ChescoWx

Below is the updated analysis comparing PHL Airport vs. All long running Chester County Observation Sites from 1940 through 2022. For the year 2022 all Chester County locations reported lower average temperatures vs. 2021. ranging from 0.4 to 1.0 degrees cooler than the prior year. Philadelphia was 1.0 degree warmer than 2021. The analysis for the last 82 years since 1940 shows overall trends of modest cooling at the Chester County stations at Glenmoore and slight warming at Phoenixville and West Chester with Coatesville/East Nantmeal showing the most warming but only very modest warming at best. Philadelphia's trends of course shows pronounced steady warming that is continuing to accelerate.

From Larry Cosgrove "When you consider that a cross-polar flow is a possibility in this configuration (likely to repeat in mid/late February), you can see the possibilities here. It might take the East Coast cities a while to get involved with the cAk domain, but I am confident that the Interstate 95 corridor will get in on the winter action at some point. The analog forecasts still call for a much milder March. But before we get there, may you live in exciting times."

4th lowest in satellite era for December....of course satellite era is not very long...current warm cycle doing it's thing!!

A few showers will pass through this morning as a cold front has just crossed the county. We have picked up 0.23" of rain since yesterday. Temperatures today will fall from our 2am high temp of 52.3 degrees we have now fallen to 46.7. We should see temps falling below freezing by 8pm this evening. Tomorrow will be our first below normal day of the year an first since December 27th. Tomorrow will also be windy. Temps should once again moderate back to above normal by Monday with our next chance of rain arriving Tuesday. The record high for today is 68 degrees set back in 1932. Our record low is the 11 degrees below zero reading from 1912. Daily precipitation record is 1.34" and our daily snow record is the 6.0" that fell today in 1964.

We have some modest elevation at the KMQS and East Nantmeal stations (~660 ft ASL) that seem to make some diffference...although honestly 88 or 91 with humidity is still hot any way you slice it!!

Always funny you fall back on faulty sensors or observation reports when the figures don't work out....

As clearly shown below the trend away from the PHL heat island airport for 90 degrees is clearly falling over the last 10 years - the disparity when compared to PHL continues to grow. The suburban locales averaging high single digit amount of 90+ days while PHL now heating up into an average of low 30's per summer. This is all over no more than a 30 nautical mile distance from the airport.

We did have some wet snow overnight that turned to some light rain with 0.05" of liquid falling. Today looks cloudy with some drizzle and more rain later in the day and this evening. We could pick up up to another 0.20" of rain. Today will be the warmest day of the next week with temps possibly reaching 50 degrees. Drying out by tomorrow PM. Much chillier Saturday with our first below normal temp day of the year. Another warming trend begins next week. The record high for today is 64 set in 2020. The record low is 7 degrees from 1981. Daily rain record is the 1.98" that fell in 1983. Our record snow for the day was the 5" that fell today in 1982.

I have made no adjustments to any analysis ever. I am a believer in climate change (it is real and constant throughout history and will continue forever) but believe this change is cyclical and not unusual. The 3 stations have been analyzed and deemed valid for analysis based on the following detailed reviews. The data set comprises only the National Weather Service COOP observations from 1888 to 1982 for Coatesville 1SW when that station moved per NWS direction to a nearby location in Coatesville beginning in 1983. That location was only 2 miles to the NW at an additional 300 ft elevation change - that station remained in use till 12/31/07. The data of both of those stations was deemed acceptable and combined by the Pennsylvania State Climate Office and is posted on their website with climatology stats using the combined 2 stations. So now we have data from 1888 through 2007 that is included in this data set. However, the Coatesville NWS observer stopped reporting in December 2007. Without that data I was required to do a statistical analysis to determine if the daily data that had been recorded at both the Coatesville NWS observer station and my NWS spotter data in East Nantmeal for Chester County (at the same elevation ~660 ft ASL) which were taken concurrently daily from 12/1/2003 through 12/31/2007 would be found statistically the same - this is critical because if this statistical significance test had failed we would not have been able to use this data for the ongoing analysis I perform. However, based on the detailed statistical analysis performed we were able to show that both data sets are statistically one and the same based on the highly significant ( p-value results were well under 0.05 required). This detailed statistical analysis provided the support that allows us to have high confidence that the total data set being used is valid and appropriate for analysis. Sorry for the long winded explanation (more than most folks would want) but want to ensure why we are so confident in these raw Chester County data sets. Thanks! Paul

The endless roll of lake cutters is really amazing.....I remain however a big believer in all things equaling out in most years. I suspect the winter is over crew will be proven wrong with at least a couple wintry events and if one threads the needle....spots like PHL that average in the low 20's for annual snow could be 75% of normal for the year. For us N and W folks that average in the mid-30's for annual snowfall....I suspect a well below normal year is increasingly likely. By the way thanks to all of you for not killing me over my winter forecast!!

Charlie you miss the point there is no slant or cherry picking data with my analysis....I have no incentive to skew anything I simply analyze the factual reporting of all available NWS COOP and spotter reports for a long period of time for Chester County PA. The fact is does not support the global warming hypothesis is not my problem. You never say my data is wrong....simply that it needs to be massaged. You can continue to post your adjusted pooled multi-station data for Southeast PA....and I will continue to report on what the trained observers and spotters report and report the facts both warm and cold for the available long term stations in my county.

