Well it is the last full day of Summer for 2012 with the Autumnal Equinox occurring tomorrow morning and for many, I’m sure they will welcome in cooler air along with a chance for some showers. It has been a very warm, to down right hot Summer for most portions of the lower 48. Numerous areas had records shattered several days in a row between June and August. Just check out the graphic below from the www.climatecenter.org showing the top 10 states that broke records across the lower 48.
Those states that saw a tremendous amount of record-breaking heat, also saw dire drought conditions. There were weeks on end that next-to-no rain fell across the nation’s heartland, which affected the crops and is leading to a very poor harvest for this Fall. Here is a map of the current drought conditions for the nation. Notice that the worst drought conditions can be found right where the most record-breaking heat occurred. Check out the image below from the Climate Prediction Center.
WHAT IS THE AUTUMNAL EQUINOX?
From timeanddate.com showing the Earth’s position during the September equinox (ill. not to scale).
It is that time of year when the Sun shines down equally across the northern and southern hemisphere, from the Antarctic to the Arctic Circle. This is unlike the Winter or Summer Solstice where the Sun shines down at a maximum angle for one hemisphere, and a minimum in the other, giving the longest day as well as the shortest day for their respective hemispheres. You can also think about it this way… You will loose more daylight over time in the northern hemisphere, and also gain an extra hour of sleep.
The official time of the Autumnal Equinox is Saturday morning at 10:49 EDT (9:49 CDT, 8:49 MDT, 7:49 PDT).
Now with the Autumn season starting, temperatures will start to drop across the nation, with the first cold outbreaks popping up across the northern plains.
A CHILLY START TO A NEW SEASON
Temps will start off very chilly on Saturday morning as the calendar turns from Summer to Fall. A cold, Canadian High pressure system will descend out on the northern plains and Great Lakes region over the course of the week, primarily thanks to a pesky upper level low system that is stuck spinning between the Great Lakes and Hudson Bay. Temperatures will free fall down to freezing levels Saturday morning across North Dakota, and we will likely see those warnings spread towards Wisconsin for Sunday morning.
Take a look at the forecasted morning low temps for Saturday morning. Notice the blue on the map! We haven’t seen chilly morning lows like that since back in April. Make sure you bring in your plants that are sensitive to freezing conditions and cover those plants that have to remain outside. This would not be a good night to leave the window open as you sleep. If you are like myself, and like a cool fresh breeze as you sleep, temps will plummet in overnight hours, and you could wake up a chill. And that would be a terrible way to welcome in Fall, and to enjoy your weekend, but to have a cold.
Take care everyone, have a great weekend and if you get the chance, enjoy Summer’s last fleeting moments.
Meteorologist Addison Green