ChescoWx

Thanks! Mike, that is really the crux of the discussion and I think we've arrived at the same place. "The magnitude of the adjustment is inferred, but not well documented in the sense that it has been verified by field measurements" - that is precisely the claim I've been making, and I appreciate you putting it plainly rather than trying to make me prove it. And thank you for the two references. Parallel observation is the gold standard and I hadn't seen either paper. Vincent 2018 is the one I want most - 88 site pairs with five-year overlaps quantifying how much uncertainty homogenisation introduces against directly measured ground truth is exactly the number missing from this discussion. If the answer is small, that's a real argument for confidence in the method that isn't an appeal to benchmarks on synthetic networks. If it's large, that's worth knowing too. Either way it's measured rather than modelled.

Most spots dry out a bit today with sun returning we could see a couple showers toward evening especially across southeast parts of the area. A bit less humidity today and especially tomorrow before the chances of showers increase again by Thursday afternoon into the night. The weekend looks to continue shower chances as we continue to erode any drought concerns across the area.

Most spots dry out a bit today with sun returning we could see a couple showers toward evening especially across southeast parts of the area. A bit less humidity today and especially tomorrow before the chances of showers increase again by Thursday afternoon into the night. The weekend looks to continue shower chances as we continue to erode any drought concerns across the area.

A general 1" to 3" of rain fell across the area yesterday and overnight with 3.18" recorded at the Warwick DEOS. We could see some sun retrun this afternoon with a slight chance of a shower toward evening before we clear out and see a couple great weather days both tomorrow and Wednesday. Humidity should also be less through mid-week. Shower chances return later Thursday afternoon and through the start of the weekend.

A general 1" to 3" of rain fell across the area yesterday and overnight with 3.18" recorded at the Warwick DEOS. We could see some sun retrun this afternoon with a slight chance of a shower toward evening before we clear out and see a couple great weather days both tomorrow and Wednesday. Humidity should also be less through mid-week. Shower chances return later Thursday afternoon and through the start of the weekend.

Just an FYI for those that may be interested.I have added a few additional stations to join the few we already have included that are while not in Chester county are close to the Chester County border and meets our area description. Some are only historical like NWS COOP locations for Pottstown which has precipitation and snow only while New Holland NWS COOP in Lancaster County is temperatures, precipitation and snow. Below are all stations not in Chester County - some are as close as 400 feet such as at Octoraro Lake , All other stations with the exception of New Holland are within 2 miles of the Chester County border. Also attached is a map with all current and historical stations included for reference.

Just an FYI for those that may be interested. I have added a few additional stations to join the few we already have included that are while not in Chester county are close to the Chester County border and meets our area description. Some are only historical like NWS COOP locations for Pottstown which has precipitation and snow only while New Holland NWS COOP in Lancaster County is temperatures, precipitation and snow. Below are all stations not in Chester County - some are as close as 400 feet such as at Octoraro Lake , All other stations with the exception of New Holland are within 2 miles of the Chester County border. Also attached is a map with all current and historical stations included for reference.

Some showers are around this morning and will likely increase in coverage later in the day into this evening. We should see some sun returning tomorrow but still a chance of additional showers. Total rain amounts look to be from 0.50" to 1.00" with the higher amounts likely over Western Chester County and into Lancaster County. Tuesday and Wednesday look like great weather with sunny skies and low humidity with temperatures slightly below normal for the middle of August.

Some showers are around this morning and will likely increase in coverage later in the day into this evening. We should see some sun returning tomorrow but still a chance of additional showers. Total rain amounts look to be from 0.50" to 1.00" with the higher amounts likely over Western Chester County and into Lancaster County. Tuesday and Wednesday look like great weather with sunny skies and low humidity with temperatures slightly below normal for the middle of August.

Great weather today with comfortable humidity and temperatures not too far from normal for mid-August. We turn wetter and a little stormy by later tomorrow into tomorrow night some spots could see upwards of an inch or so of rain. We turn sunny any by Monday with pleasant weather returning and lasting through mid-week.

Great weather today with comfortable humidity and temperatures not too far from normal for mid-August. We turn wetter and a little stormy by later tomorrow into tomorrow night some spots could see upwards of an inch or so of rain. We turn sunny any by Monday with pleasant weather returning and lasting through mid-week.

