Mild Canadian Winter Favors Above Normal US Temperatures This Summer

[bluewave]

The 20 mildest winters in Canada since 1948 were usually followed by above normal temperatures across the US during the summer.

http://www.ec.gc.ca/...En&n=24F82736-1

The US summer temperature data from the NCDC confirms this correlation.

http://climvis.ncdc..../hr-display3.pl

The average US summer temperature ranking following the 20 mildest Canadian winters is 92 with 117 being the warmest and 1 the coolest.

The mild temperatures experienced across Canada this past winter should put it relatively high on the list of the mildest

winters there.

The spring temperature pattern so far is matching up with what you would expect following a mild Canadian winter.

While this March is in record breaking territory, above normal spring temperatures are favored in those locations.

I made a series of composites for the 20 mildest Canadian winters and the US summers that followed.

Winter

Spring

Summer

I also prepared a series of composites following the 20 coldest Canadian winters since 1948.

The cooler correlation holds with the US average summer temperature ranking coming in at 56 out of 117.

Winter

Spring

Summer

All these composites are for the US as a whole. You can use the temperature data to generate specific temperatures

for cities of your choice.

[Isotherm]

Good research Chris. I checked out the H5 composite for these winters, and to no surprise, the top 20 warmest winters in Canada were generally pretty good for East Coast folks, at least in terms of the 500mb depiction. Essentially the result is exactly what we'd want with west based neg NAO blocking, negative northern annular mode, trough in the Aleutians, the works, etc.

The funny thing is - this past winter we achieved results similar to their top 20 warmest winters, but for different reasons. Many of those winters were Nino's or neutral ENSO with negative NAO/AO patterns, which yielded a mild picture especially for northern and eastern Canada. Winter 2011-12 featured very little blocking in the sense of a -NAO/AO, but the resultant sfc temp anomalies were very positive due to the incredible amount of warmth on our side of the globe.

[Isotherm]

Summer temps with a developing El Nino seem to have some relationship to NAO values.

Below are the Nino's with +NAO's from the list of 20 years June-August:

-NAO's for June-August. 1987 was a bipolar sort of summer, especially for the Northeast, with a warm first half, and cold second half

Still generally mild in the West and SE but a good amount cooler for the Plains and Northeast.

As we approach this summer, given the backdrop of a developing El Nino, I think it'll be important to monitor NAO trends to see whether we're looking at a coast to coast warm JJA or a summer w/ potentially some cooler pockets in the northern tier. Some of the climate forecast models depict this current discrepancy (one suggests a cooler Great Lakes/Northeast JJA).

2010 was a blowtorch with a negative NAO, and no doubt there are plenty of warm Northeastern summers with a -NAO. But I believe the Nino factor is also important here - and the fast that gets going (e.g. May/June?) the more likely a cooler result would occur when coupled with a negative NAO. If we remain neutral all summer, then probabilities are fairly high, IMO, for the majority of the US seeing positive temp anomalies (particularly Rockies east, in a -PDO/+AMO backdrop).

[bluewave]

Tom, thanks very much for adding that additional research.^

I also made a series of composites just focusing in on the 10 mildest and coldest Canadian winters since 1990.

Mildest Winter

Spring

Summer

Coldest winter

Spring

Summer