ChescoWx

Beautiful day today across Western Chester County....great to see the pattern and analogs aligning for what should indeed be a memorable core of the JFM winter months of storms and rumors of storms....fun times ahead for those that like winter weather in this area!

Here in Chester County we have a 1 year of every 4 or 25% chance of having snow on the ground on Christmas Day. The last 10 years are aligned with that average as we have had 3 White Christmas Days since 2009. The most recent Christmas being 2017 with 0.3" / 2012 with 2.0" and 2009 with 4.0". The greatest snow depth recorded on Christmas was the 25" of snow on the ground Christmas Night following a 21.2" Christmas Eve storm that including frequent lightning and thunder on Christmas Eve 1966 - this followed the 8.8" that fell earlier that week on the December20th 1966. The next snowiest Christmas was from a storm that began at 8am on Christmas day back in 1909 and continued into the next day ending at 6:30am on the 26th (for both of these events I have attached the coop reports for the month for both years including W.T. Gordon's note from 1909 that it was "snowing furiously and very deep snow" and the Philadelphia Electric Company COOP in Coatesville reporting that "highways in bad shape" . Of note the Christmas 1909 Blizzard represents our 2nd greatest individual snowstorm in Chester County history as 38" had accumulated by the time the storm ended on the 26th. The only greater snowstorm in our history was the 3 day Blizzard of February 12-14, 1899 when a whopping 45.3" of snow fell with temps mainly in the single digits during the storm duration. Of note temps remained below freezing the remainder of December 1909 with 39" of snow on the ground on New Years Eve. The coldest Christmas Eve and Day occurred back in 1980 when the morning lows both days were below zero with the 24th at 2 below and Christmas Day at 6 below zero. Of interest just 3 years later in 1983 we also had below zero Christmas Eve and Christmas Day with lows of 1 below and 3 below respectively. That Christmas Day in 1983 was also the coldest Christmas Day with a high of just 6 degrees above zero. By contrast the warmest Christmas Eve was just 4 years ago in 2015 when we recorded a high temp of 68.5. Christmas Day 2015 was also short sleeve weather with a high of 66.7 just off the record high for Christmas Day of 67 degrees set back in 1964. The wettest holiday was the 1.63" that fell on Christmas Eve 1986 and the 1.92" that fell on Christmas Day 1967. No matter your weather I hope all of you have a Merry Christmas!! All the best, Paul December 1966.pdf December 1909.pdf

Temps on one thermometer have finally bumped above Freezing - about 12 hours of ZR - plenty of ice in trees and non-paved surfaces - roads seem fine

Been ZR here in East Nantmeal for almost the past 6 hours (since 6:10pm) temp slowly creeping up - now at 32.3...very icy on non-paved surfaces

1 is about 30 feet higher other 2 at same elevation...

Temperature has continued to fall across NW Chester County this evening now down to the low for the day at 32.1 (I have 2 other thermometers down to 30.0 and 31.1) we have a nice glaze on the deck and ZR continues to fall steadily here in East Nantmeal Township

Some mainly sleet here in NW Chesco with a few flakes mixed in temp at 33.8

Light snow and temp slowly dropping from 34.2 now down to 33.7 - schools closing early in Chester County

WWA for NW Chesco for up to 2" of snow but doubt we see more than mood flakes today. Just a few light flakes currently with a temp at 33.2. WXSIM has never been impressed with this "event" will need to keep an eye on temps this evening to see if any rain that falls freezes later on contact - but WXSIM keeps us above so should be no big deal

WXSIM for NW Chesco sees this as a pretty minor "winter" event with some light snow developing by 7am and continuing off and on through much of the day with around 1.0" of snow before mixing with IP by 4pm - then a pretty quick transition to plain rain heavy at times by 9pm in the evening

This event has been a mighty consistent storm track for the last week with a slight jog to the south over the last 2 days - JB and most guidance has always had the low to the south of the M/D line since last Monday ....what I suspect will happen is some initial snow with the overrunning warm front and then a pretty quick change to non-snow....but of course the further N and W you go from the I95 corridor the tougher it will be to scour out the LL cold - so some moderate icing (ZR over IP) likely from the PA Turnpike north and west. The bigger issue in my mind is how much precipitation is involved. Think we see a dry slot tomorrow afternoon and then many spots will rise to above freezing from the PA Turnpike south and east. Also, still keeping an eye on next weekend....could be a significant event from this vantage point.

