CPC Review: September 2012

Let’s remind ourselves of the CPC outlook for temperature and precipitation for the month of September:

CPC temperature outlook for September 2012.

CPC precipitation outlook for September 2012.

I’ll start with the precipitation outlook first.  Below is the NCDC map for precipitation for the month of September.

Overall, it appears the CPC did pretty well in predicting areas of above and below normal precipitation.  They could’ve connected the above normal areas along the Gulf coast and Ohio river valley as well as the below normal areas in the Pacific Northwest and Upper Midwest.  The above normal area in the southwest was a little hit-and-miss, but really not too bad when you consider how difficult it is to project precipitation over a whole month.

Now, for the temperatures.  You may wish to glance back at the temperature outlook above before studying the image below from the NCDC.

The above normal temperatures in the west were accurate.  And there were below normal temperatures along the West Coast, although the outlook should’ve shifted north to include the Oregon coast and exclude southern California.  East and southeast of the Dakotas, however, is a much different story.  With the possible exception of the East Coast (from the Delmarva peninsula northward) and mountainous parts of the northeast, the outlook was pretty poor.  The bulk of the Midwest was below normal.  This is where the CPC gave the best chance for above normal temperatures in the eastern half of the country.  The southeast was also projected for above normal temperatures.  Instead, several areas were below normal with only west-central Mississippi coming in above normal.

This is the second month in a row this has happened.  Look back at the August review.  Similar to September, the CPC had projected a large area of the country to be above normal.  Instead, the north-central and southeast regions of the country came in near or below normal for the month.  And, remember, up until September 30th, the CPC projected much of the country to be above normal for the month of October.  They changed their minds at the last minute.  Given the temperatures during the first nine days of October, this was likely a good decision by the CPC.

FINAL VERDICT: On a scale of 1 to 10, with 1 being “Laughably Wrong” and 10 being “Frighteningly Accurate,” I will (subjectively) assign an overall score of 6 to the CPC September outlook.  Breaking it down, I gave them an 8 for the precipitation outlook as it was generally good with only a few minor issues.  The temperature outlook received a 4.  There was general accuracy in the western half of the country, but a complete miss in the eastern half.  The CPC wasn’t nearly as confident in their above normal projections in September as they were in August.  Thus, I won’t kill them as badly as I did for the August outlook.

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