November 20-21st Snowfall Potential Discussion
Update, 10:30 AM: Some snow totals. Congrats to West Chester, Media, and Exton with 4" of snow. Also, winter weather advisory in Chester County and Cecil County (MD) until 2 PM.
Update, 8 AM: Winter Weather Advisory Until 11 AM for one to three inches of snow on grassy surfaces. Advisory covers Philadelphia, Montco, Delco, Chester, New Castle, Gloucester, Salem, Camden, Atlantic, and Burlington Counties, mostly in that infamous narrow band that's been talked about during this thread.
Update, 7:30 AM:
Nothing like a little November snowfall to get everyone excited about the potential for a colder and snowier winter. Compared to the last two winters even an "average" winter will seem quite cold and snowy so I guess most of the snow starved should be happy regardless of the result at the end.
The photo up above is of a coating of snow on the lawn outside of my home in Montco earlier this morning.
Update, 6 AM: So far the lucky dog snow winner is Boyertown where 2" of snow fell last night through 10 PM. The snowfall reporter is at a 700' in elevation, which helped in giving him a little extra bump in getting the snowfall to stick. There are a lot of coating to 1/2" accumulations across the western suburbs but these are predominantly on grassy surfaces and cars. The band slowly shifted south overnight and now situates itself between Morgantown-Chester-and just north of Millville. Some flurries seem to be north over Allentown and these are sliding slowly southward as well.
I think that on and off flurries and, for those near this band, snow showers, will be a common feature through a chunk of the day today. Winds will pick up this afternoon once the disturbance responsible for this precipitation slides away to the southeast. Winds will run 10-20 mph from the northwest late this afternoon with higher gusts.
Update, 8 PM: We'll see on this one but the ever-optimistic Henry Margusity says some parts of the northern burbs of Philly could see 1-4" of snow tonight. Light snow and snizzle has been falling across the northwest Philly burbs for the last 90 minutes or so and I have seen a few small coatings in the grass in the yard. We'll see how it does through the night. The band continues to slide southeast with a slight shift south in the band axis over the last couple of hours. The slight southern shift could continue through the evening hours as the band continues to slide down from the Great Lakes.
Update, 5 PM: Follow the snowband on the radar I saved that is setting up near an Erie-Lock Haven-just west of Pottsville line and moving southeast. That snowband is going to move southeast, almost along the Schuylkill River over the next several hours and through the Philadelphia. This band looks to be the band where the accumulating snow will set up tonight. The inch amounts (more than an inch the farther northwest into Central PA one goes) will be setting up shop along that line.
A weak disturbance and boundary will slide southeast through Pennsylvania overnight tonight. While flurries and light snow showers will fall through the afternoon and evening hours as part of energy that is moving southeast from the Lakes and dying lake effect snow bands, the energy that will bring some more potent snow shower activity is presently back over the Great Lakes. As it tracks southeast tonight it will help to enhance snow shower activity the boundary and the disturbance itself.
I don't think everyone will see accumulating snow from this nor do I think accumulations will be significant. I think at most, an inch or so of snow is "best case" scenario from this event and it will only fall in a narrow band. Whether that band travels north of the Schuylkill (WRF), along the Schuylkill (NAM), or south of it (GFS) remains to be seen but the models have pretty much set up their thinking regarding specifically where light snowfall may occur.
The graphics up above from wxcaster.com show the snowfall potential for the NAM, WRF, and GFS computer forecasts. The resolution on the NAM and WRF is higher and seems to have a decent handle on how much may fall despite the location differences among all three models.
If the band sets up in a Reading-to-Philadelphia direction an inch of snow could greet those areas and depending on the timing it could make the morning commute a tad slower than usual, even by 422 and Schuylkill Expressway standards.
Because of the narrow swath of this snow band as it is depicted, I will not issue a Snowfall Challenge on this forecast (unless you like to grade coating to one inch events because I can see that being the forecast for most).
