ChescoWx

I don't think that map would ever produce....HP moving out - not ideal IMHO

Latest NAM still bringing around 1" of festivus snows for some in Chester County

The latest models continues to show the potential for a small accumulation of snow following the cold front passage tomorrow morning. The NWS has trended even colder for Saturday - now forecasting the record lowest high temperature ever recorded (since 1894) for Christmas Eve Day with a high of only 17 now forecast. GFS

Steady ZR temp at 31.1 DP 29.3 -hearing of some accidents being reported in the area

Light ZR and 31.5 (DP 29.4) here in East Nantmeal Township in Chester County PA. Heavy snow falling just 15 miles NW of here

GFS keep festivus miracle hopes alive....just choose to believe!!! Getting my snow blower all tuned up!!!

Indeed!! if we actually shoveled model snow output my snow blower would break down every year!

The NWS has issued a Winter Weather Advisory for Western Chester County (not Eastern Chesco) for this morning till 11am. We have some light freezing rain falling here now in East Nantmeal Twp. with a temperature at 30.9 degrees. This should change to plain rain over the next couple of hours. Plenty of rain on the way with over 2" falling before the cold front passes later tomorrow. That front should briefly turn the rain over to snow before ending. Some models still show a minor accumulation with the exception of the GFS which shows up to a couple of inches in spots across the County, Either way temps will tumble from near 50 in the morning to near 10 degrees by tomorrow evening. The record high for today is 64.7 from 2013, The record low is 1 below zero set in 1960. Record rain is the 1.63" from 1983. Our record snow is the 5.8" that fell today in 1908.

Per Joe Bastardi at WeatherBell "Models cant handle it as the pattern is in transition. So I am going to old school this. Positive at the top of Hudson Bay and shortening wavelengths argue to me for the coastal storm. Models are trying to develop a ridge ( which is coming) so the different branches get lost. So I believe we have the snow threat next week coming into the plains day 5. Ohio and Tennessee valley day 6 and on the east coast day 7. If I did not have almost all models telling me that is not going to happen, I would really be chomping at the bit But they could be right. The fact is the upper negative is right in the slot on the Euro packages. The GFS just kicks everything along as it always does I like it. I guess we will find out if I am right next week"

Agreed! I can't remember the last time we have seen snow accumulate following the FROPA

12z GFS still delivers the Christmas Miracle....if you choose to believe!

The current NWS Forecast has a High Temperature of 18 degrees and a Low of 9 degrees above zero for Christmas Eve Day. If the high is only 18 degrees that would be the coldest high temperature ever recorded on Christmas Eve day since records began for Chester County in 1894. The coldest high temp on Christmas Eve day was the 19 degree high back in 1906. Christmas Day warms up to a forecast high of 21 following a Christmas morning low of 11 degrees. If that Forecast holds the combined Christmas Eve and Day Holiday would be the 4th coldest holiday on record. With Christmas Eve the 4th coldest and Christmas Day the 3rd coldest on record. The combined top 15 combined cold holidays are in the table below. Merry Christmas to all stay warm!!

That "well respected met" JB has had his eye on this....

Another near normal late December day for the area today with temps touching 40 degrees this PM. Today is the calm before the storm that will arrive tomorrow AM. Clouds increase tonight with our temps actually rising after midnight. Some very brief sleet or freezing drizzle is possible just after rush hour tomorrow. This will quickly change to heavy rain which will last into Friday. A strong arctic cold front will sweep across Chester County during about the 10am hour on Friday. Any left over precipitation will change to snow or flurries for an hour or 2. Some models still hint at a small accumulation...more likely as we head west in the county. Either way rapidly falling temperatures on Friday afternoon with readings falling through the teens. Some models have temperatures as low as 12 degrees by 7pm. Many areas will see air temps in the single digits by Christmas Eve morning. High temperatures on Christmas Eve will not escape the teens. Wind chills will be well below zero all day. Christmas. A top 4 Coldest Christmas Eve and Christmas Day is likely. The record high for today is 62 degrees from 1971. Our record low is 1 below zero from 1942. The daily rain record is 1.56" from 1902. The daily snow mark is 2.0" from 1959.

12z GFS and NAM both showing some minor anafront snows on Friday....usually does not work out from my experience

It looks like a big fail for my analog snow forecast for December...but the below normal temps look likely....

Nothing on the 6z Euro

If you want to see what a festivus miracle can look like - the always reliable 84 hour NAM delivers a plowable snow for the western burbs of Philly on Friday!! Lock it in!!

Dry and seasonable weather will continue for Christmas Week before a stormy Thursday into Friday for Chester County PA. The storm continues to look like mainly rain after a brief start as snow or sleet. A powerful cold front will sweep across the county from west to east during the late morning hours on Friday. Most models are now showing some minor <1"of snow accumulations before the snow ends on Friday PM. A top 10 coldest Christmas holiday remains probable for the weekend.

Today was our 1st day this season that the high temperature failed to rise above freezing. The last time we failed to pass the freezing mark for a high temperature was on March 28th. That was also the latest sub freezing day in Chester County history with records back to 1894.

To put a fine point on Charlie's (Chubbs) post above. Below is a simple chart showing average actual (non-adjusted) temperature trends comparing PHL Airport (Green) vs. Phoenixville (Blue) / Glenmoore (Orange) and Coatesville Chesco (Red) from 1940 through today. The calculated trend lines very clearly show the PHL Airport trend is rapidly rising while the others show much more stable trends with slight rises at both Phoenixville and Coatesville but cooling trends shown by the Glenmoore NWS COOP observer. In fact with just 12 days remaining in 2022 both Glenmoore and Coatesville will finish between 0.5 and 1.0 degrees colder than 2021. Of course the PHL Airport is on pace to finish at greater than 1 degree warmer than 2021.

Again for the millionth time - my data is pure and not adjusted raw data. It clearly does not show what your post adjusted multiple site combined data above shows. As it shows in my data shared earlier in this thread there is a clear up and down and up and down pattern to all sites - it is not that complicated!!

Based on the current forecast it appears likely this will be a top 10 coldest Christmas Eve and Christmas Day in Chester County PA history with data back to 1894. If the current forecast verifies it would be the 9th coldest Christmas Eve and the 6th Coldest Christmas Day. See the Top 20 coldest for each day below.

Our stretch of chilly weather looks to continue for most of the remainder of 2022. In fact December looks likely to finish as our coldest December since at least 2017 and possibly the coldest since 2010! Dry weather should continue before snow arrives on Thursday morning before quickly changing to rain. A strong arctic cold front will sweep through from west to east on Friday afternoon dropping temps from the 50's at 1pm to below freezing by 8pm. High temperatures on Christmas Eve day and Christmas Day may struggle to reach the low to mid 20's. The record high for today is 62 degrees set in 1929. The record low is 1 above zero from 1951. The daily rain record is the 1.30" that fell in 1934. Our daily snow record I remember well as 15" of snow fell today back in 2009. It started at 5am and was over by 10pm. There was still 4" of snow on the ground on Christmas morning which was our next to last White Christmas - with our last such one 10 years ago in 2012 when we had 2" of snow on the ground that fell on Christmas Eve 2012.

Great info!! It looks like they reached their peak steel production in 1953. They are still in production today - even making some of the steel for the new WTC in NYC! An interesting idea - and no doubt it may have contributed a bit to the warming...but since the same pattern of cyclical warming and then cooling was seen at all of the other Chester County observation locales in West Chester, Phoenixville and Devault during that 1930's through early 1950's time frame. It provides some additional support for the observations at all the chesco spots.