bluewave

That was related to the tail end of the November phase 5. We are currently getting an interference pattern with the MJO phase 6. So this -PNA is out of place for a La Niña phase 6 composite. That’s why we need to be cautious with any expectations about how a phase 7 may look in late December. Snowman linked to a tweet mentioning the +AAM. That along with the WPAC wave breaks is probably why none of the MJO composites are and exact match right now. https://www.frenchscotpilotweather.com/mjo

While the warmth in the East and big -PNA is typical for a neutral ENSO phase 6, a La Niña is supposed to be colder here with a +PNA. So that is telling us that the MJO is not having the intended effect for a La Niña. May be some type of interference pattern which has been noted recently. Could be related to the recent wave breaks in the WPAC and AAM spike. So we will have to be cautious solely relying on the MJO composites going forward until we get more clarity.

It will be a warm up for us compared to how warm it has been to our west this month. The mid portion of December will be higher for us than the +3 to +4 of the first week . So some impressive departures by the solstice.

If you look at the daily snowfall tallies for NYC, EWR, and LGA in December and January 97-98, you will see the common error we often see at Central Park. There were multiple dates when NYC only showed a T but LGA and EWR were 0.2 to 0.5. In recent years we continue to see the same pattern in light events that melt after the snow ends. They wait too long to take the measurements and 0.1 to 0.5s go in as a trace.

The only DJF winter season to go under 1” at NYC was 1997-1998. But my guess is that it was another quality control issue for the Park since LGA and EWR had more. So they probably waited too after the snow ended to measure the snow and some of it melted. Time Series Summary for NY CITY CENTRAL PARK, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Total Snowfall Missing Count 1 1997-1998 0.5 0 2 1918-1919 1.1 0 3 1972-1973 2.6 0 4 1931-1932 2.7 0 5 1991-1992 3.2 0 6 2001-2002 3.5 0 7 2018-2019 3.7 0 8 2011-2012 4.5 0 9 2019-2020 4.8 0 10 1989-1990 5.0 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Total Snowfall Missing Count 1 1972-1973 1.3 0 2 1991-1992 2.5 0 3 2011-2012 3.6 0 - 2001-2002 3.6 0 - 1997-1998 3.6 0 4 1930-1931 4.1 62 5 1988-1989 4.8 0 6 1931-1932 5.3 0 7 1937-1938 5.6 0 - 1936-1937 5.6 0 8 2018-2019 5.7 0 - 1989-1990 5.7 0 9 2019-2020 6.9 0 10 1998-1999 7.3 0 - 1941-1942 7.3 0 Time Series Summary for LAGUARDIA AIRPORT, NY - Dec through Feb Click column heading to sort ascending, click again to sort descending. Rank Season Total Snowfall Missing Count 1 1972-1973 1.9 0 2 1997-1998 2.3 0 3 1941-1942 3.1 0 4 2001-2002 3.3 0 5 2011-2012 3.4 0 6 2018-2019 3.6 0 7 1991-1992 4.1 0 8 2019-2020 4.6 0 9 1955-1956 5.9 0 10 1958-1959 6.0 0

We need to get rid of that -PNA trough near the West Coast to see improvements after Christmas.

Looks like the record warmth building to our west will come out in waves. Our first chance for record warmth will be on Saturday. Models have mid 60s for the warm spots with the record high at Newark at 65°. Then the ridge builds again next week with a another push of warmth coming east. Newark Area, NJVersion: 16.2 (created 2021-11-30)Period of record: 1931 through 2020 12/11 65 in 1971 65 in 1966 63 in 1979 Saturday Next week

Mid-December is on track to be the 3rd warmest for the entire CONUS averaged out. You can see how many top 10 warmest years there have been since 2001. This is coming after one of the warmest first weeks of December for parts of the country. So there should be some very impressive warm departures by the solstice.

Big upgrade coming for the EPS next year. Created by Carsten Maass on Dec 06, 2021 Go to start of metadata Description of the upgrade With IFS Cycle 48r1, the horizontal resolution of the medium-range ensemble (ENS) will increase from 18 to 9 km. This will bring the ENS to the same horizontal resolution as the high resolution forecast (HRES). The vertical resolution for both ENS and HRES will remain at 137 model levels. Cycle 48r1 will also bring a major upgrade to the configuration of the extended-range ensemble (ENS extended): The forecasts will start from day 0, rather than being an extension of the medium-range forecasts starting at day 15, it will run daily, rather than twice-weekly, and the number of perturbed forecasts will increase from 50 to 100. The resolution will remain unchanged at 36 km horizontally and 137 model levels. The implementation of Cycle 48r1 is currently planned for late 2022 and it will be the first new scientific model upgrade to run in ECWMF's new Data Centre in Bologna. While no action is required at this time, as much notice as possible is given to users to plan and prepare for this increased resolution. Please note, at this lead time implementation date and content of this cycle are subject to change - please watch this page for further updates. Implementation scheduled for late 2022, TBC

