2/13 Significant/Major Winter Storm Discussion & Observations

[LibertyBell]

48 minutes ago, RU848789 said:

Euro looking similar to the GFS in many ways, although it's a little earlier and not as snowy - but a big improvement over 12Z, especially for those along 78 and even 95.  The early part would help with accumulations as ~90% of the snow falls before 7 am (after a good 3/4" of rain, at least for 95).  Euro and GFS vs. CMC and UK, I guess.  

this is wild, look at that gradient between the north shore and south shore of Long Island lol.

 

edit-- it looks like the largest gradient is south of Long Island as even the south shore gets at least 4 inches on this model run.

Poconos to NW NJ will do well of course.  That 10-12 inches in coastal CT is a little unexpected though, it's even more than what it shows for NW areas.

There is such a fine line of 10 miles or so between heavy snow and rain that there's no way to know which way this will go.

[LibertyBell]

2 hours ago, David-LI said:

 

51 minutes ago, David-LI said:

00z euro fresh from the oven

 

Interesting comparison here-- the GFS has one foot plus of snow south of NYC and on eastern Long Island and the Euro has one foot plus of snow north of NYC (but not by much.)  They both have around the same amount of snow for NYC but the GFS has more for Long Island especially the south shore and east end.  As a matter of fact, the GFS has a foot plus for eastern Long Island, even more than it does for south NJ.  Euro has zilch for south NJ lol.  They also have similar amounts of snow west of NYC into the Poconos but the GFS has much less snow north of NYC.

 

[USCG RS]

3 hours ago, RU848789 said:

Euro looking similar to the GFS in many ways, although it's a little earlier and not as snowy - but a big improvement over 12Z, especially for those along 78 and even 95.  The early part would help with accumulations as ~90% of the snow falls before 7 am (after a good 3/4" of rain, at least for 95).  Euro and GFS vs. CMC and UK, I guess.  

That much rain given the previously warm ground... I should be skeptical of those totals. Verbatim of course. 

2 hours ago, LibertyBell said:

this is wild, look at that gradient between the north shore and south shore of Long Island lol.

 

edit-- it looks like the largest gradient is south of Long Island as even the south shore gets at least 4 inches on this model run.

Poconos to NW NJ will do well of course.  That 10-12 inches in coastal CT is a little unexpected though, it's even more than what it shows for NW areas.

There is such a fine line of 10 miles or so between heavy snow and rain that there's no way to know which way this will go.

February 2013 (Nemo) had this type of cutoff. I remember driving North on William Floyd and as I passed under the LIE, you could literally see the difference over a mile. It felt quite like lake effect snow. 

2 hours ago, LibertyBell said:

 

Interesting comparison here-- the GFS has one foot plus of snow south of NYC and on eastern Long Island and the Euro has one foot plus of snow north of NYC (but not by much.)  They both have around the same amount of snow for NYC but the GFS has more for Long Island especially the south shore and east end.  As a matter of fact, the GFS has a foot plus for eastern Long Island, even more than it does for south NJ.  Euro has zilch for south NJ lol.  They also have similar amounts of snow west of NYC into the Poconos but the GFS has much less snow north of NYC.

 

Oh the fun of being the literal transition zone. Those just north of that zone tend to do rather well. "You have to smell the rain." 

I do think Long Island could take a hard hit here, given the confluence pressing down and the avaliable moisture and energy combined. 

[Franklin0529]

6z gfs triples down 

[Franklin0529]

[wishcast_hater]

1 minute ago, Franklin0529 said:

Sign me up.

[LibertyBell]

23 minutes ago, Franklin0529 said:

If anything the euro is trending to the gfs

[MJO812]

[LibertyBell]

29 minutes ago, Franklin0529 said:

I can't remember the last time the entire area, north to south, west to east, saw a foot of snow lol.

[Franklin0529]

Just now, LibertyBell said:

I can't remember the last time the entire area, north to south, west to east, saw a foot of snow lol.

It's probably wrong. But certainly a 3-6" storm is on the table 

[LibertyBell]

1 minute ago, Franklin0529 said:

It's probably wrong. But certainly a 3-6" storm is on the table 

Certainly by the ensembles too, it looks like the entire area could get a nice snowstorm out of this with not much rain at all.

