Below is my climate summary article for the local newsletter which had been delayed....
Hello again from Paul at the East Nantmeal PA Weather Station (www.chescowx.com). Be sure to follow me on twitter at chescopawxman where I am tweeting daily climate reports, forecast updates and weather and drone photos of our beautiful Township.
When I wrote my last article, in mid-February the world was a bit different, I trust all of you are staying healthy! Weather wise we would not see any additional accumulating snow, with our last snow on January 18th. The snowless February and March were only the 3rd time in 127 years of local history that we failed to see any accumulating snow in East Nantmeal. Those years being 1950 and 1973 (the only season with no measurable snow in Chester County). February was also continuing the trend begun in January (9th warmest on record) with February average temperature of 38.4 ending as the 4th warmest on record behind only 2017 (41.2) / 1998 (40.0) and 1909 (39.5). Precipitation was near normal at 3.25” while with no snowfall we were 11.8” below our normal snow for the month. March would continue the top 10 warmth for winter months with an average temperature of 46.2 – this was the 9th warmest March on record, with our warmest March on record being way back in 1921 with a 51.5-degree average temperature. Not surprisingly the first quarter of 2020 was the 2nd warmest Q1 on record, with an average temperature of 40.4, only the first 3 months of 1998 (40.9 avg.) were warmer.
Now before you begin to worry too much about any potential global warming…I decided to run an analysis of the last 13 decades back to the 1890's to see if the January to March winter months, outside of the Philadelphia heat island in the rural areas of Chester County have indicated any clear signals of either significant warming/cooling or variations in snowfall totals. Keep in mind snowfall amounts are not seasonal totals only January through March totals. Below is a chart with the analysis of the data. Of interest our most recent complete decade from 2010-2019 was the coldest first quarter since the 1980's. The warmest Q1 decade was the 1930's with the coldest being the 1970's. The snowiest was the 1890's followed closely by our most recent complete decade of the 2010's. Overall the data supports no significant Q1 warming evident outside of the urban heat island impact of Philadelphia...just typical variability and expected cyclical trends. The analysis also shows that colder does not always equal more snow.
With the 1st full month of Spring in April we began a cooler than normal pattern that would last well into May. During April, the average temperature was 49.4 (0.5 degrees below normal) ( Avg High 60.3 / Avg. Low 39.6). We did record our last sub-freezing reading of the season on April 17th at 30.3 degrees. We had plenty of rainfall in April with 6.31”falling including a record 2.40” on the 13th of the month. Our normal April rainfall totals 3.91”. The April rainfall was the 10th greatest in Chester County history with the all-time wettest April occurring just 6 years ago with the 10.33” falling in 2014. Highest Temperature was the 72.0 on the 8th. The lowest temperature and only sub-freezing day of the month was the 30.3 reading on the 17th. This however would not be our last sub-freezing day with a couple of rare late season freezes ahead during May. Although we would see some snow in the air and even sleet late in the month, we would finish the 2019/20 winter season with just 5.8” of snow this is almost 31” below our normal seasonal snow total of 36.7”. This was the 3rd lowest snow total behind the only snowless winter in Chester County history in 1972/73 and the 2.4” that fell in the winter of 1949/50.
May would continue the chillier trend with an average temperature of 58.6 (0.7 degrees below normal) ( Avg High 67.4 / Avg. Low 49.8). This was our 2nd consecutive below normal month. The 2-month average of April and May mark the 24th coldest first 2 months of Spring in Chester County history (1894-Present) and the coldest spring arrival since April/May 2008. Rainfall was 2.88" (1.40" below normal). The highest temperature was the 81.3 on the 15th - this was our 1st 80-degree day of the year and represents the 7th latest initial 80+ day since records began in 1894. The latest was on 5/27/37. Our lowest temperature was the 31.3 reading on the 9th this was the coldest for the date since the 34-degree reading in 1984. The all-time low for the day was 25 set back in 1947. The next day the 10th we recorded our last 32 degree reading of the season - this was only our 78th sub-freezing low in the 2019/20 winter season normal is 115 days. That late freezing temperature was the 15th latest freeze in 127 years of records back to 1894. Also, our latest May freeze in 24 years with the 30-degree reading on May 14, 1996. The average final freeze in Chester County is April 18th. The latest freeze in County history was the 32-degree reading on May 28, 1927. The 46.5 maximum recorded on the 9th was the 6th lowest May max daily reading in the historical climate data set.
June would begin a warming trend that well into July. The average Temperature 70.0 (+2.5 degrees above normal) ( Avg High 79.0 / Avg. Low 61.0) This was our 1st above normal month since March. The average temperature during Q2 2020 was 59.4 - this marks the 31st coldest 2nd quarter in Chester County history (1894-Present) and coldest Q2 since 2003 (58.5). June Rainfall was 3.94" (0.10" below normal) our highest temperature was the 86.3 on the 10th. The lowest temperature was the 44.1 reading on the 1st of the month. As I write this on July 12th we are in the middle of warmer and wetter than normal month. We even recorded our 1st two 90-degree day’s although here in the relative high spots of East Nantmeal we needed to round it up to actually record a 90 so with the 89.6 on the 3rd and 89.8 on the 6th. . The last 90-degree reading was last July 21st when we reached 92.5 degrees - that was the 2nd and last 90 degree reading of the summer of 2019. Here in Chester County we average 11 days that exceed 90 degrees during the summer (1983 to Present). However, in 3 of the last 10 years have seen no days exceeded the 90-degree mark and 23 of the last 37 years have seen less than 10 days exceed 90 degrees during the summer. We have also just finished up a very wet 1st 12 days of the month with 3.98” of rain so far including 2.49” of rain on the 10th from Tropical Storm Fay. YTD rainfall now stands at 29.02” which is exactly 4.00” above normal through the 12th – great news for our Township farmers! Now, for those of you that dislike the summer heat… the good news is our hottest day on average is coming up on July 18th with an average high/low temperature of 83.6/64.1. Average temperatures begin to fall from that point right on through January 18th. So, enjoy the remaining days of summer and I look forward to speaking about our weather again in the fall. Stay safe and healthy! All the best - Paul