chubbs

When you focus on periods just before and just after station changes, the changes are have very strong statistical significance. Below is an example for Coatesville, using the monthly difference between Coatesville and West Chester.  On average, Coatesville was 2.5F cooler relative to West Chester in 1949-50 vs 1944-45, before the 1946 move. The stats show that the move-related change was highly significant statistically. 

https://dashboard.theclimatebrink.com/#global

1 hour ago, Mike Cycle said:

Observer Pyle made a remark about the station move on the January 1946 record.  Then there is a record gap through to October 1948, when the first PECO observation record appears.  I don't know if this is a real gap.

During the same time, observer Pyle is also taking stream gage measurements.  

The earliest address is shown as 547 E. Main, across from the high school, but observer Gordon owned 574 E. Main, and there is no 547 E. Main on current mapping.  https://arcweb.chesco.org/LR_INFO/lr_info.aspx?PARID=1606 03640000

 

The bulk of the post-war Coatesville cooling occurred in 1946 and 1947 which is consistent with a 1946 move. The cooling relative to West Chester and ABE also matches the timing and roughly 2F magnitude of the NCEI and Berkeley Earth bias adjustments that you posted above.

19 hours ago, Mike Cycle said:

Hi All, occasional lurker and Chester County resident here.   

I have done a deep dive on Coatesville 1 SW's history, working through the 530-1, the monthly paper records and property deeds for observers Gordon, Pyle and PECO.  I then compared the record of station changes with the breakpoints identified by NOAA/NCEI and Berkeley Earth Surface Temperature (BEST).  Claude helped with the graphic.

There is remarkable agreement between the history of changes at 1 SW and the breakpoints detected.   

edit:  The HOMR record for this station, (presumably pulled from the 1956 530-1 (itself likely pulled from the B44s)) is flawed.  

Very interesting. More evidence supporting bias adjustment in Chester County. The detailed documentation describes many more station changes than the NCDC documented. Indicates that the move from the City of Coatesville to Doe Run Road occurred in 1946. Per NCDC documentation Doe Run road site wasn't used until 1949.

Most of the Arctic Ice caps are having a record or near record melt year. The exceptions are Greenland which has above average losses and Ellsmere Island the which has below average losses. The loss distribution is consistent with the average temperature map since May 1. The Atlantic side of the arctic has been warm, while the Pacific side has been cool. Other than Ellesmere, the arctic ice caps are on the Atlantic side.

https://www.climato.uliege.be/cms/c_5855702/fr/climato-arctic

On 7/30/2026 at 5:04 PM, ChescoWx said:

You limited your local review to only 3 chesco stations - My review with AI had more local stations than you including Sadsbury, Devault 1W, Kennett Square and Morgantown- I focused on only local stations in or on the immediate borders of chesco like Morgantown/Elverson to better identify if there is any actual support based on the raw data that was able to identify if any significant drifts occurred at any stations near Coatesville 1SW to suppor the NCEI chilling adjustments. The statistical analysis clearly does not support the NCEI adjustments for Coatesville 1SW
 

Nope. Your station selection and AI's method are both faulty.  The key period for evaluating the Coatesville post-war moves is 1945-1950, the period immediately after the war when the moves occurred. I didn't include Sadsbury, Kennett Square, and the other Chesco stations you listed, because they didn't operate in that period. After reading the AI analysis more closely, I see that AI used regression analysis to make its determination. As I said above, that is a poor choice because the station moves are focused in time not spread out over a long period of time. AI based its conclusion largely on regression results from Devault and Morgantown both of which didn't start operating until 1951. AI is drawing a conclusion from two stations that don't provide any information on the Coatesville post-war moves; because, they weren't operating at the time. A clear indication of a faulty analysis approach. 

With 2 of the 3 Chesco stations, Caotesville and Phoenixville, both experiencing spurious cooling between 1945 and 1950, It is important to include non-Chesco stations in the analysis.  That's why my analysis included 10 non-Chesco stations. The non-Chesco stations and West Chester agreed completely with West Chester in identifying the common weather signal between 1945 and 1955. Having the common weather signal makes identification of the Coatesville and Phoenixville moves easy; and, with plenty of stations is highly significant statistically.

A faulty analysis does not disprove a good one. To disprove my analysis, you need show that the significant difference between the move and non-move stations in the 1945-55 period changes when more data is added. Good luck with that, the P value is 0.0001.

Extended the stat analysis to the 1970s to include the West Chester move. Two comparisons were made: individual years using 1972 minus 1945 as a metric, and a 5-year average using 1971-75 minus 1941-45 as a metric. The results are the same for both metrics: the Chester County COOPs are significantly different statistically from the non-Chesco stations.   As was the case for the 1950s there is no overlap between the move and non-move stations. The Chester County COOPs have spurious cooling of over 2F. This analysis and the one above provide strong evidence that the larger NCEI bias adjustments are very robust statistically.

