bluewave

Yeah, this system has been getting stronger on the recent model runs. New run Old run

It’s nice to see North America doing better than Eurasia on snow extent for a change. https://www.star.nesdis.noaa.gov/smcd/emb/snow/HTML/snow_extent_monitor.html

A 3.8” report from Northern Nassau and 2.9” in Plainfield, NJ.

At least a step in the right direction but the KU track still remains elusive.

The H300 PDO finished November at -2.0 due to how extensive the subsurface warmth is. https://www.cpc.ncep.noaa.gov/products/GODAS/ocean_briefing_gif/global_ocean_monitoring_current.pdf

One more Arctic outbreak before the pattern moderates.

The comparison is valid since the Saranac Lake area has warmed +5.2° since 1991 in late December between 17th and 31st. NYC is up +4.6° over the same period. Many areas have experienced a steep rise in late December temperatures. Its another one of the repeating patterns which have become a regular occurrence as the climate has warmed.

Yeah, the 100-200 year blocking event that winter as per some of the historical reconstructions was just too strong for the 75”+seasonal totals to our south to make it up to the NYC Metro era. A little weaker on the blocking and NYC could have approached the 1995-1996 all-time record. Same went for 2010-2011 which could have challenged the 75” mark around NYC had the snowy pattern persisted into February and March.

2015-2016 was a super El Niño like 1982-1983 and both years had blockbuster snowstorms during the 2nd half of winter. This was the case since El Niños usually start out slow snd have their snowiest periods later. So we often can’t use December El Niños as a marker for the rest of the season. But sometimes in the cases like 2002-2003 and 2009-2010 El Niños, December is so snowy that we get epic follow up snows during the February El Niño prime time. So in those cases a December forecast for a very snowy season would have worked out.

This is broad-brushing on your part since we are discussing a particular subset of Decembers that are based on La Niña which has been more recently defined by RONI as the global oceans have rapidly been warming. La Nina’s historically have been defined by an early start to winter relative to El Niños. This is why you see frequent references to frontloaded and backloaded winters. So it makes it easier for us to use a December as a marker for the rest of the season due to the nature of La Ninas.

Well it sounded like from the tone of your posts that is what you were questioning. Bx Engine is a hard working guy and I don’t want to tie up his valuable time with disputes that didn’t exist then. Unfortunately, sometimes it’s hard to read intentions on an online forum when you aren’t meeting face to face with someone.

I was talking about the fact that repeating patterns have become more pronounced as the climate has warmed. While there was a weaker December to seasonal snowfall relationship prior to the 1990s, it has become more pronounced. My theory as to why this is that case is that we are seeing the beginnings of non-linear climate shifts. As convective thresholds begin to be crossed in tropical forcing regions with rapidly warming SSTs, it can be like flipping a switch where patterns start locking in more and become more persistent. Now the paper below is very technical, but in a tangential way to our discussion it’s the beginning of some new and potentially promising research. Circus Tents, Convective Thresholds, and the Non-Linear Climate Response to Tropical SSTs https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL101499

The data has been widely posted here by myself and other posters. This isn’t some new and controversial revelation. It’s just one of the many new repeating patterns which have become more pronounced as our climate has rapidly warmed. I suspect we are seeing non-linear shifts which make them so persistent.

