Burlington Vts temperature record because PF asked

[powderfreak]

Development a mile away from the airport can have an affect when we are talking about microclimate...which is of course important for radiational cooling.

 

Increased development a mile away will cause differential heating...which will make it harder to calm the winds at night. Someone would probably have to do a true scientific study to accurately measure the magnitude of these effects, but they do exist. I know there was a study done semi-recently for Dulles Airport west of DC...and the winds there now at night are not as calm as 30 years ago due to development around the airport.

 

That may have something to do with it...but the wind issue really just seems like BTV sees an awful lot of nights with southerly flow.  That's when it takes a mild period and makes it a torch relative to departures.

 

Like last night the low was 70F, while MVL was 59F and MPV was 58F.  So the same airmass produced departures of like +7 or +8 at the mountain valley sites, but a +15 at BTV for the overnight lows.  That's why BTV always seems to be higher than everyone else...in "warmer than normal" patterns, BTV seems to see that effect drastically enhanced over everyone else. 

 

I really think the topography is such that an increase in "warmer than normal" patterns in the last 10 years are what is really driving the departures there.  Like Nittany said, it is very representative of the Champlain Valley as a whole.  Like last night there were numerous spots from the southern end of the valley (Addison County to Rutland County) that didn't get below 70-72F, and same up in the northern end of the lake.  Maybe those spots aren't seeing an increase and have always been that warm, but I can't imagine development around BTV is really driving this when a lot of other CPV sites mimic their temperatures.

 

Maybe its just an increase in the number of days we see that nocturnal low level jet form at 950-925mb level in that very localized stripe of the valley...sort of like if we have a below normal pattern, BTV can hold its own, but if we have an above normal pattern they get absolutely torched.  Like this background global warming thing where since 2000 most sites are +1 to +1.5 in the means, but since BTV's geography is such, that gets enhanced to +2 or +3.

[ORH_wxman]

That may have something to do with it...but the wind issue really just seems like BTV sees an awful lot of nights with southerly flow.  That's when it takes a mild period and makes it a torch relative to departures.

 

Like last night the low was 70F, while MVL was 59F and MPV was 58F.  So the same airmass produced departures of like +7 or +8 at the mountain valley sites, but a +15 at BTV for the overnight lows.  That's why BTV always seems to be higher than everyone else...in "warmer than normal" patterns, BTV seems to see that effect drastically enhanced over everyone else. 

 

I really think the topography is such that an increase in "warmer than normal" patterns in the last 10 years are what is really driving the departures there.  Like Nittany said, it is very representative of the Champlain Valley as a whole.  Like last night there were numerous spots from the southern end of the valley (Addison County to Rutland County) that didn't get below 70-72F, and same up in the northern end of the lake.  Maybe those spots aren't seeing an increase and have always been that warm, but I can't imagine development around BTV is really driving this when a lot of other CPV sites mimic their temperatures.

 

Maybe its just an increase in the number of days we see that nocturnal low level jet form at 950-925mb level in that very localized stripe of the valley...sort of like if we have a below normal pattern, BTV can hold its own, but if we have an above normal pattern they get absolutely torched.

 

It is possible that some micro-climate effects of development have enhanced the southerly flow...I'm not saying that is the main cause, but it certainly could play a role.

 

I'll have to find the Dulles study, but I believe their flow became more westerly consistently at night versus 30 years ago when it was more rural.

 

The plains actually have a larger scale enhanced effect of their southerly nocturnal LLJ due to the cornfields increasing the humidity and thus causing less radiational cooling at night...this leads to more temperature differntial from east to west at nighttime...west being colder with drier air. There would be one anyway due to the difference in climate from east to west (and more importantly, the elevation change), but the increased humidity in the east enhances it. This might be an extreme example, but something on a smaller scale could have occurred near BTV.

 

Again, i don't think we could answer this without a pretty comprehensive study. We'd have to compare other stations in the Champlain Valley with BTV.

[powderfreak]

Again, i don't think we could answer this without a pretty comprehensive study. We'd have to compare other stations in the Champlain Valley with BTV.

 

I was actually just thinking of trying to add some of the longer-term co-ops in the valley to this thread.  If I get time later tonight I'll do some digging. 

