jconsor

https://www.weather.gov/source/crh/snowmap.html?zoom=7&lat=40&lon=-74&hr=24 Just to see the breadth of this storm is impressive! Totals as high as 20" extended all the way down into Delaware and the eastern suburbs of Philly in sw NJ, and then as far ne as near Boston (still snowing heavily in parts of eastern New England). The true jackpot appears to be RI with multiple reports of 30-33"! Part of SE MA southwest of Boston has seen 24-28". (Circled in purple) Wouldn't be surprised to see some scattered 36"+ reports in RI, like was seen in eastern MA or RI in big ones like Feb 1978, Apr 1997 (April Fools Storm) and Jan 2015 (Juno). Other jackpots we have discussed already - the N-S band from coastal central NJ to ne NJ to Westchester County and sw corner of Staten Island (circled in light blue). Most of NYC aside from NE Queens was pummeled by this band at times, but it was nearly stationary over NE NJ for many hours before it started focusing near NYC. And of course the eastern/central LI jackpot (circled in black).

Yep, you got the subsidence between the two bands. Where are you located and approximately how much snow did you receive? I grew up in NW Nassau (Roslyn). Looks like my area was close to the minimum for the entire NYC/LI area - happens somewhat frequently in the past 25 years, yet when I was growing up (late 1980s to mid-1990s) we had near the highest seasonal snowfall totals for all of NYC/LI.

Thank you! However, I don't see Montauk wind gusts in the NWS local storm reports. Do see lots of 60-70 mph gusts across NYC and LI. So 80-85 mph gusts on Montauk are believable. https://mesonet.agron.iastate.edu/lsr/?by=wfo&sts=202602221435&ets=202602231435&settings=0110110

LOL at the laser beams - ECMWF MJO chart has that too. Phase 7 composite for Mar does have building ridging near AK which can help to direct colder air masses down to the NE US at times, and we can benefit from overrunning events. However, it is not really a cold pattern signal with the composite showing eastern US/west Atlantic ridging. I believe we really need to get into phase 8 to see a consistently colder pattern, which EPS does show by around Mar 7-8. EPS is moving the MJO along faster, placing more emphasis on the -VP cell over Central America and the Atlantic than the one over the western Pacific starting around Mar 6-7, whereas the GEFS keeps the w. Pacific cell dominant. EPS should be closer to reality here, especially with the major warming trend in the Eastern ENSO region past two weeks, as well as the warming in the tropical Atlantic. I think we still have opportunities for snow first week of Mar (EPS and AIFS ensemble both have a confluence/cold high pressure and overrunning signal for ~Mar 2-4, with maybe another overrunning event a few days later), then likely a thaw for 5-10 days. Last 15-20 days of March have potential, as you said. ECMWF weeklies have strong signs of AK blocking and looks like southern stream will be active, unlike the Northern Stream-dominated pattern most of this winter. Though Larry's analysis shows phase 7 is the coldest one for La Ninas, I believe the atmosphere is likely to behave closer to neutral as we head later into Mar, especially given the above-mentioned major warming in the eastern ENSO region and anomalous westerly wind bursts expected to get closer to the dateline in late Feb-first few days of Mar and likely again in second half of Mar. The neutral ENSO phase 7 composite is similar to the one included below.

Larry's post was specifically about La Ninas and limited to one station - Baltimore. I think his analysis has merit and definitely is worth keeping in mind, though there is still lots of variability despite the cold lean. The composites I posted before are averages of all Mar phase 7 days, no matter what ENSO state The phase 7 neutral ENSO composites for March is pretty similar to what I showed in my previous post, with eastern US ridging and AK ridging. On the other hand, the La Nina composite is closer to what you would want for colder. Two reasons I wouldn't bank on phase 7 being cold for us this Mar- 1) The La Nina is weak and we are starting to see slow signs of atmospheric coupling with the much warmer SST in the Eastern ENSO regions. So atmosphere would probably behave closer to neutral than La Nina for Mar. 2) The phase 7 La Nina composite has a -NAO with above normal heights/hints of blocking near Greenland. No sign of that on guidance heading into early Mar. So we will have to rely on the AK ridging to deliver cold enough air for snow I think.

Phase 7 composite for Mar does have building ridging near AK which can help to direct colder air masses down to the NE US at times, and we can benefit from overrunning events. However, it is not really a cold pattern signal with the composite showing eastern US/west Atlantic ridging. I believe we really need to get into phase 8 to see a consistently colder pattern, which EPS does show by around Mar 7-8. EPS is moving the MJO along faster than GEFS. See my post in ENSO thread for details. In short, I agree with you that March has potential for snow, especially first week or so (EPS and AIFS ens showing a signal for Mar 2-4 and perhaps another overrunning event a few days after that) and last half.

Can you please send a source confirming those wind gusts? What altitude are they measured at? Montauk Airport has seen gusts to 52 mph.

This a good summary of where we stand IMHO, though it was written before the 12z cycle. https://x.com/ContentWxGuy/status/2024528387927097369 Recon data may help the models gain clarity, though the recon mission prior to Fri 0z run is significantly further west into the central Pacific than the recon mission whose data was ingested into today's 0z cycle.

All that said, I think the best potential for a significant event e.g. 6"+ is from the Delmarva to southern and coastal NJ, and especially from eastern LI to southeast New England. As others have mentioned, given the upper level setup and strong indications of bombogenesis, as well as enhanced baroclinicity with anomalous cold SST near the mid-Atlantic coast butting up against above normal SST along the Gulf Stream, this storm needs to be carefully monitored. A small change in synoptics opens up the potential for a much more impactful storm, especially from coastal NJ to LI, but possibly a little further NW as well e.g. NYC, southern CT.

This article speaks more about skill of AI models in medium range (beyond day 5), but I believe same applies in the 3-4 day range - AIFS ensemble has superior skill to EPS and other physics-based ensembles. AI-GEFS has superior skill to GEFS but isn't as skillful as AIFS ensemble. https://x.com/Brady_Wx/status/2021333729088585882 Given that GEFS and GEPS are closer than the EPS to AIFS ensemble (as well as AI-GEFS) in terms of more amplified trough initially over Ohio Valley/Great Lakes with more downstream ridging, and deeper upper low closer to the mid-Atlantic coast, I would weight them more than EPS in this setup. All models shifted in that direction (when compared to yesterday's 0z run) after ingesting a new batch of upper air data from recon. It appears to me that the EPS under-amplification bias may be at play here and it is most likely playing catch-up here, like the AI summary that Sacrus posted intimated happens sometimes in NE US winter storms.

Basically agree with Brooklynwx. From past experience given the run to run consistency and cross-model agreement amongst the various ML models including AIFS and its ensemble, WeatherNext, GraphCast and Pangu, I would expect the EPS to shift closer to their scenario in the next 24-36 hours.

It is encouraging to see two other highly skilled ML models (GraphCast and Pangu) show an outcome very similar to the AIFS and also similar to AIFS ensemble mean, without the entanglement of the the Sun-Mon system with the system ahead of it across SE Canada shown by the operational ECMWF (last image).

The GEPS showing similar trends to the AIFS ensemble, though today's 12z run is a bit more suppressed than the 0z as the trough turns negative tilt near the NE US coast.

Impressive four run trend from the AIFS ensemble. Note the western ridge trending further west and more amplified. Meanwhile the combination of the ridging east of Hudson Bay and trough over SE Canada exerts less of a suppressive influence, allowing the Sun-Mon trough to amplify more.

Most of the NE US is in the lowest 5 percentile for cold past two weeks, with many stations in the lowest 1 to 2 percentiles.