The last full day of astronomical summer
As noted in yesterday’s blogpost a cold front approaching from the west will usher in clouds and rain this afternoon. The current sunshine will soon dim and disappear behind a thick cloud deck that is fast approaching Fredericksburg and points east. Short range model runs this morning indicate the rainfall will begin in the city between 3 and 4 pm this afternoon and will continue into late tonight. The total amount of wetness may not be as much as originally thought due to thunderstorms already firing along the Gulf coast (noted by the white oval in the graphic) robbing us of a chunk of the tropical moisture streaming toward our area:
Today’s high will climb into the mid-70′s with tonight’s low temperature bottoming out around the 60 degree mark on this last full day of astronomical summer.
Sunday will then bring sunshine with a high in the mid-70′s as the official autumnal equinox occurs at 4:44 pm. As I’ve noted in previous blogposts the beginning of meteorological autumn for the Northern Hemisphere on Sept 1st usually marks the transition from a summer weather pattern to a fall-like pattern. On the other hand the beginning of astronomical autumn (the equinox) marks the time when the sun is vertically overhead at the equator. From this point until the beginning of astronomical spring in March we will have less daylight hours than we do nighttime.
Confusing? Just pick one or the other definitions of autumn and stick with it as your declaration of the beginning of fall!