jconsor

Nice find! For context, this analog set is based on the 0Z GFS run. Feb 1989 was a very heavy (in some cases) record snowstorm from GA to the eastern Carolinas and Delmarva, with heavy snow extending up to coastal NJ. It missed NYC and western LI. Two other MECS are in the top 10: Dec 30, 2000 and Feb 1, 2021. At 500 mb the best match (closest analog) to the setup at day 4 is by far the Boxing Day Blizzard of 2010. Jan 1996, Jan 2016 and Feb 2021 are also respectable matches at 300 mb. https://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=EC&fhr=F096&rundt=2026012800

EPS 6z today vs 0z today and 12z yesterday... Baby steps toward a more impactful storm closer to the mid-Atlantic coast. Notice the western US ridge shifts slightly further west and stronger in more updated EPS runs, while the "kicker" shortwave from Hudson Bay to Manitoba/Ontario and MN shifts weaker. Also the TPV drops down further west and the departing upper trough over SE Canada is a little weaker, allowing better height rises over the W. Atlantic and New England ahead of the TPV.

Tomer notes high-end potential here: https://x.com/burgwx/status/2016008474656649645

I hear ya. Especially given the perigee on Thu and full moon on Sat (thus astronomically high tides), a slow moving, intense coastal storm could cause serious coastal flooding and beach erosion for NJ and LI.

RRFS has been doing well overall with the advance of the sleet. It shows the sleet stalling and then retreating slightly next few hours, with mainly snow hanging on for North Shore of LI until around 0-1Z and northern parts of NYC even until 2-3Z. The additional snow it shows from 17Z on is likely slightly overdone, but the idea that central-eastern LI catches up vs. most of NYC makes sense.

The NBM you posted seems to be using inflated snow-liquid ratios. Compare the NBM version 5 (experimental) with the 4.3 (operational), the same as what you posted. The experimental version 5 snowfall amounts make more sense given the model QPF.

Additionally, we could see several days with highs below 20F behind the Sun-Mon storm at Central Park. Mon's high is highly uncertain - could end up close to 30F if the storm trends further north. Any streak of 5+ days at/below 25F and 4+ days at/below 22F would be quite notable. There have only been four such streaks of <=25F and two such streaks of <=22F at Central Park in the past 50 years!

I would say the atmospheric coupling with the La Nina event has been uneven. The AAM has averaged near neutral since Nov, with a notable spike from late Nov to the first few days of Dec. I agree with your last three sentences about La Nina's continued influence in the next month or two. Also, in my experience, the CFS is known to be highly +AAM biased.

Getting MJO to phase 7 by mid to late Jan would be helpful. Here are composite for strong MJO phase 7 in Jan - note strong blocking signal from north of AK to NW Canada to Greenland: https://x.com/WorldClimateSvc/status/2006751440753316061

Aside from the 12z and 0z NAM, which look unreasonable and lack a focused WNW-ESE area of heavier precip, there is a good consensus of a peak QPF axis around 0.75-0.8" extending from roughly the PA/NJ/NY border ESE toward NYC and the western third of LI. However in reality the peak QPF axis will likely be more narrow than shown by the HREF. The HREF snowfall amounts are often overdone, but given that I expect ratios of 12 to 13:1 even in NYC and Nassau County, I think they are overall pretty reasonable here. I would conservatively go with 5-8" from Orange, Rockland and Westchester counties SE into Bergen and Passaic Counties in NJ, NYC, Nassau and W. third of Suffolk. Could see local amounts up to 10-12" where best banding sets up (likely N of NYC).

The HRRR tends to be too wet at this range, so precip amounts are likely somewhat overdone. The snow map is using dynamic snow:liquid ratio calculated by the HRRR. What is interesting is the 12 to 13:1 ratios from western LI and NYC to NE NJ.

https://lab.weathermodels.com/models/blend/blend_precip.php has it if you have a subscription.

Firstly, I have noticed that the CPC charts often run a day behind. And yesterday's GEFS had the PNA significantly more negative than today's in the Dec 29-Jan 3. Secondly, the WeathermModels PNA chart looks very similar to the WeatherBell one.

True, but we just had a snowstorm produce widespread 6-8"+ from I-95 south and east (other than lighter amounts in the urban heat island near NYC) with -PNA, though in that case the NAO was slightly positive and AO highly positive. *If* we are going to see a 6"+ snowstorm in a -PNA pattern during a La Nina, it almost definitely will come from northern stream system e.g. a highly amplified clipper/Miller B.

The NWS map looks underdone to me for eastern/central LI and eastern Connecticut. I would expect widespread gusts of 55+ mph and scattered 65-70 mph gusts. HREF *mean* has 70 mph hugging the South Shore of Suffolk County and the Twin Forks, and HRRR is similar. We often overperform in southerly windstorms in the winter ahead of cold fronts.