Major Nor'easter snow storm (possible top 20) Noon Wednesday-Noon Thursday Dec 16-17, 2020

[jysamuel]

Found the jackpot - once in a lifetime event going on in Upstate NY --> southern NE 

Makes us look like plebeians worrying over inches while they're measuring in 2-foot increments lol 

 

[gravitylover]

5 hours ago, JustinRP37 said:

Yup for a few more weeks at least. Moving up to Carmel soon. But we love Tuckahoe!

Hey new neighbor.

I fell asleep and missed what looks like it was a good storm. The wind did a heckuva job smoothing everything out, it goes from nearly bare ground with grass showing and clean cars to drifts 3 feet deep filling in all the holes. Measuring this one is gonna be fun.

Radar looks like there's an ugly dry slot that wants to shut me off and unless this thing pivots now its over soon. Is that about right? I haven't had coffee yet.

[MJO812]

3 hours ago, nycwinter said:

storm bust for the city...

Not really 

 

[MJO812]

It was just snowing moderately but now sleeting right now in Brooklyn. 

I got some more accumulating snow overnight but I didn't measure just yet.

Temperature is 28 degrees 

 

[wdrag]

Am hopeful that upon further review, that the event produced at least low end of the ranges.  I see it's still moderate snow at times along and north of I80 PA NJ and much of nw LI.  I would think this is a high impact storm there and I suspect will be a top 20 event in the ne snow storms when all is said and done.  We'll try to detail that more around 11A. 

[Maureen]

I don’t know what has officially fallen in Carteret, but certainly more than a dusting!

[BuildingScienceWx]

11.0" here, light to moderate snow at 20F

[jdpack]

16 hours ago, jdpack said:

My final call:

JFK ~1-2

LGA 2-4

Central Park 3-5

EWR 4-6

Not too far off on these.... 

JFK- 2-3

LGA- 3-6

Central- 4-7

EWR- 3-6

[MJO812]

26 minutes ago, jdpack said:

Not too far off on these.... 

JFK- 2-3

LGA- 3-6

Central- 4-7

EWR- 3-6

4-8  inches was a good call city wide 

Sleet ruined this for us but can't complain 

Got more snow than the whole winter last year

[weatherpruf]

13 minutes ago, MJO812 said:

4-8  inches was a good call city wide 

Sleet ruined this for us but can't complain 

Got more snow than the whole winter last year

At least where I am it didn't sleet as much as it snowed beforehand; I don't think the sleet caused us to lose all that much, iff it had stayed snow...not sure but it still doesn't look like it would have been huge totals here. Maybe 8-10 if it stayed snow? The heaviest precip here didn't last once the sleet rolled in.  

[ILoveWinter]

I’d guess CPK will end up over 8 with the final measurement so it would be within guidance albeit on the lower end of the range.

[jdpack]

5 minutes ago, weatherpruf said:

At least where I am it didn't sleet as much as it snowed beforehand; I don't think the sleet caused us to lose all that much, iff it had stayed snow...not sure but it still doesn't look like it would have been huge totals here. Maybe 8-10 if it stayed snow? The heaviest precip here didn't last once the sleet rolled in.  

My prediction yesterday was sleet due to warm air aloft. I didnt see that big of a dry slot coming in.

Regardless, the NWS should have been a lot more conservative with the forecast, especially in the afternoon. The warning signs were there well before the 18z NAM3k rolled out. I think it was 2-3 hours after NWS was sticking to 9-14 then below had "uncertainty remains with mixing"... There was no true uncertainty.

My cardinal rule of winter storms: If a warm nose is even in the discussion, then you should remove 30-50% of the predicted totals. Even with surface temps in the lower to mid 20s, you go up 1000-2000 feet and it was 35-40f.

[jdpack]

17 hours ago, allgame830 said:

your right it doesn't but your literally the only one on here saying this.... @SnowGoose69 said right above even the NAM is running 30-40 to fast with the change to sleet.

NAM3k does very very well with temp profiles. HRRR sucks at it. When I lived in NC, we got harsh reality lessons in warm noses. With the 6600ft mtns nearby, often we could get RAIN, with surface temps in the low 20s. HRRR always thought it was snowing. NAM sniffed it out and called it.

[bluewave]

Good to see the new parallel GFS v16 seems to have fixed the cold and suppressed bias if the current v15. I hope whatever model replaces the NAM is able to correctly see strong WAA aloft like the current model does. While the HRRR is good with thunderstorms and squall lines, it’s profiles are way too cold for winter storm events like this one.