This analysis also shows the problems with AI. As Don stated above AI is handy for an initial screening; but, AI is unlikely to give a complete and accurate answer to a complex problem.

Here's a closer look at the statistics of the Coatesville and Phoenixville post war moves. Differences between stations was removed by setting 1945 to zero to facilitate comparison between stations.

Coatesville and Phoenixville behaved differently than the other stations, cooling relative to the other stations at the time of the moves; and, remaining cooler after the moves..

Using the temperature difference between 1945 and 1952 as a metric, Coatesville and Phoenixville are significantly different from 11 stations without station changes. The P value is 0.0001 which means that there is virtually no chance that Phoenixville and Coatesville are the same as the other 11 stations. Furthermore Phoenixville and Coatesville are significantly different from the other stations in every year after the moves in this period.

Finally note also the good agreement among the 11 stations without changes. Chester County shares the same weather with a much larger region. Many stations can provide useful information on the Chester County COOP stations; which makes the identification of Chester County station changes very robust.

On 7/26/2026 at 12:19 PM, ChescoWx said:

@chubbs below is some more detailed research and some solid evidence below to find if the single station NCEI applied cooling adjustments to Coatesville 1SW are supported by surrounding stations. For site moves and TOB changes.  The final finding is that the clean evidence points to a real, still-unexplained cooling signal during at least the 1952-1982 portion of this period -- not caused by a location move or TOB change (neither was validated), Also Station relocation, across the 88-year period with usable NCEI-adjusted data (1895-1982) spanning the station's six relocations, never shows up as an independent, validated driver of any adjustment on its own. Once the confounded stations are set aside, the clean evidence actually points toward a real, unexplained cooling trend during at least the 1952-1982 portion of that period — just not one caused by a location move or TOB change. Take a look at the below and let me know what this analysis is missing? This is only for Coatesville 1SW raw vs the NCEI adjusted for that individual station. Based on this I will look to see if the other NCEI station adjustments to the raw data are valid and supported by the data. I have much more supporting data so feel free to ask and I will provide more data.

