bluewave

Nothing in modern times compares to 76-77 for the duration of the extreme cold and ice build up on the local waterways from late December into early February. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Rank Ending Date Mean Avg Temperature Dec 27 to Feb 7 Missing Count 1 1918-02-07 19.4 0 2 1881-02-07 21.8 0 3 1977-02-07 22.3 0 4 1893-02-07 24.3 0 5 1888-02-07 24.5 0 6 1912-02-07 24.7 0 7 1875-02-07 24.9 4 8 1920-02-07 25.0 0 - 1886-02-07 25.0 0 9 1948-02-07 25.3 0 10 1904-02-07 25.4 0 11 1994-02-07 25.8 0

Yeah, that was the lowest monthly average. But I believe January 1985 stands as the lowest daily. That was the last time Newark almost made it to -10. https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii 1985 1 19 -6.226 Data for January 1, 1985 through January 31, 1985 Click column heading to sort ascending, click again to sort descending. Name Station Type Lowest Min Temperature SEABROOK FARMS COOP -24 HIGH POINT PARK COOP -16 ESSEX FELLS SERVICE BLDG COOP -14 BOONTON 1 SE COOP -14 Trenton Area ThreadEx -12 CHARLOTTEBURG RESERVOIR COOP -12 RINGWOOD COOP -12 EWING 3 WNW COOP -12 NEWTON COOP -11 Belvidere Area ThreadEx -10 CRANFORD COOP -10 LONG VALLEY COOP -10 BELVIDERE BRIDGE COOP -10 MOORESTOWN 4 E COOP -10 Atlantic City Area ThreadEx -9 MORRIS PLAINS 1 W COOP -9 SUSSEX 1 NW COOP -9 ATLANTIC CITY INTL AP WBAN -9 Newark Area ThreadEx -8 NEWARK LIBERTY INTL AP WBAN -8

Your best snowfall combination since 1981 is a -AO and El Niño. But occasionally a La Niña with a -AO will work. The last good La Niña -AO combo for you guys was 1999-2000. It came down to the late January event when we got the -AO dip. Snowfall since 1981 Time Series Summary for Baltimore Area, MD (ThreadEx) - Oct through Sep Click column heading to sort ascending, click again to sort descending. Rank Season Total Snowfall ENSO and AO 1 2009-2010 77.0 El Niño -AO 2 1995-1996 62.5 La Niña -AO 3 2002-2003 58.1 El Niño - AO 4 2013-2014 39.0 Neutral 5 1982-1983 35.6 El Niño -AO 6 1986-1987 35.2 El Niño -AO 7 2015-2016 35.1 El Niño -AO 8 2014-2015 28.7 El Niño +AO 9 1999-2000 26.1 La Niña -AO 10 1981-1982 25.5 Neutral -AO

I think that it’s mostly the warmer waters to our east and overall higher temperatures favor interior sections in December. Notice the wide spread between BGM and ISP snowfall in December. But they both have had the same January snowfall as the coast gets cold enough for more snow. Monthly Total Snowfall for BINGHAMTON (GREATER AP), NY Click column heading to sort ascending, click again to sort descending. Year Dec Season Mean 16.0 16.0 2015 2.2 2.2 2016 29.8 29.8 2017 11.3 11.3 2018 7.9 7.9 2019 20.1 20.1 2020 48.2 48.2 2021 8.5 8.5 2022 0.3 0.3 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Dec Season Mean 2.7 2.7 2015 T T 2016 3.2 3.2 2017 6.0 6.0 2018 T T 2019 4.2 4.2 2020 7.5 7.5 2021 0.3 0.3 2022 0.0 0.0 Monthly Total Snowfall for Binghamton Area, NY (ThreadEx) Click column heading to sort ascending, click again to sort descending. Year Jan Season Mean 16.2 16.2 2015 16.1 16.1 2016 10.2 10.2 2017 12.0 12.0 2018 14.9 14.9 2019 26.2 26.2 2020 12.7 12.7 2021 16.8 16.8 2022 20.3 20.3 Monthly Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Year Jan Season Mean 15.9 15.9 2015 30.2 30.2 2016 24.8 24.8 2017 14.0 14.0 2018 22.0 22.0 2019 0.9 0.9 2020 2.5 2.5 2021 1.1 1.1 2022 31.8 31.8

Yeah, all-time record warmth for Northern Alaska in December with such strong blocking. So the polar vortex gets displaced to the south over North America. The lingering influence from the record -EPO block in November has changed our typical warm up pattern around the solstice.

Those steep mid-level lapse rates would support a wet snow in Suffolk with light accumulations on the colder surfaces.

An east-west block from Alaska to Greenland with energy cutting underneath is usually a KU signal even for the coast. But the elongated trough from coast to coast is an oddity. We should have more of a ridge over the Rockies with so much blocking. This is what happened back in December 2000. But the models let the primary run too far north due to the lower heights in the Western US. Classic KU composite from December 2000 Odd trough under the whole length of block with no ridge in Rockies

This has to be one of the oddest combinations of teleconnections that we have seen in a while. We usually get a solid Rockies Ridge +PNA spike with so much blocking from Greenland back to Alaska. But we have an unusual east to west trough stuck underneath. There is still a tail of blue behind the cutoff back to the Rockies next weekend. So there is nothing keeping the primary low from cutting to Chicago even several days after a -4 AO block.The secondary low hugs the coast for plenty of rain and wind before ending as some snow. Never seen a 500 mb look like this before

This is one of those rare times during a La Niña that the Pacific blocking does better than the 11-15 day forecast. New run for late week storm Old day 11-15 day range runs

One of the few Decembers when the AO made it to -4 or lower. https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv 10Dec2022 -4.0676 Decembers with a -4 or lower reading 2022 2000 1995 1968 1966 1962 1950 Lower than -5 2010 2009 1976

https://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdepd The GFS was not included in tonights blend past day 4 at all. The ensemble means again support low development most consistent with the ECMWF.