Current version too cold and suppressed

New parallel warmer and further north with the precipitation shield

 

 

[weatherpruf]

1 hour ago, jdpack said:

My prediction yesterday was sleet due to warm air aloft. I didnt see that big of a dry slot coming in.

Regardless, the NWS should have been a lot more conservative with the forecast, especially in the afternoon. The warning signs were there well before the 18z NAM3k rolled out. I think it was 2-3 hours after NWS was sticking to 9-14 then below had "uncertainty remains with mixing"... There was no true uncertainty.

My cardinal rule of winter storms: If a warm nose is even in the discussion, then you should remove 30-50% of the predicted totals. Even with surface temps in the lower to mid 20s, you go up 1000-2000 feet and it was 35-40f.

Spot on. I just went out and cleaned ( damn these gas snow blowers even when new give you issues ) and it looks to be 6-8 by me. I'm not measuring; it was actually a decent event here in my part of Middlesex County. That amount in December makes it an actual snowstorm and not 2-4 inch with slush. Snow wasn't powdery but not wet either; compacted a little from sleet, but it was real nice to blow through. This is CNJ just outside NYC and storms over a foot, or even 10, are not the norm over my lifetime; this is. I'll take a bunch of these all winter rather than a big 2 footer that melts in a week ( ok I'll take that too ).

[jm1220]

1 hour ago, jdpack said:

My prediction yesterday was sleet due to warm air aloft. I didnt see that big of a dry slot coming in.

Regardless, the NWS should have been a lot more conservative with the forecast, especially in the afternoon. The warning signs were there well before the 18z NAM3k rolled out. I think it was 2-3 hours after NWS was sticking to 9-14 then below had "uncertainty remains with mixing"... There was no true uncertainty.

My cardinal rule of winter storms: If a warm nose is even in the discussion, then you should remove 30-50% of the predicted totals. Even with surface temps in the lower to mid 20s, you go up 1000-2000 feet and it was 35-40f.

The early dryslot ruined things more than the warmth aloft did. It wasn’t overly strong, and the Nam actually overdid it a little. If the snow shield would have held and not chopped up after the first few hours, we all would have a few more inches and we’d be closer to Upton’s point/click yesterday afternoon. The chopped up precip also allowed the warm mid level air to take over sooner. 

[ILoveWinter]

2 minutes ago, jm1220 said:

The early dryslot ruined things more than the warmth aloft did. It wasn’t overly strong, and the Nam actually overdid it a little. If the snow shield would have held and not chopped up after the first few hours, we all would have a few more inches. The chopped up precip also allowed the warm mid level air to take over sooner. 

Yea I agree, here in the UWS it only sleeted for an hour, so I think we would have done quite well if we maintained the heavy rates that we had earlier in the evening

[LibertyBell]

7 hours ago, MJO812 said:

There will be no big back end snows. The pivot will benefit New England. 

you were wrong....3:30 AM to 7 AM was amazing here with temps crashing into the mid 20s and heavy snow and high winds, transformers bursting looking like lightning and zero visibility here.  Didnt expect it but thoroughly enjoyed it

 

[LibertyBell]

11 minutes ago, jm1220 said:

The early dryslot ruined things more than the warmth aloft did. It wasn’t overly strong, and the Nam actually overdid it a little. If the snow shield would have held and not chopped up after the first few hours, we all would have a few more inches and we’d be closer to Upton’s point/click yesterday afternoon. The chopped up precip also allowed the warm mid level air to take over sooner. 

I was surprised at 4 am to see that the temps had crashed into the 20s and we had blizzardlike conditions here and you were still raining, JM.  

[LibertyBell]

5 hours ago, weatherpruf said:

Ya got me there. 

Outside of people in the mountains and in Binghamton it looks like I was the only one who enjoyed this storm.  I didn't expect a lot but what happened before daybreak with the heavy snow and high winds for a few hours, I thoroughly enjoyed.  I wasn't expecting this to be historic and it wasn't.  

[LibertyBell]

13 minutes ago, ILoveWinter said:

Yea I agree, here in the UWS it only sleeted for an hour, so I think we would have done quite well if we maintained the heavy rates that we had earlier in the evening

In western LI the best part of the storm was actually late last night and early this morning with the heavy snow and high winds.  I didn't think that much about the first part of the storm.

[LibertyBell]

49 minutes ago, bluewave said:

Good to see the new parallel GFS v16 seems to have fixed the cold and suppressed bias if the current v15. I hope whatever model replaces the NAM is able to correctly see strong WAA aloft like the current model does. While the HRRR is good with thunderstorms and squall lines, it’s profiles are way too cold for winter storm events like this one.