Coatesville 1SW: Overall Testing Approach and Findings
Overall Testing Approach
1. Pulled Coatesville 1SW's exact location and observation-time history from NCEI's HOMR database -- six site relocations and five distinct observation-schedule eras spanning 1888-1982, independently verified against the live HOMR page and a user-provided satellite image of the final site. 2. Initially tested using NCEI's own adjustment as the yardstick (comparing how the adjustment changed before/after each documented event). This is where standard time-of-observation-bias (TOB) theory first looked promising, then broke down: an all-morning schedule (1946-1982) should need little or no adjustment under TOB theory, not the sustained cooling actually applied. 3. Switched to raw-data-only testing -- the methodologically correct approach, since testing against NCEI's own output can't establish whether that output was justified in the first place. For each of Coatesville's 7 documented events, compared Coatesville's raw record against every available nearby raw-data station in clean, non-overlapping before/after windows. 4. Required cross-validation across independent references -- an event only counted as a real, validated discontinuity if multiple neighbor stations agreed on the direction of the shift, not just one. This is the key filter separating genuine breaks from ordinary weather noise. Expanded from 2 to up to 4 reference stations (West Chester 2 NW, Phoenixville 1E, Kennett Square, Sadsburyville) depending on era. 5. Result: only 3 of 7 documented events passed. 1916, 1922, and 1946 showed real, multi-station-confirmed shifts. 1902, 1910, 1930, and 1948 did not -- either unconfirmable (no second reference available) or references actively disagreeing (the signature of noise, not a real break). 6. Built a raw-justified adjustment chain using only those 3 validated steps, anchored to the stable, unchanged 1946-1982 era as a zero baseline, and compared it decade-by-decade against NCEI's actual adjustment, with formal significance testing at each step.
Overall Finding
NCEI's adjustment ran colder than the raw evidence supports in every single decade from the 1890s through the 1980s, with no exceptions. Restricting to the 8 complete decades (1900s-1970s), 6 of 8 reach conventional statistical significance (1900s, 1910s, 1930s, 1940s, 1950s, 1960s); the other two (1920s, 1970s) don't reach significance individually but still point the same direction. Pooled across all 88 years, the effect is overwhelming (p < 0.0001). The size of the over-cooling does not trend over time -- it is a persistent, roughly steady bias, not something that worsened or improved across the record. See "Raw vs NCEI vs Corrected Trend" for the full year-by-year data, decade table, and significance tests.
Adjustment Broken Out by Rationale (all 7 documented events)
Of NCEI's stated PHA rationale categories, only station relocation and observation-time change could be directly tested here. Only 3 of the 7 documented events show real, cross-validated evidence.
Event	Rationale Category	Validated?	Contribution to the Adjustment Chain
1902	Location move	No -- single reference, unconfirmable	0 (no independent step; folded into the 1902-1915 era)
1910	TOB change	No -- 2 references disagree in direction	0 (no independent step; folded into the 1902-1915 era)
1916	Location move + TOB shift (simultaneous)	Yes -- 4 references agree	+0.36°F, partially OFFSETTING (applies to 1902-1915 only; can't attribute to either cause alone)
1922	TOB change (location unchanged)	Yes -- 3 references agree	-1.28°F, the entire step applied to 1922-1945
1930	Location move	No -- 2 references disagree in direction	0 (no step between 1922-1945 and 1946-1982)
1946	TOB change (location unchanged)	Yes -- 2 references agree (thin sample)	Combined with 1922: the entire -2.11°F applied to 1916-1921
1948	Location move	No -- 2 references disagree in direction	0 (1946-1982 treated as one continuous baseline era)
PRACTICAL ANSWER: of all 7 documented events, only 3 (1916, 1922, 1946) show real, cross-validated raw discontinuities -- 2 of those 3 (1922, 1946) are TOB changes with no location change; the third (1916) is an inseparable combined event. The 4 location-related events (1902, 1910, 1930, 1948) show no validated evidence at all. Station relocation, across the 88-year period with usable NCEI-adjusted data (1895-1982) spanning the station's six relocations, never shows up as an independent, validated driver of any adjustment on its own.
Important: What "TOB" Explains Here, and What It Does Not
The "TOB" label in the table above explains why the RECONSTRUCTED adjustment chain steps DOWN between eras (e.g. why 1922-1945 sits 1.28°F below the 1946-1982 baseline) -- it describes validated ONE-TIME transitions in Coatesville's own raw record relative to its neighbors. It does NOT mean TOB explains or justifies NCEI's actual, continued adjustment behavior within any era, including 1946-1982. If anything, classic TOB theory says a single MORNING reading (used throughout 1946-1982) should need a mild WARMING correction, not the sustained cooling NCEI actually applied that whole period (-0.82°F in the 1950s down to -0.21°F in the 1980s). That makes NCEI's continued cooling during 1946-1982 LESS justified under TOB theory, not more -- see "No Basis Found for Any Cooling Adjustment During 1946-1982" below, which is a separate, additional finding from the step-transition analysis above, not an extension of it.
Important Caveat: What "Corrected" Does and Does Not Establish
The "Corrected" series treats the 1946-1982 era as a zero-adjustment baseline because it is the final, most stable era with no further validated events. This is a standard homogenization convention (adjust the past to match the present), but it is NOT the same as proving 1946-1982 is itself free of bias. Under classic TOB theory, a single MORNING reading (used throughout 1946-1982) should carry a mild COLD bias, not be bias-free -- meaning the true fully-corrected record might need the entire chain shifted warmer, including the baseline era, which would make the required cooling for the earlier eras SMALLER than calculated here, not larger. This analysis establishes the RELATIVE size of each validated step; it does not establish an absolute, bias-free zero point.
No Basis Found for Any Cooling Adjustment During 1946-1982
Separately from the baseline-anchoring question above, a cleaner and more direct claim: within the 1946-1982 period itself, location and observation schedule were BOTH stable throughout (no validated events of either kind). An additional check for undetected drift WITHIN this period (not just at its boundaries), using every available overlapping reference station, found no consistent evidence either: Devault 1W and Morgantown each show a significant COOLING drift relative to Coatesville (-1.15 and -0.26 F/decade), while West Chester 2 NW shows a significant WARMING drift in the OPPOSITE direction (+0.52 F/decade), and Phoenixville 1E shows no significant drift at all. By the same cross-validation standard used throughout this investigation, this disagreement means no validated drift exists either. CONCLUSION: with no validated location change, no validated TOB change, and no validated drift anywhere in this 36-year window, there is no raw-data basis found for ANY of NCEI's cooling adjustment during 1946-1982 -- not the varying decade-by-decade amounts NCEI actually applied (ranging from -0.82°F in the 1950s to -0.21°F in the 1980s), and not a flat adjustment either. This covers what could be directly tested here -- station moves and TOB, two of NCEI's four stated PHA rationale categories. No evidence of an undocumented instrument or land-use change was found either, but the available data could not specifically rule those out.
Reference Station Confound Check (added later)
The cross-validation method above assumed the reference stations (West Chester 2 NW, Phoenixville 1E, Kennett Square, Sadsburyville, Devault 1W, Morgantown) were themselves stable during the windows used to test Coatesville. Checking each one's own HOMR history directly found this was not fully true.
Reference Station	Own HOMR History	Confound Found?
West Chester 2 NW	Moved slightly in early 1921; further moves in 1936, 1955, 1970, 1998, 2009, 2016	YES -- 1921 move overlaps the 1922 test's "before" window (1918-1921); 1955/1970 moves fall inside the 1946-1982 interior-drift window
Phoenixville 1E	Stable 1915 to 1948-05-01, then moved	PARTIAL -- clean for 1922/1930/1946; its 1948 move falls inside the 1946-1982 interior-drift window
Kennett Square	Moved between 1916-11-30 and 1919-01-01	YES -- overlaps the 1916 test's "after" window (1917-1920)
Sadsburyville	Single location, entire 1910-1922 operating life	None -- clean
Devault 1W	Single location, entire 1951-1989 operating life	None -- clean
Morgantown	Single location, entire 1951-1987 operating life	None -- clean
REVISED CONCLUSIONS: (1) The 1916 finding still holds -- Sadsburyville (fully clean) and West Chester (clean for this specific window) both independently confirm it; only 1 of its 4 supporting references (Kennett Square) has a confound. (2) The 1946 finding is unaffected -- both its supporting references were stable throughout that specific window. (3) The 1922 finding is WEAKER than originally presented: it only ever had 2 supporting references, and the West Chester one is now known to be confounded by West Chester's own 1921 move. Phoenixville alone remains clean and still shows the same direction, but that is one clean reference, not the two-station cross-validation required elsewhere in this analysis -- treat 1922 as a lower-confidence, single-reference finding, not a fully cross-validated one. (4) MOST IMPORTANTLY, this partially reverses the "No Basis Found for Any Cooling Adjustment During 1946-1982" conclusion above: the earlier interior-drift check found 4 references disagreeing and read that as noise, but 2 of those 4 (West Chester, Phoenixville) turned out to have their own undocumented moves inside that exact window, while the 2 clean references (Devault 1W, Morgantown) both agreed on a real cooling drift (-1.15 and -0.26 F/decade). Once the confounded stations are set aside, the clean evidence points to a real, still-unexplained cooling signal during at least the 1952-1982 portion of this period -- not caused by a location move or TOB change (neither was validated), but a genuine physical signal nonetheless, not simply noise as previously stated.

