Crozet Weather Almanac: September 2017

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Courtesy Heidi Sonen/Roscoe Shaw

No Rain for 24 Days

We finished September on a stretch of 17 straight days with no rain.  Looking at the current weather pattern, Heidi and I think that will last through the first seven days of October, bringing the final streak to 24.  That, of course, got us digging into the record book to find the longest dry stretch on record.

Fall is interesting for rainfall because it is the wettest time of the year, but also the driest.  Most of our rain at this time of year comes from the leftover pieces of hurricanes.  The wettest month in the record books was September 1987, when over 17 inches of rain fell.  Most of the wettest months on record are in September.  But most of the driest also come in fall, such as October 2000, when just 0.01” of rain fell.

This year, there have been plenty of hurricanes but most of the moisture has missed us.  We got a little bit from the remnants of Harvey, but the others left us dusty and dry.

A scan of the record book shows the longest period without any measureable rain was 37 days in October and November of 2001.  We have mostly complete rainfall records back to 1911.  Second place goes to 2007 with a string of 34 days ending in October.  But the distant past had their dry stretches, too.  Droughts longer than 25 days also hit in 1918, 1920, 1930, 1934, 1941 and 1964.

Our current streak, expected to end at 24, will be the 13th longest in history.

The longer-term drought conditions are starting to be somewhat of a concern.  We haven’t had a significant threat to reservoirs or water tables since the drought of 2002.  The odds are that winter rains and snows will recharge the water table, but if we have a dry winter, next summer and fall could pose a drought problem.

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