July PDO: +0.66; Winter PDO Likely to Average Positive

[donsutherland1]

After peaking at +1.86 in May, the PDO has continued to decline. In June, it had fallen to +1.17 and in July it declined further to +0.66. This raises the question as to whether one might see the PDO average negative for Winter 2005-06.

Historic climatology (1900-2004) suggests that odds favor a positive PDO for Winter 2005-06 (December 2005-February 2006).

Average PDO Readings:
• July PDO: July 2005: +0.66
+0.600 or above: 29/36 (81%) winters saw the PDO average positive.
+0.650 or above: 26/32 (81%) winters saw the PDO average positive.

• June-July PDO: Average for 2005: +0.915
+0.750 or above: 25/28 (89%) winters saw the PDO average positive.
+0.900 or above: 21/23 (91%) winters saw the PDO average positive.

• May-July PDO: Average for 2005: +1.230
+1.000 or above: 18/19 (95%) winters saw the PDO average positive.
+1.200 or above: 12/12 (100%) winters saw the PDO average positive.

PDO Trends:
• Positive in July after Falling from June:
All cases: 16/22 (73%) winters saw the PDO average positive.
+0.600 or above in July: 11/12 (92%) winters saw the PDO average positive.
+0.650 or above in July: 11/11 (100%) winters saw the PDO average positive.

• Positive in July after Falling from May and from June:
All cases: 4/6 (67%) winters saw the PDO average positive.
+0.600 or above in July: 3/4 (75%) winters saw the PDO average positive.
+0.650 or above in July: 3/3 (100%) winters saw the PDO average positive

Climatology:
• 56/105 (53%) winters saw the PDO average positive.
• 49/105 (47%) winters saw the PDO average negative.

Conclusion: The PDO will likely to average positive during Winter 2005-06.

[jon]

I can't complain with that since I'm in the lakes and would love to see a west coast ridge this year as personal preference but those northwesters could use some snow and so I'm hoping they get at least some negative phase..erm..that is what happens, right?

[JETSTREAM BOB]

Ok---------- Does this mean a warm or cold winter in the east????

[JETSTREAM BOB]

After doing my own research, I answered my own ???

The Pacific Decadal Oscillation


The following table shows how air temperatures, precipitation, and related effects in North America have been correlated with with extreme PDO anomalies.

Climate Anomalies Warm Phase PDO Cool Phase PDO
Ocean surface temperatures in the northeastern and tropical Pacific Above average Below average
October-March northwestern North American air temperatures Above average Below average
October-March southeastern U.S. air temperatures Below average Above average
October-March southern U.S./northern Mexico precipitation Above average Below average
October-March northwestern North America and Great Lakes precipitation Below average Above average
Northwestern North America springtime snowpack Below average Above average
Winter and springtime flood risk in the Pacific Northwest Below average Above average

Can't Wait...........BIG SNOWS !!!!!__________YIPPEE !!!!....

[Jim Hughes]

[quote="donsutherland1"]After peaking at +1.86 in May, the PDO has continued to decline. In June, it had fallen to +1.17 and in July it declined further to +0.66. This raises the question as to whether one might see the PDO average negative for Winter 2005-06.

Historic climatology (1900-2004) suggests that odds favor a positive PDO for Winter 2005-06 (December 2005-February 2006).

Good info DS. Like they say on the B-ball court. You got game. Always


Jim

[donsutherland1]

Thanks Jim.

It will be interesting to see how the PDO evolves through the rest of the summer and autumn. Having said that, my confidence in a positive PDO for the winter is pretty good at this point in time.

[Brian_from_bellingham]

The University of Washington, who "discovered" the PDO and are the leading researchers of the PDO, think that the PDO will be nuetral for this winter.

"North Pacific SSTs have projected onto the warm (positive) phase of the PDO pattern for every month in 2005 (January-July), although the trend since May has been to weaker positive values. Notably, nearshore ocean temperatures off the coast of southern British Columbia to central California cooled considerably from exceptionally warm levels in May through mid-July to near average and even below average values from late July through present (August 18) (read related Seattle Post-Intelligencer story).

If ENSO forecasts favoring ENSO-neutral conditions in the next 3-6 months are correct, the ENSO influence on North Pacific SSTs should be expected to contribute to a continuation of recent trends toward near-zero values of the PDO index for the next 3-6 months."

http://www.cses.washington.edu/cig/fpt/cloutlook.shtml