Monday, November 24, 2014

Preliminary Snow Map

I'm going to start right off with the snow map then explain my reasoning. Please note, this is a preliminary map and the final forecast one will be issued tomorrow night.

I'm being very conservative in the urban areas and very generous in the northwestern corner of the state, and I have very good reasons for that. The above map has three points displayed on it. EWR  is Newark Airport (5 feet above seas level), MMU is Morristown Airport(180 feet above seas level), and 12N is Andover airport (600 feet above seas level) .

Now let's take those points on the map and look at a vertical slice of the atmosphere.

**Also note that in these soundings there is no warm air inversions. It's either raining, snowing, or both. Sleet and freezing rain will not be a concern.

Newark Airport (KEWR):

The two blue lines represent temperature and moisture in the air. When they come together the air is saturated and could be used to identify a cloud deck or if it's precipitating. Obviously here precipitation is hitting the surface in Newark, but if you look in the red circle the temperature during the height of the storm is well above the freezing line or 0 Celsius line at the surface. This is going to make it hard for the SNOW that is falling in this sounding to accumulate. So while it will snow here most of it will melt on contact. 

Morristown Airport (KMMU):

Now we are getting closer. The temperature in Morristown is just above freezing here and snow is probably sticking to colder surfaces and the temperature drops off dramatically with altitude so nearby hill tops are already seeing accumulations on most surfaces. 

Andover Airport (K12N):

At no point during this storm does Andover show a temperature exceeding the freezing mark. Snow at 32 degrees will stick to all surfaces and this is why I expect 6" snowfall here. This airport is only at 600 feet on the western side of the highlands. Areas above 1,000 feet will be in the upper 20's during the event and be able to get higher snowfall totals.

I hope all this helps to explain my ideas. I don't just issue a map with pretty colors without seriously looking at the situation honestly and without bias (even though I do live in the bulls eye). Check back tomorrow for my final map. 

No comments: