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Rtd208

November 2017 Discussions & Observations Thread

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There's an interesting correlation between La Nina Novembers and strong blocking near the Bering and Aleutians. All 9 La Novembers since 1950 with this pattern were followed by a -AO December. This would match the long range guidance shifting the primary NH blocking from the Bering and Aleutians to the North Pole or Greenland. This November so far has seen record 500 mb blocking near the Bering and Aleutians.

La Nina Novembers with a strong Bering and Aleutians block since 1950 and December AO.

2010...-2.631

1996...-1.721

1995...-2.127

1985..-1.948

1973...-0.181

1970...-0.399

1966...-1.401

1955...-0.444

1950..-1.928

 

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14 minutes ago, bluewave said:

There's an interesting correlation between La Nina Novembers and strong blocking near the Bering and Aleutians. All 9 La Novembers since 1950 with this pattern were followed by a -AO December. This would match the long range guidance shifting the primary NH blocking from the Bering and Aleutians to the North Pole or Greenland. This November so far has seen record 500 mb blocking near the Bering and Aleutians.

La Nina Novembers with a strong Bering and Aleutians block since 1950 and December AO.

2010...-2.631

1996...-1.721

1995...-2.127

1985..-1.948

1973...-0.181

1970...-0.399

1966...-1.401

1955...-0.444

1950..-1.928

 

Never realized December 96 had such a negative AO given it was so warm

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8 minutes ago, SnowGoose69 said:

Never realized December 96 had such a negative AO given it was so warm

It could have been a great December if the Pacific wasn't so unfavorable.

 

 

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2 minutes ago, bluewave said:

It could have been a great December if the Pacific wasn't so unfavorable.

 

 

Doesnt this make the point that a -NAO , while a good thing to have, is far from the only factor to drive cold & snow to the coast?

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1996 was one of the exceptions that had a negative ao and nao in December with nothing to show for it...November 1996 was cold...

Decembers with an ao and nao -1 or lower...

year.....ao.....nao.....

1950...-1.928.....-1.02...snow 12/27...

1961...-1.668.....-1.48...snow 12/24

1963...-1.178.....-1.92...snow 12/23

1976...-2.074.....-1.60...snow 12/26

1995...-2.127.....-1.67...snow 12/20

1996...-1.721.....-1.41...no snow...

2009...-3.413.....-1.93...snow 12/20

2010...-1.749.....-1.85...snow 12/27

1996 was the only December that was mild without measurable snow in NYC...

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23 minutes ago, uncle W said:

1996 was one of the exceptions that had a negative ao and nao in December with nothing to show for it...November 1996 was cold...

Decembers with an ao and nao -1 or lower...

year.....ao.....nao.....

1950...-1.928.....-1.02...snow 12/27...

1961...-1.668.....-1.48...snow 12/24

1963...-1.178.....-1.92...snow 12/23

1976...-2.074.....-1.60...snow 12/26

1995...-2.127.....-1.67...snow 12/20

1996...-1.721.....-1.41...no snow...

2009...-3.413.....-1.93...snow 12/20

2010...-1.749.....-1.85...snow 12/27

1996 was the only December that was mild without measurable snow in NYC...

the pna was negative in 12/96...positive in 12/95...

further review shows 2010 with a very negative pna...it was close to neutral the time of the blizzard on the 27th...1961 had a negative pna most of the month...

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51 minutes ago, bluewave said:

It could have been a great December if the Pacific wasn't so unfavorable.

 

 

Yes. It was -NAO too. The -PNA/+EPO ruined it like you said. 

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5 minutes ago, snowman19 said:

Yes. It was -NAO too. The -PNA/+EPO ruined it like you said. 

Sometimes the Pacific just doesn't wan't to play ball.

 

96.png.e8840bee71fec4e59e8c78ba61a06e43.png

 

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2 minutes ago, bluewave said:

Sometimes the Pacific just doesn't wan't to play ball.

 

96.png.e8840bee71fec4e59e8c78ba61a06e43.png

 

That actually was a pretty good month not far from the Coastal Plain.  I was a Junior in HS at the time in Ridgefield, Ct. and we had two storms within a 3 day period that produced 4-6" of snow.  Both were rain -> snow deals.  Further inland got significantly more.  That was the famous first Jim Cantore thundersnow shot (which as been since replicated several times) from Worcester, Ma.

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32 minutes ago, bluewave said:

Sometimes the Pacific just doesn't wan't to play ball.

 

96.png.e8840bee71fec4e59e8c78ba61a06e43.png

 

My memory of the 96-97 winter as whole is that it was sort of a reverse 93-94 and 14-15. Every indice argued the winter should have been cold or at least near normal but it wasn't  

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1 hour ago, danstorm said:

That actually was a pretty good month not far from the Coastal Plain.  I was a Junior in HS at the time in Ridgefield, Ct. and we had two storms within a 3 day period that produced 4-6" of snow.  Both were rain -> snow deals.  Further inland got significantly more.  That was the famous first Jim Cantore thundersnow shot (which as been since replicated several times) from Worcester, Ma.

We had several legit nor’easters that winter. I remember one specifically that was close on the island. We switched from moderate rain to heavy heavy parachutes that gave a slushy coating. Some of the heaviest snow I have ever seen. As soon as the precip intensity dropped it went back to and stayed rain. Had it been a few degrees colder it would have been a solid snow storm.