A good first step in using the raw data to identify station changes, with several station changes identified. What's missing are most of the station changes in Chester County. A couple of issues cause station changes to be missed: 1) It appears that only station moves and TOB  changes described in NCDC documentation were investigated. There are two problems: NCDC documentation is incomplete and there are many other causes of station changes besides moves and TOB. 2) The common weather signal across stations is not identified. Having this signal facilitates the identification of station changes.  and 3) Stations outside of Chester County are not used. Comments 2 and 3 work together. It easier to identify the common weather signal with more stations. The fact that many station changes are missed causes station comparison to break down.  In summary the analysis is much less thorough than NCEI's

A couple of comments on write-up itself. First like most AI its very wordy and wishy-washy. Too long to review carefully in detail. More importantly, there are no charts or quantification of any kind. Impossible to verify or compare to other results without hard numbers.

11 hours ago, Typhoon Tip said:

 it’s tentative but we may be seeing a spring 2023-like global thermal surge beginning. Air and sea presently lurching in tandem.     

That's the $64 question for this year. Will we see the same type of "gobsmaking" global warming we saw in 2023 or will this year behave more like a typical strong/super el nino. So far I'd put this year in the typical camp, with global air temperatures lagging the rise in ENSO and global SST.  

One aspect that has held back global temperatures in the past 2 months has been very cold temperatures in Antarctica associated with a strong AAO+ regime.  In 2023 AAO was strongly positive in January (see AAO table below), reversing by March, and staying negative through September. So the AAO boosted global temperatures in the first half of 2023 but are holding them back this year. One of the many factors that contributes to a different outcome in 2026 vs 2023. If the AAO reverses in August there will be an added boost in global temperatures on top of ENSO. We will see.

2023  2.304  0.554 -0.258 -0.921  1.452 -0.438 -0.818 -0.038 -1.050  0.535  0.097  1.510
2024  0.922  1.043 -0.058  1.005 -0.073  0.210 -0.597 -2.150  0.098 -0.567  1.020 -0.826
2025 -0.080 -0.271  0.733  1.138  0.509  0.209  0.753  0.357 -0.709 -1.236 -1.324 -1.136
2026  0.848  0.489  0.492 -0.125  0.544  2.506

20 hours ago, ChescoWx said:

 @chubbs you didn't answer my previous post  "The problem that NCEI and Charlie has is that in reality Coatesville was home to Lukens Steel — a continuously operating steel mill since 1810, one of the largest specialty steel producers in the country, still headquartered there through 1982 and beyond this is a station within a mile of significant industrial activity! This of course is a textbook candidate for a persistent local warm bias — waste heat, paved/industrial surfaces, altered local airflow. But here's the problem for NCEI and Charlie to address -  the Coatesville 1SW move explanation doesn't match the data adjustments made by NCEI. The facts are that Lukens was arguably at its industrial peak in the postwar decades (1946–82) — yet that's exactly the period where the adjustment (and the residual) is smallest, not largest. If growing industrial heat were the main driver, the bias should have gotten worse over the 20th century, not better. So it is not TOB adjustments and clearly not site moves behind these adjustments so what say you Charlie?