 

[LibertyBell]

4 minutes ago, MJO812 said:

What this shows is that the risk of suppression is actually more than the chances that the storm will be mostly rain. This storm could still move a little more north (like 50 miles) and still hit us hard with snow.

[RU848789]

Interesting that the GEFS mean max snow moved south with the 95 corridor being along that max for the most part (and is now fairly similar to the EPS mean), while the GFS Op max snowfall axis moved considerably north (losing a lot of snow for SNJ/SEPA). NYC looking to be set up nicely. Don't love that the GEFS surface temps never go below 35-36F from Trenton to NYC though (the GFS does get down to 32-33F as does the EPS), which will certainly cut down on accumulations some, verbatim (although with most of the snow falling at ~1"/hr rates, the snow will accumulate).  

[snowman19]

Those snow maps are pure satire. NWS Upton is not biting and for good reason:

.LONG TERM /MONDAY THROUGH THURSDAY/...
Upper levels signal a strong jet tapping into multiple sources of
moisture from the Pacific, the Gulf of Mexico and the Western
Atlantic Monday into Monday night. Vertical lift apparent from a
coupled jet structure depicted with local area close to right rear
quad of jet streak to the NE of the area plus left front quad of an
approaching jet streak to the SW going into early Tuesday.

Mid levels convey a strong shortwave moving across the local region
early Tuesday. ECMWF strongest and deepest compared to GFS and
Canadian models. Shortwave moves well east of the region Tuesday
night. Less amplified mid level shortwaves move across Wednesday and
Thursday.

Without much in the way of phasing of northern and southern branches
of the upper jet with the southerly branch being the more dominant
one, there is a limit to how amplified the wave gets. There is not
much tilt vertically. This favors a relatively faster and more
progressive solution. Also evident, is a lack of a strong high
pressure area to lock in colder air. It will difficult to sustain
any prolonged snowfall especially if more of the precipitation falls
during the day.

At the surface, low pressure develops off the mid-Atlantic Monday
night and then deepens as it tracks southeast of Long Island. ECMWF
much deeper and slower compared to other models. The current
forecast takes this low southeast of Long Island going into Monday
night with an increase of precipitation. Similar to previous
forecast, inland zones have relatively more snow in the forecast
compared to the coast. Coastal areas contain mostly rain.

Lesser chances of rain and snow accompany the smaller shortwaves
Wednesday and Thursday with otherwise mainly dry conditions Tuesday
night onward through rest of long term.

Daytime temperatures will be higher than normal, well into the 40s
on Monday but will decline closer to normal values for the rest
of the work week.

https://forecast.weather.gov/product.php?site=OKX&issuedby=OKX&product=AFD&format=CI&version=1&glossary=1&highlight=off

@MJO812 How’s the 12z ICON in Kuchera ratios looking?

[MJO812]

16 minutes ago, snowman19 said:

Those snow maps are pure satire. NWS Upton is not biting and for good reason:

.LONG TERM /MONDAY THROUGH THURSDAY/...
Upper levels signal a strong jet tapping into multiple sources of
moisture from the Pacific, the Gulf of Mexico and the Western
Atlantic Monday into Monday night. Vertical lift apparent from a
coupled jet structure depicted with local area close to right rear
quad of jet streak to the NE of the area plus left front quad of an
approaching jet streak to the SW going into early Tuesday.

Mid levels convey a strong shortwave moving across the local region
early Tuesday. ECMWF strongest and deepest compared to GFS and
Canadian models. Shortwave moves well east of the region Tuesday
night. Less amplified mid level shortwaves move across Wednesday and
Thursday.

Without much in the way of phasing of northern and southern branches
of the upper jet with the southerly branch being the more dominant
one, there is a limit to how amplified the wave gets. There is not
much tilt vertically. This favors a relatively faster and more
progressive solution. Also evident, is a lack of a strong high
pressure area to lock in colder air. It will difficult to sustain
any prolonged snowfall especially if more of the precipitation falls
during the day.

