Rain Then Snow

Just a very quick post now that the storm is upon us...and it now appears that a moderately heavy rain event will evolve into a moderately heavy snow event.  The sooner the storm strengthens, the more rapidly cooling will be able to occur not only at the surface, but where the snowflakes are produced in the cloud.  To be sure, this is a much greater event in terms of precipitation than most people saw coming as evidenced by the flood watch statements.  If this warm air from the last week were not in place, we'd be looking at a major snow event for early December.  As it is, we are looking at a 3-6" event in our area with the bulk of it falling during the sun down hours.  So if driving, don't be fooled by the statements that the roads are "warm" and snow can't accumulate on them.  When snow is thumping at 1"+/hour, driving will become tricky overnight tonight...so take caution.

I am posting just one image and that is from the ensemble plumes.  I circled in red where the changeover time seems most likely (lines go from green to blue) and placed a mark at the time scale along the bottom axis.  That is somewhere near 22-23Z or 5-6 pm this evening.  It also appears that it is about halfway along those colored lines so lets say half falls as snow and half falls as rain.  If that is the case, then at 10:1 which is what the models are suggesting for the snow, and accounting for some melting due to the recent warmth, we are looking at 3-6" from 6 pm until 3 am or so...slightly higher amounts with elevation along the Blue Mountain up into northern Lebanon County and the high ground of western York and Cumberland Counties. 

Now where can you get that type of analysis for free.....I know, I know.......just about everywhere and anywhere on the internet...but you need to go no farther than Smitty's Synoptic Synopsis!

Go Rams and D3 football!

Have a wonderful Wednesday!

Smitty

AA:  Heavy rain changing to heavy snow around sunset or just after.