Occasional Thoughts on Climate Change

[forkyfork]

5 minutes ago, ChescoWx said:

In my continuing review of after the fact NCEI temperature adjustments for Chester County PA I have reviewed the detailed monthly NCEI average temperatures for all 1,548 months since January 1895. For the first 1,271 months from January 1895 through November 2000. NCEI applied a post hoc chilling adjustment to the reported average temperatures for every single month for each and every year. So for all of those months the average reported temperatures as reported by the NWS Cooperative stations were chilled to an adjusted lower temperature. Since NCEI stopped these non-stop chilling adjustments starting in December 2000... they have now reversed gears and are now applying warming adjustments in 208 of the last 277 months or 75.1% of all available months between December 2000 and December 2023.

Also of note is that in every single summer month between June and September since way back in June 2006 and continuing through last September 2023....for each of those last 72 consecutive summertime months they have warmed each and every month. Cooling the past and warming the more recent and current years....that will get us to the answer.

you crave the abuse

[Typhoon Tip]

1 hour ago, bluewave said:

The regime shift occurred in 2007 to a much thinner sea ice state and was not forecast ahead of time. The ice free extent forecast by 2013 was an outlier that most agencies like the NSIDC never bought into. Remember there was no alarm in the early 2000s before the major shift in 2007. Complacency turned out to be the greater risk as the thickness and age of the ice has not recovered to pre-2007 levels. 
 

https://www.nature.com/articles/s41586-022-05686-x

Manifestations of climate change are often shown as gradual changes in physical or biogeochemical properties¹. Components of the climate system, however, can show stepwise shifts from one regime to another, as a nonlinear response of the system to a changing forcing². Here we show that the Arctic sea ice regime shifted in 2007 from thicker and deformed to thinner and more uniform ice cover. Continuous sea ice monitoring in the Fram Strait over the last three decades revealed the shift. After the shift, the fraction of thick and deformed ice dropped by half and has not recovered to date. The timing of the shift was preceded by a two-step reduction in residence time of sea ice in the Arctic Basin, initiated first in 2005 and followed by 2007. We demonstrate that a simple model describing the stochastic process of dynamic sea ice thickening explains the observed ice thickness changes as a result of the reduced residence time. Our study highlights the long-lasting impact of climate change on the Arctic sea ice through reduced residence time and its connection to the coupled ocean–sea ice processes in the adjacent marginal seas and shelves of the Arctic Ocean.

Our analysis demonstrates the long-lasting impact of climate change on Arctic sea ice through reduced residence time, suggesting an irreversible response of Arctic sea ice thickness connected to an increase of ocean heat content in areas of ice formation. The large reduction of summer ice extent in the Alaskan and Siberian sectors in 2005 and 2007 triggered intensive ice–albedo feedback^42,45 and initiated the perennial increase of ocean heat content in these areas⁴⁴. This resulted in the stepwise reduction of residence time of sea ice in the Siberian sector of the Arctic, and hence a nonlinear response of the system.

Yeah... "alarmist" seems to be becoming a term by 'people of a certain perspective' that allows them to automatically assess dismissibility.

There are certainly times when 'cry-wolf' tactics are counter to protection and incomparable.  CC as an agent of harm, is not one of those.

If even one failed study out of the ginormous (and growing ) compendium of empirically based, objective science, occurs, the example is cited with jackhammer repetition as  like -

The only thing it does is expose a bias to not agree with the science without any willingness to to be objective about it. 

[ChescoWx]

4 minutes ago, forkyfork said:

you crave the abuse

since facts are over feelings...they don't feel any abuse as the truth sets them free!!!

[TheClimateChanger]

Man, this guy has no shame. Imagine claiming the state record for 95+ days is in a small town nestled in the northern Pennsylvania mountains. Not Philadelphia or one of the surrounding lower elevation sites, but a tiny, tiny hamlet at 1400' surrounded by 2000'+ ridges.

 

Let's take a look at this data from 1927.

For comparison, here is downtown Pittsburgh for the same month.

Ridgway is typically 4 or 5 degrees cooler than Pittsburgh [particularly downtown]. It's not an exaggeration to say these high temperatures [which are quite obviously taken from an instrument that would have been exposed to direct sunlight] are 15-20 degrees too high.

