bluewave

Thats only true for OP run storm tracks and precipitation forecasts beyond 3-5 days. The ensemble mean 500 mb and temperature patterns forecasts have been doing pretty well through 6-10 days. But the longer range 11-15 day ran too cool for our area in early December which verified warmer. The effective range for OP runs for storm tracks is only about 3-5 days. But the general ensemble means for 500 mb patterns and temperatures skill extends to 6-10 and sometimes 11-15 if we get lucky. People on these forums are well aware that extended runs beyond 15 days don’t have that much skill. But we still like to talk about them. We never use those longer range products to try to pin down individual storm tracks. I would consider a model forecast beyond 2 weeks a success if it can identify at least one teleconnection pattern that has a significant influence.

The only constant in this pattern has been disappointment when getting invested in individual model solutions for storms beyond 5 days with such a fast Pacific flow. Sometimes I wish that they stopped making operational models available beyond 120 hrs and just had ensemble means. I have no idea why they run the GFS OP beyond 10 days. This really creates more public relations issues for the NWS than it’s worth. Way too much posting of long range snowfall charts on these forums and social media. It has the effect of eroding the public confidence in the weather forecasting profession. While ensembles do well with general 500 mb and temperature patterns, operational models have almost no skill with snowfall forecasts beyond a few days.

Just returning the favor for him giving the weenie to my earlier post.

I left off last winter since the La Niña never coupled. But you can use it if you want. NYC had a snowy December and it was reflected in the seasonal totals coming in above normal. The La Niña relationship holds for JFK also. Under the 25.9” seasonal normal if they get under 3.0” in December during a La Niña. 2017….6.7….35.5 2016….3.3…30.9 2011…..0.0….3.7 2010….15.8….42.0 2008….4.9…..22.3 2007….2.4……11.7 2005….5.0…..25.4 2000….11.9…..33.8 1999….0.1……14.1 1998….2.3…..12.3 1995….10.5…69.0 1988…..0.7….8.2 1984….5.5….27.3 1983…..1.2…..22.0

If the -NAO blocks have been strong enough over the last 10 years, they have usually been able to retrograde back to the PNA region. So what the models are showing now is something different with a strong -PNA and -NAO. It’s probably related to the record NEPAC vortex since the fall. Plus the ensemble effective range is only about 2 weeks. So we are just seeing a brief model snapshot. The actual pattern will likely vary away from what may or may not look like a match from the past. Most analog matches usually occur after the fact. That’’s why using specific analogs well before the new month starts rarely works out.

We are on track for a top 10 warmest first half of December across the area. Between 6 out of the 8 top 10 warmest years occurred since the late 90s. So with the new warmer December climate normals, the stations did this with a +4 to +5 departure. EWR….+5.4 ISP…….+3.8 LGA……+4.2 Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Dec 13 Missing Count 1 1998-12-13 50.6 0 2 2001-12-13 50.0 0 3 2015-12-13 49.2 0 4 1951-12-13 45.9 0 5 2021-12-13 45.7 0 - 1953-12-13 45.7 0 6 2012-12-13 44.8 0 7 1982-12-13 44.3 0 8 1999-12-13 44.2 0 - 1991-12-13 44.2 0 9 1973-12-13 43.7 0 10 1993-12-13 43.5 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Dec 13 Missing Count 1 1998-12-13 48.1 0 2 2015-12-13 47.7 0 3 2001-12-13 46.5 0 4 2012-12-13 43.8 0 5 1972-12-13 43.6 0 6 1991-12-13 43.5 0 7 2021-12-13 43.1 0 8 2004-12-13 42.0 0 9 1999-12-13 41.9 0 10 2011-12-13 41.6 0 Time Series Summary for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 1 to Dec 13 Missing Count 1 1998-12-13 52.9 0 2 2001-12-13 51.7 0 3 2015-12-13 50.9 0 4 1953-12-13 48.2 0 5 1951-12-13 47.5 0 6 2021-12-13 46.7 0 7 2012-12-13 46.3 0 8 1991-12-13 45.9 0 9 1999-12-13 45.8 0 10 1948-12-13 45.5 0

No recent years going into January had anything close to that 500 mb pattern. The only January with such a prominent -EPO/-PNA/-NAO was 1969. FWIW, NYC finished at 31.8°, 1.10” of precipitation, and only 1.0” of snow. It was a very dry month. The caveats are that the extended EPS is only just a snapshot of what it’s showing from the end of December into early January. Skill falls off beyond the 2nd week.

The extended EPS is -NAO/-EPO/-PNA from late December into January. Dec 20-27 Dec 27 to Jan 3 Jan 3 to Jan 10

No doubt. We will need to weaken the -PNA enough in late December into early January for the -EPO and -NAO to work for us.

It’s easier to get pattern improvements after January 20th in El Niño years since they are back-loaded like 15-16. But we want to start putting snow points on the board by the end of December in La Ninas to reach normal snowfall. That’s why the December the 3” rule for NYC has worked out every La Niña since the 1990s. La Niña years that we have to wait until after January 20th for a decent snow like 99-00 usually underperform in the snowfall department.

