OBS-NOWCAST: Back-Back snow accumulation risk (late March 16). This thread focused on March 19, 2021

[winterwx21]

I see GGEM just joined GFS and GFSv16 tonight in giving us a decent burst of snow friday morning, putting down a couple inches.

[SnoSki14]

11 minutes ago, winterwx21 said:

I see GGEM just joined GFS and GFSv16 tonight in giving us a decent burst of snow friday morning, putting down a couple inches.

There's hints at a rare flash freeze event.

Temperatures drop into the 20s with this snow burst Friday morning.

[MJO812]

1 hour ago, SnoSki14 said:

There's hints at a rare flash freeze event.

Temperatures drop into the 20s with this snow burst Friday morning.

Euro has the low further south and changes the area to snow

[snowman19]

4 hours ago, SnoSki14 said:

There's hints at a rare flash freeze event.

Temperatures drop into the 20s with this snow burst Friday morning.

Not a chance whatsoever of a flash freeze 

[snowman19]

4 hours ago, winterwx21 said:

I see GGEM just joined GFS and GFSv16 tonight in giving us a decent burst of snow friday morning, putting down a couple inches.

Expected snowfall from the National Weather Service for the metro area, just updated, hot off the presses:  https://www.weather.gov/okx/winter

[wdrag]

Advisory situation may be coming to a portion of the forum-not a lock, for the Friday morning commute, despite probable less than official criteria amounts NYC/LI due to sharply falling temps to between 25-30F with sleet to snow in the 5A-8A time frame and gusty n-ne wind of 30-40 MPH. Snow ends sometime late morning-midday with temps recovering above freezing in the afternoon. Wind gusts for a few minutes between midnight and 8A could reach 50 MPH in parts of the area. Added wind event to the thread.  Snowfall for NYC-LI T- at most 2", while a bit heavier seems likely I84 corridor extreme nw NJ of 1/2 to possibly 3". Think the best chance for 2+" in our subforum is CT. If the precip ends more abruptly, then we escape the advisory and amounts will be under 1" with the lesser snowfall of the 00z/17 cycle ICON, UKMET, 12K NAM considered.  

Note: this pgh on snow ratios added at 550A/17: as the transition to snow occurs, the first hour or two may be melting on most surfaces and certainly pack down to snow ratios less than 10 to 1, possibly closer to 7 to 1 or something like that.

Some of the modeling has complications not only Friday, but also next Monday.  For Friday, there could be two bands of halfway decent accumulative snow,  one across I84 and the other just south of I78 across central or s NJ? TBD. 

Then, next Monday:  the 00z/17 EPS and GEPS want to form a deep cyclonic circulation off the mid or south Atlantic coast this weekend and drift it north or northeast early next week, spreading rain back into the area.  Depending on latitude of formation, will determine how much warming aloft occurs.  ENS have 850 temps in the +3/+4C range next Monday, too warm for snow, provided all the excessive height rises and warming aloft that is modeled in the northeast occurs. If that shifts north, then there is a real long shot (very low chance) we might be looking at some marginal thermal profiles for a bit of wet snow in CT.  At this time, I wouldn't be promising mostly clear skies and dry weather for Sunday afternoon-Tuesday morning. 

Added the 0841z/17 NWS ensemble prob for >1" of snow Friday.  You can see the concern for going too heavy. 

[MJO812]

2 hours ago, snowman19 said:

Not a chance whatsoever of a flash freeze 

LOL

[crossbowftw3]

Looking reasonable for us northern folks to see a couple inches still. Here’s hoping we could all get some 

[Brian5671]

12z NAM has alot of rain for most of us before any change to snow/white rain

[crossbowftw3]

4 minutes ago, Brian5671 said:

12z NAM has alot of rain for most of us before any change to snow/white rain

Soaker. Up to 2” of QPF possible followed by perhaps 1-3” here inland. SNE is the probable focal point for the biggest potential snow 

[Brian5671]

8 minutes ago, crossbowftw3 said:

Soaker. Up to 2” of QPF possible followed by perhaps 1-3” here inland. SNE is the probable focal point for the biggest potential snow 

Even that is iffy-how many times have we seen the precip wrap up before true cold arrives....thread the needle for SNE as well....

