Winter '09 / '10 - Quasi-biennial Oscillation - October

-11.70.

A stronger negative value was expected b/c the cycle is five months into its easterly phase.

1991 continues to be the best YTD-analog...followed by 1986...1981...2000...and 1967.  Note its close fit...including the slight upturn through NOV before resuming its decline into spring.

Other 1991 Teleconnections

Strong +ENSO...as measured by MEI...was in excess of +1.5 and reached a max value of +2.248 during spring 1992.  The analog year is the highest-ranked of those matching the top-5 QBO years.

PDO was weakly positive during the winter...dipping close to zero in JAN before turning strongly positive by mid-spring.  It/s the fourth ranked analog.

1991 is the top analog for AO and 4th for NAO.  AO was above zero NOV through MAR...and above +1 DEC and FEB.  Similar tale for NAO...altho JAN/s dip to -0.13 did little to affect the winter/s +0.568 index average.

Sunspots for the period D-J-F-M totaled 576...not a good match for this year/s extreme minima values.

The two tables show the top-5 analog years for QBO.  The top table displays the rank of the corresponding years for other teleconnection indexes, i.e., the 1991 PDO is ranked fourth of all PDO analog years.  The 'Total' column sums all 'rank' values for the analog year.  Low score wins with this decision analysis scheme.  North American snow cover (NA SN) is not included in the scoring b/c data are not available for all analog years.

The bottom table assigns a score relative to all rankings in the same column and assumes every column carries equal weight.  Further refinement to this decision analysis table would assign relative weights to each teleconnection index.  MEI might be weighted 35% and the contribution from sun spots set to 10%.

Note the 1991 PDO is ranked 1st among the other PDO years and has the top score of 1.  The 1991 'Sun Spots' has a low score of 0.10 b/c more sun spots are not associated with colder winters.  1986 has the lowest sun spot count and is scored 1.

1991 QBO has the highest total score of 4.01.  Its score is more than twice as high as the second best analog year 1986...50% higher than 2000...and a strong choice when paired with other teleconnection indexes.

The winter of 1991 produced much below normal snowfall in the mid-Atlantic and southern New England...as is typical for QBO-east and +ENSO winters.

Richmond...VA - 0.9"

DC - 6.6"
Baltimore...MD - 4.1"
Philadelphia...PA - 4.7"
NYC - 12.6"
Binghamtom...NY - 56"
Boston...MA - 19.1"
Concord...NH - 33.6"

Previous QBO post here.