ChescoWx

As the article clearly states "If you keep the time of observation constant over time, this won’t make any different to the long-term station trends" There are no examples of a change in time of observation within any individual month in the Chester County records. So it is again a non-issue. This is not complex Charlie. If the obs time is 7am every day for 1 year and we go back and recast it to 9pm every day for the same year - the average temp over 365 days is of course exactly the same. My favorite part is where the article states a hypothetical of "well what if the the obs is at If you observe the temperature at 5 PM and reset the instrument, the temperature at 5:01 PM might be higher than any readings during the next day, but would still end up being counted as the high of the next day." The simple answer to that line is so what? In that situation irrespective of the time of obs it will of course even out in standard blocks of 24 hour days (as long as it is a 5pm to 5pm 24 hour span) recorded at the same time every day over 365 days of average temperature calculation. Even if a change was made at the start of 1 month in the middle of the year. The impact to the annual temperature over 24 days is not even close to material.

I think it is just we are due for less snow after completing 2 of our most snowy decades in our history in the 2000's and 2010's - cyclical pattern of climate change

Just to correct one point Charlie and others have often made on what Charlie calls a "major source of bias being the older temperature max and mins aren't on a midnight-to-midnight basis" This is a non-material difference. For a quick example I notice many of the old historical obs took place at 9pm. So I went back and recast the month of December at East Nantmeal and took the High and Low as of 9pm for the previous 24 hours. This resulted in a December average temperature of 40.4 degrees....this compares to.... you guessed it 40.4 degrees from the calendar day midnight to midnight obs for December. Over a month and especially over 365 days of annual records the observation time will not impact the average temperature for any location no matter what time it is taken - as long as it is consistently observed at the same time. Also of note in many historical months the observer took multiple recordings for example 7am-2pm and 9pm. Between these 3 obs they would take the lowest and maximum and record those. In some months they even listed those multiple observations on the written records they forwarded to the weather service or Department of Agriculture as it once was.

But of course still no answers from Tim.....

Charlie again the above does not answer the questions as I have the above data. The question is why were each and every Chester County station cooled to even lower than Coatesville ever reported? You mention above that Coatesville had a "cool bias" - then why give all of the Chester County stations the what you call "a well deserved bias adjustment" to make them all cooler". This bias adjustment resulted in actually cooling the all Chester County station average to cooler than the station (Coatesville) with the cool bias you mentioned above do you see my point?? This is in fact what happened in 73 of 77 years between 1895 and 1970 - as the average NCEI temperature for the county was lowered to below any averages reported by any station including Coatesville.

Charlie not crickets you have simply only showed the cumulative adjusted data...without any data that supports such post hoc adjustments across every single available station in Chester County PA. Did they use another counties data as the control? Berks? Montgomery? Lancaster? Where is proof that 95% of the county obs required after the fact adjustments?

And let me guess you think they respect you? I have been recommended by Tony Gigi with the NWS in Mount Holly to be interviewed by the Philadelphia Inquirer and my data has been used consistently by the NWS as a trained NWS spotter and the Inquirer for my detailed and stringent compliance with 20 plus years of daily weather observations. Now you go.....

Timmy you sure have insults but as always come up a wee bit short on facts and data! Psst by the way my weather station data and equipment has as always been continually verified by MADIS with the latest note being "These values are within the acceptable range. This probably means that your sensor is sited correctly and is calibrated correctly"

Hey bdgwx how about showing me the analysis specific to Chester County PA that details what station or area they used as the control to make the after the fact adjustments to the NWS cooperative data for 95% of the years from 1895 thru 1970??

Right!! So again what is the scientific explanation in Chester County PA for why they adjusted average temperatures down to a mark not just down to the lowest recorded station value....but took them all down below any available station obs for 73 of 77 years? Does that feel right to you?

Of course not an answer from you Tim...call me stunned!! LOL

GFS ensemble catching on to snow chances next week...

Some really interesting statistics for Chester County PA that really makes you question some of the historical temperature trending data we see. Incredibly the NCEI data set for Chester County PA. Of note from 1895 through 1970 (77 years) the reported average Chester County PA temperatures for 73 of those 77 (95%) years is now reported as lower than any available reporting site in the county in those years. So are we to assume all stations in Chester County were faulty and or needed post hoc adjustment for 95% of the reporting observations through 1970??

