donsutherland1

Some snow flurries have been occurring in Goshen.

I agree. The forecast development WPO+/EPO+/AO-/PNA+ pattern typically does not favor large East Coast snowstorms during January 1-10. Instead, lighter snows are the rule. If one is searching for a genuine cold and snowy pattern, a WPO-/AO-/PNA+ combination is far better.

The ongoing PNA- will eventually end, even if the 0z GEFS sustains it through its forecast period. Once that happens, recent historical experience (since 1980) suggests that the PNA will likely undergo a regime change to mainly positive values. The same kind of regime change took place for all 10 25-day or longer streaks that began in November or December.

A weathergami is a unique high-low combination in a city's climate record. This year's weathergamis in the New York City area are below:

Clouds are now breaking near sunset.

Clouds will continue to break from west to east this evening, as colder air moves back into the region. Tomorrow and Wednesday will see cooler than normal days. Below normal temperatures will continue into at least the middle of the first week of January. Some flurries or snow showers are possible late on Thursday into Friday. The first week of January will likely have a mean temperature below 30° in New York City. The last time that happened was in 2018. The only years since 2000 with a sub-30° mean temperature for the opening week of January were 2001, 2010, 2014 and 2018. December 2025 is on course to finish with a maximum monthly temperature below 60° in New York City. The last time that happened was in 2019 when the monthly high was 58°. This will be only the fifth such occurrence since 2000 (2003, 2004, 2005, and 2019 are the cases since 2000). The ENSO Region 1+2 anomaly was -0.3°C and the Region 3.4 anomaly was -0.7°C for the week centered around December 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.33°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions will likely continue into at least late winter. The SOI was +3.94 today. The preliminary Arctic Oscillation (AO) was -2.053 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal December (1991-2020 normal). December will likely finish with a mean temperature near 33.8° (5.3° below normal). That will make December 2025 the coldest December since 2010 when the monthly mean temperature was 32.8°. It would also make 2025 the third coldest December since 2000. Supplemental Information: The projected mean would be 3.6° below the 1981-2010 normal monthly value.

I had used the initial map posted by MJO812 for the benchmark. Even with the adjustment for the the additional snowfall, the outcome changes very little. The NAM has had successes. This wasn't one around the New York City area, which was the focus of the discussion/model comparison, when it came to snowfall amounts leading up to the storm. The HRRR overdid some of the totals for New York City and Newark. It seems to have a cold bias. In the end, over several days of guidance, it was clear that this was going to be a 3"-6"/4"-8" storm for the New York City area. There was no real drama for this area. The RRFS A's attempts at suppression, NAM's swings/amounts for NYC-EWR, and GFS's elevated amounts were noise. IMO, this was probably among the more straightforward forecasting situations in recent snowstorms for the City and its nearby suburbs. That outcome shows up well in NWS-New York's (OKX's) final PNS report where almost 75% of all snowfall reports fell in the 4"-8" range and nearly two-thirds were in the 3"-6" range. This will be my last comment on the NAM for the December 26-27 storm. The numbers speak for themselves.

Some morning fog as the warm, moist air as moved over snow-covered landscape.

The timing of the development of a PNA+ remains perhaps where the greatest uncertainty concerning the teleconnections lies. The EPS still developes a PNA+. A prolonged delay would risk breaking the colder pattern, especially if the WPO and EPO both go positive. If the AO goes positive along with the WPO and EPO while the PNA stays negative, that's a classic very warm pattern. For now, that doesn't seem to be a highly likely outcome, at least for the first half of January.

St. Louis had its fifth biggest daily temperature range on record yesterday, as the mercury plunged from a December monthly record 78F (25.6C) to 22F (-5.6C). That was the largest daily temperature range on record for December.

I posted the maps for both models. The numbers are from the maps. Nothing is derived. Bufkit computes snow using 4 algorithms and uses 1:1 for sleet.

Hopefully, it won’t be quite as bad as shown. That’s a terrible amount of ice.

Wonderful find.

Light rain and some freezing rain is moving into the region. Areas north and west of New York City have the highest likelihood of seeing some freezing rain. Tomorrow will see some additional showers. The temperature will likely reach the upper 40s to perhaps lower 50s before colder air moves in. It will also turn very windy with gusts reaching 40 mph to 50 mph at times. The remainder of December will see cooler than normal days. Below normal temperatures will continue into at least the middle of the first week of January. Some flurries or snow showers are possible late on January 1 into January 2. December 2025 is on course to finish with a maximum monthly temperature below 60° in New York City. The last time that happened was in 2019 when the monthly high was 58°. If 2025 has a monthly high below 60°, that would be only the fifth such occurrence since 2000 (2003, 2004, 2005, and 2019 are the cases since 2000). The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.8°C for the week centered around December 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.40°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions will likely continue through at least mid-winter. The SOI was +9.19 today. The preliminary Arctic Oscillation (AO) was -1.799 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal December (1991-2020 normal). December will likely finish with a mean temperature near 33.9° (5.2° below normal). That will make December 2025 the coldest December since 2010 when the monthly mean temperature was 32.8°. It would also make 2025 the third coldest December since 2000. Supplemental Information: The projected mean would be 3.5° below the 1981-2010 normal monthly value.

This is from Rye, NY looking across the Sound on a cloudy day.