Burlington Vts temperature record because PF asked

[Ginx snewx]

Powderfreak has noticed that BVT doesn't seem to be as cold as surrounding areas and he wondered why. Below are some charts showing average mean temps for annual and seasonal as well as high temps maxs and low temp mins, it seems apparent that BVT is not radiating as well anymore with mins in summer and winter showing the biggest increases. Multiple reasons can account for this,among those are climate,surrounding neighborhood build up or nearby agriculuture change. I don"t know but just some charts to show. Please do not quote this or EEk will ban you

[CoastalWx]

Interesting. How far is the airport from the lake?

[powderfreak]

Interesting. How far is the airport from the lake?

 

Its around 3 miles from the water.

 

That site has been there for a decent period of time, before that, way back when, I think records were from somewhere near University of VT.  Both the airport and university are in the 300-400ft elevation while lake front is down near 100-150ft.  Burlington (city) is built on a hill ranging up towards UVM and the airport...the terrain then benches out with most of the Champlain Valley sitting in that 300-400ft range before you get to the foothills when it starts to climb quickly.

 

 

[Damage In Tolland]

Could it be all the blow downs we've seen on the ski slopes, eliminating cooling effect of forest

[Ginx snewx]

Interesting. How far is the airport from the lake?

[Ginx snewx]

I'd love to see a Sat pic of that airport in the 70s and see how much suburban incursion has an effect

[powderfreak]

People wonder about urban development, and it is developed but I mean when you are there looking around, I can't see how some Williston neighborhoods or something really affect it.  Its a giant field on a mini-plateau.  I would almost wager if anything, re-forestation may be playing a part somehow...I've seen photos from way back when and the Champlain Valley didn't have a tree in it, lol.  Most of VT was clear-cut for agriculture and its sort of a recent phenomena to get the trees back in a lot of these places.  I would've almost thought the area was more wide open (and prone to winds keeping temps up at night) in the 1882-1940 type years during BTV's first 50 years of records.  

[eekuasepinniW]

I saw ginx started this so I came in looking for photos to brutally criticize.

[dendrite]

Could it be all the blow downs we've seen on the ski slopes, eliminating cooling effect of forest

Less foliage would give you better radiating at night...not worse.

[Ginx snewx]

It is in the middle of two runways, wonder if a runway was added

[Damage In Tolland]

Less foliage would give you better radiating at night...not worse.

but with less foliage you see lower dews like at a Tarmac. we keep coming back to why are Asos located in the middle of tar macs, instead of foliated areas where folks live,, like your BY for example. Your data is far more accurate and verifiable than an airfield surrounded by concrete.I think an overall increase in dews in the northeast over the last 10-20 years is a big contributer

[powderfreak]

I'd love to see a Sat pic of that airport in the 70s and see how much suburban incursion has an effect

 

Its almost like houses AND trees are going up...most of those developments were built in fields that farmers sold to developers when they figured out that was a lot more lucrative than farming.  Trees seem to be coming back in the area.

 

Its also subtle but BTV seems to sit ever so slightly higher than surrounding areas where the Winooski River travels through. 

 

I would wonder if airport development had more of an effect than the suburbs...I'm sure there's a UHI effect more downtown in Burlington, but the airport just doesn't strike me as some place that would really feel much of that for whatever reason.  I'd be curious what Nittany thinks as he works there all the time and probably is more in-tune with that stuff.

 

BTV's location is sort of exposed for the Champlain Valley...that's why at night when MVL and MPV are calm and 50F east of the Spine, BTV is up on its subtle plateau with 20-25mph winds out of the south and temps in the mid-60s. 

 

This was August 26th from BTV's FB page to show the area:

 

[powderfreak]

Less foliage would give you better radiating at night...not worse.

 

That's sort of what I'm wondering...VT used to be clear cut, and so did the Champlain Valley.  Most of VT's forests are really young (thus why there are more moose in NH/ME), and I wonder if increased trees in that area along with housing has capped some of the radiating potential?  But I'm not sure what scale has that affect, if the runways are all open fields, does it matter if a lot of trees have gone up in the past 25-50 years a mile away?

