Sunday 1/28-midday Monday 29/2024 snowfall and OBS most of the NYC subforum including potential 1/2-2" NYC-LI-heavier toward I84.

[donsutherland1]

Overnight, the GFS returned to the land of model reality after having stood alone from the operational and mesocale models, along with all of the individual GEFS members. The higher elevations from I-84 to north and west of Albany could see 4" amounts with some locally higher amounts in excess of 6".  At lower elevations, the highest accumulations will start to occur somewhere between I-84 and I-90.

Given the marginal air mass, the temperature is likely to remain above freezing throughout the duration of the storm in New York City. Lowest temperatures: GFS MOS: 38°; NAM MOS: 37°; NBE: 38°. As a result, the snow-to-liquid ratios will be very low (very likely < 5:1) for any show that falls in and around New York City. The 1/27 0z EPS cycle saw 14% of members with 1" or more snow in New York City. However, given ratios of 5:1 or less, the 2" threshold is a better indicator of the probability of 1" or more snow. Just 6% of members saw 2" or more snow.

In sum, Central Park will likely see little or no accumulation from this storm. New York City's and Newark's ongoing record streaks of 728 consecutive days without 2" or more snowfall will continue.

Historic Snowfall Amounts and Snow-to-Liquid Ratios for Above Freezing Storms:

• 0.25" Precipitation or above
• Lows of 33 or above and 35 or above
• January 1, 1869 through January 26, 2024

EPS and NBE Numbers:

WPC Guidance:

With New York City very likely to see less than 3.0" snowfall through January 31st, the historic probability of seeing 20.0" or more or 30.0" or more during February 1-April 30 is lower than the historic average.

[LibertyBell]

5 hours ago, donsutherland1 said:

Overnight, the GFS returned to the land of model reality after having stood alone from the operational and mesocale models, along with all of the individual GEFS members. The higher elevations from I-84 to north and west of Albany could see 4" amounts with some locally higher amounts in excess of 6".  At lower elevations, the highest accumulations will start to occur somewhere between I-84 and I-90.

Given the marginal air mass, the temperature is likely to remain above freezing throughout the duration of the storm in New York City. Lowest temperatures: GFS MOS: 38°; NAM MOS: 37°; NBE: 38°. As a result, the snow-to-liquid ratios will be very low (very likely < 5:1) for any show that falls in and around New York City. The 1/27 0z EPS cycle saw 14% of members with 1" or more snow in New York City. However, given ratios of 5:1 or less, the 2" threshold is a better indicator of the probability of 1" or more snow. Just 6% of members saw 2" or more snow.

In sum, Central Park will likely see little or no accumulation from this storm. New York City's and Newark's ongoing record streaks of 728 consecutive days without 2" or more snowfall will continue.

Historic Snowfall Amounts and Snow-to-Liquid Ratios for Above Freezing Storms:

• 0.25" Precipitation or above
• Lows of 33 or above and 35 or above
• January 1, 1869 through January 26, 2024

EPS and NBE Numbers:

WPC Guidance:

With New York City very likely to see less than 3.0" snowfall through January 31st, the historic probability of seeing 20.0" or more or 30.0" or more during February 1-April 30 is lower than the historic average.

Hold on Don, we had a snowstorm that dumped 5.0-5.9" of snow with temperatures of 35+ during the entire storm? How is this possible and which storm was this and what was the snow to liquid ratio in it?  Thanks!
 

[donsutherland1]

17 minutes ago, LibertyBell said:

Hold on Don, we had a snowstorm that dumped 5.0-5.9" of snow with temperatures of 35+ during the wntire storm? How is this possible and which storm was this and what was the snow to liquid ratio in it?  Thanks!
 

April 9, 1907: 5.0" (Ratio: 5.4:1). Almost all of the snow fell before dawn. Total precipitation: 0.92". The snow fell heavily during the storm (very likely visibilities < 0.25 mile).

[LibertyBell]

25 minutes ago, donsutherland1 said:

April 9, 1907: 5.0" (Ratio: 5.4:1). Almost all of the snow fell before dawn. Total precipitation: 0.92". The snow fell heavily during the storm (very likely visibilities < 0.25 mile).

wow sounds beautiful and yet very very dangerous!

