Chester County PA - Analytical Battle of Actual vs. Altered Climate Data

[ChescoWx]

The new home of all things concerning real vs.altered data....

[ChescoWx]

Below is a great illustration of how the post observation NOAA/NCEI adjustments are skewing the analysis. They are continuing to warm even the current decade - following the chilling adjustments made to the hottest summer decades back in the 1930's thru 1950's. If you believe the red NCEI trends we are warming pretty quickly....if the actual raw blue data is viewed....almost flat! No summer warming here in Chester County PA....

[rcostell]

ChescoWX- Would you mind going back into the "Climate Change Thread" and letting a couple folks know that you created this new thread for the "Chester County" observations battle. Thank You

[ChescoWx]

As we have just passed Christmas in July....and for the many of you on Team Snow - why not list out all of the greatest annual snow seasons (October-April) on record across the Chester County NWS cooperative and trained spotter observation sites. That 1957-58 winter looks like the snow winner.

[ChescoWx]

Below is an analysis of the actual average annual Chester County PA temperatures over the last 100 years from 1924 through 2023. We have been in our current warming cycle since the 1990's but have to date still failed to reach the warmth we experienced in the 1930's. Will we get as warm as then before our next cooling cycle??

[Brewbeer]

dedicated thread for this - great idea

[ChescoWx]

I thought we would focus just on the post hoc NOAA adjustments they made to the average annual high temperatures for Chester County PA for the last 128 years since 1895. They chilled the actual NWS recorded highs for the first 95 consecutive years across Chester County PA. Unsurprisingly they have now started to warm the actual readings for each and every year for 21 of the last 24 years since 2000. Included warming adjustments added to each and every year for the last 18 consecutive years. The impact of these adjustments is clear....the red shows strong warming signals...while the actual raw data shows effectively NO WARMING at all.

[chubbs]

Below is Coatesville with a very rough adjustment for the town-->outside of town move, 2F phased in between 1946 and 48 (2 moves in that period). This single, crude, move adjustment removes most of the difference between NOAA and the raw data.  The agreement isn't perfect, but you wouldn't expect it to be.  Coatesville 1SW had multiple in town locations and Chescowx is 3 different sites (Coatesville 1SW, Coatesvelle 2W and East Nantmeal). Each move would have some impact on measured temperatures.  There can be non-move station changes as well. With all the station moves at Coatesville and West Chester, you get a much better answer by accounting for station changes.

[Stormchaserchuck1]

I know locally it doesn't seem like things are too much warmer vs when I was a kid. For all this panic about +2 anomalies, humans sure can possibly do much more damage than that.. We are also surrounded by Space that is absolute zero. I'd say the rate of warming to concern is less than our capacities. Also Russia and Canada are pretty much empty. There is a jet stream shift north though, that is occurring with more south wind. Hard to say if that is something independent of technological revolution effects. 

[ChescoWx]

On 8/11/2024 at 2:24 PM, chubbs said:

Below is Coatesville with a very rough adjustment for the town-->outside of town move, 2F phased in between 1946 and 48 (2 moves in that period). This single, crude, move adjustment removes most of the difference between NOAA and the raw data.  The agreement isn't perfect, but you wouldn't expect it to be.  Coatesville 1SW had multiple in town locations and Chescowx is 3 different sites (Coatesville 1SW, Coatesvelle 2W and East Nantmeal). Each move would have some impact on measured temperatures.  There can be non-move station changes as well. With all the station moves at Coatesville and West Chester, you get a much better answer by accounting for station changes.

Right! They are of course only 3 sites in the county....but because of that we should accept that NOAA chose to chill 106 straight years?? In most cases below any recorded station in the entire county?? But don't ask that Paul.....it's just science and we should not question it!!!

[ChescoWx]

August Average Temps since 1893.....don't be scared!!!

[ChescoWx]

thoughts I would split down the middle the entire Chester County PA data set. With an annual average temperature analysis of the first 66 years of data from 1893 thru 1957 vs. the last 65 years from 1958 thru 2023.

The average temperature from 1893-1957 was 53.0 degrees

The average temperature from 1958 - 2023 was 52.6 degrees

The last 65 years have been 0.4 degrees cooler than the previous 66 years.....alarming!!!!

[forkyfork]

here's a graph of real data for you

[chubbs]

Using monthly raw data and comparing to nearby County sites it is very easy to spot when the West Chester station was shut down for several months and moved to a cooler site in 1970. The 1970 station move accounts for the bulk of the West Chester bias adjustment over the lifetime of the station.  The older stations in Chester County were in much warmer locations than the stations we have today, older towns mainly, in the south and east portion of the county where people lived. Over the years stations moved to more rural sites and shifted north and west to better cover the whole county. If you assume that the Chesco monitoring network is the exactly the same today as it was 130 years ago you will be way off.