[Ginx snewx]

People wonder about urban development, and it is developed but I mean when you are there looking around, I can't see how some Williston neighborhoods or something really affect it.  Its a giant field on a mini-plateau.  I would almost wager if anything, re-forestation may be playing a part somehow...I've seen photos from way back when and the Champlain Valley didn't have a tree in it, lol.  Most of VT was clear-cut for agriculture and its sort of a recent phenomena to get the trees back in a lot of these places.  I would've almost thought the area was more wide open (and prone to winds keeping temps up at night) in the 1882-1940 type years during BTV's first 50 years of records.  

This is very true and could be a reason you don"t see the max differences that much, anyway thought I'd share with you some stats to ponder as you wish. EEk sucks, don't you have some gardens to rake up dying foliage? ha

[CoastalWx]

One reason might be to look at the prevailing winds. The last several summers have been warm and there seems to be a correlation to srly winds and their anomalous warmth. That and other small scale features could explain some of the issues.

[Nittany88]

If you go back and read some of the posts I've had with Powderfreak about that, it is most certainly in the lows.

 

And BTV may seem like an outlier, but it is VERY represenative of the Champlain Valley.

[powderfreak]

Personally I think a lot of it has to do with the nighttime minimums too...I know Nittany has stated that as well.

 

I think that's a function of wind more than anything.  BTV is a windy place compared with a lot of other New England sites.  The topography of the Champlain Valley and BTV sitting up just slightly above some surrounding areas...it takes a lot for them to go calm all night long.  But I can't imagine that climo has changed at all...its not like the mountains have changed locations.  The wind still funnels through there like it has for thousands of years.

 

I don't know how you could do it, but would be interesting to see a plot of prevailing wind direction and magnitude in recent years compared with past years.

[dendrite]

but with less foliage you see lower dews like at a Tarmac. we keep coming back to why are Asos located in the middle of tar macs, instead of foliated areas where folks live,, like your BY for example. Your data is far more accurate and verifiable than an airfield surrounded by concrete.I think an overall increase in dews in the northeast over the last 10-20 years is a big contributer

well I'm not talking microscale effects. There was major deforestation and poor agricultural practices 100+ years ago across the country.

[Nittany88]

One reason might be to look at the prevailing winds. The last several summers have been warm and there seems to be a correlation to srly winds and their anomalous warmth. That and other small scale features could explain some of the issues.

 

The wind essentially blows two directions here due to the orientation of the valley, south and north. On north winds, we can be colder than the surrounding areas. But south winds? Forget about it. No radiation whatsoever. And on calm nights, its the normal UHI, Lake Champlain, broader valley warmer temperatures you'd expect.

[Damage In Tolland]

well I'm not talking microscale effects. There was major deforestation and poor agricultural practices 100+ years ago across the country.

And very little in the way of concrete jungle infrastructure.

[Ginx snewx]

Orientation to what PF is posting

[Nittany88]

Orientation to what PF is posting

 

Map of the topo:

 

[Ginx snewx]

If you go back and read some of the posts I've had with Powderfreak about that, it is most certainly in the lows.

 

And BTV may seem like an outlier, but it is VERY represenative of the Champlain Valley.

Cool, I was waiting for your educated input, why do you think its happening?

[Damage In Tolland]

well I'm not talking microscale effects. There was major deforestation and poor agricultural practices 100+ years ago across the country.

Lets take a place like BTV for example or even BDL. I'd argue both tar macs are not representative of the surrounding environments . Both areas in all directions are full of rural, tree lined countryside. The idea being an airfield where official obs are taken is in itself an asphalt created microclimate

[Ginx snewx]

Personally I think a lot of it has to do with the nighttime minimums too...I know Nittany has stated that as well.