I wonder if something like this could happen today?

I see there was a 33 degree storm of 5.0-5.9 in there too, was that more recent?

 

[wdrag]

Good Saturday morning everyone,

It's a forum but I think those who malign the models would be nowhere had their been no models.  For this forum I hope a respectful approach is preferred (at least I hope that is preferred by our moderators).  

Each weather situation is different and we'll see at Noon Monday which model or blend of models verified most accurately at their portrayal of an elevation dependent event. Tuesday CoCoRaHs)post of snowfall, maybe sooner if WFO's need to issue PNS's. 

I did not substantially change the thread title this morning. A slight delay and smoothing out of the date-day and added OBS.  

I95 to the coast wet roads, despite any wet snow at the front and back end of this moderate elevation dependent I84 northward snow event with potential for power outages north of I84 in 4+" wet snow areas near 1000 feet and above. 

Modeling suggests bands (yes newd transitory banding) of heavy qpf tomorrow morning that between 8AM and Noon could be mixed with wet snow down to I78 and NYC (no accum or spotty 0.1" grass) for NYC-LI.  

Back side of the event is in question but some of the modeling is continuing to drag its heels in storm departure (and was at thread inception). I think the implication is the remaining 5H vort-sharp trough passing eastward across NJ will send a cluster of showery mixed r/s newd from BWI_PHI at dawn Monday and try to merge-blend in with the 850MB nose of the northeast jet band in NYS/CT around sunrise in NYC to bring periods of wet melting snow to I95 and LI. This too may come down briefly 3/4Mile in parts of NJ/NYC-LI Monday morning-midday with a whitening of the grass and snowboards possible. 

I think we have a major test between ensemble (and operational) positive snow depth change and the NBE snowfall when modeled 2m temps are 33-36F.  I may be misunderstanding the use of positive snow growth, especially in the ensembles...  for now I use positive snow growth as a useful tool for roads... and double it for a base to max range of measurable snow.  When it snows, temps tend to drop to between 32-34F an hour or 2 after it starts.--not sure if modeling can capture that. Obviously at night its an easier accum on all surfaces. 

Cooler air is now leaking ever so slowly south down to I90 and will be drawn into the BL over our area from northeast during this event while strong lift from the approaching 5H short wave and 850MB se inflow will help cool the column Sunday before backside comma head curls southward and eastward of our area Monday morning.

My 530AM expectations for NNJ remain as is:

Northern NJ-Poconos -southeast NYS Sunday-Sunday night: GREAT UNCERTAINTY with vastly differing modeling for an elevation dependent event and much more conservative NWS forecast (see their graphic attached).

 

1/2-2" wet snow Easton PA-Warren County and the south two thirds of Sussex County (including Newton) over to Kinnelon but 3-6" wet snow likely Poconos and the north border of Sussex County including High Point, Vernon and northern Wantage locations above about 1000 feet as well as Orange County NY elevations above 1000 ft. Rain changes to a 3 hour period of heavy wet snow sometime near 8-9AM Sunday then either quits in the afternoon or back to rain. Sunday night periods of mixed precip changes to lighter wet snow during the night. Temps fall during the snow Sunday to 32-34F Suggest factor in possible delays into the Poconos - I84 itself. Manageable mostly wet road travel Easton PA to Newton and Kinnelon NJ but slushy slippery at times elevations above 1000 feet. Not all modeling agrees but plan for the worst and it may turn out much less hazardous than I expect if the NWS much more conservative snow forecast is correct (see their graphic).  This forecast is slightly less impact than what I was thinking on previous daily issuances.

 

I'll check back in tonight or tomorrow morning. Have a day and fingers crossed that everyone realizes most snow events NYC-LI tend to be minor.  I'm pretty sure you'll see a little white rain as some say tomorrow and some minor accum Monday.

 

[Dark Star]

51 minutes ago, LibertyBell said:

Hold on Don, we had a snowstorm that dumped 5.0-5.9" of snow with temperatures of 35+ during the wntire storm? How is this possible and which storm was this and what was the snow to liquid ratio in it?  Thanks!
 

No doubt a heavy rate can overcome temperature concerns, but sounds rare indeed?