At the surface, low pressure develops off the mid-Atlantic Monday
night and then deepens as it tracks southeast of Long Island. ECMWF
much deeper and slower compared to other models. The current
forecast takes this low southeast of Long Island going into Monday
night with an increase of precipitation. Similar to previous
forecast, inland zones have relatively more snow in the forecast
compared to the coast. Coastal areas contain mostly rain.

Lesser chances of rain and snow accompany the smaller shortwaves
Wednesday and Thursday with otherwise mainly dry conditions Tuesday
night onward through rest of long term.

Daytime temperatures will be higher than normal, well into the 40s
on Monday but will decline closer to normal values for the rest
of the work week.

https://forecast.weather.gov/product.php?site=OKX&issuedby=OKX&product=AFD&format=CI&version=1&glossary=1&highlight=off

Being cautious like always but it's a good starting point.

[wdrag]

I'm in agreement about caution: All modeling except the previous storm overzealous EPS has less than 1" accum NYC. Ensemble temps are above freezing NYC metro midday Tuesday. Even sign of near freezing temps aloft which means mixing. 

I think caution warranted... The Canadian especially all over the place.  Maybe it will coalesce into a nice event, but for now I think northern PA, I84 corridor is a best fit with a probable climo snow on the back side for NYC of 1/2-2". Could be wrong but that's what I'm publishing privately for a D4 outlook.  

[MJO812]

Icon coming south

[LibertyBell]

9 minutes ago, wdrag said:

I'm in agreement about caution: All modeling except the previous storm overzealous EPS has less than 1" accum NYC. Ensemble temps are above freezing NYC metro midday Tuesday. Even sign of near freezing temps aloft which means mixing. 

I think caution warranted... The Canadian especially all over the place.  Maybe it will coalesce into a nice event, but for now I think northern PA, I84 corridor is a best fit with a probable climo snow on the back side for NYC of 1/2-2". Could be wrong but that's what I'm publishing privately for a D4 outlook.  

We have had had nice snowfalls before though with temps just above freezing.  

April 2, 2018 is a good example that we were talking about before, NYC had close to 6" of snow and the temperature never got below 33 F.

[jm1220]

4 hours ago, LibertyBell said:

this is wild, look at that gradient between the north shore and south shore of Long Island lol.

 

edit-- it looks like the largest gradient is south of Long Island as even the south shore gets at least 4 inches on this model run.

Poconos to NW NJ will do well of course.  That 10-12 inches in coastal CT is a little unexpected though, it's even more than what it shows for NW areas.

There is such a fine line of 10 miles or so between heavy snow and rain that there's no way to know which way this will go.

Happened last 2/28. The south shore had white rain, I had 5” because it was 2-3 degrees colder where I live. The airmass coming into this is quite marginal, that shouldn’t be forgotten either. Maybe this will work out for all of us, who knows, but there are definitely obstacles to be overcome. The odds are still better north of the city. We want it to track a good 100 miles south of the city and for it to be quick developing-not sheared crap like the GGEM so dynamically it can get cold enough. 

[Greg g]

I know it’s way too early to know for sure… i have a flight into LaGuardia that’s supposed to land at 10:30 am.. what are chances that still happens?

[Greg g]

10:30 on Tuesday morning 

[LibertyBell]

13 minutes ago, jm1220 said:

Happened last 2/28. The south shore had white rain, I had 5” because it was 2-3 degrees colder where I live. The airmass coming into this is quite marginal, that shouldn’t be forgotten either. Maybe this will work out for all of us, who knows, but there are definitely obstacles to be overcome. The odds are still better north of the city. We want it to track a good 100 miles south of the city and for it to be quick developing-not sheared crap like the GGEM so dynamically it can get cold enough. 

The storm that immediately comes to mind when we had a nice snowfall with temps just above freezing was April 2, 2018.  That was much later in the season, but our weather had been cold for weeks before that storm-- still it's strange to say early April was more favorable for snow than early February lol.

 

[jm1220]

Just now, LibertyBell said:

The storm that immediately comes to mind when we had a nice snowfall with temps just above freezing was April 2, 2018.

 

It can definitely still happen but people should keep their expectations low near the city and ignore the 10-1 clown maps given we have such a lousy preceding airmass. Some will be wasted trying to get the snow to accumulate. And that’s not factoring in the usual late trends north with these kind of systems. If the confluence weakens it’s off to the races back north. I want this to happen for sure but also want to factor in the likelihood the rug gets pulled. 

