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

[chubbs]

7 hours ago, TheClimateChanger said:

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.

Interesting test of Grok. I'd give it a failing grade.  This statement says it all: "@ChescoWx's refusal to share raw data or engage peer review undermines their case". How can you give "partial merit" to Chescowx's claims if you don't know what was done.   The reality is that Chesco's claims are flat-out wrong. The raw data shows plenty of warming in Chester County, but he doesn't know how to analyze it. Per chart below, Chescowx's monitoring network has changed significantly. The stations of the past tended to be warmer. Chescowx takes a simple average and Its well known that a simple average of a changing temperature station network skews the results. No wonder he can't find the local warming.

Recognize that it is hard for Grok to evaluate Chescowx, since the methods aren't fully disclosed and Chescowx is constantly overselling his analysis. A problem with Grok, though if it can't distinguish between BS and science.

There is another technical problem here that Grok should detect even if they know nothing about Chescowx's methods. Weather data and climate trends are correlated over hundreds of kilometers. This was established long ago by testing temperature data.  There is no indication that Chester county is behaving differently from  nearby counties.

Finally both NOAA and Chescowx have track records.  No one complains about NOAA's climate analysis in a technical forum. On the contrary, there are many papers that demonstrate sound results, including independent tests with synthetic data.  Meanwhile Chescowx has no publication in any technical forum and is constantly repeating climate denier talking points.

Grok's performance here makes me question the value of AI. Can provide general information but no insight. Also can't distinguish BS. Perhaps the training on twitter is the problem. Garbage in garbage out.

 

[ChescoWx]

19 minutes ago, chubbs said:

Interesting test of Grok. I'd give it a failing grade.  This statement says it all: "@ChescoWx's refusal to share raw data or engage peer review undermines their case". How can you give "partial merit" to Chescowx's claims if you don't know what was done.   The reality is that Chesco's claims are flat-out wrong. The raw data shows plenty of warming in Chester County, but he doesn't know how to analyze it. Per chart below, Chescowx's monitoring network has changed significantly. The stations of the past tended to be warmer. Chescowx takes a simple average and Its well known that a simple average of a changing temperature station network skews the results. No wonder he can't find the local warming.

Recognize that it is hard for Grok to evaluate Chescowx, since the methods aren't fully disclosed and Chescowx is constantly overselling his analysis. A problem with Grok, though if it can't distinguish between BS and science.

There is another technical problem here that Grok should detect even if they know nothing about Chescowx's methods. Weather data and climate trends are correlated over hundreds of kilometers. This was established long ago by testing temperature data.  There is no indication that Chester county is behaving differently from  nearby counties.

Finally both NOAA and Chescowx have track records.  No one complains about NOAA's climate analysis in a technical forum. On the contrary, there are many papers that demonstrate sound results, including independent tests with synthetic data.  Meanwhile Chescowx has no publication in any technical forum and is constantly repeating climate denier talking points.

Grok's performance here makes me question the value of AI. Perhaps the training on twitter is the problem. Garbage in garbage out.

 

 

LOL! Charlie knows my data is available and not hidden. Anyone can obtain and analyze the data. It is all public data. The data is the data! My methods are fully and completely disclosed.  My method is to only include the actual certified NWS Cooperative Data....nothing more! No data manipulation so no methods - just raw and the facts!!

[chubbs]

36 minutes ago, ChescoWx said:

LOL! Charlie knows my data is available and not hidden. Anyone can obtain and analyze the data. It is all public data. The data is the data! My methods are fully and completely disclosed.  My method is to only include the actual certified NWS Cooperative Data....nothing more! No data manipulation so no methods - just raw and the facts!!

LOL, you are using plenty of data that isn't "certified" NWS Cooperative, your own house to start with, also DEOS, airport ASOS, etc. You results can't be evaluated without knowing how the Chesco station network has changed with time and you don't provide that information. The first thing a technical group would want to see is something similar to the chart I posted above. How many of your readers know that the early Coatesville data is from the City of Coatesville or that the station cooled significantly when it was moved after the war. We've been discussing Coatesville for years and that was news to me until I found out for myself last year.

