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Increased Blocking & Historic Snowy Run Since 2000-2001


bluewave

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The one common denominator in our historic snowfall run since 2000-2001 comes down to increased blocking. The blocking patterns have increased in both

the Atlantic and Pacific high latitude regions from 50N to 90N. We have experienced an amazing 12 out of the last 16 winters with normal or above normal

seasonal snowfall. Those 12 winters experienced a variety of ENSO and PDO conditions. So there hasn't been any noticeable correlation between whether

there was a La Nina or El Nino and if the PDO was in a positive or negative state. The only connection between those 12 snowy winters were 

a strong enough Atlantic, Pacific, or combination of the two.

 

The main correlation between the minority 4 well below normal snowfall winters of 01-02...06-07...07-08..11-12 was a +EPO that overpowered the pattern.

Although the majority of those winters featured -ENSO and -PDO conditions, the 08-09...10-11..12-13 near to above normal snowfall seasons also were

also cold PDO and ENSO winters. So those winters weren't dominated by the strong +EPO patterns of the less snowy years. It's very impressive that only

4 winters since 2000-2001 had a strong enough +EPO to briefly interrupt the dominant snowy regime.

 

Winter....NYC snowfall....BNL snowfall...ENSO....PDO

00-01......53.0..................51.2.............-0.7.....+0.47

01-02.....3.5......................5.5.............-0.2.....-0.43

02-03.....49.3....................62.1............+0.9...+1.98

03-04....42.6.....................60.2............+0.3....+0.41

04-05....41.0.....................78.5............+0.7...+0.36

05-06....40.0....................30.5.............-0.7....+0.63

06-07....12.4.....................9.5.............+0.7....-0.18

07-08....11.9.....................11.5............-1.4....-0.78

08-09....27.6.....................43.0............-0.7....-1.27

09-10....51.4.....................67.8...........+1.3....+0.58

10-11....61.9.....................61.5...........-1.3......-0.99

11-12....7.4........................5.5............-0.7......-1.34

12-13...26.1......................51.8...........-0.4.......-0.03

13-14...57.4......................57.5...........-0.5.......+0.09

14-15....50.3......................62.2...........+0.6......+2.42

15-16...32.1......................35.9............+2.2......+1.43

 

Near to above normal snowfall seasons with strong high latitude blocking patterns 

 

B.png

 

 

 

Well below normal snowfall seasons featuring an overpowering +EPO pattern

 

NB.png

 

 

 

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big storms were hard to come by especially in December...during the early 90's one wondered if we would ever see another major snowstorm in NYC...since March 1993 there have been 15 of 24 winters with a snowstorm 10" or more...the previous 23 winters 1969-70 to 1991-92 produced only three winters with a 10" storm...the previous 23 winters 1946-47 to 1968-69 produced 10...

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15 hours ago, donsutherland1 said:

Very nice discussion, Bluewave.

 

15 hours ago, uncle W said:

big storms were hard to come by especially in December...during the early 90's one wondered if we would ever see another major snowstorm in NYC...since March 1993 there have been 15 of 24 winters with a snowstorm 10" or more...the previous 23 winters 1969-70 to 1991-92 produced only three winters with a 10" storm...the previous 23 winters 1946-47 to 1968-69 produced 10...

 

It's remarkable how dramatic a turnaround we experienced from the winters of 89-90 to 99-00 when 7 out of 11 years experienced below normal seasonal snowfall.

You can see how most of those years were dominated by a very unfavorable +EPO and lack of blocking with a +NAO/+AO. Funny how our snowiest 

winter of all 95-96 was right in the middle of that.

 

90's.png

 

 

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not only have we seen more heavy snows but the number of times there were 20" of snow on the ground has increased dramatically...

Dec... 1872 est...

March 1888

Feb... 1899

Feb... 1926

Dec... 1947

Feb... 1961

Feb... 1994

Jan... 1996

Feb... 2003 ...LGA

Feb... 2006

Feb...2010

Dec...2010

Jan... 2011

Jan... 2016

 

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23 minutes ago, uncle W said:

not only have we seen more heavy snows but the number of times there were 20" of snow on the ground has increased dramatically...

Dec... 1872 est...

March 1888

Feb... 1899

Feb... 1926

Dec... 1947

Feb... 1961

Feb... 1994

Jan... 1996

Feb... 2003 ...LGA

Feb... 2006

Feb...2010

Dec...2010

Jan... 2011

Jan... 2016

 

This may have a lot to do with the much greater frequency of mega-snowstorms (18" or more) in recent years. During the 1900-99 period, there were 3 such snowstorms (about one every 3.3 years). Since 2000, there have been 6 (once every 2.8 years). At least for this limited period of times, mega-snowstorms have been nearly 12 times as frequent as they were during the 1900-99 period. 12" or greater snowstorms have been just over 2.5 times as frequent. Put another way, about 8% of storms that brought a foot or more of snow were mega-snowstorms during the 1900-99 period. Since 2000, 40.0% have been mega-snowstorms.

 

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the foot or more snowstorms are on the increase...

NYC 10" or greater snowfalls...

snowfalls 10" or greater......
Year....date....amount"...
1872...12/26.......18.0"
1877...1/1-2........13.0"
1879...1/15-16....13.0"

1888...3/12-14....21.0"

1896...3/15-16....12.0"
1899...2/12-14....16.0"

1914...3/1-2.........14.5"
1916...12/15........12.7"

1920...2/4-7.........17.5"
1921...2/20..........12.5"
1926...2/9-10.......12.0"

1935...1/23-24.....13.0"

1941...3/7-8.........18.1"...ended as a mix...
1947...12/26-27...26.4"
1948...12/19-20...16.0"

1959...12/21-22...13.7"

1960...3/3-4.........14.5"
1960...12/11-12...15.2"
1961...2/3-4.........17.4"
1964...1/12-13.....12.5"
1967...2/7............12.5"
1969...2/9-10.......15.3"

1978...1/19-20.....13.6"...ended as ice...
1978...2/6-7.........17.7"
1979...2/19..........12.7"

1983...2/11-12.....17.6"

1994...2/11..........12.8"
1996...1/7-8.........20.2"

2000...12/30........12.0"
2003...2/16-17.....19.8"
2003...12/5-6.......14.0"
2005...1/22-23.....13.8"
2006...2/11-12.....26.9"

2010...2/25-26.....20.9"...changed to rain for a time...
2010...12/26-27...20.0"
2011...1/25-26.....19.0"

2014...2/13-14.....12.5"...(9.5" or snow changed to heavy rain and ended as 3" of snow)...

2016...1/22-23.....27.5"* biggest of all time...

 

3 minutes ago, donsutherland1 said:

 

 

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Another feature that we have seen during this amazing snowy run has been record snowstorms following record warmth.

While this past 15-16 winter was the most  extreme example, a version of this occurred in 04-05 and 05-06.

 

December 2015...+13.3..#1 most extreme warm December and month followed by #1 heaviest NYC snowfall 1/22-1/24 27.5"

January 2006.......+8.8...#3 warmest followed by #2 heaviest snowstorm 2/11-2/12 26.9"

January 2005.....1/1-1/14 +11.1 followed by sharp cool down late month and #21 heaviest snowstorm 1/22-1/23 13.8"

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this big turn a round from many lousy winters to many great ones started in early February 1993...the last 10" snowfall up to then was 2/12/1983...An arctic front passed early February 93 and NYC had its first single digit day in three years with a 3" snowfall...the main storm track was mostly right over us or to the west that year...93-94's storm track was mostly to the south or close to us...after a lousy 1994-95, 95-96's main storm track was perfect all year...

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