A Noticeable Step Down Into A Vermont Autumn In The Coming Week

Like most of the landscape in Vermont's Champlain Valley
the big maple and other trees around my St. Albans house
are still green. That might start to change as noticeably
cooler weather settles in tomorrow and 
probably lasts through next week

 Very often, when seasons change, there are steps up or down. Sometimes in the fall, you get a stretch of weather that's relatively stable for a week.  

Then suddenly, it's a few degrees cooler, and that chillier regime holds for a week or so. Then it gets cooler yet. 

It's not an even process. As we know we get some lingering warm spells thrown in. Indian Summer, or just a stretch of warm days with balmy southwest breezes.

I bring this up because we're about to take a step down, further into autumn. 

This deeper dive into autumn won't start until tomorrow. Let's get into the details

TODAY

Still warm, and, truth be told, vaguely humid. Certainly not the humidity we deal with in the summer. Just a hint of moisture in the air that will make you sweaty if you really exert yourself. 

Highs should get into the 70s, but this won't be a late breaking brilliant summer day. Clouds should dominate, though there might be a break or two of sun, especially north. Don't count on it, though. 

 A weak disturbance should set off some rain and showers today, mostly in the southern half of Vermont. There might even be some brief downpours. We were already seeing a few very light showers in central Vermont as of 8 a.m., but the bulk of the rain will hit this afternoon

Rainfall in southern Vermont should come out near a quarter inch, maybe a little more in a few spots. 

The north, especially far northwest should be mostly dry, with rainfall amounts today ranging from nothing to maybe a tenth of an inch. 

FRIDAY

The step down to cooler weather should definitely be noticeable tomorrow. A cold front tonight will sweep in much drier air, leading to a sunny, delightful, slightly cool September day. Highs should reach the 60s for most of us. Maybe some upper 50s in the Northeast Kingdom and near 70 in the warmest banana belt valley towns. 

This will all happen with pleasant northwest breezes and under blue skies, flecked with a few clouds. 

That'll set us up for a cold night. I think the National Weather Service might issue frost advisories again for the Northeast Kingdom and the Adirondacks across the pond in New York. Lows in the cold hollows could easily touch freezing. 

For the rest of us, lows will probably be in 36 to 46 degree range by dawn Saturday, with the warmest readings near Lake Champlain. 

SATURDAY

Even cooler as autumn continues to establish itself. After the chilly morning, highs should only get into the 60s under generally sunny skies. Some clouds might increase later in the day. But all in all, a nice day. 

SUNDAY

This looks like the first cold, raw, damp day of the autumn. That first gloomy, chilly day usually comes about now, so it's right on schedule. A storm sliding by the south will provide more rain to the bottom half of Vermont, not so much to the north. 

Early guess are maybe a tenth of an inch of new rain up by the Canadian order to as much as three quarters to an inch of rain far south. 

Highs should only be near 60. Especially in rainier southern Vermont highs could hold only in the 50s. 

NEXT WEEK

At this point, it looks like another big, fat high pressure system will come down from central Canada and then stall nearby. Early in the week, probably Monday and/or Tuesday morning, we'll need to look at the risk of frost again. Monday will probably be the coolest  day, but it will slowly warm up after that. 

But not much. The step down to autumn weather is complete. Daily highs should be in the 60s Monday through Thursday. In the Northeast Kingdom, there will probably be at least give consecutive mornings, starting Saturday, with lows in the 30s. 

Forecasters are unsure whether the stalled high will keep skies sunny all week, or whether some moisture could work on in from the south with clouds and a risk of light rain. 

KEY MESSAGE 3: Our region should be under the influence of a
seasonably cool high pressure area gradually moving eastward to
start the work week. Temperatures should be about 10 degrees
below normal Monday trending to around normal on Wednesday. With
this pattern and 925 millibar temperatures falling to near the
10th percentile, Tuesday morning should be another frosty one 

for sheltered areas that already saw frost Saturday morning.s