This is the first time since 1989. But now we are getting the typical moderation which has become a repeating pattern every year as we approach the 17th to 25th period. Dec 1989 stayed cold through the end of the month before its moderation for all of January and February. Climatological Data for NEWARK LIBERTY INTL AP, NJ - December 1989 Click column heading to sort ascending, click again to sort descending. Sum 1012 573 - - 1215 0 0.75 0.5 - Average 32.6 18.5 25.6 -12.4 - - - - 0.0 Normal 44.8 31.2 38.0 - 837 0 4.14 5.4 1989-12-01 35 22 28.5 -13.5 36 0 0.00 0.0 0 1989-12-02 47 18 32.5 -9.2 32 0 T T 0 1989-12-03 38 19 28.5 -12.9 36 0 T T 0 1989-12-04 29 15 22.0 -19.2 43 0 0.00 0.0 0 1989-12-05 32 24 28.0 -12.9 37 0 0.00 0.0 0 1989-12-06 47 27 37.0 -3.6 28 0 0.02 0.0 0 1989-12-07 43 22 32.5 -7.8 32 0 0.00 0.0 0 1989-12-08 26 22 24.0 -16.0 41 0 0.01 0.1 0 1989-12-09 30 18 24.0 -15.7 41 0 0.00 0.0 T 1989-12-10 35 22 28.5 -11.0 36 0 0.00 0.0 0 1989-12-11 40 29 34.5 -4.7 30 0 0.00 0.0 0 1989-12-12 35 30 32.5 -6.4 32 0 T T 0 1989-12-13 32 22 27.0 -11.6 38 0 T T T 1989-12-14 31 15 23.0 -15.4 42 0 0.00 0.0 0 1989-12-15 41 19 30.0 -8.1 35 0 0.10 T 0 1989-12-16 37 19 28.0 -9.9 37 0 T T 0 1989-12-17 33 17 25.0 -12.6 40 0 0.00 0.0 0 1989-12-18 29 15 22.0 -15.4 43 0 0.00 0.0 0 1989-12-19 27 16 21.5 -15.6 43 0 T T 0 1989-12-20 33 19 26.0 -10.9 39 0 T T T 1989-12-21 23 12 17.5 -19.1 47 0 T T T 1989-12-22 20 7 13.5 -22.9 51 0 0.00 0.0 0 1989-12-23 22 7 14.5 -21.7 50 0 0.00 0.0 0 1989-12-24 21 8 14.5 -21.4 50 0 0.00 0.0 0 1989-12-25 26 12 19.0 -16.7 46 0 0.00 0.0 0 1989-12-26 34 13 23.5 -12.0 41 0 T T 0 1989-12-27 21 8 14.5 -20.8 50 0 T T 0 1989-12-28 37 19 28.0 -7.1 37 0 T T T 1989-12-29 33 23 28.0 -6.9 37 0 0.00 0.0 0 1989-12-30 30 25 27.5 -7.2 37 0 0.14 0.4 T 1989-12-31 45 29 37.0 2.5 28 0 0.48 0.0 T Climatological Data for NEWARK LIBERTY INTL AP, NJ - January 1990 Click column heading to sort ascending, click again to sort descending. Sum 1478 1027 - - 756 0 4.72 2.4 - Average 47.7 33.1 40.4 7.6 - - - - 0.1 Normal 40.0 25.5 32.8 - 1000 0 3.42 9.1 1990-01-01 46 32 39.0 4.7 26 0 0.14 0.0 0 1990-01-02 43 27 35.0 0.9 30 0 0.00 0.0 0 1990-01-03 50 29 39.5 5.6 25 0 0.00 0.0 0 1990-01-04 51 33 42.0 8.3 23 0 T 0.0 0 1990-01-05 49 36 42.5 8.9 22 0 0.00 0.0 0 1990-01-06 47 34 40.5 7.1 24 0 T T 0 1990-01-07 44 26 35.0 1.7 30 0 0.00 0.0 0 1990-01-08 41 31 36.0 2.9 29 0 1.14 1.4 0 1990-01-09 46 32 39.0 6.0 26 0 0.00 0.0 1 1990-01-10 47 39 43.0 10.1 22 0 0.03 0.0 1 1990-01-11 46 37 41.5 8.7 23 0 0.00 0.0 0 1990-01-12 43 31 37.0 4.3 28 0 T T 0 1990-01-13 35 25 30.0 -2.6 35 0 T T 0 1990-01-14 37 22 29.5 -3.0 35 0 0.00 0.0 0 1990-01-15 40 33 36.5 4.1 28 0 0.10 0.2 T 1990-01-16 57 32 44.5 12.1 20 0 0.00 0.0 0 1990-01-17 62 40 51.0 18.7 14 0 0.00 0.0 0 1990-01-18 66 44 55.0 22.7 10 0 T 0.0 0 1990-01-19 44 31 37.5 5.3 27 0 0.00 0.0 0 1990-01-20 36 30 33.0 0.8 32 0 0.46 0.8 0 1990-01-21 38 31 34.5 2.3 30 0 0.30 T 0 1990-01-22 47 30 38.5 6.3 26 0 0.02 T 0 1990-01-23 46 34 40.0 7.8 25 0 0.00 0.0 0 1990-01-24 57 41 49.0 16.8 16 0 T 0.0 0 1990-01-25 55 46 50.5 18.3 14 0 1.12 0.0 0 1990-01-26 58 36 47.0 14.7 18 0 0.20 0.0 0 1990-01-27 46 30 38.0 5.7 27 0 0.00 0.0 0 1990-01-28 58 32 45.0 12.6 20 0 0.00 0.0 0 1990-01-29 44 35 39.5 7.0 25 0 1.07 0.0 0 1990-01-30 46 37 41.5 9.0 23 0 0.14 0.0 0 1990-01-31 53 31 42.0 9.4 23 0 0.00 0.0 0 Climatological Data for NEWARK LIBERTY INTL AP, NJ - February 1990 Click column heading to sort ascending, click again to sort descending. Sum 1382 846 - - 699 0 1.71 2.8 - Average 49.4 30.2 39.8 4.7 - - - - 0.1 Normal 43.0 27.2 35.1 - 837 0 2.98 10.1 1990-02-01 54 32 43.0 10.3 22 0 0.00 0.0 0 1990-02-02 53 39 46.0 13.1 19 0 0.06 0.0 0 1990-02-03 40 31 35.5 2.5 29 0 0.10 0.0 0 1990-02-04 40 34 37.0 3.9 28 0 0.29 T 0 1990-02-05 38 22 30.0 -3.3 35 0 0.00 0.0 0 1990-02-06 57 30 43.5 10.1 21 0 0.00 0.0 0 1990-02-07 55 39 47.0 13.4 18 0 T 0.0 0 1990-02-08 57 33 45.0 11.3 20 0 0.00 0.0 0 1990-02-09 63 40 51.5 17.6 13 0 T 0.0 0 1990-02-10 63 35 49.0 14.9 16 0 0.52 0.0 0 1990-02-11 49 31 40.0 5.8 25 0 0.00 0.0 0 1990-02-12 47 32 39.5 5.1 25 0 0.01 0.1 T 1990-02-13 53 29 41.0 6.4 24 0 0.00 0.0 0 1990-02-14 60 41 50.5 15.7 14 0 0.02 0.0 0 1990-02-15 41 35 38.0 3.0 27 0 0.07 0.0 0 1990-02-16 58 37 47.5 12.2 17 0 0.01 0.0 0 1990-02-17 59 24 41.5 6.0 23 0 0.00 0.0 0 1990-02-18 38 20 29.0 -6.7 36 0 0.00 0.0 0 1990-02-19 57 33 45.0 9.1 20 0 0.00 0.0 0 1990-02-20 38 27 32.5 -3.6 32 0 0.00 0.0 0 1990-02-21 50 23 36.5 0.1 28 0 0.00 0.0 0 1990-02-22 63 34 48.5 11.9 16 0 0.13 0.0 0 1990-02-23 66 50 58.0 21.2 7 0 0.22 0.0 0 1990-02-24 50 31 40.5 3.4 24 0 0.15 1.3 0 1990-02-25 33 10 21.5 -15.8 43 0 0.13 1.4 2 1990-02-26 26 8 17.0 -20.6 48 0 0.00 0.0 2 1990-02-27 35 20 27.5 -10.3 37 0 T T T 1990-02-28 39 26 32.5 -5.5 32 0 0.00 0.0 T