Actually, anyone with half a brain should be able to see it's actually proof of just how much it's warmed since then. 1927 - despite absurdly unrepresentative summertime high temperatures which are clearly 15-20 degrees too high most days - is only about a degree or so warmer than many recent years on the annual mean! And that is without any of the much-maligned adjustments for Time of Observation [was 5:30 p.m. in 1927] or change in instrumentation [MMTS]. 

[ChescoWx]

I will repost as it seems no one has been able to come up with where the heck are the cooling adjustments for the known PHL UHI problem???

Below is an analysis of the PHL Airport average annual temperature from 1941 through 2023. I have overlaid the adjusted NCEI temperatures vs the actual reported averages. Why in the last 30 years have the PHL Airport Temps been adjusted upward in 19 of the last 30 years despite UHI?? And the overall cumulative adjustments over those years has been an overall net upward adjustment of 3.45 degrees in PHL actual reported temps. Thoughts????

[bluewave]

54 minutes ago, ChescoWx said:

where the heck are the cooling adjustments for the known PHL UHI problem???

 

The rise in minimum temperatures at the airport is nearly identical to the one in Mt Holly at the NWS forecast office over the last 30 years. The population at Mt. Holly around 25 miles to the east has remained nearly steady at 10k as the population in Philadelphia has held steady around 1.5 million. It doesn’t appear that the Philadelphia UHI intensity has changed much in 30 years at the airport. So all the warming over the last 30 years is the result of a steadily warming climate and not a local increase in UHI intensity at the airport. 
 

Philadelphia International Airport 30yr minimum temperature rise +2.6°F.
 

Mt.Holly NWS WFO 30 year minimum temperature rise +2.8°F

[ChescoWx]

1 hour ago, bluewave said:

 

The rise in minimum temperatures at the airport is nearly identical to the one in Mt Holly at the NWS forecast office over the last 30 years. The population at Mt. Holly has remained nearly steady at 10k as the population in Philadelphia has held steady around 1.5 million. It doesn’t appear that the Philadelphia UHI intensity has changed much in 30 years at the airport. So all the warming over the last 30 years is the result of a steadily warming climate and not a local increase in UHI intensity.
 

Philadelphia International Airport 30yr minimum temperature rise +2.6°F.
 

 

Mt.Holly NWS WFO 30 year minimum temperature rise +2.8°F

 

Why start in 1995 we do have data back to 1941 for PHL (RED TREND) a quick comparison vs. All Chester County (ORANGE TREND) stations paints a quite different story in trend lines. Rural counties like Chester County clearly show only minor if any real warming in comparison. As I showed before the real UHI impact started in 1970 at PHL as I detailed with the construction projects earlier. Look at how the lines diverge from 1970 on as the UHI impact at PHL accelerates!

[LibertyBell]

2 hours ago, bluewave said:

The regime shift occurred in 2007 to a much thinner sea ice state and was not forecast ahead of time. The ice free extent forecast by 2013 was an outlier that most agencies like the NSIDC never bought into. Remember there was no alarm in the early 2000s before the major shift in 2007. Complacency turned out to be the greater risk as the thickness and age of the ice has not recovered to pre-2007 levels. 
 

https://www.nature.com/articles/s41586-022-05686-x

Manifestations of climate change are often shown as gradual changes in physical or biogeochemical properties¹. Components of the climate system, however, can show stepwise shifts from one regime to another, as a nonlinear response of the system to a changing forcing². Here we show that the Arctic sea ice regime shifted in 2007 from thicker and deformed to thinner and more uniform ice cover. Continuous sea ice monitoring in the Fram Strait over the last three decades revealed the shift. After the shift, the fraction of thick and deformed ice dropped by half and has not recovered to date. The timing of the shift was preceded by a two-step reduction in residence time of sea ice in the Arctic Basin, initiated first in 2005 and followed by 2007. We demonstrate that a simple model describing the stochastic process of dynamic sea ice thickening explains the observed ice thickness changes as a result of the reduced residence time. Our study highlights the long-lasting impact of climate change on the Arctic sea ice through reduced residence time and its connection to the coupled ocean–sea ice processes in the adjacent marginal seas and shelves of the Arctic Ocean.