Current version too cold and suppressed

New parallel warmer and further north with the precipitation shield

 

 

why is the NAM being replaced when it's been doing so well?

 

[LibertyBell]

2 hours ago, jdpack said:

Not too far off on these.... 

JFK- 2-3

LGA- 3-6

Central- 4-7

EWR- 3-6

You were off on JFK..... I'm 4 miles east of there and I got 4 inches in the first part of the storm and about 3 in the second half (which I found more exciting because of the high winds and whiteout conditions).

 

[LibertyBell]

3 hours ago, wdrag said:

Am hopeful that upon further review, that the event produced at least low end of the ranges.  I see it's still moderate snow at times along and north of I80 PA NJ and much of nw LI.  I would think this is a high impact storm there and I suspect will be a top 20 event in the ne snow storms when all is said and done.  We'll try to detail that more around 11A. 

yup sw long island too, we changed back to snow a lot sooner than the north shore of suffolk county did, I thoroughly enjoyed the three hours of white out conditions I had beginning at 3:30 am with heavy snow and high winds.

 

[ILoveWinter]

17 minutes ago, LibertyBell said:

In western LI the best part of the storm was actually late last night and early this morning with the heavy snow and high winds.  I didn't think that much about the first part of the storm.

Truthfully I fell asleep so I missed the 1-6AM period but I took a walk at around 630 last night and it was insane!

[LibertyBell]

Just now, ILoveWinter said:

Truthfully I fell asleep so I missed the 1-6AM period but I took a walk at around 630 last night and it was insane!

Yes haha for some reason I was outside and documented the first flakes that fell around 2:30 PM and counted like 10 flakes between 2:30 and 2:42 PM and then the storm started to get down to business here after 2:45 PM.  It started sticking as soon as the snow got heavier, around 3 PM and it definitely felt like the middle of winter for a few hours after that and also early this morning between 3:30 AM and 7 AM

 

[bluewave]

22 minutes ago, LibertyBell said:

why is the NAM being replaced when it's been doing so well?

 

https://vlab.ncep.noaa.gov/web/environmental-modeling-center/fv3-convective-allowing-forecast-system

UNIFIED FORECAST SYSTEM : CONVECTIVE-ALLOWING FORECAST AND DATA ASSIMILATION SYSTEM

 

UNIFIED FORECAST SYSTEM : Convective-Allowing Forecast and Data Assimilation System

 

1. Preamble

The UFS Convective-Allowing Model (CAM) Working Group’s charge is to create, using the FV3 dynamical core, a convective-allowing ensemble-based data assimilation and forecast system for the 0-3 day range to replace This development is a collaborative effort between NWS (NCEP/EMC), OAR (NSSL, GSD, GFDL), NCAR, the DTC, and academia. Experience gained from the development of earlier operational and experimental CAM systems such as the GSD’s HRRR/HRRRE, the NAM nests from EMC, the NSSL Experimental Warn-on-Forecast System for ensembles (NEWS-e), the NCAR experimental CAM ensemble, and GFDL’s FV3-based CAM efforts, will guide this project as it evolves. The anticipated operational system, the Rapid Refresh Forecast System (RRFS), will be a single-core (FV3) CAM ensemble-based data assimilation and forecast system. The RRFS is planned for operational implementation in FY2023.

 

2. Background and Development Timeline

As part of its commitment to the implementation of a unified forecast system in NCEP’s Production Suite, NOAA is planning to replace NCEP’s myriad mesoscale and convective-allowing systems with new guidance systems based on the FV3 dynamic core. As of July 2018, the NCEP meso/CAM scale modeling suite currently consists of the following components:

1. North American Mesoscale (NAM) system: Runs the Non-hydrostatic Multiscale Model on B-Grid (NMMB). The NAM consists of a North American 12-km parent domain run to 3.5 days and 4 non-moving nests run to 2.5 days at 3-km resolution over the CONUS, Alaska, Puerto Rico, and Hawaii. An additional 1.5 km nest is run over a pre-selected part of the CONUS or Alaska to 1.5 days for fire weather support operations. The NAM features an 6-h data assimilation cycle with hourly analysis updates for the 12 km parent domain and the 3 km CONUS/AK nests.
2. High-Resolution Window (HiResW):  Consists of ~ 3-km runs of the NMMB model and two configurations of the ARW model over the CONUS, Alaska, Hawaii, Puerto Rico, and Guam (single ARW run only).
3. High-Resolution Ensemble Forecast (HREF) system: Current/time-lagged HiResW and NAM CONUS nests are used to generate ensemble products. Currentversion is an 8-member ensemble for CONUS with HiresW and NAM CONUS nest members; HREF for Alaska, Hawaii, and Puerto Rico are a 6-member ensemble with HiResW members only.
4. Short-range Ensemble Forecast (SREF) system: Runs at 16 km over North America and currently consists of 26 members (13 NMMB, 13 ARW) with physics/initial condition diversity. The replacement of the SREF and deterministic NAM systems will be based on whether they can be replaced by improved forecast guidance from the FV3-GFS and FV3-GEFS. 
5. Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR): The RAP and HRRR are run hourly out to 21 hr and 18 hr, respectively. RAP is run at 13-km resolution over North America (identical to the NAM parent domain), while HRRR is run at 3 km over CONUS. As of July 2018, the 00/06/12/18z HRRR cycles were extended to 36-hr, and the 03/09/15/21z RAP cycles were extended to 39-hr. A HRRR-Alaska system was also added, running every 3 h. 

NAM development was frozen after the March 2017 upgrade, and RAP/HRRR development with the WRF-ARW model will cease after the RAPv5/HRRRv4 upgrade in 2020. However, operational execution of these modeling and associated DA systems will continue until comparable FV3-based systems are able to give similar performance. The transition of these deterministic modeling systems to FV3-based configurations will be prioritized as follows; these milestones are also summarized in the chart below:

 

FY2019-FV2020 : HRRR v4 implementation and SAR-FV3 development Development of the FV3-based stand-alone regional model (SAR-FV3) to bring its capabilities and performance up toward the current CAM systems  Finalize and implement RAPv5/HRRRv4 Add the extended HRRR forecasts to HREF, possibly replace NMMB members in HREF with SAR-FV3 members Preliminary ensemble DA testing with SAR-FV3 Begin evaluation in NOAA testbeds   FY2020-FY2021 :SAR-FV3 development/testing for Meso/CAM  Finalize porting of HRRR physics into CCPP for use in SAR-FV3 Finalize FV3-based RAP Continue evaluation of FV3 SAR against existing systems Continue development of DA capabilities with SAR-FV3 Continue evaluation in NOAA testbeds   FY2021-FY2023 : Evolution to a FV3-based single core Rapidly Refreshed Forecast System (RRFS) : FV3 CAM ensemble with DA Ensemble analysis and forecast system development with SAR-FV3 and JEDI Development of stochastic physics for single core Continue evaluation in NOAA testbeds Pursuant to favorable evaluation, implement v1.0 RRFS [2023]

 

3. Ongoing Efforts

 

EMC : Developed a limited area regional version of the FV3 and adapted the NCEP Unified Post-Processor (UPP) and Grid-scale Interpolation (GSI) analysis for the FV3SAR. Currently running two real-time forecast experiments:

 

•        A control run of a 60-h forecast over the CONUS of a 3 km limited area standalone FV3 with initial and boundary conditions from the operational FV3GFS
•       A parallel run of the 3 km FV3 for dynamics/physics tuning tests

 

EMC is also developing a hourly ensemble data assimilation capability with the limited area FV3.

 

GSD : Developing RAP-sized FV3 domain and modifying pre-processing to use RAP instead of GFS / Fv3GFS input for lateral boundary conditions. Working with EMC on developing better grid-spacing uniformity for the continental FV3-RAP domain

 

EMC/GSD/NSSL/Developmental Test Bed Center (DTC) : Develop commonly-shared FV3SAR workflow

 

4. Links to Relevant Documents/Web Sites

•         Link to CAM Working Group Google Docs folder 
•         UFS Implementation Plan 
•         UFS Web Portal

[HVSnowLover]

Still light snow out. Hard to tell but eyeballing maybe another 1 to 3 inches since went to bed around 3 am. Haven’t been out so it’ll be interesting to see what the combination of sleet and powdery snow looks like 

[mikem81]

1 hour ago, LibertyBell said:

yup sw long island too, we changed back to snow a lot sooner than the north shore of suffolk county did, I thoroughly enjoyed the three hours of white out conditions I had beginning at 3:30 am with heavy snow and high winds.

 

I am in Garden City. We were all Snow thrugh 11pm when it started pouring sleet. Feel asleep after that. Wat happened overnight? Did we ever flip to rain?

[forkyfork]

how on earth did this give bgm 40 inches? this has to be climate change