[LibertyBell]

5 minutes ago, jm1220 said:

It can definitely still happen but people should keep their expectations low near the city and ignore the 10-1 clown maps given we have such a lousy preceding airmass. Some will be wasted trying to get the snow to accumulate. And that’s not factoring in the usual late trends north with these kind of systems. If the confluence weakens it’s off to the races back north. I want this to happen for sure but also want to factor in the likelihood the rug gets pulled. 

I'd be shocked if we at the high end got more than a couple inches, but none of the official forecasts have even that much for us right now.

The only ones who are talking about significant accumulations near the coast is the weather channel, and it looks like they're going by the straight model runs lol.

For example, my local weather channel forecast has snow (no mix, just snow) all day Tuesday with a high of 40 after a low of 34 Tuesday morning.

 

[NCPOW]

24 minutes ago, Greg g said:

I know it’s way too early to know for sure… i have a flight into LaGuardia that’s supposed to land at 10:30 am.. what are chances that still happens?

It’s way too early to know for sure

[donsutherland1]

Early thoughts:

The February 13th storm will very likely be another classic low ratio storm (under 5:1) where 10:1 snowfall maps will overstate the potential snowfall. During the storm, readings will remain well above freezing (possibly 35 or above). At present, the WPC probabalistic winter storm severity index map gives the NYC area about a 20% probability of a minor event.

Select part of the WPC probabilistic winter storm severity index map (Minor Impact):

The 6z GFS is the most aggressive model. It takes the temperature down to 33 and its soundings are consistent with a wet snow event. Given the marginal air mass involved and differences with the other guidance, including the warmer NBE and warmer 0z GFS MOS, it makes sense to wait for other guidance before buying into the GFS's idea. For now, the idea of a light event seems to be a reasonable course until there is strong and consistent support for something bigger.

[LibertyBell]

2 minutes ago, donsutherland1 said:

Early thoughts:

The February 13th storm will very likely be another classic low ratio storm (under 5:1) where 10:1 snowfall maps will overstate the potential snowfall. During the storm, readings will remain well above freezing (possibly 35 or above). At present, the WPC probabalistic winter storm severity index map gives the NYC area about a 20% probability of a minor event.

Select part of the WPC probabilistic winter storm severity index map (Minor Impact):

The 6z GFS is the most aggressive model. It takes the temperature down to 33 and its soundings are consistent with a wet snow event. Given the marginal air mass involved and differences with the other guidance, including the warmer NBE and warmer 0z GFS MOS, it makes sense to wait for other guidance before buying into the GFS's idea. For now, the idea of a light event seems to be a reasonable course until there is strong and consistent support for something bigger.

Don is it possible the rapidly strengthening storm will bring down even colder air?  The weather channel mentioned the storm will get down to 950 mb (!) and will stall out, but that's when it's near Nova Scotia.  Still this storm is going make major headlines next week.

 

[donsutherland1]

7 minutes ago, LibertyBell said:

Don is it possible the rapidly strengthening storm will bring down even colder air?  The weather channel mentioned the storm will get down to 950 mb (!) and will stall out, but that's when it's near Nova Scotia.  Still this storm is going make major headlines next week.

 

Its deepening will bring in some colder air, but the overall air mass involved isn’t especially cold. There might be some moderate wet snow at the height of the storm, but it will be a fast mover. Most of its precipitation will fall over a 12-hour period and it won’t all be accumulating snow. 

[MJO812]

3 minutes ago, donsutherland1 said:

Its deepening will bring in some colder air, but the overall air mass involved isn’t especially cold. There might be some moderate wet snow at the height of the storm, but it will be a fast mover. Most of its precipitation will fall over a 12-hour period and it won’t all be accumulating snow. 

So all the maps that show several inches are wrong ? I know sometimes we have to be cautious but this is February and snow will stick in the low 30s.

[donsutherland1]

Just now, MJO812 said:

So all the maps that show several inches are wrong ? I know sometimes we have to be cautious but this is February and snow will stick in the low 30s.

Several inches is something that's on the table. 6" or above is unlikely.