Don’t really know since it has become such a persistent feature since the 2018-2019 winter.

This looks like it could actually thread the needle. Kicker coming into BC probably will prevent the low from riding too far north. The weak ridge to our east will work against a complete suppression to the south. So a 2” scenario like the 12z Euro has in NYC would be a decent outcome for such a fast Pacific flow pattern. Perhaps there is a 1” downside -upside risk for a 1-3” event in NYC.

The 12z Euro 2” for NYC would be a nice little event.

All the area needs to finish December with a multi-station average of -2 to -3 is to go +2 to +3 from December 17th through the 31st which isn’t very extreme. Models have been notorious for missing the magnitude of both warm ups and cool downs in the long range. Most of the time our climate has above average temperatures. So there are more total opportunities for the models to underestimate the warm ups than the cool downs. This is why the models underestimation of the current cold pattern from back in late November was more memorable. This was our only real colder pattern here of this magnitude since last January. The other repeating pattern has been that the warm ups which follow the cool downs eventually rank higher than the cool downs did. Sometimes it takes several months as last spring and summer were much warmer than the cold last January.

It’s possible that some areas to our south with the strong cold departures through the 10th could finish December close to average with the coming warm up. This also fits the pattern since at least the 1990s of the 2nd half of December warming at a faster rate than the 1st half in our area.

I grew up in Long Beach on the South Shore and we only needed the AC a handful of times back in the 1970s. First for the August 1973 heatwave and then the July 1977 heatwave. We gradually increased the AC usage during the 1980s and especially the early 1990s. By the time we reached 2010, we had three ACs running much of the time compared to only one in the 1970s. Plus there was a rapid expansion of central AC even in Long Beach when it was a rarity near the shore in the 1970s. This is one of the reasons that HVAC is such a good career opportunity for people due to the increased demand in a warming world. As for the UHI issue, there was a 10°+ difference between NYC during 1896 heatwave and the surrounding countryside. This mostly occurs with summer heatwaves where the city absorbs more heat during the day. It also occurs during calm and clear nights with radiational cooling. The growth of skyscrapers in Western Brooklyn and Queens certainly changes the character of the neighborhood and of course you can see the change in the skyline since around 2004. But prior to that that area had densely packed lower rise buildings built of bricks. These new high rises are mainly glass and steel which absorb significantly less solar energy than bricks do. Plus a cluster of tall buildings will create a big area of shade which prevents the streets and sidewalks from absorbing as much heat as they did with smaller buildings with less shadows. The warmest parts of NYC are in Queens near spots like Corona were small to medium size brick structures dominate. So changing from lower rise brick and concrete structures to skyscrapers may not change the UHI much in Western Brooklyn and Queens to really be noticeable to residents there. That’s why I said a drop in the bucket to what was already one of the largest UHI zones in North America. The rural and suburban areas have warmed at a similar rate to places like Corona Queens over the years. So this is why both areas require more summer AC usage than they did during the 1970s. My guess is that the higher dewpoints and maybe stronger winds are probably why a rural spot like the Charlotteburg Reservoir has seen a steeper increase in low temperatures than LGA since 1981.