OK lets see what the raw data says. After all bias adjustments are based solely on raw data. If the the steel mill impacted the Coatesville station it would be reflected in the raw data and in the NCEI bias adjustment.  Below is a plot of Coatesville 1SW minus West Chester and the Coatesville bias adjustment (right axis). A station change at either Coatesville or West Chester causes a sudden change in relative temperature of Coatesville and West Chester. While a growing steel mill or an urban heat island in one of the towns would cause a gradual change in the difference between the two stations.

There are many large sharp changes in Coatesville's temperature relative to West Chester. These are all station changes. There is no indication of a gradual long-term trend so a large change in the steel mill impact can be ruled out. Station changes are the primary cause of Coatesville's (and West Chester's) cooling.

The Coatesville bias adjustment (right axis) tracks the raw temperature data at Coatesville and West Chester closely, capturing the each wide swing due to station changes.  The only exception to the close tracking is when West Chester had station changes: 1915, the 1920s, the 1960s and with the West Chester move in 1970. 

Both stations start out at about the same temperature in the 1890s. Between 1894 and the 1960s,  most of the chart movement is due to Coatesville station changes as West Chester experienced relatively minor station changes. After 1920 Coatesville cools relative to West Chester. The change is anything but gradual with several large swings due to station changes.  From the late 1940s to the late 1950s Coatesville is 2F cooler than West Chester. The rural Doe Run Road site is the coolest Coatesville station location. Coatesville warms by roughly 0.5F around 1960. After 1960 the main station changes are at West Chester, ending in the 1970 move which cools West Chester to down Coatesville's level.   Note that station changes can be warming or cooling, but on balance both stations cooled significantly over the period due to station changes.

This exercise is another feather in NCEI's cap. The Coatesville and West Chester raw data shows that bias adjustments are needed and accurate in Chester County.  No surprise if you have been reading the thread.

13 hours ago, ChescoWx said:

I removed Phoenixville and no statistical change to the raw data at all!!

You left in all the other station changes. Your current station population is much cooler, more rural, and higher elevation compared to the older COOPs. All the COOPs were in towns before the Coatesville post-war move.

The more I look at the Chesco COOP data the more problems I find. Per NCDC the Coatesville 1SW shelter was made of window blinds before 1902. The "window blinds" apparently produced a big spike in 100F days in 1900, which wasn't observed in West Chester or Philadelphia. After the "window blind" spike, the Coatesville 1SW data is similar to Philadelphia and West Chester with no indication of the pronounced downtrend you are showing. Once again the local raw data doesn't agree with the climate trend you are reporting. 

11 hours ago, ChescoWx said:

Don you may want to look at my last post and help answer these gaps or as you call them "breakpoints" on why on a single station basis with rigorous long term station data such as Coatesville 1SW the annual supporting data from raw to adjusted for 99.7% of years from 1895 through 1971 was chilled by NCEI. We can see it is certainly not TOB and not site moves so what is it and why can't we quantify it if the science is so transparent by year with attribution to all of the potential reasons for chilling the data basically every single year for this station. Where is the NCEI detailed file explaining this particular stations unique adjustments by year?

Yes TOB is not an issue at Coatesville. The big issue is station moves and other changes. The NCDC chart below shows all the locations of the Coatesville COOP station. The station numbers increase as you go back in time: Site 1 is the newest and site 6 is the original site. The most consequential move was the last one from site 2 in the City of Coatesville to to a rural site on Doe Run Road. The pictures illustrate the change. As documented in the Chester County thread roughly 2F spurious cooling with this move. 

photos

July to-date satellite OiSST has reached the peak anomaly from the 2023-24 nino.

7 hours ago, GaWx said:

Thanks, Don! 

 This is the first time I can recall becoming aware of this observation time bias potentially causing overcounting of high max temps due to double counting of these highs as a result of observers getting 24 hour max prior to 1940s during late afternoon, near the time of most very hot highs, as opposed to mainly doing it near sunrise 1940s+.

 Do you have a source with more details on this? How widespread was this practice of getting 24 hour max late in afternoon? Do you by chance know how often this would result in double counting hot highs?

We have a good example in Chester County PA. Here are high temperatures for July 1934 and 1936 for 4 local stations. Phoenixville ran much warmer than the other stations probably due to poor shelter placement. Phoenixville also carried over hot temperatures to the next day when the other stations cooled. This shows that the Phoenixville max/min thermometer was flipped near the time of peak temperature while the other stations were not. Phoenixville completely dominates the # of 95 and 100F days in Chester County in the 1930-40s, but the data is spurious. This is why I don't trust plots of historic max temperatures  in the US, unless the data has been scrutinized for bad data. Only takes one or two  bad apple stations to create a spurious result. 

17 hours ago, ChescoWx said:

A member asked for an analysis of 100 degree days by decade since the 1890's. This is normalized as days per station per year (total 100°F+ days across all stations in a decade, divided by the number of station-years of data in that decade) rather than a raw sum — otherwise a decade with 22 stations would look "hotter" than a decade with 4 stations just from having more thermometers out there, which would be misleading.

