The First Windy, Rainy Autumn Storm About To Hit Vermont, Though Rainfall Might Not Be As Impressive As First Thought

Henry the Weather Dog enjoyed an unexpectedly 
sunny day yesterday in St. Albans, Vermont. A
sort of summer/autumn hybrid storm is expected
tonight, with some decent amounts of rain.

Once we get to September, the nature of storms starts to change. In the summer, it's mostly all scattered showers and thunderstorms. 

Sometimes the thunderstorms get a little too rambunctious with high winds and hail, but most of the time it's OK.  

September comes, and the nature of the storms start to change. They become more of a steady rain. Southern Vermont got a taste of that yesterday morning, as a disturbance zipped through with periods of rain. 

Many places south of Route 4 had between a quarter and a half inch of  rain. Under the cloud cover, temperatures stayed in the autumnal 60s in some parts of the south. 

Up north of Route 2, the sun made an unexpectedly strong showing, boosting temperatures into the upper 70s to score us up there a nice late summer day.

Let's get into what happens next:

TODAY

We'll get through the day mostly or completely dry, but it probably won't be all that bright and sunny. Oh,, sure we'll have a few breaks, especially this morning,   A few light reengage showers could arrive this afternoon, but don't count on any rain during the day. 

The upcoming storm isn't fully an autumn type system. It's sort of not quite summer, not quite autumn thing, so there's elements of both seasons in it.  You'll feel the humidity increase somewhat during the day today, a little like you'd expect ahead of an approaching summer cold front.

Winds will pick up today, too, the way they do ahead of an autumn storm. The winds won't be horrific by any stretch of the imagination, But south winds could gust to 30 mph in the northern Champlain Valley and higher elevations this afternoon and evening before the rain gets here. 

Today is not the day to take your boat or kayak out onto Lake Champlain.

The hybrid nature of the storm meaning areas to the south - not affecting us here in Vermont - will be rather hot and humid. With a risk of severe thunderstorms along a broad band from the southeastern Great Lakes down through the Mid-Atlantic states.

Already, early this morning, there were already severe thunderstorms moving southeastward off of Lake Erie and western Lake Ontario. As of shortly before 8 a.m. there was already a tornado warning in northwestern Pennsylvania. 

Which leads us into tonight:

TONIGHT IN VERMONT

The rain and thunderstorms will move toward Vermont this evening. The thunderstorms will become elevated, meaning a layer of stable air will hold near the ground. That will prevent severe thunderstorms here, but still allow for chances of lighting, thunder and bursts of heavier rain overnight. 

The downpours will be interspersed with a steadier light rain, again like you'd see in the autumn. 

Unfortunately, forecasts for rainfall amounts have been trending downward. We need the soaker, and this won't be as great a soaking as we'd hoped. But, anything is better than nothing. 

For now, we're expecting a half inch to an inch of rain across Vermont.  However, there's still a chance we'll get a little less than that, given the trends I've seen in the forecast. 

THURSDAY

Showers should continue into Thursday morning and maybe into the early afternoon. Thursday should also bring a brief interlude of humid weather.  Showers should end later in the day and with any luck we'll have some sun later in the day. 

FRIDAY/WEEKEND

A bit fall-like again. Our storm will slow down and spin around the Canadian Maritimes, as autumn storms often do. That means at least partly cloudy or mostly cloudy skies, with light showers, mostly over the mountains and Northeast Kingdom. 

It won't be all that chilly, with highs within a few degrees either side of 70 and lows in the 50s. The brief humidity from Thursday will have been solidly flushed out of here.

At this point, Sunday looks sunnier with continued seasonable high temperatures near or a little above 70.

Vermont August Mostly Warm, Dry, Main Measuring Station Burlington Decided To Be An Exception.

A severe, rotating storm over St. Albans, Vermont on
August 10. Despite  frequent, sometimes severe
thunderstorms, August rainfall in 
Vermont was mostly below average. 

Vermont overall had a pleasantly warm, dry August, though that was interrupted by several bouts of severe weather.

Burlington, which is arguably the main weather reporting station for Vermont decided to buck the statewide trend a little. 

In Burlington, the average temperature for August was 70.4 degrees, or just 0.3 degrees below the modern average. 

Remember, the current normal August temperature is the average from the years 1990 to 2020, when climate change had already begun to change our world. 

By 20th century standards, Burlington's average temperature was on the warm side. It was the 29th warmest out of the past 136 years.  The average high and low temperature for the month were both   within a few tenths of a degree of the "new" normal, 

Elsewhere in Vermont, August turned out to be on the warm side, but not extremely so. Montpelier, St. Johnsbury and Woodstock were between 1.4 and 1.8 degrees on the warm side. Rutland was 0.6 degrees on the warm side. Like Burlington, Bennington was just a tiny bit on the cool side, averaging just 0.2 degrees on the cool side. 

Burlington was also the exception to a generally dry Vermont August. Burlington had 3.99 inches of rain during the month, which was just under a half inch above normal. It was near the middle of the pack as it was the 51st wettest month out of the past 144 years in Burlington. 

Much of Burlington's rain came in a little over an hour on August 8 when a strong thunderstorm dumped 1.2 inches of rain. Much of Vermont had little or no rain that day. A few other areas had light to moderate amounts, except for a narrow section of the Champlain that got nailed. 

That storm was on of several in Vermont that caused some damage. The August 8 storm caused damaging wind and hail in a small area around South Hero, Milton and Colchester.  