Maybe that record -EPO block back in November changed our typical pattern of recent years? https://www.cpc.ncep.noaa.gov/products/intraseasonal/z500_nh_anim.shtml https://downloads.psl.noaa.gov/Public/map/teleconnections/epo.reanalysis.t10trunc.1948-present.txt

NYC snowfall 2000 12 29 -4.688…13.4” 1995 12 19 -4.353…11.5” 1962 12 31 -4.159…4.5”

We’ll probably need the primary to squeeze south of Chicago in order for the the secondary to take a benchmark instead of hugger track. You can see 12z Euro comparison with the 6z GFS. That Euro primary cut just a little too far north. If the 12z guidance has any clue, then the 12z GFS extreme suppression track looks like an outlier. So maybe this will turn out to be a battle between a benchmark or hugger track. Something in between those two would work.

AO getting closer to -4 which would increase the chances of more blocking JFM and a possible SSW. https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv 09Dec2022-3.6473

Yeah, the only reason the 6z GFS has a nice snowstorm is due to the skinny Rockies Ridge and +PNA spike closer to neutral. This scenario is showing up in the ensembles. So to me, all these OP runs beyond 120 are just ensemble members anyway.

The EPS mean has several members near the BM with a little Rockies Ridge + PNA spike.

Great -EPO -AO pattern. But the -PNA pumps the SE ridge next week on the Euro and GEM allowing the storm to tuck in. So you can see the Euro and GEM keeping this an interior snow event for now. Need the +PNA Rockies Ridge idea of the Euro control for snow at the coast and a 982mb BM track. Snowier Euro control 982 mb BM track

It’s tough to compare analogs until the full monthly 500 mb composite is in. But the common theme of both months is a -PNA -AO. So we’ll need to verify some Pacific improvement in order to have a shot at above normal December snowfall in NYC. It could be something as simple as a transient Rockies Ridge able to produce an accumulating snow. But the long range ensembles aren’t really good enough to see short term details like that.

The size of the snow events can be quite variable in the -3 to -4 -AO range during December in NYC. Anywhere from a trace to 1 to around 10.5”. So the AO dipping to around -4 in itself can’t tell you much how much snowfall NYC will get in December. We can usually count on bigger events the closer that we get to -5. That seems to be the level when the AO can start to push back against any negative Pacific influences. But a -4 in December is usually a good indication that there will be further blocking intervals JFM.

ISP has been the best spot since the super El Niño. Individual events and the highest snowfall totals 2022 Jan 28-29….Islip….24.7 2021 Jan 31-Feb 2....Blomingdale, NJ.....26.1 2020 Dec 16-17 East Tremont, NY....12.4 2019 Mar 3-4...Monroe, CT....12.0 2018 Nov 15....Mount Hope, NY.......18.3 Mar 21-22...Patchogue, NY......20.1 Mar 13...Southampton,NY.....18.3 Mar 8....New Farfield, CT..........26.8 Mar 2...Monroe, NY.................14.0 Jan 4...Islip, NY.......................15.8 2017 Mar 14...Montgomery, NY.......23.5 Feb 9...Selden, NY...................16.0 Jan 7...Orient, NY....................12.5 2016 Feb 5...Setauket, NY................12.0 Jan 23..JFK,NY.........................30.5 2015 Feb 2..New Faifield, CT............12.0 Jan 26-27....Orient,NY.............28.5 2014 Feb 13-14...Roselle, NJ............16.7 Jan 21-22....Centerreach,NY....14.0 Jan 2-3......Lindenhurst, NY.....12.5 2013 Mar 8....Harriman,NY..............15.0 Feb 8....Upton, NY..................30.9 2012 Nov 7-8.....Monroe, CT..........13.5 Jan 21......North Haven, CT....12.0 2011 Oct 29.....Harriman, NY.........16.0 Jan 26-27...NYC................... 19.0 Jan 11-12.......Meriden, CT....29.0 2010 Feb 25-26...Mount Hope, NY...27.5 Dec 26........Elizabeth, NJ........31.8 Feb. 10.....Sound Beach, NY....16.2 2009 Dec 19-20....Upton, NY..........26.3

Yeah, ISP has become the new Boston for 16”+ snowstorms since the super El Niño. There have been 4 events at ISP and only 1 at Boston. So ISP has been the place to be for big snowstorms in recent years. Maximum 2-Day Total Snowfall for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Missing Days 1 24.7 2022-01-29 0 2 23.7 2016-01-24 0 0 0 3 18.4 2018-03-22 0 0 4 16.0 2018-01-04 0 Maximum 2-Day Total Snowfall for Boston Area, MA (ThreadEx) Click column heading to sort ascending, click again to sort descending. Rank Value Ending Date Missing Days 1 23.8 2022-01-29 0

Would make sense given how ISP has become the new snowfall capitol around the area.

Yeah, the 12z CMC really backed off 0z at the coast but the interior still does well. So it looks more like the Euro and GFS now. Really need a stronger closed low to get more than a T-2 or T-3 near the coast. Marginal cod air masses at the start require a very strong 500 mb closed low for rains to change to 4”+ snows at the coast this time of year.

Yeah, the NW Atlantic has warmed too much to allow SSTs as cold as the 1970s and 1980s.