Our analysis demonstrates the long-lasting impact of climate change on Arctic sea ice through reduced residence time, suggesting an irreversible response of Arctic sea ice thickness connected to an increase of ocean heat content in areas of ice formation. The large reduction of summer ice extent in the Alaskan and Siberian sectors in 2005 and 2007 triggered intensive ice–albedo feedback^42,45 and initiated the perennial increase of ocean heat content in these areas⁴⁴. This resulted in the stepwise reduction of residence time of sea ice in the Siberian sector of the Arctic, and hence a nonlinear response of the system.

I wonder if people realize their "freedoms" will be going out the window when faced with an existential threat.

[LibertyBell]

1 hour ago, ChescoWx said:

since facts are over feelings...they don't feel any abuse as the truth sets them free!!!

the UHI problem will go away once they stop using concrete (this is already underway in NYC where the goal is to make the city 30% green by 2030 by making rooftop gardens atop most buildings).... but the problem of global warming will keep increasing.

[bluewave]

36 minutes ago, ChescoWx said:

Why start in 1995 we do have data back to 1941 for PHL (RED TREND) a quick comparison vs. All Chester County (ORANGE TREND) stations paints a quite different story in trend lines. Rural counties like Chester County clearly show only minor if any real warming in comparison. As I showed before the real UHI impact started in 1970 at PHL as I detailed with the construction projects earlier. Look at how the lines diverge from 1970 on as the UHI impact at PHL accelerates!

The real impact of UHI has been around for over 100 years in Philly so starting in 1970 or 1994 makes no difference. Chubbs has shown the errors in the way that you have put together the Chesco data. Remember global emissions and temperatures really began to accelerate around 1980. Rural locations have been warming at the same rate as urban ones since then.

 

[ChescoWx]

32 minutes ago, bluewave said:

The real impact of UHI has been around for over 100 years in Philly so starting in 1970 or 1994 makes no difference. Chubbs has shown the errors in the way that you have put together the Chesco data. Remember global emissions and temperatures really began to accelerate around 1980. Rural locations have been warming at the same rate as urban ones since then.

 

While some very slight warming during our current warming cycle in rural Chester County as you can see below - certainly not at the rate of PHL. See below updated comparison since 1980 see below again nowhere near the warming rate!

[bluewave]

4 minutes ago, ChescoWx said:

While some very slight warming during our current warming cycle in rural Chester County as you can see below - certainly not at the rate of PHL. See below updated comparison since 1980 see below again nowhere near the warming rate!

Bradford, PA far from any UHI influence has been warming even faster than Philly over the last 30 years.

Bradford, PA continues to be one of the fastest warming parts of the state. The minimums have risen +3.5° since 1994 and the maximums at +3.2°. 
 

 

[chubbs]

The Philadelphia Airport, NOAA Chesco and Paul's own Chescowx series are all in very good agreement on the local warming since 1970. Chescowx is 2 Coatesville COOP stations and Paul's house (since 2004). The other NWS climate sites in our area are also in good agreement (Atlantic City, Allentown and Wilmington).  It has warmed strongly in our area since 1970 and high quality datasets show it.

Paul you are wasting our time by repeating essentially the same chart over and over again. Yes, we know you don't know how to analyze weather station data and that you are unaware of your own bias.

 

[TheClimateChanger]

 

[TheClimateChanger]

 

[bdgwx]

9 hours ago, FPizz said:

"Tipping Point" is a term used to scare people.

A "tipping point" is a term that describes the breakpoint of physical process effected by hysteresis. An analogy that many physicists use is that of a marble in bowl being jostled around chaotically. It will tend to settle back to its equilibrium level at the bottom bowl. Except...if the marble is jostled hard enough it crests the lip (or "tipping point") of the bowl allowing the marble to escape the confines of the bowl forcing it to find a new and completely different equilibrium level. Like the marble in the bowl the climate system has tipping points, which if triggered, result in new and completely different equilibrium states. It's a term with a very specific scientific meaning. It has nothing to do with scaring people.

 

9 hours ago, FPizz said:

The hysterics and failed claims/predictions (ice free by 2013 for example) ruin it for the alarmists.

The myth that never dies. As I've mentioned numerous times the science did not predict the Arctic would be "ice-free" (< 1e6 km2) by the summer of 2013. The most aggressive prediction I've seen using a broad based consilience of evidence approach so far is from the IPCC AR6 report in which they say "The Arctic is likely to be practically sea ice-free in September at least once before 2050." This is a significant downward revision from their 2070 target in the early 2000's and 2100 target in the 1990's. It is important to point out that the IPCC has a poor track record of Arctic sea ice declines. For example, in 2001 they said annual mean Arctic sea ice extent would not drop below 10.5e6 km2 until 2040. It first happened in 2007 followed by 2011, 2012, 2016, 2017, 2018, 2019, 2020, and 2023. And this is systematic of scientific community in general. Scientists have woefully underestimated Arctic sea ice decline. 

