NYC Snowfall Volatility Index Has Risen Dramatically Since The Early 1990's

[bluewave]

I wanted to develop an index which does justice to the extremes in seasonal snowfall that NYC has been experiencing

since the early 1990's. We have been seeing a greater number of all or nothing type snowfall seasons since the winter

of 1992-1993. Before the last 20 winters, there was more balance with seasonal snowfall totals averaging closer

to the 25.1 inch seasonal average. The big annual swings in seasonal snowfall are expressed in this index. I used

20 winter seasons in each grouping going back 100 years.

Points are given to each season for finishing above or below 25.1 inches.

For example, the winter of 2001-2002 gets 21.6 points for finishing with 3.5 inches.

The winter of 1995-1996 gets 50.5 points for finishing with 75.6 inches

The totals for each year are added up for each 20 year SVI number.

1992-1993...2011-2012..............SVI..........361.8

1972-1973..1991-1992...............SVI..........157.6

1952-1953..1971-1972...............SVI..........205.8

1932-1933..1951-1952...............SVI..........222.0

1912-1913..1930-1931...............SVI..........241.7

[NEG NAO]

I wanted to develop an index which does justice to the extremes in seasonal snowfall that NYC has been experiencing

since the early 1990's. We have been seeing a greater number of all or nothing type snowfall seasons since the winter

of 1992-1993. Before the last 20 winters, there was more balance with seasonal snowfall totals averaging closer

to the 25.1 inch seasonal average. The big annual swings in seasonal snowfall are expressed in this index. I used

20 winter seasons in each grouping going back 100 years.

Points are given to each season for finishing above or below 25.1 inches.

For example, the winter of 2001-2002 gets 21.6 points for finishing with 3.5 inches.

The winter of 1995-1996 gets 50.5 points for finishing with 75.6 inches

The totals for each year are added up for each 20 year SVI number.

1992-1993...2011-2012..............SVI..........361.8

1972-1973..1991-1992...............SVI..........157.6

1952-1953..1971-1972...............SVI..........205.8

1932-1933..1951-1952...............SVI..........222.0

1912-1913..1930-1931...............SVI..........241.7

What were the numbers previous to 1912 ? back to 1869 - I have a feeling your index would probably show the same volitility or greater if records were kept previous to the late 1880's - 100 years out of how long the earth has been in existence is an extremely low sampling IMO... Its interesting though.....

[Sundog]

What were the numbers previous to 1912 ? back to 1869 - I have a feeling your index would probably show the same volitility or greater if records were kept previous to the late 1880's - 100 years out of how long the earth has been in existence is an extremely low sampling IMO... Its interesting though.....

You don't use a time range like how old the Earth is. 100 years is a good sampling considering most factors that affect our weather have cycles that are less than several decades long. If you go too far back the conditions (Milankovitch cycles) drastically change and then the data is not representative of anything anymore.

[bluewave]

What were the numbers previous to 1912 ? back to 1869 - I have a feeling your index would probably show the same volitility or greater if records were kept previous to the late 1880's - 100 years out of how long the earth has been in existence is an extremely low sampling IMO... Its interesting though.....

The last 20 winters are unique even going back to 1869. None of those earlier twenty year intervals approached

the highs and lows combined of the last 20 years. They were in the 210-270 range. I would love to have a continuous

snowfall record for the Park going back centuries before to compare. But since 1869, the last 20 winters really

stand out for a lack of middle ground.

[NEG NAO]

I bet if you also look at all the records set during the same period they would out number the other periods of time you mentioned. We have been in a period of extremes for just about every category - snowfall , rainfall , high temperatures etc. etc. daily monthly and seasonal - only records that are not as numerous are low temps - will that be next ?

[uncle W]

this is snowfall broken down into number of times snowfall was...

since 1869-70...

00-09.9".....9...6%

10-19.9"...38...27%

20-29.9"...38...27%

30-39.9"...25...18%

40-49.9"...17...12%

50-59.9"...11...8%

60+...........5...3%

since 1992-93

00-09.9".....3...15%

10-19.9".....6...30%

20-29.9".....2...10%

30-39.9".....1...05%

40-49.9".....4...20%

50-59.9".....2...10%

60+...........2...10%

the percent of winters with less than 10" went up from 6% to 15% for the last twenty years compared to the 143 years of record...The percent of 50+ inch winters went up from 11% to 20%...

[bluewave]

this is snowfall broken down into number of times snowfall was...

since 1869-70...

00-09.9".....9...6%

10-19.9"...38...27%

20-29.9"...38...27%

30-39.9"...25...18%

40-49.9"...17...12%

50-59.9"...11...8%

60+...........5...3%

since 1992-93

00-09.9".....3...15%

10-19.9".....6...30%

20-29.9".....2...10%

30-39.9".....1...05%

40-49.9".....4...20%

50-59.9".....2...10%

60+...........2...10%

the percent of winters with less than 10" went up from 6% to 15% for the last twenty years compared to the 143 years of record...The percent of 50+ inch winters went up from 11% to 20%...

Thanks, Uncle. It's interesting to see the percentage change of each category.

[donsutherland1]

In terms of volatility, the 30-winter period with the highest standard deviation is the 1982-83 through 2011-12 period (18.3" standard deviation). The 30-year period with the lowest standard deviation was the 1961-62 through 1990-91 (10.8" standard deviation). Much of the volatility in NYC's snowfall has occurred in the period stretching from the early 1990s to the early 2000s. The 1993-94 through 2002-03 period had the highest decadal standard deviation at 24.7". The lowest decadal standard deviation was 6.4" from 1983-84 through 1992-93. The historic standard deviation is 14.8" (1869-70 through 2011-12).