The pattern holds up clearly at the county level, same as it did for individual stations: the 1930s stand out sharply at about 1.1 days per station per year — nearly double any other decade — consistent with the well-documented Dust Bowl-era heat. From there the rate declines fairly steadily, bottoming out near zero in the 1970s and again in the 2020s (0.01 and 0.02 days/station/year respectively), with the 2000s-2010s sitting in a modest middle range around 0.11–0.15.

Worth flagging directly: the two lowest decades in the entire 130-year record are the 1970s and the current 2020s — and the current decade of the 2020s (partial decade).

Nope no dust bowl in Chester County, just Phoenixville with a bad shelter location. Philadelphia and West Chester don't agree at all with your plot. Not surprising since once again you are confounding station changes and weather. East Nantmeal and West Grove are a little different than the City of Coatesville or West Chester don't you think? 

18 hours ago, ChescoWx said:

AI knew the Chesco COOPs are included in the SE PA climate division but did not feel it material enough to change the statistical fact that the raw data at Chesco was cooling the same as the surrounding stations so again no need for further cooling. Plus with all those AM TOB readings at Coatesville and West Chester why didn't NCEI apply some warming adjustments? Again only non-stop chilling adjustments. 

Clear that you do not understand the science behind bias adjustments. Bias adjustments are not made in an ad hoc manner or to raise or lower the temperature of a station. Bias adjustments are only made to correct station changes. If the station observation time doesn't change, then no adjustment is needed. Adjustments are based solely on raw data. A station has to change with time in a manner that is different from all other stations that experience the same weather. The goal is to include weather and exclude station changes when calculating long-term climate trends.

The only way to evaluate bias adjustments is to inspect raw station data at the time of the station change. Here's an example using the West Chester 1970 move. The old West Chester COOP shut down in December of 1969 and re-opened in May of 1970 at a new location. Subtracting Coatesville from West Chester isolates the relative temperature changes at the two stations at the time of the move.  The raw data shows that the new West Chester site cooled by significantly relative to Coatesville after the move. That's all the proof needed to identify a major station change at either Coatesville or West Chester.  We know from raw data from Phoenixville that West Chester is the guilty party. The Chesco raw data clearly shows that West Chester cooled significantly after its 1970 move.

The NOAA bias adjustment is in complete agreement with the raw data from Coatesville and West Chester.  That shouldn't be surprising. NCEI is using all the raw data that experiences the same weather as West Chester, hundreds of stations potentially. I've looked at multiple large station changes at the Chesco COOPs and NCEI nails every one.

Note that NCEI is asking a similar question as your AI analysis. Does West Chester respond to local May 1970 weather in the same as the other regional stations? However the NCEI procedure is much more targeted than AI, is using more data, and it is using the right conceptual model. The temperatures at West Chester do not vary independently of the temperatures at Coatesville or other stations. This gives the NCEI analysis much more power. It can correctly flag the West Chester move as a major station change. While your AI analysis can not. 

The raw data is the final arbiter and in this case NCEI is clearly superior to AI.

19 hours ago, ChescoWx said:

Of course @chubbsWidening the interval to 1941 - 1975 does not change the previous answer. Both series show a real, statistically significant cooling trend on their own — this isn't noise, and it fits the well-documented mid-century cooling that shows up across the eastern US from the 1940s into the 1970s.

Are the two trends statistically the same?

This is the more interesting question, and the answer depends on the test:

• Naive comparison (treating the two trends as independent): the difference in slopes (−0.66 vs. −0.46 °F/decade) gives t = −0.92, p ≈ 0.36 — not remotely significant. By this test they're indistinguishable.
• Paired comparison (the right test here, since both series describe the same regional weather in the same years — they're correlated at r = 0.83, so a paired test on the year-by-year difference is more powerful): the difference series trends at −0.021 °F/yr (−0.21 °F/decade), 95% CI [−0.042, +0.001], p = 0.057.

So the more rigorous test lands just on the wrong side of the conventional 0.05 cutoff — the station data cooled somewhat faster than the division average, and that gap is close to, but doesn't quite clear, statistical significance. The honest read: the two trends are not clearly, statistically different so no need to cool the raw data further as they are already a strong match.

Repeating what  I said above garbage in, garbage out.  Your analysis and AI's conclusion is faulty. You aren't telling AI that the Chesco COOPs are included in the SE PA climate division. You can't conclude that Chester County is the same as the non-Chesco stations if you include Chester County with the other stations. Second the regression slopes depend on the end-date. You need to include enough years before and after the moves for the station moves to be fully reflected in the regression. For the period 1941-1975 I get a much bigger difference in slopes -.69 for Chesco and only -.32 for the Division. Excluding Chester County from the Division would lower the Division slope further. Finally AI already has a Pvalue of 0.057, i.e, there is a 94% chance that Chesco is different using your faulty comparisons. Correct the errors and the P value will shrink considerably.

