Possible Record Breaking Cold + Snow Sunday 1/25 - Tuesday 1/27

[MANDA]

1 minute ago, NEG NAO said:

FYI  a few of the more reliable METS are even mentioning 20:1 around the metro.

I believe you but that is an absurd statement for them to make.

[NEG NAO]

Just now, MANDA said:

I believe you but that is an absurd statement for them to make.

once again why ?

[SnowGoose69]

Well the TWC behind the scenes folks sure like the NRN most solutions.  Their depictions at least in the MA on S and W are on par with the CMC or UKMET.

[MANDA]

Just now, NEG NAO said:

once again why ?

No way in hell at this point to determine where best snow growth will be, banding and lift etc.  We're still trying to figure out the synoptic situation much less pull apart soundings 120 hours out.   Surface temperatures alone do not determine ratios.  A gusty wind can reduce ratios.  Not to mention how much against climo 20:1 would be for the metro.

JB is a great one for pushing 20:1 / 30:1 ratios and I can't think of ONCE when he was right on that during a moderate or major storm.  

[SnowGoose69]

Just now, MANDA said:

No way in hell at this point to determine where best snow growth will be, banding and lift etc.  We're still trying to figure out the synoptic situation much less pull apart soundings 120 hours out.   Surface temperatures alone do not determine ratios.  A gusty wind can reduce ratios.  Not to mention how much against climo 20:1 would be for the metro.

JB is a great one for pushing 20:1 / 30:1 ratios and I can't think of ONCE when he was right on that during a moderate or major storm.  

20:1 is tough here outside of maybe a clipper in a very cold setup.  Coastal lows usually its either too warm or too windy for ratios that good.  PD2 is a case though where I think ratios may have been close to that and 2016

[North and West]

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[NEG NAO]

Just now, MANDA said:

No way in hell at this point to determine where best snow growth will be, banding and lift etc.  We're still trying to figure out the synoptic situation much less pull apart soundings 120 hours out.   Surface temperatures alone do not determine ratios.  A gusty wind can reduce ratios.  Not to mention how much against climo 20:1 would be for the metro.

JB is a great one for pushing 20:1 / 30:1 ratios and I can't think of ONCE when he was right on that during a moderate or major storm.  

It wasn't JB and I should have mentioned they only said it was a possibility not definite - I think 15:1 is reasonable considering this air mass coming in from the north is quite unusually cold for this area during a snow event.

[TriPol]

10 minutes ago, NEG NAO said:

FYI  a few of the more reliable METS are even mentioning 20:1 around the metro.

The density and structure of snowflakes are influenced by wind. Strong winds can cause sheer forces and collision forces that can break up delicate snowflakes and cause damage to them before they fall to the ground. When a snowflake breaks up, it will typically become much smaller and denser than an intact snowflake because the intact snowflake has significant amount of air trapped within it, which enables snowflakes to be stacked on top of each other. When snowflakes are broken up due to wind, they will lose their structure, making it impossible to stack them. Therefore they will not develop the same amount of height per volume of water as intact snowflakes due to density.

As a second point, strong winds often contain turbulent airflows and sublimation. Because they contain a high ratio of surface area to mass, smaller fragments of snowflake are more likely to be partially sublimated away or lifted into the upper atmosphere than intact snowflakes. Thus, much of the snowflakes created by strong winds won't reach the ground where we measure snow accumulation. Thus, the end result is a classic example of meteorological misrepresentation. When looking at radar images and the equivalent liquid from the snowfall, they may appear to be large amounts of moisture, but the awash in total in the ground will be relatively small when compared to the amount of snow that fell as part of the event. This is why windy events tend to produce low totals even when the snow continues to fall steadily.

 

 

[NEG NAO]

3 minutes ago, SnowGoose69 said:

20:1 is tough here outside of maybe a clipper in a very cold setup.  Coastal lows usually its either too warm or too windy for ratios that good.  PD2 is a case though where I think ratios may have been close to that and 2016

1. This will be a very cold setup

2. The storm track won't favor a very windy event

[BoulderWX]

4 minutes ago, NEG NAO said:

1. This will be a very cold setup

2. The storm track won't favor a very windy event

You asked a question. Many people replied with detailed answers. At this point just go with what you think best. No need to debate it. Most of us agree it’s best to wait to figure details like snow ratio out. If you don’t want to, then just multiply what you think ratios will be X Qpf output and have a field day with it

[mob1]

JMA looks pretty good as well

[MANDA]

12 minutes ago, NEG NAO said:

It wasn't JB and I should have mentioned they only said it was a possibility not definite - I think 15:1 is reasonable considering this air mass coming in from the north is quite unusually cold for this area during a snow event.

15:1 possible assuming soundings are favorable.  Me personally I'd stick with 12:1 for now when calculating snowfall off the current QPF forecasts.

Not to mention in a long duration storm the ratios can change from high to low or vice versa during the storm duration.  Deformation death bands can produce great ratios.  So maybe a storm that has 10:1 to 20:1 throughout the storm duration averages out to 15:1 when all is said and done.  Just to early make ratio forecasts.  Way to premature to even stay 15:1 IMO.  