 

[ChescoWx]

Updated Chester County Average Temperatures by Decade 1890's thru 2020's (only 4 years) IF we don't start to see some cooling over the remainder of the decade we have a chance that the 2020's could be the warmest complete decade since reliable climate data began to be recorded in the 1890's. So far in the 2020's we are running 0.6 degrees warmer than our warmest full decade - the 1930's.

[chubbs]

You can't understand Chester County's recent climate history if you don't account for station moves at Coatesville and West Chester. Easier to spot the cooling associated with moves from built-up towns---> less built-up sites, by separating before- and after-move portions of the station records. The moves are easily identified by the difference in the timing of move-related cooling: Coatesville cooled between 1945 and 1948; while, West Chester cooled in 1970. NOAA's scientific approach, using raw data from additional stations, confirms that the move-related cooling is spurious.

[ChescoWx]

Below is an analysis of average September Temperatures from 1893 through 2023. Here in the Philly burbs of Chester County PA the first month of Autumn has been getting chillier on average.

[ChescoWx]

Below is an analysis of the average fall (September - November) temperatures across the Philly burbs of Chester County PA since 1893. The data shows our falls are actually getting cooler over the last 130+ years.

[ChescoWx]

NOAA has adjusted the actual temperatures upwards for Chester County for the summer of 2024.

Below is the actual and the adjusted NOAA average temps

June -  Actual 72.5 - adj to 72.8 = +0.3 degrees

July - Actual 76.8 - adj to 77.9  = +1.1 degrees - only 2 stations of 18 was this high

August - Actual 72.6 adj to 73.7 +1.1 degrees - only 1 station of 18 were this high

[AdMC]

How's your echo chamber going? Haven't read any of it, and I suspect no one else has either. 

[ChescoWx]

For @chubbsso he can more clearly see the adjustment made to each available Chester County PA station from 1927 thru 1947. As is clearly shown NCEI adjusted every station to colder than any station of record in the county for each of those years with the exception of 1940!!  Charlie let us know if you can now see the adjustments made by NCEI clearly and that yes it does chill the raw temperatures every single year. It is clear as can be!! The NCEI average annual Chesco temp for all those years was in fact adjusted below what any station reported in their raw observations.

[chubbs]

14 hours ago, ChescoWx said:

For @chubbsso he can more clearly see the adjustment made to each available Chester County PA station from 1927 thru 1947. As is clearly shown NCEI adjusted every station to colder than any station of record in the county for each of those years with the exception of 1940!!  Charlie let us know if you can now see the adjustments made by NCEI clearly and that yes it does chill the raw temperatures every single year. It is clear as can be!! The NCEI average annual Chesco temp for all those years was in fact adjusted below what any station reported in their raw observations.

The circled yellow numbers and your "post hoc adjustment" rows are meaningless and don't shed any light on NOAA's work. Why? The average of the city of Coatesville, Phoenixville, West Chester Borough, and West Grove is not the county average, not even close. Those stations are all warmer than the county as a whole. Of course the NOAA number is cooler, that isn't surprising at all.

[ChescoWx]

12 hours ago, chubbs said:

The circled yellow numbers and your "post hoc adjustment" rows are meaningless and don't shed any light on NOAA's work. Why? The average of the city of Coatesville, Phoenixville, West Chester Borough, and West Grove is not the county average, not even close. Those stations are all warmer than the county as a whole. Of course the NOAA number is cooler, that isn't surprising at all.

So you are admitting there is no actual annual average thermometer readings that you can show us in the entire county for that period that support the cooler altered NOAA/NCEI data for even one of those 21 years of data across all of those stations?? Hello McFly......

[chubbs]

24 minutes ago, ChescoWx said:

So you are admitting there is no actual annual average thermometer readings that you can show us in the entire county for that period that support the cooler altered NOAA/NCEI data for even one of those 21 years of data across all of those stations?? Hello McFly......

Nice insult at the end. What I have come to expect when we exchange data/information. I have shown you umpteen charts which validate NOAA. You dismiss/deny them all. Here's another. After the big moves, Coatesville and NOAA had exactly the same warming between 1948 to 2024. Once again NOAA is spot on.

[ChescoWx]

24 minutes ago, chubbs said:

Nice insult at the end. What I have come to expect when we exchange data/information. I have shown you umpteen charts which validate NOAA. You dismiss/deny them all. Here's another. After the big moves, Coatesville and NOAA had exactly the same warming between 1948 to 2024. Once again NOAA is spot on.

