Crozet Weather Almanac: August 2018

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Crozet Weather August 2018. Chart courtesy Heidi Sonen and Roscoe Shaw.

Exactly nine inches of rain fell in our gauge in August which is slightly more than double the normal for the month. For only the second time in 100 years, we have picked up over six inches of rain in four consecutive months.  The last time that happened was the same four months in 1948…May through August.

Normally, at some point in the summer, we hit a dry spell and the grass turns brown. But this year, the incredibly consistent rainfall made August as green as a normal May.

One characteristic of summer rainfall is that it can vary greatly from place to place.  In August, about 12 inches of rain fell along Skyline Drive north of Crozet while only about 3 inches fell in the Keswick area. July had a similar disparity with seven inches in Crozet but less than two inches in Louisa.

Weather Underground is a great online site for watching rainfall in real time.  Anyone with an automated weather station can add it to the worldwide network of stations. The last time I checked, they had over 250,000 stations that were linked online with about 35 in Albemarle County alone.

We recommend going to Weather Underground and wandering around just to look at the crazy array of data that is available. You can plot the data on a map with other stations or you can look at minute detail for a single site, often in 5 min increments.

My favorite Crozet station is at Crozet Elementary school.  The readings are generally accurate and outages are rare. The station sits in a low spot away from the big city of Crozet so on clear, calm nights, cold air settles there and the morning lows are often the coldest around.  Chiles Peach Orchard is the opposite.  It sits on a high area with a gentle slope below Jarman’s Gap.  On clear, calm nights, cold air drains away down the hill and Crozet Elementary can easily be 5 degrees colder.  Of course, Chiles is on the hillside for a reason.  The cold-air drainage keeps the fruit from getting hit by frost.

One caveat: watch out for bad data.  The stations are run by part-time amateurs and often suffer from poor location and calibration. A common error is that a poorly sited station will heat up way too much in the afternoon on a sunny day.  Rain gauges are often poorly calibrated.  Our old-fashioned manual rain gauge is more consistent and accurate than all but the best calibrated electronic gauges. Wind measurements are almost always poor both due to location difficulties and instrument limitations.

What these stations lack in accuracy and reliability, they make up for in sheer quantity.  With 35 locations in just one county, you get a pretty good idea of what the truth is and you get the data in real-time, as it happens.

If you are a real weather junkie, give it a try. 

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