Did the old switcharoo in the closet today! I swapped out the summer clothes and put in the big bulky sweatshirts and sweaters. Naturally, I had to take a look at the long range forecast to feel good about this move, so let me share with you!
Long range forecasts show a slightly cooler than average period setting up to finish out this month. the 8-14 day forecast from both the ECMWF and GFS (both longer range, reliable weather models from Europe and America, respectively) show a deep trough developing across the Great Lakes and northeastern US region. A trough allows cooler air to dip down from the poles. (see photo to left- click to enlarge).
I know what you're thinking...long range forecast? psh! The 3 day forecast is hardly ever right! Yeah, yeah... this isn't a daily forecast where I'm forecasting an exact temperature or amount of rain (that is very difficult!). This is more of a generalization of a trend. This type of forecasting is much different. Picking out a longer term trend is sometimes more clear than a single, individual storm system.
With that, I am going to make a forecast for snow! (again, don't rely on this too much...) But I am going to forecast that the mountain areas of our region see the first flakes of snow somewhere from September 26-28th. Looks like there will be some energy to develop some precip, and with that cooler air in place, that's my current thought, snow lovers! Let's see if it verifies!
For more longer range forecasting, check out the Climate Prediction Center. There are some neat visuals here and explainations to global circulations, teleconnections, and trend forecasting. (the CPC, I might add, agrees on a cooler than average period to finish this month for most of the eastern US)