Private Beach on the Bay Live Cam

• Osprey Private Beach on the Bay Tide Entrance Channel Fuel Dock Marina

Advertisement

Transition To Autumn

The month of September is a transition month, a bridge from summer to fall. 90 degree heat is still possible early even in the northern areas, but by the end of the month frosts and freezes are common in the north and pleasantly mild nights are being enjoyed even in the south.

It is also the peak of the hurricane season with historically, on average, nearly a third of the annual total of tropical storms and hurricanes. The tropical disturbances that form over western Africa are at their peak frequency in September. Some of the storms that develop to tropical storms or hurricanes recurve north over the Atlantic and die over the cool waters of the North Atlantic, or become absorbed in extratropical storm systems.

Others manage to make their way westward to the West Indies and eventually the mainland. As we observed early in the season, the western Caribbean and southern Gulf of Mexico again becomes a potential breeding ground in September. These storms threaten the U.S. Gulf Coast or Mexico.

The most prevalent weather features are the sub-tropical high pressure systems off both the east and west coasts. The Pacific high is at its most northernmost position, approximately 39 degrees N, in September, but begins to weaken especially at the northern end near the Pacific Northwest coast where their dry season is coming to an end. The Bermuda high in the Atlantic begins to shift south and weaken too, although it can still build west and deliver hazy, hot and humid weather to the coast especially early in the month.

The Aleutian low reappears, fed by Pacific storms and dying typhoons. This feature will become a dominant feature for the next 8 months. The exact position and orientation of the low will have a profound effect on the weather across North America.

The jet stream on average enters the West Coast near the Canadian border and lies near the U.S. Canada border across Lake Superior to the Canadian Maritimes. The primary storm track is still in Canada (near 60 degrees N) although the cold fronts it drags behind begin to push further and further south.

The polar highs are beginning to grow in size and become increasingly cold as sunshine in the northern latitudes source regions rapidly dwindles. It is these high pressure systems that drop south and expand to bring for some areas the first relief from the heat and humidity of summer since May or June.

As the air cools, it stabilizes which causes the frequency and intensity of convection to diminish. Soon most of the precipitation will be stratiform caused by widespread lifting by fronts and convergence into low pressure. Until these features become more significant later in the fall, the precipitation across a large part of the nation diminishes.

There are a few exceptions to this drying trend. In the far northwest, the weakening of the Pacific High and the return of the polar front bring increased rainfall. This is true most years also in southernmost Florida and across the Gulf and southern Plains states, where the effects of tropical waves and storms are at peak frequency.

Temperature extremes for September range from 126 at Mecca, CA on September 2, 1950 to -9 degrees in West Yellowstone, MT on September 25, 1926.