Yep same here in NW Chesco....it's easy to change from Snow to non-snow of course....but going from ZR to plain rain is the problem....no doubt we will change to snow faster than progged but struggle to get above freezing especially the higher spots like around here....

Not looking like much front end snow....but sheesh if this amount of ZR were to fall...

Steve agreed 100% will be a battle to scour out the LL warm air and will likely take till toward evening to get above freezing

Words of wisdom Steve....wish we had more folks on here but I truly appreciate all the peeps that do choose to post here - thanks!!

I unlike most here are quite enthused with the pattern. I remain confident we end up with an above average snow month and January remains on path for some very interesting times IMHO. Folks sometimes forget even out here in the NW burbs - we only average 4.7" of snow in December - we have already had 1.5" of snow this month and I expect we will add to the snow total on Monday before the change to rain (I suspect it will be a slow process once N and W of I95) - watch for another winter event around Christmas and toward the New Year. Interesting times ahead....

I like him but he blocked me on twitter because he does not believe KMQS is a valid weather site....does not like folks to disagree with him

JB still on the snow and ice train north of the m/d line - as depicted on the 6z Euro means run

The well respected MET - JB from WB is on board the snow and ice train for north of the mason dixon line with the next event (16th-18th) since last Saturday. He is still not getting into accumulation but sees a Miller B storm running to the lakes with a secondary popping off the coast....and then some strong to near record cold to follow by the pre-Christmas weekend.

East Nantmeal Twp. in NW Chester County as of 6:45 am Temp 31.9 still light snow Snow so far = 1.5"

Timing looks to be mostly in the overnight early AM - so I would not expect much struggle with accumulations with the exception of paved surfaces. Which of course don't matter when it comes to snow accumulations

I thought I would share an excerpt of my winter forecast that is being published this week in the East Nantmeal Sweetwater Reporter. Unlike some winter outlooks that are chance outlooks - I have tried to put actual numbers into the forecast (keep in mind this is specifically for East Nantmeal Township in NW Chester County PA)...which will likely show exactly how far I am off when we validate as we go along. So, what does this portend for the upcoming winter season? Below is my forecast for 2019/2020 for East Nantmeal Township. with average temperature and snowfall estimates by month. To summarize regarding temperatures. I see a slightly above normal December with a bit of a roller coaster. Cold to start warm up mid-month and turning cold by Christmas week. We generally have a 25% chance of a White Christmas with our last being in 2012. I do believe we have a chance of a White Christmas this year. I expect a below normal and snowy January followed by a near normal but snowy February, a below normal March and an above normal April. Regarding snowfall I am forecasting around 51” of snowfall this winter season or about 14” above our seasonal average of 36.7”. Unlike the past few years I do think we see at least one or two major snowstorms with greater than 10” accumulations. December 2019 – Avg. Temperature 35.1 degrees (+1.5) above normal with Snowfall of 7.5” which is 2.8” above normal January 2020 – Avg. Temperature 27.7 degrees (-2.2) below normal with Snowfall of 19” or +8.1” above normal February 2020 – Avg. Temperature 32.9 degrees (+0.5) above normal with Snowfall of 17” or +4.8” above normal March 2020 – Avg. Temperature 38.9 (-1.4) below normal with Snowfall of 7” or +0.7” above normal April 2020 – Avg. Temperature 53.9 (+2.6) above normal with Snowfall of 0.5” or 0.6” below normal

AM low 31.5 Normal today 43.1/29.1

Not yet in my NWS forecast but keep an eye on tomorrow AM...expect squalls to make it at least into Western Chester County and maybe all the way to the coast. May get more tomorrow (easy to do with just a coating from yesterday) than our 1st little winter event...something to watch for...