Network News

X My Profile
View More Activity
The new Washington
Post Weather website
Jump to CWG's
Latest Full Forecast
Outside now? Radar, temps
and more: Weather Wall
Follow us on Twitter (@capitalweather) and become a fan on Facebook
Posted at 11:00 AM ET, 05/20/2008

NOAA: It Could be Hot This Summer

By Jason Samenow
Probability of above average temperatures this summer. Credit: NOAA

If you think the above headline is vague, you're onto something. The National Oceanic and Atmospheric Administration's (NOAA) Climate Prediction Center (CPC) recently released its updated 90-day summer outlook and it tells us... not much of anything and what little it does is confusing.

It includes a map (shown to the right) that colors the metro area in an inferno-like orange shade, but it turns out this means there's just about a 37% (or somewhere between 33-39% as indicated by the light orange shade; the darker orange shade indicates a 40%+ chance of above average temperatures) chance it will be hotter than average this summer. That doesn't impress me, because on the flip side it means there's a 63% (or 60-67%) the summer will be something other than hot.

Keep reading for more on the summer outlook. For the full forecast through the weekend, see Matt's post and see NatCast if you're headed to tonight's game.

What the outlook is really trying to communicate, but does not do so effectively, is that it is slightly more likely that it will be hot than either of the two other alternatives: average or cooler than average. A better way to convey this would simply be to give the probability for each possibility (in different regions of the country) instead of drawing up a map with difficult to understand contour values that require a long technical explanation . The following presentation would be more clear:

Chance it will be hotter than average: 37%
Chance it will be near average: 33%
Chance it will be cooler than average: 30%

This information could also be effectively presented in a bar chart or pie-chart.

On the plus side, NOAA's CPC does clearly state in its discussion: "Above normal temperatures are expected ... in the Northeast based on nearly all tools." But you've got to wade through a lot of text to find this clear statement.

Next week, we'll release our own summer outlook. I promise it will be more transparent, direct, and meaningful than NOAA's.

By Jason Samenow  | May 20, 2008; 11:00 AM ET
Categories:  Local Climate  
Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati   Google Buzz   Previous: NatCast: Shower Chances Fade
Next: CommuteCast: Brightening Skies in Some Places


Ha -- but if one gave the clear explanation, which your text version is, then there would be no excited headlines and salacious global warming stories

Posted by: ah | May 20, 2008 12:11 PM | Report abuse

Jason, I too thought the NOAA forecast was vague. I am looking forward to seeing the Capital Weather Gang's forecast soon!

Posted by: David A. in Stafford | May 20, 2008 1:10 PM | Report abuse

I could use a cool summer.

Posted by: Murre | May 20, 2008 4:05 PM | Report abuse

Thanks, Jason, for the enlightening remarks on the reality of the CPC summer outlook - which apply equally as well to all CPC seasonal outlooks. As one who played a role in preparing these forecasts while working at CPC, it was and remains disconcerting that the information content of these predictions is generally misinterpreted.

Most disturbing is when media sensationalizes the message in absolute terms, e,g, the "A" is parlayed as an abnormally hot summer. In reality the forecasts are expressed (justifiably) in probbilistic terms - and the odds of being in any particular category (Above, Below normal) are invariable quite small. Moreover, as all should recognize, the predictions are averages over the season, such that a very hot period of a couple weeks or so could be counterbalanced by slightly cool conditions over most of the season.

As to the forecasts being "vague", it must be recognized that the current science and modeling capabilities do not permit being any more specific. Of course there are those who will argue otherwise, probably the same folks who claim they can accurately predict the temperature, wind, humidity on a specific day and time 3 months from now. The "butterflies" reign supreme (see:

Posted by: Steve Tracton | May 21, 2008 9:58 AM | Report abuse

The comments to this entry are closed.

RSS Feed
Subscribe to The Post

© 2012 The Washington Post Company