My biggest complaint though is that your statistical model is inadequate. Temperature observations are highly correlated across a region because all stations experience the same weather. The Chesco and SEPA stations should be very close. Instead the chart clearly shows that Chesco COOPS cool significantly vs the SEPA Climate Div. The different temperature response by the Chesco Coops is closely associated with the timing of station moves. End of story.

19 hours ago, ChescoWx said:

So we did a little fact check on Charlie's claim that the raw data cooled more than surrounding stations.....The facts are that the raw cooling data is well supported by the surrounding regions! Below is the AI review of the raw data for the 3 stations in question. 

What that regional record shows for 1946–1970

Using Penn State's State Climatologist office data (built from this same NCEI divisional dataset):

Metric	Official SE PA Division (Chester/Berks/Montgomery/Lancaster region)	Your 3-station Chesco composite
1946 annual avg	54.0°F	—
1970 annual avg	52.4°F	—
Trend	−0.093°F/yr	−0.083°F/yr
Total change, 1946–1970	−2.23°F	−2.00°F
R²	0.365	0.352
p-value	0.0014	0.0018

That's a remarkably close match — both in direction, magnitude, and statistical significance. Individually, Phoenixville 1E (−2.34°F, p=0.0008) and West Chester 2NW (−2.48°F, p=0.0014) track the regional figure almost exactly; Coatesville 1SW is a bit weaker (−1.17°F) and only marginally significant on its own (p=0.055), but still points the same direction.

Bottom line: Yes, the cooling is well supported by the surrounding region. This is a case where the "raw" county data and the "official" broader regional data agree closely

So @chubbs if the cooling in the raw data is statistically the same as the surrounding data why did NCEI choose to chill the raw data further in each and every year between 1946-1970??

Nope. The Chesco COOPs cool significantly relative to the SE PA Division data from the PA climatologist. Regression isn't a good tool because the station changes are sudden not gradual and you picked an interval that started after the initial Coatesville move and ended before the West Chester move took full effect. If you widen the interval to 1941-1975, the difference in slope is large.

Per table below, comparing the five years before the first move and the five years after the last move, the Chesco COOPs cool by 1.7F relative to the SE Pa Division. Note that the Pa SE Division includes the Chesco Coops so the two items compared are not independent. For that reason it is not surprising that the delta for the SE PA is slighly smaller than ABE. 

Funny seeing your persistent effort to dismiss what the the raw data from Chester County clearly shows.  The 3 stations each cooled significantly after the 1945-1970 moves: first Coatesville cooled relative to Phoenixville and West Chester; then Phoenixville cooled relative to Coatesville and West Chester; and finally West Chester cools relative to Coatesville and Phoenixville.  Clear as day in the raw COOP data.

1 hour ago, bluewave said:

It temporarily removes warmth from around the equator in the ENSO regions. But the heat release following each super El Niño finds its way into the adjacent oceans and land areas.

You can see how the oceanic and atmospheric heat increases following each El Niño back to 1997-1998.  This is why the global baseline temperature sets a new record during each super El Niño.

The temperatures pullback slightly in the following years but a well above the previous years which were neutral or La Niña. 

The 1997-1998 event below was followed by warming in the Arctic. The heat release from the ENSO regions in 2015-2016 founds its way into the 30N to 60N mid-latitude regions. This is the persistent -PDO that we have seen since around 2019.

Also notice how the Nino 1+2 and other regions didn’t fully release all the heat following the 2023-2024 before recharging with more heat only 3 years apart. So this is a first in our modern climate era. That’s why when I saw the record WWBs in the spring it wasn’t a surprise when the ENSO forecasts started showing another super El Niño so soon.

So the big to watch story going forward following this strongest event on record is what areas will see the greatest temp jumps in the late 2020s? 
 

Plenty of ocean heat to be re-distributed, as ocean heat content increased at a rapid pace in the first quarter. The ocean as a whole is warming much faster now vs 97/98.

17 hours ago, ChescoWx said:

I had AI review the raw unadjusted data of those 3 stations from 1945-1980, The Bottom line: the direction, timing, and general shape of the cooling at Coatesville 1SW, Phoenixville 1E, and West Chester 2NW was found to be consistent with the raw data of surrounding stations during the well-documented mid-century cooling seen across the Northeast and eastern U.S more broadly. The magnitude at your stations is plausible relative to hemispheric averages — which fits, since this region was one of the more prominent expressions of that cooling episode with more local variance than a regional composite.

Your AI isn't very well informed about the changes with time at the Chester County COOP stations. That's on you. Garbage in, Garbage out.

The raw data clearly shows that Coatesville, Phoenixville, and West Chester cooled by roughly 2F after station moves in the 1946-70 period.. As discussed above, The roughly 2F cooling at the 3 Chesco COOPs matches the 2F cooling relative to ABE. The station move cooling isn't a small change. Very easy to see in the raw data. 

