Friday: Updated Winter Storm Forecast

Good morning. The new data is in, and it is time to make a few tweaks to my original forecast. A major winter storm will be impacting most of the region Saturday into Sunday.As the story goes every single time no forecast is easy. In this case, my biggest concern is trying to nail down a narrow 20 mile band of freezing rain that I think will occur with this storm and cause big impacts. Also, trying to nail down where the heavy snow accumulations cutoff is the next challenge. Combining model data with experience I have come up with this as my updated forecast map.

The timing is Saturday afternoon through Sunday Morning...

Looking at this map the critical areas are the light and dark pink. Somewhere in this area should see signifigant icing. At this time I think its in the form of freezing rain for the light pink area. Just to the NW in the dark pink I expect more sleet than freezing rain. Some models are warmer than what I have and would shift this whole map NW but I think those models are under doing the cold air as I have discussed all week.

So lets get to the play by play of how this may evolve...

Very cold air settles into the region by Saturday morning...

A low pressure system loaded with moisture then begins to approach this cold air from the southwest...

By the time we get to mid afternoon Saturday or just past mid afternoon (3-7pm) Saturday, snow will start to break out for many areas in our region...

For areas in CNJ northward, I think the initial few hours later on Saturday is a pretty good front end thump of snow where even areas like CNJ can see a few inches pile up with several more to the NW.

By the time we approach midnight below, warm air starts to work in aloft and the snow changes to sleet and freezing rain for many s...

This is the critical forecast point as models are mixed on how far north the mixing and rain line goes. Some have it more north than what you see above. I am going on the colder side here based on experience which is why I am showing this model.

Regardless, if I am right, surface temps stay cold for many during this critical period...

This is where my iceing concerns come into play for areas in the light pink zone as there is a chance a good amount of freezing rain can occur.

As an example, this high resolution model at 4 am Sunday shows that freezing rain band. It is prob a little too far south in this model projection but you get my point...

The pink to the north is a sleet storm. Again the placement of these features is still pretty uncertain but my forecast map tries to make a prediction.

By daybreak Sunday morning the back end of the storm approaches and the narrow freezing rain band and sleet continue with heavy heavy snow to the NW. 

There is a chance that just after daybreak things can change back to snow for areas seeing ice seen below...

The storm is over for many by late morning and by mid afternoon in New England.

Then comes a major major cold shot Sunday night which will cause any liquid areas to flash freeze by Monday morning...

Although this may be a little overdone you can see how serious this cold air is. Sub zero temps possibly all the way down to the NJ boarder...

Snow and ice removal will be key Sunday ahead of this brutal air mass.

Stay tuned for my next update at 6pm tonight. I will be making the final tweaks if necessary to this forecast.