Winter '19 / '20 - Eurasian Snow Cover: AUG

Eurasia/s areal snow cover for AUG-19:  ~158,300 km2

-61% below 48-year P-O-R-N (~403,000 km2)
-46% below 48-year Median (~294,000 km2)
Rank: 39th

7th highest past 10 years
19 of past 20 years below median
 Last year:  ~140,800 km2

Analog years for winter '19 / '20

CORRECTION:  Second instance of 15/16 should be 16/17
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Snow cover data courtesy Rutgers University Global Snow Lab
http://climate.rutgers.edu/snowcover/index.php

Winter '19 / '20 - Arctic Oscillation (AO): AUG

AUG AO:  -.722
Leading analog contenders ... as of AUG-19.

Consensus Outlook:  Winter '19 / '20 AO < 0

KEY
ENSO:  nada- (-0.5 < SSTa <  0); C- (weak La Nina); W- (weak El Niño); W (moderate El Niño); W+ (strong El Niño)
NAO:  sign of D-J-F average
PDO:  sign of O-N-D-J-F-M average
QBO:  + ==> west; - ==> east; +/- flipped west to east

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Present state
ENSO: 0 < ONI < 0.5 trending lower
NAO < 0 past 5 months
QBO > 0 past 10 months.  Peaked JUN-19; trending lower.  Possible flip during upcoming winter
PDO (MAR-18 to OCT-19) < 0 No trend.

Winter '19 / '20 - North Atlantic Oscillation (NAO): AUG

AUG NAO:  -1.17
Leading analog contenders ... as of AUG-19.

Consensus Outlook:  Winter '19 / '20 NAO > 0

CORRECTION:  '50 / '51 ENSO should be 'C-'

KEY
ENSO:  nada- (-0.5 < SSTa <  0); C- (weak La Nina); C (moderate La Nina)
AO:  sign of D-J-F average
PDO:  sign of O-N-D-J-F-M average
QBO:  + ==> west; - ==> east

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Present state
ENSO: 0 < ONI < 0.5 trending lower
QBO > 0 past 10 months.  Peaked JUN-19; trending lower.  Possible flip during upcoming winter
PDO (MAR-18 to OCT-19) < 0 No trend.

Winter '18 / '19 - North Atlantic Oscillation (NAO) Analog Verification

The analog forecasting technique seeks similarities to the NAO state in the run-up to the coming winter with NAO run-up states of winters past.  Presented here is the verification of NAO analogs for the '18 /'19 winter.

The NEWxSFC method ranks analog years by their the sum of square errors (SSE) statistic.
Lower SSE errors ==> stronger analog

Constraining the number of analog winters for analysis to five is arbitrary.

North Atlantic Oscillation (NAO) Index Analog Forecast Verification

In the run-up to Winter '18 / '19 ... '84 / '85 was the leading analog followed by '72 / '73 ... '59 / '60 ... '89 / '90 ... and '91 / '92.  Winter '18 / '19 NAO started weakly positive ... approached zero at meteorological winter's end ... then climbed above 1 in MAR.

A qualitative assessment of the analog forecast's accuracy would rate the analogs #2 or #5 as 'best' with #1 ... 3 ... and 4 'poor.'

A quantitative assessment of the other '72 / '73 and '91 / '92 teleconnections ... not so much.

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