Chubbs/Charlie follows the NOAA view of adjusting for that pesky "excess cooling" with "proper adjustments" at those Chester County Stations from 1940-1970. My data (as noted with the disclaimer in my signature below) will continue to trust the multiple NWS COOP observers and am quite confident that they all did not have faulty equipment at the same time. Just no proof of that at all! So we must continue to only analyze the actual approved NWS data validated at the time it was submitted to the NWS office. Unfortunately, for Charilie it does not support the warming story as well without that critical "excess cooling" adjustments. I would also add that the fact I simply produce the actual raw data for all of these Chester County locations without adjustment does not allow me to have any so called "confirmation bias on my part" I can't adjust the numbers for any perceived pesky excess cooling or warming as that may introduce some analyst bias which I won't ever do.

The PHL Airport Heat Island Contamination is strong.....since 1940 vs. NWS COOP reports in the western suburbs. In 2022 PHL had another year of warming while the Philly burbs were actually cooler.

For those hanging on to winter hope - from Larry Cosgrove "Many of you have gotten used to the rather benign nature of January so far. There is the (usual) talk of "winter cancel", and speculation that spring has already begun. This is, of course, rather unwise. Even with the alterations caused by global warming, winter is still here, lurking in Siberia and northern Canada. And when it returns full force to the lower 48 stats around January 20, my best advice is to be prepared. What is happening in California is actually the start of the transition process. One of the storms in the sequence is now reforming in the Oklahoma Panhandle, and will pull down modified Arctic air into the Midwest and East Coast for perhaps two days (with thunderstorms along the East Coast, followed by snow showers and squalls around the Great Lakes and Appalachia). But warmth will quickly rebound next week east of the Rocky Mountains. The last cyclone in the sequence, over the western Pacific Basin, will break up the current pattern. All of the model guidance shows this feature battering California with heavy precipitation (so what else is new....) next Wednesday and Thursday, then redeveloping over southern Colorado. Ten days from now, cold advection into the Great Plains gets going as the low center deepens and heads for the interior Northeast. You will notice changes in the air mass character behind this disturbance, with a shift back to mild/dry West and cold/stormy Central and East for North America."

Another slightly above normal temperature day across the county today before rain arrives overnight tonight. Mild with rain tomorrow with between 0.25" to 0.50" likely across Chesco. Chillier weather this weekend with Saturday looking like possibly our first below normal day of 2023. Temps will start to trend milder again to start next week. The record high for today is 67 degrees from 1975. Record low was 5 below zero in 1981. Record precipitation was the 1.19" from 1924 and our daily snow record was the 7.2" that fell today in 1922.

Some may wonder how often have we gone through a January with no measurable snow during the month? Well here in Chester County PA it has not happened in 50 years....but overall it has occurred 6 times including 3 straight January's from 1932 through 1934. The other years a green January has taken place include 1960, 1967 and 1973. Of note that last time in 1973 took place during the only winter season in Chester County PA history that no snow at all fell during the winter. We will not suffer that fate this year as we have already recorded a whopping 0.8" of snow during December!!

We have not had a below normal temperature day since 12/27. While most days over the next week should be closer to normal we will still run above normal for the foreseeable future. Rain chances increase by Thursday evening and we should reach the 50's by that day. Clearing skies over the weekend with slightly above normal temps continuing. The models did show a potential low moving up the coast on Saturday with some snow possible...but that for now appears to be staying far enough off shore to continue our snow drought. Through yesterday we are at only 9% of normal snowfall through today. Of course in this area it only takes a couple big storms to get us back to normal. I still remain confident we see a couple snowstorms before we are done with the snow season in early April. Snow geese keep the faith! The record high for today is 62 degrees from 1950. Our record low is 3 below zero from 1982. Daily rain record is the 1.06" from 2016. The snow record for today is the 9" that fell today in 1954.

Yep I suspect validation......

As we await the possible return of winter weather at some point later this winter. Below is a list of the Top 25 all-time January Snowstorms here in the Western Suburbs of Philly in Chester County PA

For those that blinked and missed the peak of our overnight 3rd snow event of the season....shot attached!!

The sun should return today. We should stay dry and a few degrees above normal (what's new) for most of the week. Temps will rise well into the 40's with rain by Thursday night into Friday. Temps will fall to near normal for next weekend with dry weather. The record high for today is 68 degrees from 1930. Our record low is 1 below zero from 1970. Daily rain record is the 1.66" from 1964. Daily snow record is the 3.0" from that very cold January of 1977.

Would be surprised if anyone sees even this little...

We are now at 10% of normal snowfall....can we get to 15% of normal snow by tomorrow AM? call me excited!!!

Latest 12z runs for the impending snowstorm....The Euro and NAM Jackpot Chesco while the GFS and GEM go north!!! Buckle up!!!

Increasing clouds today with some models still showing our "largest" snow event of the year starting after midnight tonight and wrapping up by the Monday morning rush. If there really is any accumulation at all it is most likely on grassy and non-paved surfaces above 550ft across the County. Temperatures will for the most part remain above freezing while any snow is falling with maybe the exception of the highest spots in Western Chester County. A mainly dry and slightly above normal temperature week looks likely with a large mainly rain event looking likely by Thursday night with it possibly starting as snow. The record high for today is 67 degrees set in 1998. The record low is 5 below zero from 1981. Daily rain mark is the 1.81" from 1978. Our daily snow record was day 2 of the Blizzard of 1996....when a final 6.1" fell bringing our final total to 28.9" of snow with 30" on the ground at storms end.