Monday, December 8, 2014

Complex Nor' Easter Coming...

This storm is one of the most difficult I've ever had to forecast. Looks like we will see ALL forms of precipitation and lots of wind. Let's start off with EURO surface maps and sounding combos. Early tomorrow morning around 6:00 AM the snow will start and continue for a couple hours. This could accumulate to up one inch in spots but it will quickly change over.

Next we can see the warmer air has won out (just barely). The surface is still around freezing but the mid levels are a couple degrees above. A slight shift could keep the wintry precip over NW NJ longer than expected but this still seems like primarily rain for most. 

As the storm pulls away the colder air can start to make a return, at the surface. There is now a strong mid level inversion late afternoon tomorrow and sleet and freezing could now be an issue after the rain. Yes, we have gone from snow, to rain, sleet and freezing rain, and now the wind is really kicking up.

A few models show a significant shot of snow on the backside of the storm Wednesday morning. (Yeah, now back to snow.) This is where things could get interesting and potentially give us several inches of snow. The whole situation is so complicated and this part of the event depends on how the storm intensifies, and this thing hasn't even formed yet. 

This storm can have an effect on us till Thursday and has many phases:

1. Starts off as snow tomorrow morning (up to 1")
2. Snow changes to a cold rain (temps struggle to break 32)
3. The warm air wins out at mid levels but surface temps are below 32 (freezing rain)
4. Sleet can start to mix in with the freezing rain Tuesday night
5. The winds will get strong tomorrow night
6. The wintry mix now changes to back to snow (accumulation possible)

Tomorrow night I'm going to post a snow map for the end of the event. Doing it now would be setting myself up for failure because the models are all over the place. This storm needs to actually form first before I make a forecast on the "wrap around" snow which rarely actually happens in NJ. 

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