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14 minutes ago, uncle W said:

96-97 had major snow chances in early December and March 31st...both times temperatures were above freezing and the city got mostly rain..

Yes that was the April fools day storm which had a crazy gradient. Nyc was basically all rain, coastal westchester and SW CT was around 5-6”, just 10 or so miles inland at Armonk was around13” and another 10 or so miles at Yorktown was around 18”. Pretty sharp to say the least.

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Record Heat on Tap for Phoenix/Southwest…

Today’s preliminary Arctic Oscillation (AO) value was -3.582. That figure, if finalized, would surpass the November 21 daily record low AO reading of -3.357, which was set in 1985. The only other November 21 cases with AO values of -3.000 or below occurred in 1950 (-3.113) and 1959 (-3.239). The kind of very strong blocking that is present at this time of year has typically provided a good indication that the following winter would feature blocking (often with at least one month with an average AO figure of -1.000 or below). The return of Atlantic blocking for winter 2017-18 would be a big change from the near absence of such blocking during winter 2016-17.

Perhaps the biggest weather story in the United States will be the extreme heat that will build across the Desert Southwest in coming days. The forecast high temperatures for Phoenix (11/21 12z MOS) are as follows:

November 22: 89° (Record: 89°, 1950)
November 23: 91° (Record: 87°, 1950) **Possible latest 90° reading on record**
November 24: 89° (Record: 88°, 1950)
November 25: 88° (Record: 88°, 1950)
November 26: 86° (Record: 87°, 2014)

Latest 90° reading on record: November 15, 1999: 90°

Two years had extended outbreaks of extreme heat at this time of year that approached the magnitude of that forecast for Phoenix. Those years were 1933 and 1950. After a very warm December across the CONUS, winter 1933-34 would shift dramatically. The outcome would be much above normal snowfall in much of the eastern United States and outbreaks of extreme cold. In contrast, December 1950 was very cold across the eastern third of the United States except for parts of New England. That winter underwent a dramatic change to warmer than normal conditions that prevailed, on average, through January and February. Snowfall wound up being much below normal, especially on the coastal plain. Seasonal snowfall totals included:

Baltimore: 6.2”
Boston: 29.7”
Bridgeport: 13.7”
New York City: 11.6”
Newark: 10.9”
Philadelphia: 4.6”
Poughkeepsie: 40.8”
Washington, DC: 10.2”

Currently, the CFSv2 is forecasting temperature anomalies that are closer to those of December 1933 than December 1950. However, the Middle Atlantic and New England regions are trending colder. Based on the idea that there will be blocking during parts of December, a colder solution in the Northeast still appears somewhat more likely than a warmer one.

During winter 1933-34, the PDO turned positive.

October-March 1933-34:
October 1933: -1.19
November 1933: +0.55
December 1933: -1.10
January 1934: +0.17
February 1934: +0.68
March 1934: +1.34

During winter 1950-51, the PDO remained strongly negative to negative:

October-March 1950-51:
October 1950: -1.36
November 1950: -2.46
December 1950: -0.76
January 1951: -1.54
February 1951: -1.06
March 1951: -1.90

La Niña-PDO+ winters tend to have above to much above normal snowfall in the eastern United States. La Niña-PDO- winters tend to have below to much below normal snowfall in that region. Winter 2010-11 was an exception to the La Niña-PDO- relationship with much above normal snowfall courtesy of extreme blocking that predominated from roughly mid-December to mid-January. Once the blocking ended, there was very little additional snowfall going forward. Winter 2017-18 is likely to see the PDO closer to neutral than was the case for winter 1950-51 (possibly somewhat positive). Therefore, I continue to believe that snowfall across the Middle Atlantic and New England regions should be much higher than it was during winter 1950-51 with much of the region seeing above normal snowfall. Should strong blocking redevelop in December and the winter turn out to feature abundant strong blocking, the potential for much above normal snowfall would be on the proverbial table.

CFSv211212017.jpg

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2 hours ago, bluewave said:

All that I remember about that winter was that it was my first on the internet and had no snowstorms to track. I kept wishing that I got online a year earlier for the epic 95-96 winter. Really got started tracking the patterns once online and enjoyed reading the legendary Walt Drag long range AFD's.

We had a surprise event in early January that ended up a 2 to 4" localized event. 

http://www.raymondcmartinjr.com/weather/1997/11-Jan-97.html

 

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Looks like the fast Pac Jet pattern continues for the remainder of the month with up and down temperatures.

 

NEW YORK CITY-CENTRAL PARK
 KNYC   GFSX MOS GUIDANCE  11/21/2017  1200 UTC                       
 FHR  24  36| 48  60| 72  84| 96 108|120 132|144 156|168 180|192      
      WED 22| THU 23| FRI 24| SAT 25| SUN 26| MON 27| TUE 28|WED CLIMO
 N/X  50  52| 33  44| 37  50| 44  58| 43  50| 36  50| 44  56| 49 36 49

 

KNYC_2017112112_forecast_240.thumb.png.6aade18d11c8aa17e7f9031dd85e7411.png

 

 

 

 

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