Another storm on August 10 mainly affected Franklin County. Rotation in the storm prompted a tornado warning, but no twisters are known to have touched down. However, strong straight line winds caused extensive damage, especially on Maquam Shore in Swanton and in St. Albans. 

On August 12, a severe storm hit southern Chittenden County, knocking down four large trees in St. George. Another large tree fell and blocked Route 116 near the South Burlington/St. George line. 

The next day, a severe storm dumped ping-pong sized hailstones in Fair Haven, and knocked down several trees along Route 30 in Castleton.  Another storm in North Troy, in northeastern Vermont.  

METEOROLOGICAL SUMMER

Meteorological summer runs from June 1 through August 31. That time period is what climatologists consider as summer. It makes the bookkeeping easy. 

As measured in Burlington, meteorological summer was the 11th hottest summer out of the past 128 years. 

All but three of Burlington's hottest summers have happened since 2005. (The other three were in 1901, 1949 and 1995).

Burlington had the 12.73 inches of rain during meteorological summer. That's a little less than an inch above normal. 

Since summers have in generally been getting warmer amid climate change, this turned out to be the 30th wettest summer out of the past 128 years. 

LOOKING AHEAD

No matter what happens, you'll know very soon that summer is over. The average temperature falls rapidly in September. In Burlington, we normally have a high of 78 degrees and a low of 58 degrees. By September 30, the normal high and low is 66/47.

I guarantee somewhere in Vermont during September, there will be frost. It's even possible in the banana belt Champlain Valley. September freezes were once fairly common in Burlington. But, it hasn't been 32 degrees there in September since 2014.

For what it's worth, NOAA says it's a tossup as to whether we'll see a warm or cool September. NOAA is leaning toward a wet September in Vermont. We shall see!

 

Vermont Has One Shot At Drenching Rain Before A Likely Long Dry Spell

Hand it to the National Weather Service, whether radar this morning is exactly what was forecast. 

Weather radar this morning showed areas of rain moving
northwest to southeast across central and southern Vermont
The light blue shading on the northern edge is just 
clouds and very light rain evaporating before it hits the
ground.. Heavier, more drenching rain is forecast
to arrive Wednesday night. 

Areas of rain, most of it light but some of it moderate, to almost heavy, were racing northwest to southeast across southern and central Vermont this morning. 

Northern Vermont was missing out. Clouds were thick and threatening in northwest Vermont, close to the rain band, but thinner up in the Northeast Kingdom.. 

That state of affairs will continue to day, though the rain in southern Vermont will tend to taper off as the afternoon goes on

North of Route 2, I wouldn't be at all surprised if some sunshine breaks out this afternoon.

A stalled weather front to our south and west is responsible for today's rainy weather. 

Total rainfall through tonight looks like they'll amount to a quarter to a half inch in the southern half of Vermont with very little north. 

Scattered showers overnight tonight might deposit a paltry few hundredths of an inch of rain north of Route 2. Too bad, as the Northeast Kingdom needs the rain more than other parts of the state. 

Under the rain and clouds, highs in southern and central Vermont will only get into autumnal  highs in the 60s. Northern Vermont, outside the rain, could make it into the 70s. 

Our sole chance of soaking rains will come later Wednesday through the pre-dawn Thursday. 

WEDNESDAY

We need the rain, and it's still looking like we'll get a decent dose of rain Wednesday night. 

We'll likely get through the day Wednesday without much of rain. It'll be cloudy and vaguely humid, but any showers should be light and few and far between. Highs should get into the 70s, with some mid and upper 60s under areas with thicker clouds, especially east of the Green Mountains. 

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A stronger area of low pressure will push that stalled front toward us. The system will fire up severe thunderstorms from western New York southeastward to New Jersey, Maryland and Delaware. 

Up here in Vermont, thunderstorms should weaken and fade away before reaching us, but we do have a shot at some fairly heavy downpours. The rain will reach us in the evening and continue overnight. 

Over all, the National Weather Service expects a nice three quarters to an inch of rain for most spots, with over an inch in some areas of the Green Mountains. Unfortunately the far corners of the Northeast Kingdom might receive as little as a half inch of rain.

The rain will be steady enough, without too many short, sharp bursts of torrential downpours, that flooding looks pretty unlikely 

THURSDAY-SATURDAY

The storm system will amble on to the east, but not in any kind of hurry. This will keep cool-ish, sort of moist north winds blowing. That could set off some scattered showers, especially Thursday as a secondary weak cold front drifts through Vermont. 

This rain will not be heavy, and it will be scattered. Northern mountains have the best shot at seeing the showers.

Day by day, the showers will become lighter and more scattered so that by Sunday, there shield be few if any sprinkles left over. 

Daytime temperature should be pretty comfortable through the period as highs should reach the 70s, with some upper 60s on cooler, northern areas, especially the Northeast Kingdom. 

SUNDAY AND BEYOND

We'd better hope the above forecast for a soaking rain comes true, as we look to be in for a fairly long period of dry to mostly dry weather. 

Once we get into September, we often see big, dry high pressure systems hang out nearby.  The next chance of rain looks like it will be just scattered showers ahead of a cold front early Tuesday. 

A storm system riding along that front could bring heavier rain to the south. This is a long way off, so there's always a chance that storm could come closer to us than forecast, and give us some rain.  But we'll wait to worry about that in a few days.