Autumn is the season of the year between summer and winter during which temperatures gradually decrease. It is often called fall in the United States because leaves fall from the trees at that time. Autumn is usually defined in the Northern Hemisphere as the period between the autumnal equinox (day and night equal in length), September 22 or 23, and the winter solstice (year’s shortest day), December 21 or 22; and in the Southern Hemisphere as the period between March 20 or 21 and June 21 or 22. The autumn temperature transition between summer heat and winter cold occurs only in middle and high latitudes; in equatorial regions, temperatures generally vary little during the year. In the polar regions autumn is very short, meaning with the daylight fading and darkness the rule they go to cold and snowy quickly.
As expected we will see a fall in temperatures, a decrease in daylight and an increase of clouds around the Great Lakes, especially along the western coastal counties. We are losing three minutes a day of daylight – the sun is setting before 8pm now. I am outside between 7 and 8pm playing with the dogs and one of my cats – it is pretty much dark by the time I herd them inside.
We are starting this fall with above normal temps which may be the theme for the next couple months. The big question is how the end of fall and the first part of winter will play out. At this time there is a pool of cooler air over the western U.S. which I believe will eventually move to the east. I am not sure if it will last if and when it does. It is my thinking we will have one of those strange late fall and early winters which may surprise us with ice and snow. Remember, even with above normal temps we can still see snow though it may be the wet heavy stuff we all dread to shovel.
September is when the ice begins to build in the Arctic regions and snow begins to fall above the 60th parallel. Snow pack in this region has a bearing on our winter weather – below is a chart showing the average snow extent by month for the northern hemisphere.
It is really to early to talk about snow and a winter forecast, this will come as we get towards the end of October. As we get into October our chances of 80° days diminish and the low 70s will be above normal but welcomely pleasant. By the end of October the chill generally sets in and the upper 40s to low 50s are more prevalent. It is not unheard of to have thunderstorms in October due to the battle between the cold and warm moist air masses as the seasons change. We shall see how it all plays out as forecasts tend to change as we look out even beyond even 5 days…