« Archives in December, 2017

Snow Problem!

I like my broad brush outline from a couple days ago for Raleigh….

…lots of rain, mixing at times with snow as the day wears on tomorrow.  then, finally changes to all snow.  The question will be, how much moisture is left when the changeover happens.  i.e. how much snow falls at the end?

Additionally, there is thermodynamical cooling to consider with bursts of heavy precipitation as snow melts.  Translation…when it snows in an above freezing boundary layer, if it snows hard, then as all those snowflakes melt, they rapidly cool the local atmosphere.  This cooling lets the subsequent snow survive all the way to the ground.  It can briefly accumulate on the ground and stir folks into a tizzy before the snow melts a little later.

It looks like there will be a fair bit of rain tomorrow morning, then after lunch Raleigh will see periods of rain/snow mix or maybe even a period of snow, but mostly rain until later in the afternoon when snow mixing in becomes favored.  Into the evening, snow becomes more likely to the end on Saturday AM.  In Raleigh, I think there will be a minor dusting accumulation (an inch would be lucky) on the grass.  Nothing on the roads.  Travel will not be impacted.  North and west of the Raleigh you are more likely to see slightly higher accumulations on the grass, especially later in the evening and Saturday AM.

Let’s nowcast this tomorrow!


And the Sky Is a ‘Hazy Shade of Winter’…

…but will there be flakes falling from that sky?

I’m fairly confident that flakes will fly in the Triangle Friday into Saturday morning.  That’s the good news.  The bad news for snow lovers is that flakes flying could be all that happens with nothing to show for it on the ground.  Or…precip rates could be hard enough to push surface temperatures close enough to freezing that would allow minor accumulations on grassy surfaces.  In the spectrum of possibilities, (remembering…nearly three days left to go) I favor a scenario where precip begins as rain on Friday, mixes with snow Friday afternoon, changing to all snow Friday evening and overnight Saturday morning.

Accumulation should be limited by the warm surface layer.  So, best guess now is the ‘everyone is happy’ scenario:  that is, snowflakes in the air…minor accumulation on the grass to make it look pretty…no travel problems!

More tomorrow!