It will be fun to watch the band set up and more importantly, see the first snows of the season for some parts of the region that have yet to see accumulating....or even any...snow in the cold season so far.
Update, 8 AM: Winter Weather Advisory Until 11 AM for one to three inches of snow on grassy surfaces. Advisory covers Philadelphia, Montco, Delco, Chester, New Castle, Gloucester, Salem, Camden, Atlantic, and Burlington Counties, mostly in that infamous narrow band that's been talked about during this thread.
Update, 7:30 AM:
Nothing like a little November snowfall to get everyone excited about the potential for a colder and snowier winter. Compared to the last two winters even an "average" winter will seem quite cold and snowy so I guess most of the snow starved should be happy regardless of the result at the end.
The photo up above is of a coating of snow on the lawn outside of my home in Montco earlier this morning.
Update, 6 AM: So far the lucky dog snow winner is Boyertown where 2" of snow fell last night through 10 PM. The snowfall reporter is at a 700' in elevation, which helped in giving him a little extra bump in getting the snowfall to stick. There are a lot of coating to 1/2" accumulations across the western suburbs but these are predominantly on grassy surfaces and cars. The band slowly shifted south overnight and now situates itself between Morgantown-Chester-and just north of Millville. Some flurries seem to be north over Allentown and these are sliding slowly southward as well.
I think that on and off flurries and, for those near this band, snow showers, will be a common feature through a chunk of the day today. Winds will pick up this afternoon once the disturbance responsible for this precipitation slides away to the southeast. Winds will run 10-20 mph from the northwest late this afternoon with higher gusts.
Update, 8 PM: We'll see on this one but the ever-optimistic Henry Margusity says some parts of the northern burbs of Philly could see 1-4" of snow tonight. Light snow and snizzle has been falling across the northwest Philly burbs for the last 90 minutes or so and I have seen a few small coatings in the grass in the yard. We'll see how it does through the night. The band continues to slide southeast with a slight shift south in the band axis over the last couple of hours. The slight southern shift could continue through the evening hours as the band continues to slide down from the Great Lakes.
Update, 5 PM: Follow the snowband on the radar I saved that is setting up near an Erie-Lock Haven-just west of Pottsville line and moving southeast. That snowband is going to move southeast, almost along the Schuylkill River over the next several hours and through the Philadelphia. This band looks to be the band where the accumulating snow will set up tonight. The inch amounts (more than an inch the farther northwest into Central PA one goes) will be setting up shop along that line.
A weak disturbance and boundary will slide southeast through Pennsylvania overnight tonight. While flurries and light snow showers will fall through the afternoon and evening hours as part of energy that is moving southeast from the Lakes and dying lake effect snow bands, the energy that will bring some more potent snow shower activity is presently back over the Great Lakes. As it tracks southeast tonight it will help to enhance snow shower activity the boundary and the disturbance itself.
I don't think everyone will see accumulating snow from this nor do I think accumulations will be significant. I think at most, an inch or so of snow is "best case" scenario from this event and it will only fall in a narrow band. Whether that band travels north of the Schuylkill (WRF), along the Schuylkill (NAM), or south of it (GFS) remains to be seen but the models have pretty much set up their thinking regarding specifically where light snowfall may occur.
The graphics up above from wxcaster.com show the snowfall potential for the NAM, WRF, and GFS computer forecasts. The resolution on the NAM and WRF is higher and seems to have a decent handle on how much may fall despite the location differences among all three models.If the band sets up in a Reading-to-Philadelphia direction an inch of snow could greet those areas and depending on the timing it could make the morning commute a tad slower than usual, even by 422 and Schuylkill Expressway standards.
Because of the narrow swath of this snow band as it is depicted, I will not issue a Snowfall Challenge on this forecast (unless you like to grade coating to one inch events because I can see that being the forecast for most).
It will be fun to watch the band set up and more importantly, see the first snows of the season for some parts of the region that have yet to see accumulating....or even any...snow in the cold season so far.
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