Our snowstorm is underway and behaving pretty much as expected.  As of late evening, snow was increasing intensity and spreading northward.  I expect this trend to continue through midnight when everyone will be having moderate to heavy snow.

I’ll be updating the snow forecast as it changes on Twitter at @growingwisdom Please follow me there. Feel free to comment or ask questions too.

There is a tremendous contrast in temperature to our south and east, across something called a coastal front.  The front divides marine air off the ocean from arctic air inland.  The temperatures along the coast have risen well into the 20s, while it’s in the teens inland.  The contrast in temperature is helping lift the moisture up high into the atmosphere where it is producing billions of snowflakes and then falling back to earth.  The western side of a coastal front is where the heaviest snow will ultimately fall.

I expect this front to stay just of the coast, although it could flip inland across some of the islands and extreme eastern sections of York and Cumberland counties towards dawn.

Snowfall rates are going to increase dramatically over the next several hours and at times, between now and dawn,  the snow could fall at 1 or 2 inches per hour.  I would not advise traveling during this time unless you need to be out. 

The snow will be very light and fluffy and therefore amounts will rapidly grow during the night. 

I expect the entire system to quickly exit the area between 8AM and 10AM north to south.  After that time there could be a quick rain shower or snow shower, but the bulk of the storm will be over.

 Winds are not going to be a problem with this storm, so power issues should be negligible. There is always a risk for a power issue in a snowstorm, but this storm won’t produce the conditions normally favorable for power loss.

I am going to leave the snowfall map as I drew it this morning. (above).  While there might be a few areas that don’t meet what I expected then, I still feel good about it.  Remember, amounts can vary a great deal in just a few miles.  In these types of storms, 5 or 6 inch difference in 10 miles is not unheard of and I actually expect to see some very interesting totals on the high side by midday Sunday.

The map below is based on one computer model and closely resembles the overall forecast.  Notice the tight gradient of snow from the coast to the mountains.  The model tries to pick on the varies affects the mountains have during these storms.

The bulk of the storm is over  just after sunrise with lingering lighter precipitation until mid-morning.  Temperatures will be quite interesting tomorrow.  The extreme southern coastal areas could near 30 in the morning and then fall back in the afternoon. 

The weather looks cold and dry Monday with a bit of additional light and fluffy snow for Tuesday.  Some moderation of temperatures is likely by the end of the week.

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