Now you jump to another time period....let's stay focused on the period in question (1927-1947). Show us some actual data for the period we are looking at above that validate NOAA/NCEI adjusting all temperatures lower than any thermometer anywhere in the county recorded during those 21 years in question.

[TheClimateChanger]

Can we let Grok decide what is the truth? As an AI, Grok has no dog in this fight. If he agrees with @ChescoWxso be it! But if, in its unbiased opinion, @ChescoWxis off the mark, then he agrees to stop?

[ChescoWx]

29 minutes ago, TheClimateChanger said:

Can we let Grok decide what is the truth? As an AI, Grok has no dog in this fight. If he agrees with @ChescoWxso be it! But if, in its unbiased opinion, @ChescoWxis off the mark, then he agrees to stop?

Grok even mentions me! It cannot confirm!!! "Without specific data for Chester County, PA, from NCEI’s raw versus adjusted records, I can’t confirm the exact nature or extent of changes for that location. However, local weather enthusiasts, like those at chescowx.com, have noted that NOAA/NCEI adjustments have historically "chilled" Chester County data from 1893 to 2005 and "warmed" more recent years.

[TheClimateChanger]

Interesting @ChescoWx. Here is the analysis I received from Grok. I include the question prompt to show that I was as neutral as can be, simply providing the claim, and asking whether it was valid or not. Like you said, Grok indicates that he cannot validate whether there has been no warming without access to your data. However, Grok defends the NOAA adjustments. I suspect if it had access to your data, it would also conclude that Chester County has warmed.

 

Question Prompt: 

User @ChescoWx claims that Chester County, Pennsylvania has not actually warmed, but that NOAA temperature adjustments create warming. Is there any validity to this claim or is it out to lunch? Please provide a detailed analysis supporting your view either way.

Grok's Analysis:

To assess the claim by @ChescoWx that Chester County, Pennsylvania, has not actually warmed and that NOAA temperature adjustments artificially create a warming trend, we need to break this down into two parts: (1) whether there’s evidence of warming in Chester County based on unadjusted data, and (2) whether NOAA’s adjustments are responsible for fabricating that warming. Let’s dive into the science, data, and reasoning step by step.

 

Background on NOAA Temperature Adjustments

 

NOAA, through its National Centers for Environmental Information (NCEI), maintains the U.S. Historical Climatology Network (USHCN), which includes weather station data dating back over a century. Raw temperature data from these stations often contain inconsistencies due to changes in instrumentation, station locations, observation times, and local environmental factors like urbanization (e.g., the urban heat island effect). To address these, NOAA applies adjustments to create a homogenized dataset that better reflects regional climate trends rather than artifacts of measurement changes. These adjustments are peer-reviewed, publicly documented, and aim to improve accuracy, not to push an agenda.

 

Part 1: Has Chester County Warmed?

 

First, let’s consider whether Chester County has experienced warming, independent of NOAA adjustments. Temperature trends can be evaluated using raw data from local stations, though accessing unadjusted data specific to Chester County requires digging into historical records or independent sources, as NOAA primarily publishes adjusted data.

• Raw Data Availability: The Chester County Weather page (@ChescoWx's apparent source) claims to use unadjusted data from 27 local stations, including National Weather Service (NWS) Cooperative Observers, since 1893. They assert that this raw data shows no warming. However, without direct access to their full dataset or methodology (beyond their website’s general claims), we can’t verify this outright. Instead, we can cross-check with broader Pennsylvania trends and local proxies.
• Pennsylvania State Trends: NOAA’s adjusted data for Pennsylvania, as reported in the 2022 State Climate Summaries, shows a temperature increase of nearly 2°F since 1900. This is based on long-term stations statewide, including. If Chester County followed a similar trajectory, we’d expect some warming signal in the raw data too, unless local factors uniquely offset it. The @ChescoWx site notes Chester County’s elevation (around 685 ft) and distance from Philadelphia’s urban heat island (e.g., Philadelphia International Airport at 59 ft) might moderate extremes compared to coastal areas. But natural variability alone is unlikely to erase a century-long warming trend entirely.
• Proxy Evidence: Tree rings, ice cores, and other paleoclimate data for the Northeast U.S. generally support a warming trend over the 20th century, consistent with global patterns. Local anecdotal evidence from

  @ChescoWx—like fewer summer nights in the 50s or rare lows below 45°F—suggests a shift, but this isn’t systematic enough to counter long-term data.
• Independent Data: The U.S. Climate Reference Network (USCRN), started in 2001, uses pristine, well-sited stations. While it lacks century-long records, a 2016 study (Hausfather et al.) found that adjusted USHCN data (like NOAA’s) aligns closely with USCRN data from 2004–2015, suggesting adjustments don’t wildly distort recent trends. For earlier periods, raw data from rural stations (like some in Chester County) might show less warming than urban ones, but a flat trend would be an outlier compared to regional and global increases.

