March 13, 2005 NAO: -5.264

[donsutherland1]

With a -5.264 value for 3/13, this is the 8th time the NAO has fallen to or below -5.000 during this blocking pattern. Only two blocking patterns have seen more days at -5.000 or below: 1958 and 1962

• 1958 Extreme Block
Started: January 17, 1958
Ended: April 10, 1958
Days below 0: 84 days
Days at or below -5.000: 9
Average NAO Value: -2.583

• 1962 Extreme Block
Started: February 24, 1962
Ended: March 30, 1962
Days below 0: 35 days
Days at or below -5.000: 9
Average NAO Value: -4.048

• 2005 Extreme Block
Started: February 17, 2005
Ended: N.A.
Days below 0: 25 days (through March 13)
Days at or below -5.000: 8
Average NAO Value: -3.875

[snow_wizzard]

Wow!! There is no doubt we are in VERY rare territory here! For what it's worth, I would say the details of this episode bear much more resemblence to the 1962 block. That season had weather very similar (in some ways) to this one in the Pacific NW.

Another thing that is certainly noteworthy, is this type of thing has not happened since 1962! Could this be a sign that we have indeed began a major regime shift? You put this together with New York City having it's first occurance of three 40" + winters in a row, and you get an interesting picture. It sure looks like we have left the regime that has dominated since 1975. Good riddance!

Further addition: To add even more intrigue to all of this, it would appear that after this winter, the 5 year running average for the PNA, AO, and NAO will all be negative for the first time since 1972! In my book that means something. It would appear that everything could well be lining up for the west to finally get cold winters again. Past history is clear that when the running average is minus on all three indices, the west gets slammed!

[donsutherland1]

Just a quick note:

The 3/14 NAO was -5.228. This is the 9th day at which the NAO came to -5.000 or below during the current extreme blocking pattern. This ties the record for most such days in any blocking pattern:

• 1958 Extreme Block
Started: January 17, 1958
Ended: April 10, 1958
Days below 0: 84 days
Days at or below -5.000: 9
Average NAO Value: -2.583

• 1962 Extreme Block
Started: February 24, 1962
Ended: March 30, 1962
Days below 0: 35 days
Days at or below -5.000: 9
Average NAO Value: -4.048

• 2005 Extreme Block
Started: February 17, 2005
Ended: N.A.
Days below 0: 26 days (through March 14)
Days at or below -5.000: 9
Average NAO Value: -3.927

[donsutherland1]

Snow_wizzard,

I believe the long-term trend is toward a PDO- cycle. Whether or not Winter 2005-06 sees a negative PDO is still quite uncertain. At some point, and sooner rather than later, I believe there will be a negative PDO winter.

[MGC]

One thing that is missing from this year compared to 1962 is the absense of cold in the deep south.....MGC