Tuesday: Winter Weather to Hit Areas Thursday

Good morning. As we approach the next storm that will hit the area Thursday into Friday, it is time to estimate what the impacts will be. It is shaping up to be the first winter storm of the season for many areas off the coast and of course I will give you my initial thoughts on what will happen. 

Here is my preliminary impact map:

Summary:

• Expect snow to spread into the Pink and Blue zone by mid morning to early afternoon Thursday
• No travel impacts expected in pink zone unless at higher elevations
• Some flakes can fly in the northern part of the Green Zone but mostly a liquid event for those areas
• By Friday afternoon/Evening expect any snow in pink zone to change to ice than plain rain
• Areas in the blue zone should stay mostly snow
• When it is all said and done expect some minor accumulations in the higher elevations of the pink zone and moderate accumulations in the blue zone

A very complex forecasting scenario here as its is a race against time in terms of when the precipitation arrives Thursday and when the cold air leaves.

Many models do show the initial burst of snow/mixed precip Thursday morning or afternoon (timing uncertain)...

Although things will be cold at the surface, warm air will quickly try to work in aloft within hours of the event starting. This means many areas change to sleet then rain (pink zone). Below you can see how the cold air is fighting the warm air at 5000ft. Basically blue is cold enough for snow green is not.

Notice how the blue retreats then trys to filter back in. This is a classic case of snow to start then mixed precip as the cold air mixes with warm aloft.

Many models try to show this the best they can. Pink is mixing.

There snow printouts for any area south of New England and central PA are 100% wrong due to sleet being counted as snow...

THIS IS WRONG!

So the bottom line is this, many areas off the coast see their first winter precipitation of the season on Thursday but there will be limited impacts unless you are at an elevation above 800ft or into the interior blue zone. This is nothing to get concerned about for most.

I will have frequent updates including one tonight.

Welcome to winter!!