[LibertyBell]

2 minutes ago, Dark Star said:

No doubt a heavy rate can overcome temperature concerns, but sounds rare indeed?

and I was amazed it happened in April, but it was almost 120 years ago....I'm not sure it could happen in the modern day of concrete lol

[donsutherland1]

33 minutes ago, LibertyBell said:

wow sounds beautiful and yet very very dangerous!

I wonder if something like this could happen today?

I see there was a 33 degree storm of 5.0-5.9 in there too, was that more recent?

 

April 2, 2018: 5.5" (Low: 33)

[LibertyBell]

Just now, donsutherland1 said:

No, that was in the 1890s.

also in April Don?

[LibertyBell]

40 minutes ago, donsutherland1 said:

April 9, 1907: 5.0" (Ratio: 5.4:1). Almost all of the snow fell before dawn. Total precipitation: 0.92". The snow fell heavily during the storm (very likely visibilities < 0.25 mile).

6 hour storm Don? that sounds absolutely amazing, the snowflakes must have been HUGE

[donsutherland1]

22 minutes ago, LibertyBell said:

also in April Don?

I made an error. That storm was April 2, 2018.

[LibertyBell]

12 minutes ago, donsutherland1 said:

I made an error. That storm was April 2, 2018.

Wow, well I guess it can still happen.

So the 5.0-5.9" storm that happened with the temperature at 33 degrees or above for the entire storm happened less than 6 years ago....

[TheClimateChanger]

2 hours ago, LibertyBell said:

Hold on Don, we had a snowstorm that dumped 5.0-5.9" of snow with temperatures of 35+ during the wntire storm? How is this possible and which storm was this and what was the snow to liquid ratio in it?  Thanks!
 

Only possible on a poorly sited, warm-biased rooftop station. Snow that heavy should drop the surface air temperature to 32 or 33.

[donsutherland1]

HREF:

[wdrag]

So far, the HRRR continues on its path of rain to snow I78 by 12z Sunday...so far. Am not guaranteeing but its still an option, especially since it like the Canadian suite tend to run slightly warm and amped.

[donsutherland1]

1 hour ago, TheClimateChanger said:

Only possible on a poorly sited, warm-biased rooftop station. Snow that heavy should drop the surface air temperature to 32 or 33.

The surface temperature for the April 2, 2018 storm dropped to 33° and held there. The 1907 storm, for which hourly data is not available, had a low of 35°.

Below is the data for the April 2, 2018 storm:

[psv88]

30 minutes ago, donsutherland1 said:

HREF:

Good for Boston! I’d prefer this cloudy and misty weather over a moderate snowfall event in peak climo…

[snywx]

19 minutes ago, wdrag said:

So far, the HRRR continues on its path of rain to snow I78 by 12z Sunday...so far. Am not guaranteeing but its still an option, especially since it like the Canadian suite tend to run slightly warm and amped.

I’m roughly 800’ sitting about a mile N of 84. Only expecting 1-2” here. I think it will snow most of the event here but that boundary layer is gonna be a problem. I can see areas above 1200’ with a modest 4-6” snowfall. Towns like cragsmoor which sit at 2200’ on the shawangunk ridge should cash in

[CPcantmeasuresnow]

20 minutes ago, psv88 said:

Good for Boston! I’d prefer this cloudy and misty weather over a moderate snowfall event in peak climo…

I doubt it ends well for Boston either. The proximity to the coast has been killing them the last two years, plus being at 20 feet above sea level. 

[wdrag]

1 hour ago, snywx said:

I’m roughly 800’ sitting about a mile N of 84. Only expecting 1-2” here. I think it will snow most of the event here but that boundary layer is gonna be a problem. I can see areas above 1200’ with a modest 4-6” snowfall. Towns like cragsmoor which sit at 2200’ on the shawangunk ridge should cash in

I'm at 740'MSL. You'll know seeing my reports or those of nearby Vernon on mPing between 7and 9A in north central SC, whether our thinking will work   I'm counting on 2"  slushy snow here at this Wantage elevation and probably 4-5" total Vernon and High Point.  This might be high per NBE?    You're thinking it out well and so its too close to be certain except am pretty sue we'll whiten the ground for a while.