The only "expert" I know of that gave an early prediction was Peter Wadhams in a The Guardian article from 2013. His prediction was immediately criticized by the scientific community as not being supported by the evidence. It's also strange that Wadhams' own research at the time only stated within the next 30 years [Wadhams 2012] so it's not clear to me how this discrepancy gets resolved. Did he actually say what The Guardian said he said? If he did then why did he give a prediction to The Guardian that contradicts his prediction given in his own peer reviewed publications? 

[ChescoWx]

4 hours ago, chubbs said:

The Philadelphia Airport, NOAA Chesco and Paul's own Chescowx series are all in very good agreement on the local warming since 1970. Chescowx is 2 Coatesville COOP stations and Paul's house (since 2004). The other NWS climate sites in our area are also in good agreement (Atlantic City, Allentown and Wilmington).  It has warmed strongly in our area since 1970 and high quality datasets show it.

Paul you are wasting our time by repeating essentially the same chart over and over again. Yes, we know you don't know how to analyze weather station data and that you are unaware of your own bias.

 

As always Charlie you are just not seeming to understand or comprehend the actual depth and breath of real world data we are now showing here. Let's review again - There is no such thing as a ChescoWX data set you keep talking about in the data we are reviewing here. There are of course not simply 2 Coatesville COOP sites and "Paul's House" in the data set!!  The data set we are looking at includes at least 27 National Weather Service COOP/AWOS and MADIS sites in the historical data set between 1894 and Today. Including in the current data set here in 2024 an active 16 currently reporting NWS/AWOS and MADIS reporting sites in the current data. Charlie just to put a a fine point on this so you understand. The Chester County PA data we present here is far from what you call the ChescoWX data which only includes 3 stations....it is a robust 27 stations across more than 130 years of NWS Data. Is this getting clearer for you?? As we yet again showed you the actual Chester County PA data is far from "in good agreement" with the PHL UHI Airport data and of course as you see is not "warming strongly since 1970" in Chester County. This is not that difficult Charlie!!

[chubbs]

9 hours ago, ChescoWx said:

As always Charlie you are just not seeming to understand or comprehend the actual depth and breath of real world data we are now showing here. Let's review again - There is no such thing as a ChescoWX data set you keep talking about in the data we are reviewing here. There are of course not simply 2 Coatesville COOP sites and "Paul's House" in the data set!!  The data set we are looking at includes at least 27 National Weather Service COOP/AWOS and MADIS sites in the historical data set between 1894 and Today. Including in the current data set here in 2024 an active 16 currently reporting NWS/AWOS and MADIS reporting sites in the current data. Charlie just to put a a fine point on this so you understand. The Chester County PA data we present here is far from what you call the ChescoWX data which only includes 3 stations....it is a robust 27 stations across more than 130 years of NWS Data. Is this getting clearer for you?? As we yet again showed you the actual Chester County PA data is far from "in good agreement" with the PHL UHI Airport data and of course as you see is not "warming strongly since 1970" in Chester County. This is not that difficult Charlie!!

Love the little dig at the end. It isn't difficult to figure out what you are doing: bad analysis to fit your worldview.  More data is not better for long-term climate analysis if it isn't consistent. That is what you don't understand about NOAA. They take great care to remove as much inconsistency as possible, to make data taken 100+years ago as consistent with the data taken today as possible.

Your 27 station network, on-the-other-hand, is very inconsistent in its make-up. The station population changes with time, as old stations drop out and new ones are added. Most of the 27 stations are recent, mainly from the Deos Network, with short data records; so they don't provide any climate information. They are however cooler as a whole than the Coop stations that make up the historic Chesco data. Why are they cooler? They are further N+W, higher elevation, and located primarily in parks instead of backyards.  In this case "more" stations is degrading local climate information. As I showed above, all you are showing with your plots is the effect of changing station mix. The 3-station Coatesville/ENant data is much more consistent than your 27 station network and hence provides a more accurate picture of our climate.

