I love September. No month can deliver such a large number beautiful, clear days. For the most part spells of heat and humidity are short lived and there’s always several bouts of fall weather that slide in from Canada.
It looks like our first bout with fall weather will come later this week and early this weekend. A big, sprawling, cold high pressure now in the Northwest Territories is diving south behind a rather potent (and autumnal-looking) trough.
By Friday morning most of our computer models have the high over the Great Lakes with an unseasonably cold air mass moving in with it. Here’s a look at the 850mb temperature anomalies off the GFS model. These anomalies give us an indication of just how chilly the air may be compared to what’s normal for mid-September.
-10C or so at 850mb is an impressive anomaly and we will see some impressively cool temperatures for mid-September by Friday and Saturday. The GFS MOS shows high temperatures stuck in the mid 60s in the metro Hartford area with full sun! That means elevated areas in the hills will likely see highs in the 50s.
This type of setup, if it stays as modeled, could lead to some patchy frost in some of the normally colder spots in northeast and northwest Connecticut. For those of you who don’t like the cold it’s all downhill from here.