 

South of BTV is almost all corn fields, lol (like all of western Addison County south of the Burlington area) is all fields...wonder if that and the lake have anything to do with it.  Middlebury College station is similar to BTV and only dropped to 70F last night as they are in Addison County and in that low level jet belt.  Would be cool to do a study.  The warmth seems to be on the VT side of the lake though, while even Plattsburgh (KPBG) does not have this issue.  PBG on the western side of the lake dropped to 61F last night while BTV and most of the VT side was in the low 70s.  That's a huge difference for the same elevation and in the same valley.  And PBG is also developed with malls, universities, etc. 

[nzucker]

I was actually just thinking of trying to add some of the longer-term co-ops in the valley to this thread.  If I get time later tonight I'll do some digging. 

 

South of BTV is almost all corn fields, lol (like all of western Addison County south of the Burlington area) is all fields...wonder if that and the lake have anything to do with it.  Middlebury College station is similar to BTV and only dropped to 70F last night as they are in Addison County and in that low level jet belt.  Would be cool to do a study.  The warmth seems to be on the VT side of the lake though, while even Plattsburgh (KPBG) does not have this issue.  PBG on the western side of the lake dropped to 61F last night while BTV and most of the VT side was in the low 70s.  That's a huge difference for the same elevation and in the same valley.  And PBG is also developed with malls, universities, etc. 

Middlebury would always be brutally warm at night when we returned to campus from summer break...I remember quite a few nights hanging around 70F, with no A/C in the dorms, which surprised me given it's so far north. Of course it didn't last long into September as we'd usually get a mild frost by the end of the month, but it started out uncomfortably hot.

[powderfreak]

Middlebury would always be brutally warm at night when we returned to campus from summer break...I remember quite a few nights hanging around 70F, with no A/C in the dorms, which surprised me given it's so far north. Of course it didn't last long into September as we'd usually get a mild frost by the end of the month, but it started out uncomfortably hot.

 

Middlebury is in that belt of southerly flow at night during warm periods... I've heard BTV reference the nocturnal low level jet at 950mb-925mb that develops at night out of the south a lot recently in AFD's.  Any sort of south flow just gets enhanced at night through that whole VT side of the Lake.

[nzucker]

Middlebury is in that belt of southerly flow at night during warm periods... I've heard BTV reference the nocturnal low level jet at 950mb-925mb that develops at night out of the south a lot recently in AFD's.  Any sort of south flow just gets enhanced at night through that whole VT side of the Lake.

I wonder if the effect is as pronounced on the New York side of Lake Champlain. I'd tend to think that area of the Champlain Valley (CPV) runs a little colder than its Vermont counterpart. I believe average elevations are higher, as the terrain is rugged along and north of Route 4 from Whitehall up to Ticonderoga/Crown Point. However, the geography is similar to Vermont (Vermont's CPV is against the Green Mountains, whereas New York's CPV backs onto the Adirondacks)and it has even more southerly exposure to the Hudson Valley. I wonder if warm air running up the Hudson Valley on southerly winds could actually reach the New York side more easily than the Vermont part of the CPV.

 

Any ideas?

[powderfreak]

I wonder if the effect is as pronounced on the New York side of Lake Champlain. I'd tend to think that area of the Champlain Valley (CPV) runs a little colder than its Vermont counterpart. I believe average elevations are higher, as the terrain is rugged along and north of Route 4 from Whitehall up to Ticonderoga/Crown Point. However, the geography is similar to Vermont (Vermont's CPV is against the Green Mountains, whereas New York's CPV backs onto the Adirondacks)and it has even more southerly exposure to the Hudson Valley. I wonder if warm air running up the Hudson Valley on southerly winds could actually reach the New York side more easily than the Vermont part of the CPV.

 

Any ideas?

 

I think without a doubt the VT side of the lake is warmer... looking at a topo-map you can see how if you had a warm southerly flow, it would come out of NY state and get deflected into the VT side of Lake Champlain by the terrain in the southeast Adirondacks.  The terrain is much higher closer to the lake on the NY side, especially the southern Champlain Valley.

 

That warm air coming out of NY state would head towards the Middlebury/Addison County area, get deflected again by the Breadloaf Wilderness and Sugarbush ridgelines and head due north from there.  The Spine in that area acts as a great blocker as its oriented almost due north-south.  The far northern NY side of the Champlain Valley can get quite warm though as you have downsloping on a S/SW flow off the Adirondacks, plus warmth moving up the valley on the VT side.  Plattsburgh is sort of tucked in there though and sheltered by higher terrain to the south at night, so it can go calm and stay out of that nocturnal low level jet. 

