donsutherland1

Don't forget the back to back 50" winters (2013-14 and 2014-15).

If, for example, NYC gets to 30" and its winter mean temperature is 32° or below, it was a great winter in objective terms. The only such winters that met such criteria since 1960 are 1960-61, 1977-78, 1993-94, 2002-03, and 2014-15.

This is why one should use probabilistic descriptions, particularly in the medium-range. Making deterministic "yes-no" declarations assumes that the general public is not capable of understanding complexity. That assumption says more about those who make it than the general public. I provided an example in recent days where I referred to the high-end solution being a low probability, high-impact scenario rather than dismissing it out-of-hand. 4-5 days out allows for a lot of change.

The preliminary RSI value for the Northeast was Category 2.

I agree. I'm thinking 8"-12" for NYC and nearby areas with higher amounts on parts of Long Island, central and southern NJ.

That's the national blend of models.

Most of the New York City, NJ, and Long Island region has > 70% probability of seeing 6" or more snow. The spread remains large. The overall NBM forecast:

In my school district in Westchester, 3 snow days are built into the schedule. If they aren't used, the school year ends a bit earlier. We still meet the 180-day state requirement. Post-Covid, there was some discussion about going the route New York City chose. But the conclusion was that students would be distracted/not motivated, so remote learning would not necessarily be beneficial from a learning standpoint.

New York City switches to remote learning.

Watches are usually issued 48 hours in advance (sometimes 72 hours if confidence is high); warnings are issued when an event is ongoing or imminent (usually 24 hours or less from the event).

Although the 15z NBM shows highs of 38° on Sunday and 37° on Monday, I suspect that the temperature will be near or just below freezing during the height of the storm. The 38° high on Sunday will occur before the onset of the storm. The 37° high on Monday will likely occur late in the day after the snow has moved away. Based on the standard deviation band, a reading in the upper 20s cannot be ruled out. We'll have to see where things are in the soundings for ratios, but this doesn't look like a low snow-liquid ratio event.

How did you get it to assimilate your hopes and dreams into its forecast? On a more serious note, it looks terrific. The evolution of the guidance overnight and into 12z so far has been very encouraging.

The problem with his hypothesis is that a number of models have trended toward the GFS solution, even if the 6z GFS proves to have been overdone. At shortening lead times and the shift in the guidance, it's difficult to argue that an increasing number of models are misinterpreting an IVT. Far more likely, the shift in the guidance suggests that his hypothesis concerning the GFS is incorrect, even if the GFS returns to its earlier solutions.

Yes. That's correct. The snow could be falling or blowing.

Yes, but the temperature criterion was eliminated.

From here: https://sites.gsl.noaa.gov/desi/

This system has more latitude to come farther north than the 2/6/2010 blizzard had, though there's a limit to how far north it will come. It will depend on the timing and location of phasing and the timing when the trough goes neutral/negative. I suspect 50 miles is within the realm of possibility, as underscored by spreads between the 25th/75th percentile outcomes. In 2010, there was an overwhelming block that precluded the storm's gaining latitude (AO: -5.205; NAO: -0.985) and locked strong confluence into place. In any case, the area of heaviest snows will probably be focused somewhere from the northern Delmarva across central/southern New Jersey barring some large changes. But it is plausible that warning-level snows could extend into northwest New Jersey/adjacent northeast Pennsylvania, NYC's northern/western suburbs, and the southern half of Connecticut.

The issue with the idea of posting blizzard warnings later today was that the lead time is too long. Blizzard warnings are only posted when blizzard conditions are ongoing or imminent in the next 12-18 hours.

No. Even if a blizzard is likely, the criteria do not allow for a blizzard warning at the lead time involved. A Blizzard Warning means that the following conditions are occurring or expected within the next 12 to 18 hours. 1) Snow and/or blowing snow reducing visibility to 1/4 mile or less for 3 hours or longer AND 2) Sustained winds of 35 mph or greater or frequent gusts to 35 mph or greater. There is no temperature requirement that must be met to achieve blizzard conditions. https://www.weather.gov/lwx/warningsdefined#Blizzard Warning

We agree about the NAM. I mentioned it just for purposes of reference. I give it very little weight at this timeframe and I'm looking forward to its retirement. I started somewhat conservatively, as there is enormous spread among the guidance and among the NBM's 25th/75th percentiles and 10th/90th percentiles. Hopefully, the spread will be smaller after the 12z and 18z cycles. I'll revisit the numbers late in the day. Finally, as you note, 4"-8" might also be a better initial call.

For reference, here are the 7z NBM numbers, including the spread between the 25th and 75th percentiles: Snowfall: Spread: A large area, including the New York City region has a 6" or above spread. In short, big changes are still possible.

Last night had some favorable developments. Although a significant or major snowstorm remains a low probability/high-impact scenario, there was a notable increase in EPS members supporting such a solution. 6" or above: 2/19 12z: 8%; 2/20 0z: 24% 10" or above: 2/19 12z: 0%; 2/20 0z: 12% Model disagreement, especially at the surface, persists. The GFS remains the most aggressive model. The NAM shows no accumulating snow in New York City. Things should start to narrow today. A good starting point might be a 3"-6"-type snowfall for New York City and its nearby suburbs with more than 6" likely in an area running from central/southern New Jersey northeastward across central and eastern Long Island. These numbers are subject to change as the situation remains dynamic.

The 18z ECMWF-AIFS has thrown a lifeline to the GFS. Overall, a much snowier run.

Not at 18z.

Another round of rain will arrive tonight and could continue into early Saturday. Most of the region will see less than 0.50" of rain. Highs will likely reach the lower 40s through Saturday. Another storm could bring some snow to parts of the region Sunday into Monday, but there remains some uncertainty about its track and impacts. A significant or major snowstorm remains a low probability, high-impact event. Currently, the GFS is the only operational model supporting this solution. No individual EPS member shows 10" or more snowfall and just 8% have 6" or more. The ENSO Region 1+2 anomaly was +0.7°C and the Region 3.4 anomaly was -0.2°C for the week centered around February 11. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.03°C and the ENSO Region 3.4 anomaly has averaged -0.47°C. Neutral ENSO conditions are now developing. Neutral ENSO conditions will develop during the close of winter. The SOI was +0.48 today. The preliminary Arctic Oscillation (AO) was -0.065 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 99% probability that New York City will have a cooler than normal February (1991-2020 normal). February will likely finish with a mean temperature near 31.8° (4.1° below normal). Supplemental Information: The projected mean would be 3.5 below the 1981-2010 normal monthly value. Overall, Winter 2025-2026 is on track for a seasonal mean temperature of 32.0°, but the forecast development of an AO+ regime could lead to a sufficiently mild outcome to result in a winter mean temperature that exceeds freezing. If a 32.0° or below seasonal mean temperature occurs, that would be the lowest winter mean temperature since Winter 2014-2015 when the mean temperature was 31.7°. Winter 2025-2026 would only become the fourth winter of the 21st century with a mean temperature of 32.0° or below.