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

Arctic Oscillation (AO) composites of 500 mb (5H) geopotential height anomalies (GPHa) and 2-meter air temperature anomalies (2m Ta) for analog winters '53 / '54 ... '54 / '55 ... '59 / '60 ... '97 / '98 ... '14 / '15.

5H GPHa composite

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

- Negative TNH ==> 1)  stronger than normal Pacific jet farther south of its normal axis and 2) well above normal temperatures in eastern North America.

- Active sub-tropical jet

- Positive GPHa over eastern Canada would 1) advect cP flow from hi-latitude snow fields into the eastern U.S. and 2) effectively displace the Hudson LOW from its climatologically favored location.

5H GPHa weighted-composite

2m Ta weighted-composite



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CORRECTION:  '54 / '55 ENSO should be 'C'

KEY
ENSO:  nada- (-0.5 < Region 3.4 SSTa <  0); C (moderate La Nina); W- (weak El Niño); W (moderate El Niño); W+ (strong 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
QBO:  + ==> west; - ==> east

CORRECTION:   Analog table - PDO:  should be '-'