Summer 2011 Winding Down

[CanisLupusArctos]

Many signs now exist that show summer 2011 has begun the cooldown process. Fall is in the very beginning stages of setting up shop.

Last night in Alaska brought a frost advisory for "the first frost of the season" with anticipated temps down to 30 F. The cold air is getting ready to come back.

One big sign of this (in the lower 48) is the severe weather season is starting to work its way south again. Severe thunderstorms and tornadoes most often occur along cold fronts. In springtime, the cold fronts are still sweeping down from Canada (a la winter) and the spring season starts getting in the way. The season ends when the cold fronts stop coming for the summer. It stabilizes as summer.

The reverse happens when the cold fronts start coming again. Over the rest of this month you will see severe weather threats increasingly further south in the continental U.S. as the cold air starts to force summer's heat to be spent.

This comes as bittersweet relief to anyone who's been in the major heat wave in the middle part of the country. The heat area is already showing signs of shrinking. But the cooldown process is likely going to involve thunderstorms and tornadoes. For the ocean, the cooldown process leads to hurricanes, as the progression of autumn forces a certain amount of heat to be released from the waters. It releases as storm energy.

For right here at the lake, we're transitioning away from what has been a very dry past few weeks. It's been a very low-humidity summer this year. That has affected the water temperature, which hit a max of 76 F at Black Cat Island this summer. It hit 87 F last summer, amid constant humidity, even when the air wasn't hot.

This summer many of our most humid days were not that hot. We had one heat wave, and it was barely a heat wave (only 3 days.) Not every day of that heat wave was humid. Most of the time we were getting air flow from off the continent -- from the west or from out of Canada. That's very dry air. It made for some incredibly beautiful summer days.

The Canadian air masses remained not far to our north all summer, and now they are starting to nudge their way south again. It's leading us into a showery next few days, and the rain has just begun here tonight.