Friday's Long Range Thoughts - 9/14

For some reason, when the nights get longer, so do my peeks into the future. Between the excitement of looking into a change of seasons and preparation for my Wintercast in November, I start to delve more into the longer range forecasts. So here are my thoughts for now:

The stage is being set for a couple of early shots of chilly air from the middle into the ladder part of September. As seen below, the NAO (North Atlantic Oscillation) is getting ready to tank. What does this actually mean? Well when the NAO is negative, there is a lot of blocking over Greenland and helps to suppress the jet stream over the eastern United States which can give us periods of cool and more unsettled weather with a slow progression of systems to the coastline.



On top of that, the AO (Arctic Oscillation) is also poised to turn negative.



When the AO is positive, the jet stream tends to be stronger and more west to east keeping arctic air bottled to our north. When it turns negative it allow for arctic air to spill southward into the mid-latitudes. It's not always a guarantee that we get the flow into the US, but combined the negative NAO, it seems like two shots of cool air will be coming our way. One mid-week next week and another for the following weekend into early the next week.

Next week's highlights

- First frost of the season Monday night or Tuesday night for the Upper Midwest states (specifically parts of Minnesota and Upper Peninsula of Michigan and perhaps as south as Wisconsin).

- Perhaps first flakes of the season in the Upper Peninsula of Michigan in the next 4 to 10 days.

- Closer to home, the higher elevations of PA may have a tough time getting out of the 50s Wednesday of next week.