There’s a reason the TV weather people are essentially saying it will snow tomorrow and accumulations will range anywhere from 1-6 inches.  (That’s quite a range when you think about it!)

But the inconvenient truth is that even in established storms, the models have trouble with the exact placement of moisture plumes, the convergence of winds and the dynamics of lift that leads to precipitation.  As an example, the ‘blizzard’ a few weeks ago was expected to have its heaviest snow south and west of the city.   But the heaviest snow turned out to be north and west.  That error occurred with an existing storm system that was moving and strengthening in time, a relatively ‘simpler’ situation.

In the situation tomorrow, we are dealing with something totally different.  Tomorrow,  the models are ‘smart enough’ to predict the dynamic development of a new storm off the coast, but that’s where the limits of current atmospherics modeling end.   The models have already been inconsistent with the exact placement of this development and they simply can’t do the exact math with moisture, precipitation etc. because the exact initial state of the atmosphere where it will develop can’t be measured right this moment.

Anyone that get’s the exact snow amounts correct tomorrow in any specific location will do it only by luck.  And that includes me.

The best we can do tomorrow is talk about what the models are saying.  It’s likely not going to accurate enough.    For instance, the GFS has already backed off of it’s high QPF, while the NAM now shows another low pressure system forming towards evening at the coast, and its QPF is now very high, over 0.68 inches water.  So 1-6  inches is a good guess of a range.  It could be less and it could be more.

Sometimes, the most accurate forecast is being honest about the fact that we just can’t know precisely this time around.