 

Unrelated, but can also see on this map how the Northern Greens have that subtle SW-NE orientation that really helps with the NW flow upslope...and how flat it is upstream of the northern Greens on a NW flow.

 

[klw]

One thing to remember is the area near the airport has probably seen the most development in the entire State since the mid-sixties.  I think it was the late sixties when IBM began building its massive Essex Jct complex.  The entire Williston/Taft Corners development has been since the late 1980 and includes one of the top grossing Walmarts in the country.

A bit of the Taft Corners history can be read here:

http://libraries.vermont.gov/sites/libraries/files/supct/171/99-431op.txt

The massive development that started in the late 60's with the the completion of I89 helped drive the Act 250.  If you look at Chittenden County as a whole, the population has more than double since 1960 (74,425 to 156, 500 in 2010).  Williston has gone from less than 1500 to almost 9000.  Essex 7k to 19.5k, S. Burlington 6.9 k to 17.9 k.  Plus all the businesses, additional roads, etc.

http://en.wikipedia.org/wiki/Historical_U.S._Census_totals_for_Chittenden_County,_Vermont

 

It is less than 2 miles from the airport runway to the intersection at the heart of Taft Corners.  UVM is in the other direction has tripled its enrollment since the 1960's and Fletcher Allen Hospital has had a huge growth in size too.

https://www.uvm.edu/~isis/sbinfo/ughis.pdf.  The University Mall and the Dorset St development has all happened during this time period as well.  

 

These are the areas closest to the airport and has transformed that area since the sixties and may have lead to an increased heat island effect.

[ORH_wxman]

One thing to remember is the area near the airport has probably seen the most development in the entire State since the mid-sixties.  I think it was the late sixties when IBM began building its massive Essex Jct complex.  The entire Williston/Taft Corners development has been since the late 1980 and includes one of the top grossing Walmarts in the country.

A bit of the Taft Corners history can be read here:

http://libraries.vermont.gov/sites/libraries/files/supct/171/99-431op.txt

The massive development that started in the late 60's with the the completion of I89 helped drive the Act 250.  If you look at Chittenden County as a whole, the population has more than double since 1960 (74,425 to 156, 500 in 2010).  Williston has gone from less than 1500 to almost 9000.  Essex 7k to 19.5k, S. Burlington 6.9 k to 17.9 k.  Plus all the businesses, additional roads, etc.

http://en.wikipedia.org/wiki/Historical_U.S._Census_totals_for_Chittenden_County,_Vermont

 

These are the areas closest to the airport and may have lead to an increased heat island effect.

 

 

 

Were there a lot of open farms in Chittenden county before the development started picking up?

 

The talk of the low level jet in powderfreak's post above just reminded me of what I said about the plains further back in the thread. If a lot of forest has grown in where farms used to be, then that would enhance the nocturnal low level jet out of the south. This would not even be directly because of UHI...simply replacing a more efficient radiating landmass with a less efficient one with more tree/plant growth would do the trick.

[klw]

Were there a lot of open farms in Chittenden county before the development started picking up?

 

 

I believe so but I did not move to VT and start going to Burlington regularly until 92.  There are still farms and throughout Chittenden County. It is an odd blend in spots where in one field they grow corn, the next is for cows, the next is for Colonials and the last is solar panels.

 

Oh this is on the VT Division of Forestry web page:

http://www.vtfpr.org/htm/for_climatechange.cfm

Here in Vermont, we have observed some changes linked to climate change. The timing of spring is generally earlier, resulting in changes to associated ecosystem activities, as well as activities such as the timing of maple syrup production. Likewise, there is evidence that tree species elevation limits may be changing. A recent study on Camel’s Hump showed that as temperatures over the 40-year period (1964-2004) increased on the mountain (1.1 C), deciduous trees from the low elevations were able to grow at higher elevations. Other species changes, including a reduction in balsam fir and sugar maple trees, are predicted in this century. Our current climate, supporting a sugar maple-beech-birch forest, will transition to favor more of an oak-hickory or oak-pine forest. Maintaining the health of trees can help slow species changes. See below for a list of links on Vermont climate change impacts.