Some really interesting statistics for Chester County that really makes you question some of the historical temperature trending data we see. Incredibly the NCEI data set for Chester County PA. Of note from 1895 through 1970 (77 years) the reported average Chester County temperatures for 73 of those 77 (95%) years is now reported as lower than any available reporting site in the county in those years. So are we to assume all stations in Chester County were faulty for 95% of the reporting observations through 1970??

Some really interesting statistics for Chester County that really makes you question some of the historical temperature trending data we see. Incredibly the NCEI data set for Chester County PA. Of note from 1895 through 1970 (77 years) the reported average Chester County temperatures for 73 of those 77 (95%) years is now reported as lower than any available reporting site in the county in those years. So are we to assume all stations in Chester County were faulty for 95% of the reporting observations through 1970??

Sunny skies should be the rule through Thursday. Chillier today with temps remaining in the 30's but warming trend starts tomorrow topping out well into the 50's by Saturday. Shower chances increase on Sunday night and much colder air appears likely with even some wintry weather chances next week. Records for today: High 66 (2008) / Low 6 below (1895) / Precipitation 3.00" (1896) / Snow 12.3" (2010)

Sunny skies should be the rule through Thursday. Chillier today with temps remaining in the 30's but warming trend starts tomorrow topping out well into the 50's by Saturday. Shower chances increase on Sunday night and much colder air appears likely with even some wintry weather chances next week. Records for today: High 66 (2008) / Low 6 below (1895) / Precipitation 3.00" (1896) / Snow 12.3" (2010)

In comparing the NCEI average post observation temperature adjustments applied to the actual recorded averages recorded by the NWS Chester County Coop data show the average temperature data was adjusted downward every single year from 1895 through 2004 or for 110 consecutive years. The greatest adjustments were reductions in average temperatures of 2.76 degrees in 1945 / 2.69 degrees in 1943 /2.62 degrees in 1942 / 2.58 degrees in 1951. Conversely. In the 18 years since 2005 every year has been adjusted upwards with the exception of 2019 with the greatest adjustments upward to temperatures being applied to 2018 +1.87 degrees and 2005 with a +0.66 degree adjustment. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/time-series/PA-029/tavg/ytd/12/1895-2023

In comparing the NCEI average post observation temperature adjustments applied to the actual recorded averages recorded by the NWS Chester County Coop data show the average temperature data was adjusted downward every single year from 1895 through 2004 or for 110 consecutive years. The greatest adjustments were reductions in average temperatures of 2.76 degrees in 1945 / 2.69 degrees in 1943 /2.62 degrees in 1942 / 2.58 degrees in 1951. Conversely. In the 18 years since 2005 every year has been adjusted upwards with the exception of 2019 with the greatest adjustments upward to temperatures being applied to 2018 +1.87 degrees and 2005 with a +0.66 degree adjustment. https://www.ncei.noaa.gov/access/monitoring/climate-at-a-glance/county/time-series/PA-029/tavg/ytd/12/1895-2023

Since 2000 using the 1991-2020 average temperature for December through February which is 32.8 degrees here in Chester County - we have seen 10 winters that have averaged below normal temps.... but none have been below normal since the DFJ of 2015 - winters with below normal DJF have been 2000/2001/2003/2004/2005/2009/2010/2011/2014/2015

Since 2000 using the 1991-2020 average temperature for December through February which is 32.8 degrees here in Chester County - we have seen 10 winters that have averaged below normal temps.... but none have been below normal since the DFJ of 2015 - winters with below normal DJF have been 2000/2001/2003/2004/2005/2009/2010/2011/2014/2015

Most spots were in the 20's to start the day with the lowest I could find in both Warwick Township and down in Kennett Square at 22 degrees. Tomorrow and Wednesday look to be close to normal temps while the rest of the week should see above normal temps rising into the 50's toward the weekend. Next week should see a return to a stretch of below normal temps. Records for today: High 66 (1991) / Low 11 below (1918) / Precipitation 1.90" (1907) / Snow 12.0" (1907)

Our beautiful stretch of February weather looks to continue for most of the next week with average to above temps and sunshine much of the upcoming week. The rumored pattern change to colder....if it occurs is still at least 10 or more days away. Records for today: High 63 (1991) / Low 1 below (1898) / Precipitation 1.35" (1920) / Snow 9.1" (1995)

Go Phillies!!!!!

Our beautiful stretch of February weather looks to continue for most of the next week with average to above temps and sunshine much of the upcoming week. The rumored pattern change to colder....if it occurs is still at least 10 or more days away. Records for today: High 63 (1991) / Low 1 below (1898) / Precipitation 1.35" (1920) / Snow 9.1" (1995)