So let's address Charlie @chubbs post above Charlie, of course no dispute that Phoenixville stepped down at the 1948 move. But you've written the very objection into your own post: "Not surprising because the bias adjustments are calculated from the raw data." Charlie, your test is pairwise comparison of a target against raw neighbors across a break date. But so is the PHA! You've actually hand-implemented the method NCEI automates. Agreement demonstrates reproducibility, but of clearly not correctness as you are simpling showing us the same method, same data. It's the same issue as Berkeley and NCEI agreeing being offered as independent confirmation - they are of course not! On your "bullet proof" claim - the four available estimates of this one documented move: Berkeley -1.23 F / yours vs Coatesville -1.49 F NOAA -1.88 F / yours vs West Chester -2.03 F Four pairwise estimates of the same event spanning 0.80 F; the largest is 65% bigger than the smallest. Same sign and rough scale but the real question here as always has been the magnitude is what's in dispute here, and that spread isn't what bullet proof looks like!!. Also, your 2 references disagree by 0.54 F. If both were stable through 1947-50 they should agree on that Phoenixville's step. They don't, so they moved relative to each other in your window - and you date West Chester to 1970 and Coatesville to 1946, before your "before" period even opens. So you also say "all of the major county COOP stations moved in the same direction and roughly the same magnitude after the war". If so, doesn't that actually represent a real problem for the method, not support for it??. Pairwise comparison sees only RELATIVE change - a shift common to the whole network differences out and is invisible by construction. The more synchronised those moves were, the less your test and the PHA can detect, in exactly the era carrying the county's largest adjustments. So Charlie while none of this says your step estimate wrong. It means the method you are using is simply being validated against itself, the spread across implementations exceeds the confidence claimed, and the scenario you offer as clinching is the one the method handles worst.!! Paul

That is a great answer Mike! that transformer efficiency improving over time means declining waste heat, which puts spurious cooling into the raw record, which needs the later data warmed. That's the sign NCEI applied. It's a coherent mechanism and it's the first one offered in this thread that resolves the direction problem. Thank you for it. However....I think it may cost you a bit more than you think this buys you! A few posts ago your position was "100% documented evidence of microsite impacts" and "Coatesville's breakpoints are fully documented at this point." Now the site is "literally a thermal zoo" and the complexity "obviates all the musings about what caused a precise shift at time X and magnitude Y." Those are different arguments. The first says the causes are documented and therefore the corrections are validated. The second says the causes can't be pinned down and therefore we have to trust the detector. I don't think both can be true of the same station, and the second is a much weaker claim than the one you started with. It also runs into my actual objection rather than around it. If the microsite is too complex to attribute a given shift to a given cause, then it is also too complex to verify that the correction applied was the right size. You're offering unverifiability as a reason for confidence. Unverifiability is the thing I've been objecting to. And your mechanism argues against the correction's shape. Transformer technology improving across decades is gradual. A cooling pool installed at one point and removed after 2005 is two events. Steadily declining waste heat produces a ramp, not a staircase. The PHA fits steps. By your own account the physical signal is the wrong shape for the correction being applied to it - and that's your description of the site, not mine. There's a specific case I'd like your read on. The 1946-01 changepoint is +0.79 C, warming everything from 1946 forward. That's the move TO Newlinville. If the station relocated onto a substation with massive transformers and high loads, the raw record should have jumped warm at that moment and needed a cooling correction. NCEI warmed it instead. That only works if Newlinville was cooler than the water plant site it came from - which is your earlier "hot location to progressively cooler ones" account, and I don't see how it sits alongside "massive heat sources" at the same site in the same year. Last thing, If Coatesville 1SW spent 36 years in a thermal zoo with industrial heat sources that moved, changed technology, and gained and lost a cooling pool, there's a conclusion available that neither of us has put on the table: that this record can't be salvaged for trend estimation and shouldn't be used for it. "Automated detection is the only way to salvage this data" assumes it can be salvaged. What's the basis for that, given everything you've just described? And is it a kind of a funny coincidence that the station carrying the county's largest adjustments is the one you're describing this way? Paul