Conclusion:

 

Without @ChescoWx’s raw data, we can’t definitively say Chester County hasn’t warmed at all. However, the regional 2°F rise, proxy evidence, and basic thermodynamics (rising greenhouse gases trap heat) make a no-warming scenario improbable unless Chester County’s microclimate defies broader physics—possible, but unlikely without robust proof.

 

Part 2: Do NOAA Adjustments Create Warming?

 

Now, let’s tackle the claim that NOAA adjustments fabricate the warming trend.

• Adjustment Purpose: NOAA adjusts for known biases: station moves (e.g., from downtown Chicago to O’Hare), time-of-observation changes, and urban heat effects. For Chester County, a station move from a warmer valley to a cooler ridge could lower recorded temperatures, requiring an upward adjustment to maintain consistency. @ChescoWx might see this as “creating warming,” but it’s correcting for a shift that would otherwise mask the true trend.
• Adjustment Impact: Globally, NOAA adjustments reduce warming over the full record (1850–present) by about 0.2°C, largely due to ocean corrections (e.g., bucket-to-engine intake shifts in the 1940s). For U.S. land data, adjustments slightly increase the 20th-century trend (by ~0.3°F), but this is because early records (pre-1950) often had cool biases (e.g., afternoon readings vs. modern 24-hour averages). A histogram of NOAA adjustments shows roughly half increase temperatures and half decrease them—hardly a systematic “warming conspiracy.”
• Chester County Specifics: @ChescoWx claims NOAA “chilled” data from 1893–2005 and now “warms” recent years. This could reflect real methodological shifts—e.g., NOAA’s transition from version 2 to version 3 adjustments around 2011, which refined urban heat corrections and buoy data integration. But these changes are documented and tested against pristine stations (like USCRN), not arbitrary fudges. If Chester County’s raw data is flat, adjustments might indeed add a warming signal to align with regional trends, but that’s not “creating” warming—it’s reconciling local quirks with reality.
• Validation: Independent datasets (e.g., Berkeley Earth, Hadley Centre) also show U.S. warming, using different adjustment methods. Satellites (since 1979) and radiosondes show tropospheric warming, though surface trends differ slightly. If NOAA were fabricating warming, these datasets wouldn’t converge on similar results.

Conclusion:

 

NOAA adjustments don’t “create” warming from thin air. They correct biases, sometimes increasing trends (especially post-1950), sometimes decreasing them (pre-1940). For Chester County, adjustments might amplify a muted raw trend, but that’s not proof of manipulation—it’s standard homogenization.

 

Is @ChescoWx’s Claim Valid?

• Partial Merit: If Chester County’s raw data shows no warming (a big “if” without public data), @ChescoWx has a point that adjustments introduce a trend not seen locally. Their skepticism about urban-influenced baselines (e.g., Philadelphia) is fair—microclimates matter.
• Mostly Out to Lunch: The claim overreaches. A flat raw trend in Chester County contradicts regional, national, and global evidence, requiring extraordinary local factors (e.g., elevation, land use) to offset physics. NOAA adjustments aren’t perfect—rural stations can be overcorrected based on urban-heavy models—but they’re not a grand conspiracy. @ChescoWx’s refusal to share raw data or engage peer review undermines their case. Extraordinary claims need extraordinary evidence, and they’re light on the latter.

Final Take

 

Chester County likely warmed, though perhaps less than Philadelphia due to its rural, elevated setting. NOAA adjustments may exaggerate that trend locally, but they’re grounded in science, not fiction.

@ChescoWx raises a valid question—how well do adjustments fit Chester County?—but their no-warming assertion is a stretch without hard data. The real story’s in the numbers they won’t show.

[ChescoWx]

Thanks @TheClimateChangerExcellent!!  Likely but.....drum roll please "we can’t definitively say Chester County hasn’t warmed at all. "

Fake news if it was Grok to " @ChescoWx’s refusal to share raw data or engage peer review undermines their case. Extraordinary claims need extraordinary evidence, and they’re light on the latter"

I have often shared my raw data file plus it is all available via the internet. It is available upon request to anyone. Let me know if you want it?

[ChescoWx]

@TheClimateChanger in case you forgot - below is the available on the internet raw data and the analysis comparing the Actual Raw data vs the altered NCEI Data for Chester County PA. This clearly shows Chesco has not warmed 2 degrees (see orange actual raw temps) according to the unaltered data. However, you can clearly see in the blue line the altered post hoc data in blue that does show that warming that can only be accomplished by recasting the actual data and ignoring all of the actual raw data in Chester County.