[SACRUS]

 

GGEM / GEPS

 

[SACRUS]

 

EPS Total QPF Mean 

 

[SACRUS]

2 hours ago, SACRUS said:

 

12Z QPF Totals (NYC)

ICON: 0.9 - 1.1
GFS: Trace
GGEM: 0.6 - 0.8
GEFS: 0.5 - 0.6
UKMET: 1.00 - >1.00
Euro AI AIFS: 0.5 - 0.6
Euro: 0.7 - 0.8
GEPS: 0.9 
EPS: 0.6 - 0.7

 

Final 12z - solid snowstorm on 8 of 9 outputs

[eduggs]

On the EPS individuals I count 13 misses and 11 big hits out of 50. The rest are light to significant hits. ~25% miss rate is still pretty high. Still plenty of variability. 

[donsutherland1]

At present, it appears very likely that Washington, DC will see 6" or above snowfall during the January 24-26, 2026 snowstorm. Since 1950, below is the distribution of outcomes based on 6" or above and 10" or above January-February snowstorms in Washington, DC for New York City and Philadelphia.

In theory, guidance with the higher-skill initialization (4dVAR)/better resolution (ECMWF, GGEM, and UKMET) should have a better handle at the current lead time. One can't fully dismiss the GFS, especially as there are ensemble members that support its solution.

However, if one also weighs the historical outcomes while waiting for the guidance to reach higher skill levels in resolving the synoptic details (usually within 3 days of the event), it seems plausible that New York City and Philadelphia are possibly in line for at least a 3"-6" snowfall with upside potential if full phasing takes place and the storm tracks closer to the coast.

[CPcantmeasuresnow]

29 minutes ago, NEG NAO said:

FYI  a few of the more reliable METS are even mentioning 20:1 around the metro.

The January 1996 blizzard dropped 21 inches on JFK airport with 1.1 qpf. This storm would have similar temperature profiles at least, don't know about the other dynamics involved.

[MANDA]

WPC is not known to making large jumps with this product which is issued twice a day.

Over the last several issuance's the 1/2" area has been gradually shifted north to a TTN to NYC line.   

I believe they rely heavily on NBM but not sure.

 

[MANDA]

14 minutes ago, CPcantmeasuresnow said:

The January 1996 blizzard dropped 21 inches on JFK airport with 1.1 qpf. This storm would have similar temperature profiles at least, don't know about the other dynamics involved.

Only difference is that was a coastal bomb with very intense deformation banding for hours mid and late storm.  This upcoming event is not really a synoptic comparison.    At least not at this time.  Get the full energy out of the SW and a complete, clean phase then all bets might be off.

No matter what, we have a legit threat of something late weekend into early next week and for me half the fun and excitement is in the tracking.

[Tatamy]

4 hours ago, Brian5671 said:

Ice is often overdone on these models...heavy ZR doesn't accrete well-just runs off.

Your comment is not correct.  These photos were taken on January 14th, 1978 at East Northport on Long Island.  Heavy rain fell most of the night with below freezing temperatures resulting in this severe ice storm.

[SnoSki14]

Ensembles mean QPF of 0.5-0.9 at 5-6 days lead time is pretty darn good. 

[RockawayRowdies]

Just now, SnoSki14 said:

Ensembles means of 0.5-0.9 at 5-6 days lead time is pretty darn good. 

Add to that pretty good ratios.. 
we're looking at 6"-12" mean right now. 5 days out.

[Nibor]

5 minutes ago, Tatamy said:

Your comment is not correct.  These photos were taken on January 14th, 1978 at East Northport on Long Island.  Heavy rain fell most of the night with below freezing temperatures resulting in this severe ice storm.

The argument is that modeled output of freezing rain qpf isn’t 1:1 with accretion.

Nice photos. 

[ILoveWinter]

6 minutes ago, SnoSki14 said:

Ensembles mean QPF of 0.5-0.9 at 5-6 days lead time is pretty darn good. 

Yea this is what you want to see, Op runs don’t have as much meaning this early on.

[SnoSki14]

3 minutes ago, ILoveWinter said:

Yea this is what you want to see, Op runs don’t have as much meaning this early on.

Best part is there's no mixing threat. 

[jm1220]

9 minutes ago, Nibor said:

The argument is that modeled output of freezing rain qpf isn’t 1:1 with accretion.

Nice photos. 

If the temp is 30-31 with the heavy freezing rain absolutely-a lot will just run off. When it gets below about 28 or so much more of it will accrete. 

[donsutherland1]

For comparison, the January 19th and January 20th heavy snow outlook from WPC:

January 19:

January 20:

 

[Yanksfan]

2 minutes ago, ILoveWinter said:

Yea this is what you want to see, Op runs don’t have as much meaning this early on.

This.^^^ Any individual op run at 5 days out can give wildly different solutions especially with a setup like this. Wouldn’t shock me in the least if the Gfs shows a massive snowstorm at 18z while the Euro is a miss. I’ve seen this movie before. Got to give it 48 hrs or so before the models can get a better handle on this.

[SACRUS]

 

One consistent trend is this is more a Sun (PM) - Mon (PM) or even early Tue (AM) event.