There really is not set time limit on how long a pattern can last. While some patterns only last weeks, other can extend to a year or even longer. Plus you can have sub patterns existing within even larger patterns. The larger over the top warm pattern ran from last December until this November with only short breaks. This month is something new with the warmest departures to our south. So any cool down to the pattern will begin to press from the north rather than the Southeast cooling off first.

In very warm winter patterns like we have now, it usually takes a series of steps to shift the pattern to something more favorable. Some models try to rush things. So it’s often better to look at the more conservative outcomes before the pattern flips. New England usually cashes in before our area does. So that is the place to look at first if you want to start seeing more wintery outcomes. The good news is that the longer range guidance continues to indicate that the pattern right after Christmas is showing improvements.

That’s fine. I guess the tone you are seeing is a result of the pattern through the 20th. Hopefully, we get a window of opportunity late month into early January. Kind of looks like the CFS is trying to show something like this. But the question then becomes how long can it last? The CFS retrogrades the pattern to something less favorable by mid-January . It may take a SSW to get a longer lasting boost from from this MJO progression and +AAM spike. Maybe the next few runs of weeklies will provide some clues.

I just mean that I wouldn’t consider a pattern critique trolling. I have no problem with anyone criticizing a pattern or a weather model. It would be nice if the GEPS is right about the SE Ridge flattening out during the last week of the month. It kind of looks like what we would hope for with a MJO 8 and +AAM.

People making posts discussing the current actual pattern is not trolling.

You have to realize that the discussion we are having is about the pattern leading up to Christmas. Not sure what you mean by changing goalposts.The post Christmas pattern potential has been discussed here at length. The hope has always been that the Pacific can relax enough to flatten out the SE Ridge. Getting a MJO closer to phase 8 with a +AAM could be helpful. So try going back and reading more before you leave a snarky quick post telling us how we are all gloom and doom.

Anything too amped will cut in this pattern leading up to Christmas. A system that is too weak will get sheared out and suppressed by the fast Pacific flow. Thread the needle will be a challenge for us but easier in New England. But any snow here at all is a big win in such a hostile Pacific pattern.

We just saw how poorly the GFS did with the fast Pacific flow last week.

Getting a favorable Pacific is more important for our area. New England can get by with a -EPO/-PNA/-NAO. But a -PNA trough over the West will push the gradient into New England. We will need to eventually flatten out that SE Ridge near the end of the month.

That’s what made it so easy to remember the individual storms. We had the surprise 15” on 1-20-78 that was forecast to be a rainstorm. The Feb 78 blizzard followed a few weeks later. The next season featured the PD1 storm. April 82 had our greatest very late season blizzard on record. It was followed up by the Feb 83 snowstorm. Next memorable event was the surprise 1-23-87 snow that was also supposed to be rain. Central Long Island got a surprise narrowly focused norlun band that left areas just east and west with nothing in Dec 88.

The 3” snowfall marker for December in NYC has only worked with La Niña winters since they are supposed to be front-loaded. It’s not something we can us use in El Niño’s since they usually are back-loaded. But since this year we are getting a February strong -PNA pattern in December, it may or may not be valid. If we can’t make it to 3” before the end of December, that would put us in the below normal category for what we have since the 1990s.

Snowfall for our area really comes down to getting intervals of -NAO and -AO blocking. But this must be accompanied by a relaxation of the hostile Pacific patterns. While all our winters since the 15-16 Super El Niño have been warmer than average, the snowfall has been up and down. Even though December warmth has been a winning bet for the last 9 out of 10 years, it’s tough to forecast seasonal snowfall correctly from October or November.

While ENSO is a part of the pattern, we have been getting irregular expressions of those various ENSO states in recent years. The background warming pattern in December is independent of any ENSO state. 9 out of the last 10 Decembers have been warmer than average. Time Series Summary for NY CITY CENTRAL PARK, NY - Month of Dec Click column heading to sort ascending, click again to sort descending. Year Mean Avg Temperature Temperature Departure 2020 39.2 +1.7 2019 38.3 +0.8 2018 40.1 +2.5 2017 35.0 -2.5 2016 38.3 +0.8 2015 50.8 +13.3 2014 40.5 +3.0 2013 38.5 +1.0 2012 41.5 +4.0 2011 43.3 +5.8

Newark had a high of 69° which was the 6th highest December monthly maximum temperature on record. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 121 AM EST SUN DEC 12 2021 ...RECORD HIGH TEMPERATURE SET AT NEWARK NJ... A RECORD HIGH TEMPERATURE OF 69 WAS SET AT NEWARK NJ YESTERDAY. THIS BREAKS THE OLD RECORD OF 65 SET IN 1966. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Dec Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 1998 76 0 2 2001 74 0 3 2006 72 0 - 1982 72 0 - 1946 72 0 4 2015 71 0 - 2013 71 0 - 1984 71 0 5 1978 70 0 6 2021 69 20 - 1964 69 0 - 1956 69 0

The other problem is that there are forecasts using analogs from a much colder era than we have now. Cold analogs from the 70s to even the mid 90s have not worked out. But we still see forecasts trying to use those colder analogs without success in recent years. 76-77 was the last top 10 coldest winter in our area and nothing has come close since then.