 

[ChescoWx]

40 minutes ago, chubbs said:

LOL, you are using plenty of data that isn't "certified" NWS Cooperative, your own house to start with, also DEOS, airport ASOS, etc. You results can't be evaluated without knowing how the Chesco station network has changed with time and you don't provide that information. The first thing a technical group would want to see is something similar to the chart I posted above. How many of your readers know that the early Coatesville data is from the City of Coatesville or that the station cooled significantly when it was moved after the war. We've been discussing Coatesville for years and that was news to me until I found out for myself last year.

 

Sorry Charlie - the DEOS data is actually runs operationally by NCEP and all of this data has been QC'd and added to NOAA's data archive and is being used by the NCDC. The data above was in reality run without "my house". It is only NWS QC data. So which of my data has not been certified by the NWS??

[chubbs]

7 hours ago, ChescoWx said:

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.

OK, but you need to understand the impact of the 1970 West Chester station move. Before 1970 there is a roughly 1.8F offset between West Chester and NOAA reflecting the warmer West Chester location in the middle of town. Per the chart below,  NOAA tracks West Chester closely for the entire 1895-1969 period once the offset is removed. After the move, West Chester cooled and the offset disappeared. Once again NOAA is spot on. After the station moves are accounted for, Coatesville and West Chester validate the entire NOAA series.  Phoenixville also confirms the warming over the 1895-2024 period, recognizing that Phoenixville ran too warm during the 1930s-50s, as we discovered last year. That is the vast bulk of the county long-term data supporting NOAA. Where's your validation?

[ChescoWx]

1 hour ago, chubbs said:

OK, but you need to understand the impact of the 1970 West Chester station move. Before 1970 there is a roughly 1.8F offset between West Chester and NOAA reflecting the warmer West Chester location in the middle of town. Per the chart below,  NOAA tracks West Chester closely for the entire 1895-1969 period once the offset is removed. After the move, West Chester cooled and the offset disappeared. Once again NOAA is spot on. After the station moves are accounted for, Coatesville and West Chester validate the entire NOAA series.  Phoenixville also confirms the warming over the 1895-2024 period, recognizing that Phoenixville ran too warm during the 1930s-50s, as we discovered last year. That is the vast bulk of the county long-term data supporting NOAA. Where's your validation?

I actually went back and looked at the NCEI adjustments specifically for the West Chester Station (there are some gaps on both the actual and adjusted figures for quite a few years especially in 1910's / 1970's and 1990's) - but from what we have they chilled every single year from 1880 thru 1969...then began additional cooling adjustments from 1979-83 of 0.6 degrees. NCEI then decided to alter the actual data with some of the largest cooling adjustments on record from 1987 thru 1990 of between 3 and 4 degrees each year. To cap it all off they then began to consistently warm the final 10 years of actual data with a steady 0.3 degree warming adjustment made to each of the years between 2007-2017.

[ChescoWx]

After our below normal temperature winter across the county we have now seen a much warmer than normal March. Through today we are at the 25th warmest March since 1893. With warmer days before we finish the month we could finish close to a top 10 warm Month. Below is the average temperature trend line for all March months since 1893. Average temperatures have clearly not changed much over the past 132 years across the area.

[chubbs]

When adjusted for the post-WWII station moves to a cooler location, the Coatesville data agrees very well with the NOAA county temperature series; over the entire record back to 1895.  The move-adjusted series uses raw data from 3 Coatesville stations since 1948 and NOAA bias-adjustments before 1948 when the 1SW station moved between several Coatesville city sites.  The Coatesville data, properly corrected for station moves, is a very good proxy for the county-average temperature. Once again NOAA is spot on. 

[ChescoWx]

On 3/29/2025 at 7:23 AM, chubbs said:

When adjusted for the post-WWII station moves to a cooler location, the Coatesville data agrees very well with the NOAA county temperature series; over the entire record back to 1895.  The move-adjusted series uses raw data from 3 Coatesville stations since 1948 and NOAA bias-adjustments before 1948 when the 1SW station moved between several Coatesville city sites.  The Coatesville data, properly corrected for station moves, is a very good proxy for the county-average temperature. Once again NOAA is spot on. 

Charlie but where is the station data to support applying downward adjustments to the raw data to lower than any and all stations in the county (including Coatesville) for 80+ straight years? Just show us which station they used as the proxy? Clearly it is not a station in Chester County? As we have all of those stations and for almost all of those years not one station in the entire county reported average temperatures as low as the recast altered "move adjusted" figures? Did the proxy station come from Berks, Lancaster, Montgomery? Which county and which station??