 

I think that's a function of wind more than anything.  BTV is a windy place compared with a lot of other New England sites.  The topography of the Champlain Valley and BTV sitting up just slightly above some surrounding areas...it takes a lot for them to go calm all night long.  But I can't imagine that climo has changed at all...its not like the mountains have changed locations.  The wind still funnels through there like it has for thousands of years.

 

I don't know how you could do it, but would be interesting to see a plot of prevailing wind direction and magnitude in recent years compared with past years.

Interestingly Blue Hill has published research that shows winds have slowed the last 3 decades

[powderfreak]

One reason might be to look at the prevailing winds. The last several summers have been warm and there seems to be a correlation to srly winds and their anomalous warmth. That and other small scale features could explain some of the issues.

 

Yeah I think that's getting to something...there's most certainly a correlation to southerly flow and BTV absolutely torching.  There are a lot of warm spells where the interior sites like MVL/MPV will be decoupling every night while BTV is sitting there with southerly winds and roasting with 70F+ mins during heatwaves.  If there is any hint of a southerly flow, BTV will be above normal temperatures.  That's pretty much a given.  While the rest of New England is sort of damming in colder air and going calm and radiating.  During summer warm spells, BTV will be the first to rise and stay up if that warmth is coming in from the south.

 

It reminds me of a study by John Goff from BTV touching on wind climo in that area...

 

This is July direction and magnitude and you can see that southerly winds rip more than any other direction...so if we have had some warm summers with prevailing southerly flow, BTV is going to torch at night.

 

 

No amount of low level inversion is going to be able to counter act the southerly flow funneling up the valley...so I agree with Coastalwx, if southerly flow and warmth has been more frequent in recent summers, BTV local climate will cause those positive departures to be enhanced while the rest of VT outside of that hairdryer flow will stay considerably closer to average temperatures.

 

[Nittany88]

Cool, I was waiting for your educated input, why do you think its happening?

 

I could speculate 2 reasons for it. One is a developing UHI that has taken place WITHIN the past 30 years. That is not present at other sites in VT, and has already been present for much longer at other climate sites, so its been reflected in the normals.

 

The second is related to global warming, whether man-made or natural. In theory, and observation, it affects the low temperatures first and foremost, with whatever it is, clouds, can't radiate efficiently, etc... So this would show up more at a place that already had trouble radiating, eg: BTV (marginal radiating nights would not radiate while others still would). Water temperatures have warmed as well, and this has been noted at Lake Champlain, where it takes an act of God to get it to freeze:

 

http://www.weather.gov/btv/lakeclose

 

This was the first time in 7 years, and if you look back, the frequency of closing has definitely gone WAY down. So the warmer lake waters would keep BTV warmer.

 

 

You could add wind to it too, although I don't have any data right now to say the winds have gone up or down. But certainly an uptick in southerly winds would keep us warmer. We roast on south winds with some extreme cases where we don't fall at all or even rise overnight.

[dendrite]

Lets take a place like BTV for example or even BDL. I'd argue both tar macs are not representative of the surrounding environments . Both areas in all directions are full of rural, tree lined countryside. The idea being an airfield where official obs are taken is in itself an asphalt created microclimate

Meh. Large scale concrete infrastructure is one thing...a few paved tarmacs and runways is another. A driveway probably functions closer to a black body than most grassy surfaces anyways. CON radiates like crazy still. I don't come close to their mins on an ideal radiating night.

[powderfreak]

Interestingly Blue Hill has published research that shows winds have slowed the last 3 decades

 

Is that just for Blue Hills or everywhere?

 

I could imagine if the prevailing direction changes slightly, some locals may see decreased winds while others see increased winds? 

 

Cool discussion to start Ginxy on a boring weather day. 

[CoastalWx]

The wind essentially blows two directions here due to the orientation of the valley, south and north. On north winds, we can be colder than the surrounding areas. But south winds? Forget about it. No radiation whatsoever. And on calm nights, its the normal UHI, Lake Champlain, broader valley warmer temperatures you'd expect.

Yeah I'm referring to the mins there and I bet the winds have something to do with it. Plus tack on the other features you mentioned.