Winter '19 / '20 - Quasi-Biennial Oscillation (QBO): Leading Analogs' 500 mb Anomaly Height Composite ... as of SEP-19

Analog 5H composite ('78/'79 ... '85/'86 ...'95/'96 ... '99/'00 ... '02/'03) ... as of SEP-19

- Ridge-W Trof-E
- Hi-latitude blocking ==> AO & NAO < 0
- EPO < 0

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Analog years for Winter '19 / '20

CORRECTION:  '78 / '79 & '85 / '86 ENSO should be 'W-' & 'C-' ... respectively.
 
KEY
ENSO:  nada- (-0.5 < SSTa <  0); C- (weak La Nina); C+ (strong La Nina); W (moderate El Niño)
NAO:  sign of D-J-F average
AO:  sign of D-J-F average
PDO:  sign of O-N-D-J-F-M average

Read more »

Winter '19 / '20 - Eurasia Snow Cover: SEP

Eurasia/s areal snow cover for SEP-19: ~1,570,000 SQ-KM

3% below 48-year P-O-R-N (~1,629,000 SQ-KM)
1% below 48-year Median (~1,588,000 SQ-KM)

Rank: 26th
4th lowest past 10 years
11 of past 20 years below median
SEP-18:  ~1,300,000 SQ-KM
SEP-19 21% greater than SEP-18

KEY
ENSO:  nada+ (0 < SSTa <  0.5); 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

Read more »

Winter '19 / '20 - Arctic Oscillation (AO): Leading Analogs' 500 mb Anomaly Height Composite ... as of SEP-19

Analog 5H composite ('53/'54 ... '54/'55 ...'59/'60 ... '97/'98 ... '14/'15) ... as of SEP-19

 

- Overall North American pattern mimics Tropic/Northern Hemisphere's (TNH) negative phase often associated with +ENSO.

- Positive height anomaly over eastern Canada displaces climatologically favored position of Hudson Bay trof limiting high-latitude cold air supply to the Lower 48.

- TNH associated with stronger than normal Pacific jet farther south of its normal axis and well above normal temperatures in eastern North America.

CORRECTION:  '53 / '54 ENSO should be 'W-'

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

Read more »

Winter '19 / '20 - North Atlantic Oscillation (NAO): Leading Analogs' 500 mb Anomaly Height Composite... as of AUG-19

UPDATE:  SEP/s NAO did not change the analog years other than to shuffle the 4th and 5th ranks.

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Analog 5H composite ('50/'51 ... '08/'09 ... '12/'13 ... '16/17 ... '17/'18) ... as of AUG-19

- Another round of Trof West - Ridge East

- EPO-like ridge offset slightly to the west of preferred position for a 'Trof-East' regime

- Azores HIGH suggests NAO > 0

- Negative height anomaly over south-central Canada favors primary storm track through the Upper Plains and across the Great Lakes in line with current soil moisture axis.

Winter '19 / '20 NAO analog analysis here.

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.

Read more »

Winter '18 / '19 - Arctic Oscillation (AO) Analog Verification

The analog forecasting technique seeks associations to the AO state in the run-up to the coming winter with AO run-up states of past winters.  Presented here is the verification of AO 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.

In the run-up to Winter '18 / '19 ... '55 / '56 was the leading analog followed by '64 / '65 ... '84 / '85 ... '99 / '00 ... and '91 / '92.  Observed AO values for Winter '18 / '19 began neutral in DEC ... turned weakly negative in JAN ... then surged positive at meteorological winter/s end and into MAR.

A qualitative assessment of the analog forecast/s accuracy rates '84 / '85 as best.

A quantitative assessment of the other '84 / '85 teleconnections ... not so much.

Read more »

Winter '19 / '20 - NCDC Issues Updated Period-of Record Snowfall Climatology

Here

It's only been four years since the last update.

More NCDC climo data here