Skywatch Friday: Meteorological Fall

September 1 is the first day of "meteorological fall" and our weather has changed right on schedule.  This is the sky over Skagit Bay this evening.  This seasonal reckoning is different from "astronomical fall."  It begins this year with the autumnal equinox on September 22nd.  The tilt of the earth defines it.  The months of September, October and November make up meteorological fall defined by the weather.

This is what the sky looked like three days ago.  That night and the next day, September 1, we would get almost an inch of rain.  Before that, the last time it had rained here was July 9th.  With one of the warmest summers on record, we were experiencing a significant drought.  Gardens and woodlands were suffering.  A statewide outdoor burn ban was in effect.  The drought was finally broken with a convergence zone sitting over us for several hours.  At one point, my weather station measured a rainfall rate of 3.11 inches/hour, 78.99 cm/hour.

Those roll-shaped clouds reveal turbulence and predict possible thunderstorms.  That's exactly what we experienced that night.  Before the rain came, the sky had been mostly cloudless and hazy.  It is much more interesting now.