Once again you have fallen in love with an answer that fits your worldview. So much so that the Chescowx data posted on your website, as representative of Chesco's climate,  is tossed aside. Just like the winter "weenies" on this board fall in love with a 10-day snowfall map.  Very easy for me, and others, to see the bias you are introducing in your new Chesco analysis. Its the same bias you've exhibited for a decade or more.

 

 

[ChescoWx]

2 hours ago, chubbs said:

Love the little dig at the end. It isn't difficult to figure out what you are doing: bad analysis to fit your worldview.  More data is not better for long-term climate analysis if it isn't consistent. That is what you don't understand about NOAA. They take great care to remove as much inconsistency as possible, to make data taken 100+years ago as consistent with the data taken today as possible.

Your 27 station network, on-the-other-hand, is very inconsistent in its make-up. The station population changes with time, as old stations drop out and new ones are added. Most of the 27 stations are recent, mainly from the Deos Network, with short data records; so they don't provide any climate information. They are however cooler as a whole than the Coop stations that make up the historic Chesco data. Why are they cooler? They are further N+W, higher elevation, and located primarily in parks instead of backyards.  In this case "more" stations is degrading local climate information. As I showed above, all you are showing with your plots is the effect of changing station mix. The 3-station Coatesville/ENant data is much more consistent than your 27 station network and hence provides a more accurate picture of our climate.

Once again you have fallen in love with an answer that fits your worldview. So much so that the Chescowx data posted on your website, as representative of Chesco's climate,  is tossed aside. Just like the winter "weenies" on this board fall in love with a 10-day snowfall map.  Very easy for me, and others, to see the bias you are introducing in your new Chesco analysis. Its the same bias you've exhibited for a decade or more.

 

 

Again Charlie has an answer to his question "Why are they cooler?" His answer is that they are further N+W, higher elevation. Again let's go to the facts for the truth.

According to the NWS Mount Holly CWA forecast zones - of the current 16 stations reporting 9 of them are in the Eastern Zone of Chester County and only 7 are in the Western Zone. So they are in fact NOT more located to the N and W. So now how does the elevation look at these stations? Well in fact 11 of them are at lower elevations below 465 feet ASL while only 5 are located at greater than 525 feet ASL. So there are actually more at lower than higher elevations. Facts over feelings as always!

[Stebo]

NWS data is all that matters.

[TimB]

2 minutes ago, Stebo said:

NWS data is all that matters.

That’s cool and all, but you see, Chesco has spliced his 20 years of records in with 110 years of already existing NWS data, so it basically is NWS data.

[Stebo]

Just now, TimB said:

That’s cool and all, but you see, Chesco has spliced his 20 years of records in with 110 years of already existing NWS data, so it basically is NWS data.

No one cares about his data that is more than likely poorly sited, lower quality, and not augmented regularly.

[bluewave]

Another issue with Chester County is that it’s pretty small and new stations don’t come online to replace the older retiring ones. There are many reporting gaps especially with the COOP stations. I noticed that Phoenixville hasn’t been reporting as reliably over recent years as it did in the past. It’s one of the warmer spots in the county. When they were reporting more regularly from 2005 to 2015 they actually had more 90° days than the Philadelphia International Airport. 

 

Data for January 1, 2005 through December 31, 2015
Click column heading to sort ascending, click again to sort descending.

Name	Station Type	Number of Days Max Temperature >= 90
NORRISTOWN	COOP	419
Philadelphia Center City Area	ThreadEx	407
PHILADELPHIA FRANKLIN INSTITUTE	COOP	407
YORK 3 SSW PUMP STN	COOP	376
PHOENIXVILLE 1 E	COOP	342
NORTHEAST PHILADELPHIA AIRPORT	WBAN	332
Philadelphia Area	ThreadEx	321
PHILADELPHIA INTL AP	WBAN	321
SHIPPENSBURG	COOP	303

 

 

[ChescoWx]

2 hours ago, TimB said:

That’s cool and all, but you see, Chesco has spliced his 20 years of records in with 110 years of already existing NWS data, so it basically is NWS data.

Nope not true at all. 27 NWS COOP stations included AWOS etc.

[chubbs]

20 hours ago, ChescoWx said:

Again Charlie has an answer to his question "Why are they cooler?" His answer is that they are further N+W, higher elevation. Again let's go to the facts for the truth.