Funny how parts of the area have had a top 10 snowiest month every season since 09-10. 09-10…..Dec…..Feb….. 10-11…….Dec…..Jan 11-12…….Oct 12-13……Nov…Feb….Nemo 13-14……Jan….Feb 14-15……Jan….Feb…Mar 15-16…….Jan 16-17……..Mar….Stella interior 17-18……..Mar….30” at ISP 18-19……..Nov 19-20……..May 20-21….….Feb

The only La Niña MJO composite that comes close to the pattern this month is a January phase 5. All the ensembles keep this pattern going through at least the solstice. Maybe the MJO will make more sense near the end of December and beginning of January.

Maybe the extreme marine heatwave during the summer near Japan was a precursor to the record fall into winter NEPAC vortex and supercharged Pacific Jet?

It’s tough to know if this one test case means the big upgrade improved East Coast storm tracks. But suppression seems to have been an issue since the January 2016 blizzard. Last February was the most recent winter example. https://confluence.ecmwf.int/display/FCST/201601+-+Snowstorm+-+US+east+coast 5. Good and bad aspects of the forecasts for the event Early signal (from Sunday 17 Jan 00z) and very consistent forecasts Too low accumulation over NYC Question about snow density for the case

The Euro came south before the GFS and CMC which were too amped up. We usually don’t start tracking until around 120 hrs out. So the Euro did the best from 120hrs to the present.

You can see why the models keep correcting warmer from the weekend going forward. They now how one of the deepest -PNA +EPO troughs near NW Canada on record for December. This is accompanied by a 6 sigma Jet max. So a continuation of the fall record breaking +EPO and Pacific Jet pattern.

This start of December was a great example of models correcting warmer with an unfavorable -PNA and +AO pattern. The first week of December was originally forecast to be around -2. But the 5 station average is +4.5 through the 6th. EWR….+5.9 NYC….+3.6 LGA…..+4.4 JFK…..+4.4 ISP…….+4.1 AVG…..+4.5

Maybe this means they fixed the East Coast storm track issue with the Euro since all the other models were too amped up for such a fast Pacific flow.

This happens all the time with rain and convection events. But people aren’t paying such close attention unless it’s snow. When was the last 36-48 hr forecast rainfall -convection event that the models nailed to within a T to .3 of an inch of liquid? This is all with in the margin of error at 36 to 48 hours out.

A west based -EPO with a -PNA and +AO is a warm pattern for us. This is what happened in February 2018. We want a -EPO to link up with a -AO like March 2018. So it may require a stratospheric warming event near the start of January to fully shift the pattern.

The latest extended EPS continues the warm -PNA +AO pattern into late December. It develops a west based EPO ridge near Alaska during late December. But still has a SE Ridge here due to the -PNA and +AO. So Western Canada gets much colder. The MJO eventually gets over to 7, but it’s forecast to destructively interfere with the La Niña. So that may be why it takes longer to build the ridge into Alaska. We would probably need a cleaner MJO 7 response to start pushing the gradient closer to the Northeast during the last week of December. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjoupdate.pdf • A Pacific MJO event is likely to destructively interfere with La Niña, and there remains uncertainty as to whether the MJO will maintain an organized structure, as evidenced by large ensemble spread in the RMM forecasts through mid-December. Dec 6-13 Dec 13-20 Dec 20-27

Winter version of the Ambrose Jet. Cooler conditions and winds gusting near 35 mph along the South Shore. Mid-60s at the usual spots in NJ. Kennedy Intl PTSUNNY 53 51 93 S29G37 29.74F FOG Breezy Point N/A 52 N/A N/A S25G35 N/A Newark/Liberty PTSUNNY 65 52 62 S15G29 29.69F Teterboro MOSUNNY 62 53 72 S17G25 29.68F Caldwell LGT RAIN 64 52 64 VRB7 29.69F Somerville PTSUNNY 64 54 69 S8 29.66F Linden PTSUNNY 65 50 59 SW10G21 29.69F Perth Amboy N/A 63 N/A N/A S18G25 N/A

Going warm has been the winning forecast for 9 out of the last 10 Decembers. 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 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

That’s not how it works. December has been warming at close to 1° per decade over the last 40 years. We started out closer to 35° and now are approaching 40° in the averaged means for our whole climate division. So by mid-century, averages closer to 45° will become the norm. The warming baseline makes it easier for the more extreme years like 2015 to occur. We saw this in February 2018 with our first 80. So one of these Decembers in the future will eventually produce an 80° reading also.

While December 2015 has been the most extreme expression of the US December warming trend, the composite of the other years since 2011 shows the same pattern.

December has been the warmest winter departure month over the last decade. It’s no surprise that the models have corrected so much warmer in recent days. Summer has been extended into fall and fall into early winter.