Mike, I'll take your four questions in order Q1 - yes. Raw records could potentially carry non-climatic biases that don't cancel but not always! Q3 - yes. Williams 2012, Venema 2012 and Killick 2022 are real, adversarial, and they show homogenisation reduces error if a station has proven data issues, I accept that and I'm not going to pretend the literature says otherwise. Q2 - one correction. You say breakpoint detection is "even unstable run-to-run (shown in this thread's own evidence)." It wasn't shown. I went looking for it: two pulls of the West Chester QCF taken a few years apart were identical across all 119 complete years, unadjusted series identical too. NCEI told me the output can change daily; I tested it and found none over that interval. That concession isn't mine to accept. Q4 is where we really differ, and it's about scope. My claim is narrower: the specific magnitudes applied to specific Chester County stations haven't been independently verified, and showing an event occurred doesn't verify the size of the correction attached to it. The benchmarks measure whether homogenisation moves a NETWORK closer to truth on average - the right quantity for a national series, and a different question from whether one station in one decade got the right number. Venema's own write-up notes it modelled small European networks at high station density without network-wide trend biases; Williams found improvement in the presence of widespread systematic errors. Both are aggregate statements under stated conditions. The conditions matter here. Before 1951 this county has three continuous stations. Menne and Williams say it themselves in the 2009 paper: false alarms at neighbouring stations reduce the number of homogeneous neighbours and thereby prevent the estimation of adjustments. That's the sparse-network failure mode described by the algorithm's own authors, in the era carrying the largest adjustments. On cherry-picking - you introduced Coatesville as the exemplar and called it two resounding yeses. If it's representative enough to validate, it's representative enough to examine. You asked for a case. Here's the beginning of one, and it's a magnitude test rather than an occurrence test. So I built a regional reference for Coatesville from the raw, unadjusted Chester County records only - leaving Coatesville 1SW out so that it never contributes to its own comparator, and no homogenised product anywhere in the calculation. Measured drift of Coatesville against those raw neighbours over 1895-1982 is -0.190 F/decade using every available station, or -0.113 F/decade using a fixed panel that can't change membership. The applied NCEI adjustment runs +0.303 F/decade, which implies a drift of -0.303. That value falls outside the 95% confidence interval of the measured drift under both reference constructions. The adjustment also tracks the drift year to year - r = -0.74 - so it's aimed at something real. It's the size I'm questioning, not the existence. What this is so far in all of my multiple years of review which has been my analytic goal of this process of reviewing the adjustment of raw data at one targeted station Coatesville 1SW is that the correction appears larger than the divergence it corrects, measured without using any homogenised data. If that's wrong I'd like to know how?? Paul

Mike, those aerials are genuinely useful and I'm glad to have them. They establish something I'd have had a hard time establishing myself: that the site was disturbed, repeatedly, across that whole period. I'm not disputing that. But again they just don't get you to either of the two claims you're making. Documenting that something happened at a site is not the same as documenting how much it changed the temperature, or in which direction. The aerials show construction. They don't measure its thermal effect. Every step magnitude in the NCEI record was sized by neighbor comparison, not by anything visible in a photograph, and that is the number that has to be right for the correction to be right. And there's a direction problem I raised earlier that I have not heard you answer or reconcile. An electrical substation with megawatts running through it, accumulating buildings and hard surfacing from 1946 through 1982, that is clearly a warming influence on the raw record. Correcting a progressive warming bias means pushing the later data down or cooler relative to the earlier. NCEI's correction goes the other way - the two NOAA changepoints in that window are +0.45 F at 1959 and +0.95 F at 1971, net +0.40 F, raising the later data, and the overall adjustment lifts the modern era relative to the early one. You do offer a second mechanism - that the station itself may have moved as office space changed. If it moved away from the heat sources, that would produce cooling steps needing a warming correction, and the sign would work. But that's the opposite mechanism from the one the aerials show, and it's offered as a possibility rather than as something documented. Both can't be driving the same window. Which one do you think it is, and in which years? The other thing that doesn't sit right: if construction were producing stepwise changes throughout 1952-1982, I'd expect the detectors to be finding them. NOAA places two changepoints in that window. Berkeley places five, and by your own figure they come to about -0.10 F net across seventeen years. That's a lot of documented disturbance producing very little net correction. So where I see us in reality standing on this analysis is on validity: showing that an event occurred does of course not validate the size of the correction applied to it. That would take an independent measure of the effect, and I don't think you have so far produced one yet - yours truly also! Of clear necessity: demonstrating that the adjustment is essential requires showing the uncorrected data gives the wrong climate answer, which requires knowing the right answer independently. Neither of those has been establish here. I'm not claiming the adjustments are wrong. I'm saying "documented" and "validated" are different words, and the work so far has established the first, not the second. If you have something that speaks to magnitude rather than occurrence, I'd genuinely like to see it. But again we are far away from any proof you claim to see!