The increase in development in Western Brooklyn and Queens last 20 years in relation to the totality of the existing UHI footprint is still very small compared the increasing CO2 forcing over the same period. Drop in the bucket for sensible temperatures but a big shift to the character of those neighborhoods that have more high rises than they used to. The skyscrapers replaced already dense low rise urban development that was there previously driving the UHI. It’s not like the new development is replacing a rural area that was great for radiational cooling before 2004.

Not enough for you to notice much of a change in Brooklyn and Queens sensible temperatures since 1980 had the CO2 levels remained steady instead of rapidly climbing. The recent development last 20 years in Western Brooklyn and Queens is a drop in the bucket compared to the overall UHI footprint of NYC which really expanded between the 1890s and 1960s. Add 15-20% to snowfall totals from the late 1800s through the 1980s and the long term downward decline becomes even steeper.

This is due to the overall climate warming since the 1970s and not an expansion of UHI. Even cooler surrounding areas are wall to wall AC usage now from May to September when they weren’t in the past. The warming in rural, suburban, and urban areas has been proportional.

UHI was already well established in NYC as early as 1896. Notice the more than +10° low temperature difference between Central Park and rural areas in August 1895. LGA and JFK UHI began to increase with the Queens urbanization and population growth expansion in the 1920s. So this isn’t much of a change from the current 10°+ difference between NYC-LGA-JFK and surrounding areas when UHI episodes are more pronounced like during summer heatwaves and radiational cooling during the winter. Data for August 9, 1896 through August 9, 1896 Click column heading to sort ascending, click again to sort descending. NY NY CITY CENTRAL PARK WBAN 82 NJ NEWARK LIBERTY INTL AP WBAN 76 NY WORLD TRADE CENTER WBAN 75 NJ PATERSON COOP 75 NY BRONX COOP 75 NJ PLAINFIELD COOP 73 NJ ELIZABETH COOP 73 NY PORT JERVIS COOP 72 NY SETAUKET STRONG COOP 72 CT MIDDLETOWN 4 W COOP 72 NY WEST POINT COOP 71 CT BRIDGEPORT COOP 71 NY BRENTWOOD COOP 70 CT COLCHESTER 2 W COOP 70 CT NORWALK COOP 69 CT WATERBURY ANACONDA COOP 69 CT NEW LONDON COOP 69 NJ CHARLOTTEBURG RESERVOIR COOP 67 Data for August 10, 1896 through August 10, 1896 Click column heading to sort ascending, click again to sort descending. NY NY CITY CENTRAL PARK WBAN 80 NJ NEWARK LIBERTY INTL AP WBAN 78 NY WORLD TRADE CENTER WBAN 77 NY BRONX COOP 77 CT BRIDGEPORT COOP 76 NJ PATERSON COOP 75 NY WEST POINT COOP 75 NY SETAUKET STRONG COOP 75 NJ PLAINFIELD COOP 74 NJ ELIZABETH COOP 74 CT NORWALK COOP 74 CT WATERBURY ANACONDA COOP 74 CT NEW LONDON COOP 73 CT COLCHESTER 2 W COOP 73 NY BRENTWOOD COOP 72 CT MIDDLETOWN 4 W COOP 72 NY PORT JERVIS COOP 71 NJ CHARLOTTEBURG RESERVOIR COOP 69 Data for August 11, 1896 through August 11, 1896 Click column heading to sort ascending, click again to sort descending. NY NY CITY CENTRAL PARK WBAN 81 NJ NEWARK LIBERTY INTL AP WBAN 78 NY BRONX COOP 78 NY WORLD TRADE CENTER WBAN 76 CT NEW LONDON COOP 75 NJ PATERSON COOP 74 NJ PLAINFIELD COOP 73 NJ ELIZABETH COOP 73 CT BRIDGEPORT COOP 73 NY SETAUKET STRONG COOP 73 CT WATERBURY ANACONDA COOP 72 NY PORT JERVIS COOP 71 NY WEST POINT COOP 71 CT MIDDLETOWN 4 W COOP 71 CT COLCHESTER 2 W COOP 71 NY BRENTWOOD COOP 70 CT NORWALK COOP 69 NJ CHARLOTTEBURG RESERVOIR COOP 67

The NYC UHI intensity hasn’t changed much since the 1980s on clear and calm nights when we get radiational cooling in the surrounding areas.