[uncle W]

The years with the greatest seasonal snowfall differences...

season...snowfall...

1876-77...40.5"

1877-78.....8.1"

1878-79...35.7"

1917-18...34.5"

1918-19.....3.8"

1919-20...47.6"

1957-58...44.7"

1958-59...13.0"

1959-60...39.2"

1993-94...53.4"

1994-95...11.8"

1995-96...75.6"

2000-01...35.0"

2001-02.....3.5"

2002-03...49.3"

2010-11...61.9"

2011-12.....7.4"

2012-13...???

all these years had a rebound after a good winter followed by a dismal one...If this trend continues next winter will get over 30" of snowfall...

[LongBeachSurfFreak]

Amazing to see 8.1 in 1877-1878! In that much colder period imagine what had to go wrong to cause that to happen!

[uncle W]

Amazing to see 8.1 in 1877-1878! In that much colder period imagine what had to go wrong to cause that to happen!

at least 8" fell in one storm on 1/31-2/1/1878...

[donsutherland1]

Amazing to see 8.1 in 1877-1878! In that much colder period imagine what had to go wrong to cause that to happen!

There was a super El Niño that winter. Ironically, there was a single big storm for parts of the East, just as was the case during the super El Niño of Winter 1982-83.

[uncle W]

There was a super El Niño that winter. Ironically, there was a single big storm for parts of the East, just as was the case during the super El Niño of Winter 1982-83.

1877-78 is the 4th strongest el nino...

ftp://www.coaps.fsu.edu/pub/JMA_SST_Index/jmasst1868-today.filter-5

strongest...snowfall

1997-98 +33.....5.5"

1982-83 +28...27.2"

1888-89 +23...16.5"

1877-78 +22.....8.1"

1972-73 +20.....2.8"

1930-31 +19...11.6"

[JBG]

I wanted to develop an index which does justice to the extremes in seasonal snowfall that NYC has been experiencing

since the early 1990's. We have been seeing a greater number of all or nothing type snowfall seasons since the winter

of 1992-1993. Before the last 20 winters, there was more balance with seasonal snowfall totals averaging closer

to the 25.1 inch seasonal average. The big annual swings in seasonal snowfall are expressed in this index. I used

20 winter seasons in each grouping going back 100 years.

To be fair the prior 20 year period was unusually stable by that index, and the most recent 20 year period unusually volatile Could they both have been flukes?

[JBG]

Amazing to see 8.1 in 1877-1878! In that much colder period imagine what had to go wrong to cause that to happen!

The 1790's had winters where tulips and daffodils were sprouting in Philadelphia.

[JBG]

1877-78 is the 4th strongest el nino...

ftp://www.coaps.fsu....-today.filter-5

strongest...snowfall

1997-98 +33.....5.5"

1982-83 +28...27.2"

1888-89 +23...16.5"

1877-78 +22.....8.1"

1972-73 +20.....2.8"

1930-31 +19...11.6"

Interesting. A bit off topic but most of those winters had "warning" storms in very late winter or early spring of KU or near KU intensity.

1. April 1, 1997
   
2. Apri. 7, 1982 (one of my favorite storms)
   
3. Blizzard of 1888;
   
4. February 20, 1972 (near miss ridge-runner that gave central New York record snows, i.e. Ithaca got 26", an all-time record).
   

I don't know much about the meteorological sprints of 1877 and 1930.

[Guest Pamela]

Interesting. A bit off topic but most of those winters had "warning" storms in very late winter or early spring of KU or near KU intensity.

1. April 1, 1997
   
2. Apri. 7, 1982 (one of my favorite storms)
   
3. Blizzard of 1888;
   
4. February 20, 1972 (near miss ridge-runner that gave central New York record snows, i.e. Ithaca got 26", an all-time record)
   

January 1982 was an extremely cold month...not quite to the point of January 1977...but close. And much, much stormier. Both Patchogue and Bridgehampton on Long Island recorded monthly extreme minimums of -10 F.

When you think about it, the 60's were cold, the 70's were fairly cold, even the first half of the 1980's (throw out 1982-83 winter) was reasonably cold...it was not until say 1987-88 that this mild crap started to set in in earnest....interrupted in 1993-94....the '96 winter was pretty seasonable temperature wise...again cooling by autumn 2000 and being rather up and down over the last decade.

[NEG NAO]

The 1790's had winters where tulips and daffodils were sprouting in Philadelphia.

Where did you get this info from ? Any links to stories or pics ? I wonder if anyone back then recorded daily temperature - precip in this area .........

[uncle W]

Interesting. A bit off topic but most of those winters had "warning" storms in very late winter or early spring of KU or near KU intensity.

1. April 1, 1997
   
2. Apri. 7, 1982 (one of my favorite storms)
   
3. Blizzard of 1888;
   
4. February 20, 1972 (near miss ridge-runner that gave central New York record snows, i.e. Ithaca got 26", an all-time record).
   

I don't know much about the meteorological sprints of 1877 and 1930.

it was cold and snowy from March 11-20th, 1877...April 24th 1930 had a hard freeze in parts of the area...

[JBG]

Where did you get this info from ? Any links to stories or pics ? I wonder if anyone back then recorded daily temperature - precip in this area .........

I'm a bit of a history buff and got this from stories about the assembly of Congress. I'll look for links.

[donsutherland1]

I'm a bit of a history buff and got this from stories about the assembly of Congress. I'll look for links.

A good source of information is Pierce's A meteorological account of the weather in Philadelphia.