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Things continue on track for the main storm to arrive Wed.  We are experiencing a minor ‘flurry’ of activity now.  And we can expect the 2nd round of snow tomorrow, especially south of the Triangle into SC.  Probably very little if any accumulation with that this far north, but there will be accumulations south to the tune of a couple inches.

The headliner begins to spread precip in the Triangle late morning or just after lunch on Wednesday.  It will begin as snow, change to sleet and then to freezing rain.  The biggest question, which remains without an answer at this point, is how long does it precipitate in each form at any given location.  What is very clear at this point and the main point I’d like to drive home is that this storm will drop a lot of ‘something’.  What form that ‘something’ will take will be the debate.  In the met world we call this QPF (quantitative precipitation forecast) or liquid equivalent.  So even though there is uncertainty with how much of each p-type will occur in your backyard, what is more certain is there will be a lot of QPF.  And by a lot I mean over an inch of liquid equivalent.  Consensus among various models and ensembles of those models is centering in on between 1 and 1.5″ of liquid equivalent.  From the Triangle and to the west all this precip will be in some version of something frozen.  So anyway you look at it, it spells crippling winter storm.  Toward Winston-Salem through the Foothills down to Shelby looks confidently all snow.  Then points east of this line could begin to mix with sleet as the storm pulls in a mid-level warm tongue off the Atlantic.  And even farther east then there’s freezing rain to deal with.  Finally, along the eastern Sandhills and Coastal Plain the precip is likely to change to all rain.

Where all these transition zones line up will depend on the exact track of the surface low.  There is still wrestling going on with the track, but not by wide swings…more like quibbling over 100 miles…again, which makes a big difference inland.  Over the next 3-4 run cycles we’ll play these watch the track ebb back and forth, while hoping to get it nailed down.

I promised a map for this afternoon, but instead I’d like to offer a first guess for the Triangle and hold off on a map until tomorrow.  For the Triangle, we begin the real accumulating snow Wed near lunch.  We see 3 or 4 inches before changing to sleet and then add about 1/2″ of accrual of ice from freezing rain.  Then the mid-level cold pushes out the warm tongue on the backside of the low and we change back over to snow for a little more bonus accumulation.  Use this as a guideline to interpolate what you get.  As you go west, you add more snow and less ice.  So that in Winston-Salem they are looking at a foot.  As you go east and south, you get less snow and more ice and eventually a changeover to rain.

Bottom line is that now is the time to be making preparations.  You want to think about changing travel plans (all up the East Coast because this will ride up the coast).  You should also make preparations for loss of power.  1/2″ of ice would be crippling.

NWS is issuing Winter Storm Watches all around valid beginning Wed.

More to come…