South Florida Weather Continues To Wilt Vermont. High Humidity, Storms Loom

The high humidity left the evening sky over St. 
Albans, Vermont look more like southern Florida

 We're stuck in South Florida weather. It feels like South Florida. The humidity, the scattered storms and the sky is what you'd typically see down there this time of year. Even the local weather patterns in Vermont are mimicking South Florida for now.  

This will end, but it will be a slow process and one that still has the potential to bring some high water to some areas. 

Humidity levels were about as high as they possibly can get in Vermont, especially Saturday evening. There's no good way to know for sure, but dew points, a measure of how humid it is, had to be near record high levels. 

First, though, as a weather geek, I was impressed with Saturday and the Florida weather patterns. The air of course was humid, but there were no nearby weather systems to trigger any organized storms or major shifts in conditions. 

One interesting little storm formed in and around Burlington Saturday afternoon.  It appears a breeze off the lake collided with much hotter air just inland to create an updraft. That created a downpour that hit mostly right along the lake shore, but extended inland at least to the airport in South Burlington.

This was almost exactly like what often happens in a Florida summer.  

The rainfall dropped the temperature in Burlington from 93 degrees to 80 degrees, though it later bounced back up to 85 degrees. So cooler, yay?

No. The shower took humid air and made it ridiculous. The dew point is the measure of how humid air is. It's the temperature you'd have to reach to completely saturate the air, producing fog, rain etc. 

If the dew point is over 70 degrees, it's oppressively hot. We in Vermont usually get dew points in the low 70s a couple or handful of times per summer. Usually such oppressive humidity only lasts a day or two.

The dew point in Burlington last evening peaked at 78 degrees. It's the highest I can remember, but I don't know if it's a record high. Like I said, it had to be close. 

I reached out to the National Weather Service in South Burlington and they said they don't keep track of record high and low dew points. 

However, meteorologist John Hickey did manage to find four hours on September 5, 1973 in which the dew point was at 79 degrees, and one hour at a 79 dew point on July 2, 2002. So my guess is that is the record high. 

Also, according to a chart provided by climate scientist Craig Ramseyer, before yesterday, since at least 1960, the dew point in all Augusts in Burlington was at or above 76 degrees for a grand total of just ten hours. Not even half a day. The dew point last evening was at or above 76 for four hours. 

The dew point since last evening has retreated to the merely miserable low 70s. Still, the overnight low (actual temperature) in Burlington was 78 degrees. If that holds through midnight tonight, it will shatter  the current record high minimum temperature for the date of 71 degrees.

If it gets up to 90 degrees in Burlington today, which is quiet likely, it will be the eleventh day this year to make it to the "magical" 90 degree level.

WHAT'S NEXT 

We're rinse and repeat today as the rest of the day will be a lot like Saturday. Skies will be partly cloudy, and some of those clouds will billow up into hit and miss showers and thunderstorms. It'll be about as hot as yesterday, with heat indexes also about the same.

And, if you do get hit by a shower, it'll cool the air, but the dew point will get ridiculous like it did last evening in Burlington. 

Just like yesterday, the storms will form near updrafts in the mountains, or where breezes off Lake Champlain collide with areas of hotter air inland. 

The one difference from yesterday could be up by the Canadian border. A cold front that will harass us for a few days might do an opening salvo. The front is way, way to the north, but will probably generate some thunderstorms north of Ottawa and Montreal and Quebec City.  

This could send a gust front toward the border with Vermont.  In turn, this gust front could produce some evening thunderstorms north of Route of 15.  Some of those storms could easily produce gusty winds and especially locally heavy rain. 

By the way, southern Quebec is under heat, severe thunderstorm and heavy rainfall alerts. 

The front that's way north will struggle southward through Vermont Monday, Tuesday and possibly even into Wednesday.  Since it will move so slowly and bump up against such wet air, we're still seeing a flash flood threat Monday into Tuesday.

The biggest threat overall is in southern Quebec and western Maine. For Vermont, the biggest flood threat is north of Route 2. Local downpours could be enough to send too much water down the slopes of the northern Green Mountains and the hilly terrain of the Northeast Kingdom. NOAA's Weather Prediction Center has these areas under a slight risk for flash floods tomorrow. 

However, if these floods develop, current forecast don't have them turning into the epic kind of flash floods we've seen in Kentucky, Illinois, Arizona and, most recently early this morning in South Dakota. 

Temperature forecasts during this transition will be tricky, and depend where the front is set up. Tomorrow, we might have a big range from humid low 70s up north to 90 down by Bennington and Brattleboro.