I see the 18z EPS and HRRR continure. If the 18z NAM loses it and the future HRRR too, then it wont happen.  Decisions will need to be made for the 330PM advisories Pocs northeastward, and maybe a warning Catskills and possibly Litchfield Hills where power outages more likely (imo).  Only my opinion.

[hudsonvalley21]

21 minutes ago, wdrag said:

I'm at 740'MSL. You'll know seeing my reports or those of nearby Vernon on mPing between 7and 9A in north central SC, whether our thinking will work   I'm counting on 2"  slushy snow here at this Wantage elevation and probably 4-5" total Vernon and High Point.  This might be high per NBE?    You're thinking it out well and so its too close to be certain except am pretty sue we'll whiten the ground for a while.

I see the 18z EPS and HRRR continure. If the 18z NAM loses it and the future HRRR too, then it wont happen.  Decisions will need to be made for the 330PM advisories Pocs northeastward, and maybe a warning Catskills and possibly Litchfield Hills where power outages more likely (imo).  Only my opinion.

18z NAM held ground from the 12z run

 

[jm1220]

2 hours ago, psv88 said:

Good for Boston! I’d prefer this cloudy and misty weather over a moderate snowfall event in peak climo…

They probably get 1-3” and toward the end as the cold air comes in and especially if there’s a CCB feature that develops. The lousy airmass and easterly wind problem hurts them too. I just want to get some pattern to develop that gets me meaningfully over the way below average 5” on the season. Even more sucky is that DC has up to double what we have. This is just god awful for mid winter. But if not I’d rather not have false hope and we just torch from here on out. Rather be able to enjoy the outdoors then. 

[NorthShoreWx]

9 minutes ago, jm1220 said:

They probably get 1-3” and toward the end as the cold air comes in and especially if there’s a CCB feature that develops. The lousy airmass and easterly wind problem hurts them too. I just want to get some pattern to develop that gets me meaningfully over the way below average 5” on the season. Even more sucky is that DC has up to double what we have. This is just god awful for mid winter. But if not I’d rather not have false hope and we just torch from here on out. Rather be able to enjoy the outdoors then. 

If DC didn't have seasons like this, their averages would be even lower.  We'll probably catch up, and if we don't, they're entitled. 

Was up on the Palisades this morning and the sun came out for a bit.  Looked nice.  You can easily make out Harbor Hill in Roslyn from there.  Must be over 20 miles away.

[snywx]

13 minutes ago, hudsonvalley21 said:

18z NAM held ground from the 12z run

 

Storm king should do well

[snowman19]

That 12K NAM map is not even going to be close to reality. First off, it’s the NAM, second, that’s in 10:1 ratios, third, no other model, global or mesoscale is showing anything at all like that. Even the 3K NAM looks absolutely nothing like it. Extreme outlier, toss it right in the trash where it belongs. Here is that ridiculous 12K NAM run without 10:1 ratios: https://www.pivotalweather.com/model.php?m=nam&p=snodpc_acc-imp&rh=2024012712&fh=69&r=us_ne&dpdt=&mc=&pwplus=1

[gravitylover]

35 minutes ago, hudsonvalley21 said:

18z NAM held ground from the 12z run

 

I think that NW CT jackpot is a little too enthusiastic. 

[CPcantmeasuresnow]

34 minutes ago, gravitylover said:

I think that NW CT jackpot is a little too enthusiastic. 

Cut it in half. 

[HeadInTheClouds]

Expecting 1-2 in the HV 20 miles north of 84. Elevated areas should do pretty well. 

[gravitylover]

3 minutes ago, HeadInTheClouds said:

Expecting 1-2 in the HV 20 miles north of 84. Elevated areas should do pretty well. 

I'm a few miles south of 84 and I'm expecting a half inch of white rain! I figure if I keep my expectations low I can't be too disappointed

[HeadInTheClouds]

4 minutes ago, gravitylover said:

I'm a few miles south of 84 and I'm expecting a half inch of white rain! I figure if I keep my expectations low I can't be too disappointed

This is a tough one with thermals but if you are around 1000 in elevation you should get more than that I would think. We will find out soon enough.