Old Weather? What?

Old weather? What? Why should anyone care?

Do you need to know the weather for a particular day at a particular location in the past? Is the weather pertinent to a legal case? Or do you just want to settle an argument with your spouse?

The Weather Underground site at http://www.wunderground.com/ will tell you the weather at the closest data collection points for dates back through the early 70’s.

First fill in the search box in the upper left corner of the home page to identify the location for which you are searching for weather data. Hit “enter”.

Then go to the “History and Almanac” box on the page that comes up for the location you selected. Fill in the date of interest and hit the “Go” button. You get a page showing a summary of weather details for that location.

Some pages will give you more detailed data (hourly observations and seasonal weather averages) for that date and location; be sure to scroll down to get the extra data when provided.

Remember that the data you get is specific to the location and date you selected. Click on “View Current Conditions” to get the latitude, longitude and elevation for the data collection point.

Microclimates matter. Weather varies over time and, for a specific time, over geographic location and elevation, so, unless the data collection point is your real point of interest, you can only make inferences about the data being true for some other location, even close by.

You can triangulate by getting data from surrounding data collection points. For a recent case, I collected data for Boeing Field, Everett and Bothell to allow more reliable inferences about road conditions for a location near to, but outside of, Bothell.

Be sure to play with the site; it offers a considerable amount of interesting and educational information.

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