Good 2-part blog from last year on Canadian wildfire history outlining the role of forest management and climate. Canadian forest fires are less numerous than in the past; but, larger and burning a wider area. The cause of fires has transitioned from mostly man-made in the past to mostly ignited by lightning today.

https://thetradeoff.substack.com/p/north-americas-forests-used-to-burn

https://thetradeoff.substack.com/p/part-2-many-of-north-americas-forests

21 hours ago, ChescoWx said:

Charlie you keep avoiding my question for the years I am highlighting in the chart  1927-1951. There are 16 years before 1942.  To make my question clearer I updated the chart (see below) to add the delta between Allentown and Chesco. You again never answer the question so I will ask it again later. By the way in looking at the surrounding nearby stations at the Navy Yard and Point Breeze it looks clearly like opening of the more rural location with less runways and building etc. at the new PHL Airport resulted in the new site being 1.6 degrees colder than the neighboring Navy Yard in 1941 and continued to run at least 1 degree colder than Point Breeze every year through 1951. So you have to  wonder why NCEI failed to warm the new PHL airport site during those years due to the station move to a more rural/colder location? But even without the likely need to warm PHL for those years - the facts remain the same PHL was and is always warmer than average Chesco in every single year except one (1943) ! So I will try again - a simple question why is all of Chester County altered and adjusted to an average temperature for 17 years during this period to colder than Allentown PA?? This is 2 counties north and 50 miles away? Not just Coatesville Charlie - the average of all of these stations. Sorry Charlie in no world should the average temperature for those 25 years have Allentown at 51.8 and the all Chesco Avg. colder at 51.7  Why is NCEI correct based on their adjustments that Chester County should be altered and adjusted to be colder than Allentown for a quarter of a century based on these chilling alterations to the data? Can you answer that?

Why is NCEI cooler than the Allentown COOP? Because the Allentown COOP is in downtown Allentown and runs warmer than the Allentown Airport. NCEI has Chester County exactly where it should be: warmer than the Allentown Airport and cooler than downtown Allentown.

Per the Table below, NCEI does a much better job of tracking the Allentown Airport (ABE) than the Chesco COOP average. Two five-year periods are chosen: 1941-45 before the first big Chesco station move in 1946 (Coatesville) and 1971-75 just after the last move in 1970 (West Chester). NCEI is 0.4-0.5F warmer than ABE, before and after the station moves. While the COOP average cools by 2F relative to ABE. The 2F cooling matches the roughly 2F cooling at the individual Chesco stations and is completely spurious.

Once again the raw data shows that, by removing station moves, NCEI is far superior to the COOP average.  

As I said above the pre-1945 Chesco COOPs are very warm. It isn't only the City of Coatesville either. Phoenixville ran very hot on sunny days and West Chester was in a built-up town location. All 3 stations cooled significantly after post-1945 station moves. 

On 7/11/2026 at 12:37 PM, ChescoWx said:

Not sure where you are getting this assertion or I guess it may be a feeling... that "the average of Phoenixville, Coatesville and West Chester is as warm as PHL airport in the early 1940's. So let's as I always do go to the actual data for the Chester County stations vs the PHL Airport and the 2 stations relatively close to PHL prior to the temperature being recorded at the airport in 1941. Over the 25 years we are focusing on 1927-1951 the raw average temperature data of those 3 Chester County stations vs PHL was clearly always colder in each and every year!!  So sorry Charlie the average is most certainly not as warm as PHL at all. In fact  Chesco in those years is running as cold as much as 4 degree colder than the PHL stations. With during the entire period the average running between 1.1 and 2.5 degrees colder. We can now put to bed this false claim that Chesco was running as warm as the PHL airport area from 1927-1951. Of even more interest and brings additional questions is how the heck for most of those 25 years did NCEI decide that Chester County is actually colder than Allentown 50 miles north in Lehigh County??

 

You aren't looking at the chart I posted. Per your table the Chesco COOPs and the Philadelphia Airport both averaged 54.1 between 1942-44. After 1945 the large cooling moves started in the Chesco COOPs. By the early 1970s the COOPs were almost as cool as ABE. Clearly shown in the chart I posted above. If you don't correct for station moves, the raw COOP data is unusable for climate purposes in this post-war period.

Not sure why this is so hard for you to accept. The Coatesville stations below, 1930-1945 and 1949+ are very different. One is much cooler than the other and the local raw data shows it. You can't treat these two sites as the same station, an adjustment is needed. That's why NCEI gets the right answer for Chesco and you don't.

7 hours ago, donsutherland1 said:

The chart implies that the mix of stations is different depending on the year. Changing mix, alone, means one is not consistently calculating the same mean across time.

Notice that Charleston SC and New Haven, CT are "rural" stations. There were large reverse heat island effects at 2 of the COOP stations in "rural" Chester County. Bottom-line US historical weather data is very inconsistent. It needs to be carefully analyzed not cherry-picked.