A Gray October?
Posted November 2, 2009
We often think of October as a transition month that features a number of outbreaks of crisp, cool autumn air and bright blue skies, and historically, climate records tell us that we average almost 13 days with "fair" skies, defined in the records as having 8/10 or more of the sky free of opaque clouds on average during the day. If this October seemed a little gray to you, though, you weren't mistaken. We ended up with 17 "cloudy" days (8/10 or more of the sky covered by opaque clouds) at the Raleigh-Durham airport, compared to a normal of 11 cloudy days, along with 9 "partly cloudy" days and 5 "fair " days.
One might think that so much cloud cover would yield a goodly amount of rain, but we had several situations during the month involving high pressure to our northeast, and stalled fronts with weak low pressure waves well south and east of us. This commonly results in shallow layers of moisture that produce lots of low clouds, and some sprinkles and periods of drizzle, but not an awful lot in the way of measurable rain. As a result, while it was cloudy and damp rather often in October, we only ended up with 1.10 inches of rain, a little over two inches below normal.
Temperature-wise, we were pretty close to normal, although the clouds did limit our average"diurnal range," which is the difference between the low and high temperature on a given day, so that our average high was slightly below normal for the month while our average low was a little above normal.
We kicked off the month of November yesterday with some chilly temperatures (a daytime high of 55 at RDU) and some very substantial rainfall (one-half inch to around two inches) across the northwestern half or so of the viewing area, which will hopefully help with the developing drought conditions, but it is looking as though the remainder of this week and probably the coming weekend will feature a dry pattern with lots of sun and seasonably mild afternoon temperatures.