According to the NWS Mount Holly CWA forecast zones - of the current 16 stations reporting 9 of them are in the Eastern Zone of Chester County and only 7 are in the Western Zone. So they are in fact NOT more located to the N and W. So now how does the elevation look at these stations? Well in fact 11 of them are at lower elevations below 465 feet ASL while only 5 are located at greater than 525 feet ASL. So there are actually more at lower than higher elevations. Facts over feelings as always!

Your "facts" don't address my criticism. I said the station mix is CHANGING WITH TIME. You didn't mention time above. I posted the table below many pages ago and you have been ducking the station mix issue ever since, despite having multiple opportunities to respond. This isn't a complicated point. The station mix is shifting N+W and to higher elevation with time. Compare 1930-52. There are many more stations north of the Turnpike, 6 vs 1, and above 550', 5 vs 0, now vs 1930-52. Also fewer south and east on a % basis. Makes sense population has been steadily N and W in the County, out of the older valley towns.

[chubbs]

20 hours ago, Stebo said:

NWS data is all that matters.

The NWS climate sites (abe=Allentown, ilg=Wilmington, acy=Atlantic City) in our area all show warming similar NOAA Chesco and the Philadelphia Airport. We don't have quality sites that differ from NOAA in recent decades. Another indication that he is way off.

[ChescoWx]

10 hours ago, chubbs said:

The NWS climate sites (abe=Allentown, ilg=Wilmington, acy=Atlantic City) in our area all show warming similar NOAA Chesco and the Philadelphia Airport. We don't have quality sites that differ from NOAA in recent decades. Another indication that he is way off.

LOL!! "quality sites" meaning those that disagree with your NWS Climate sites including both PHL and ILG Heat Island impacted stations and of course add in those after the fact chilling adjustments to the past and warming tweaks to the current data. Quite the different look from the above for Chester County if we don't make warming adjustments to the actual current data. Regarding the sites in more detail yes there was as a % more lower elevation sites in the past....which likely skewed those results too warm...even though they were in fact the warmest decades. The good news is we now have a good balance and mix that as long as we keep breaking it out by elevation will clearly show the non-adjusted factual real world warming or cooling depending on the current climate change cycle.

[ChescoWx]

22 hours ago, chubbs said:

Your "facts" don't address my criticism. I said the station mix is CHANGING WITH TIME. You didn't mention time above. I posted the table below many pages ago and you have been ducking the station mix issue ever since, despite having multiple opportunities to respond. This isn't a complicated point. The station mix is shifting N+W and to higher elevation with time. Compare 1930-52. There are many more stations north of the Turnpike, 6 vs 1, and above 550', 5 vs 0, now vs 1930-52. Also fewer south and east on a % basis. Makes sense population has been steadily N and W in the County, out of the older valley towns.

This was already addressed the east and west is not as critical as the elevation above sea level which we have already detailed in the above post with those splits.  There are of course today...consistent with the older data more stations at the relatively lower elevations. Not at the higher elevations. We will of course be analyzing data that reviews the data individually at both the relative higher and lower elevation locales to account for any variables due to these elevations.

[ChescoWx]

Yep sure looks like a similar warming trajectory from the UHI PHL Airport vs all of those Chester County NWS COOP and MADIS sites just since 1980....which of course only includes our current warming cycle of climate change

[chubbs]

13 hours ago, ChescoWx said:

This was already addressed the east and west is not as critical as the elevation above sea level which we have already detailed in the above post with those splits.  There are of course today...consistent with the older data more stations at the relatively lower elevations. Not at the higher elevations. We will of course be analyzing data that reviews the data individually at both the relative higher and lower elevation locales to account for any variables due to these elevations.

Wow that's lame. West and east aren't critical? Where's the evidence? That's not what your website says: “The National Weather Service split out this zone (PAZ101) from the lower elevations seen across most of Eastern Chester County (PAZ102) a few years ago to better distinguish the climate differences attributed to relative elevation and more inland location from the Atlantic Ocean.” Temperature is a variable that isn't impacted by elevation? Are you kidding? And you completely overlooked north in your comment. Are you denying that north, west and elevated are colder in Chester County?

Finally as I showed above your elevation split is inadequate to remove bias. The new 550+ stations added after 2000 have many fewer 90+ days than the pre-2000 stations.There are other factors besides elevation which impact the station temperatures and skew the results. Without properly accounting for station differences you are cooking the books. You assertions are to the contrary are worthless without evidence.