the 16th).  

00z-06z/10 ensembles used to modify the op cycles which would say, forget it for the subforum on the 15th-16th.  This could be my mistake.  I tend to use ensemble patterns in the longer range and focus on the ops inside of 4 days.  659A/10

Walt is it possible with that first one that the mixing stays confined to south of I-78?

It looks like a southern storm.

 

[the moors in england]

icon has snow.

[wdrag]

I'll post additional impressions around 745A. Running a little late (slept in).

As I see it... game on... if these models can finally hold serve as intended when the thread started. Even NYC might see a bit of snow.  IF, in the future, all this fritters to minuscule under 1" amounts of snow and only n and w of NYC, then this thread will hold for OBS/NOWCAST.  That's me thinking downside.

As of now, 00z/11 UK/EC ops trying for a hazardous snow event n of I80 (hills best for road acc at this mid March sun angle). I just haven't caught up yet with ensembles etc. At least now, the models are agreeing on an event of sorts directly NYC subforum, with a period of extensive ice/snow potential interior NC- New England, mainly nw of I95.  604A/11

[crossbowftw3]

So....probable advisory level snow that probably doesn’t stay around? EC has temperatures spike into the 40s and 50s for most the next day 

[wdrag]

32 minutes ago, crossbowftw3 said:

So....probable advisory level snow that probably doesn’t stay around? EC has temperatures spike into the 40s and 50s for most the next day 

My guess is your's as well. That's the season.  If you get 4", I think you'll have an inch leftover before the next one.   I cant say for sure how much we'll get, tho I think minimum is 1" for I84. 

[crossbowftw3]

8 minutes ago, wdrag said:

My guess is your's as well. That's the season.  If you get 4", I think you'll have an inch leftover before the next one.   I cant say for sure how much we'll get, tho I think minimum is 1" for I84. 

1-4 with some 4-6” is a good range. If this is winter’s last gasp I’m all for it. Still need about another 7-8” to make average—funny to think again because ~65” is average for MSV, but this was a good winter regardless 

[wdrag]

8 minutes ago, crossbowftw3 said:

1-4 with some 4-6” is a good range. If this is winter’s last gasp I’m all for it. Still need about another 7-8” to make average—funny to think again because ~65” is average for MSV, but this was a good winter regardless 

Agreed - ditto here. am at 60.3" (if I measured reasonably accurately). I think you/we get some more 18-19, and then possibly again 22-23.  Thereafter,  NAEFS suggests warming and struggles for wintry weather returns to our subforum excepting robins (1" max) snow, but i haven't studied LR MJO etc, for which we should informed by others hereon regarding the chances of favorable indices for another surge of winter in early April. Right now, CFS looks pessimistic after the 23rd and not putting much stock in the 00z/06z cycles snow events this far south, after the 23rd.  

Let's see what we can muster Tuesday. 

[crossbowftw3]

Just now, wdrag said:

Agreed - ditto here. am at 60.3" (if I measured reasonably accurately). I think you/we get some more 18-19, and then possibly again 22-23.  Thereafter,  NAEFS suggests warming and struggles for wintry weather returns to our subforum excepting robins (1" max) snow, but i haven't studied LR MJO etc, for which we should informed by others hereon regarding the chances of favorable indices for another surge of winter in early April. Right now, CFS looks pessimistic after the 23rd and not putting much stock in the 00z/06z cycles snow events this far south, after the 23rd.  

Let's see what we can muster Tuesday. 

Which is exactly why I’m keeping shovels around for one more week, even though the much stronger sun lends itself well to rapid melting of virtually any snow now—today will be a good example of that as we start with some spotty areas around here still having full cover

[wdrag]

Monday - Wednesday (15-early 17): Snow-ice probably ending as rain for a large chunk of the northeast USA.  Snow develops sometime Tuesday and ends by sunrise Wednesday either as ice or rain. Too early to lock in snowfall but my guess:  I84 anywhere from 1" minimum to a low chance of a much as 7" for a few high terrain locations. Models still uncertain on developments but something wintry is coming. EPS is the only ensemble less than 1/4" w.e. qpf now, and this was followed by WPC on the their overnight shift which has basically nothing for I84.  So uncertainty continues but from my perspective snow to ice is an 80-90% chance of occurrence for the suburbs w-n NYC, in part by the -NAO.  NYC, barring BL warming, I see a pretty good chance of snow or sleet to start on the 16th.  Please see attached 06z/11 GEFS ensemble 500MB for 18z/Tue-16 and 06z/Wed-17 with confluence to our north and nice short wave heading into the mid Atlantic.  I like this look and presuming it holds (still spaghetti uncertainty in the members- tho I don't think south bears the brunt of there snowfall anymore except VA's highest terrain). 

 

[wdrag]

3 minutes ago, crossbowftw3 said:

Which is exactly why I’m keeping shovels around for one more week, even though the much stronger sun lends itself well to rapid melting of virtually any snow now—today will be a good example of that as we start with some spotty areas around here still having full cover

I'm looking at large patch 1-3" snow depth to start at sunrise here in Wantage, other areas fully melted. Still need boots to trod around the yard. 

[gravitylover]

Good waterproof boots. This is some good mud over still frozen ground ~3" down.