[MJO812]

I hope we get 2 inches of snow. Want Central Park to reach 40 inches.

[jm1220]

32 minutes ago, MJO812 said:

I hope we get 2 inches of snow. Want Central Park to reach 40 inches.

Highly unlikely. Much more likely is Boston getting their 5-6” event that overtakes NYC for good this season. I don’t see it being more than a burst of snow at the end that barely or doesn’t accumulate around the city. Looks like a standard washout that becomes a cold washout with some slush at the end. North of town especially north of 84 could get a few inches. 

[SnoSki14]

7 hours ago, snowman19 said:

Not a chance whatsoever of a flash freeze 

Pretty much every model shows a burst of snow Friday morning with temps in the 20s as low transfers to coast and winds blow from the NE.

[MJO812]

23 minutes ago, SnoSki14 said:

Pretty much every model shows a burst of snow Friday morning with temps in the 20s as low transfers to coast and winds blow from the NE.

Agree

 

[Brian5671]

1 hour ago, bluewave said:

Hard to believe that the last 1.50”+  rainstorm in NYC was at the end of October.

 

 

 

the xmas eve storm wasn't 1.50?

[crossbowftw3]

Euro looks to deliver for our SNE friends snow wise while some of us may see 2-4 inland here.

[JustWeatherWx]

I still think this is mostly North and West of 287 for real chances with brief white rain elsewhere. 

[hudsonvalley21]

Psssst. Don’t tell anyone, I stole this from the New England thread

 

[hudsonvalley21]

A couple of 12z maps

 

[MJO812]

46 minutes ago, hudsonvalley21 said:

Psssst. Don’t tell anyone, I stole this from the New England thread

 

Slide that south

Where is the NAO when we need it

[sferic]

1 hour ago, crossbowftw3 said:

Euro looks to deliver for our SNE friends snow wise while some of us may see 2-4 inland here.

I see a WWA for us, do you?

[crossbowftw3]

3 minutes ago, sferic said:

I see a WWA for us, do you?

I say probable with a range dependent on elevations. You should do well compared to me relatively speaking

[crossbowftw3]

3 minutes ago, sferic said:

I see a WWA for us, do you?

I say probable with a range dependent on elevations. You should do well compared to me relatively speaking

[jm1220]

21 minutes ago, MJO812 said:

Slide that south

Where is the NAO when we need it

Even if the snow maps did show accums down here I’d be skeptical. It’s rare that we start with upper 40s and heavy rain but end up with decent snow accums in this area. This is an upstate NY/New England setup. 

[Brian5671]

3 minutes ago, jm1220 said:

Even if the snow maps did show accums down here I’d be skeptical. It’s rare that we start with upper 40s and heavy rain but end up with decent snow accums in this area. This is an upstate NY/New England setup. 

yeah and it's March too so the ground is that much warmer.   The heaviest precip moves out before the real cold gets in.   Maybe a car topper if we're lucky.

[snowman19]

1 hour ago, Brian5671 said:

yeah and it's March too so the ground is that much warmer.   The heaviest precip moves out before the real cold gets in.   Maybe a car topper if we're lucky.

The 10:1 ratio snowmaps that count sleet as snow being posted here are going to be complete and total garbage and extremely inaccurate, never mind the fact that ratios are going to be much lower than 10:1. Ratios Friday morning are going to be somewhere around 7:1 or even lower, mid-March, this is white rain, less than an inch total for the metro area

[crossbowftw3]

the RAP goes 100% aggressive for us inland folks, delivers 6"+.

 

Obviously sell that, probably not realistic at all.

[MJO812]

Euro is better for our area 

[crossbowftw3]

6 minutes ago, MJO812 said:

Euro is better for our area 

snow map? or at least a generalization on what it has?

edit: i got it, stolen from NE forum