Storm Number Three

Even though our particular area won't see a major snowstorm there is a lot in play with this storm.  Take a look at the watches and warnings.

It's actually very interesting to see this map because of all that is going on.  Another classic case of a nor'easter.  You can start in the southern portion of the map where Baltimore and Washington D.C. have no watches whatsoever.  Meanwhile all of Delaware is either in a Coastal Flood Warning or Watch.  The same can be said for most of New Jersey.  However many places have multiple warnings and since you can only use one color per county, there is more to the story.  Take Atlantic City.  They have a Coastal Flood Warning, Flood Watch and Wind Advisory.  Other counties like Hunterdon, Bucks and Montgomery have both a flood advisory and winter weather advisory.  Even the open ocean is covered with gale warnings, craft advisories and high surf warnings.  Move inland and at a point where Lehigh, Carbon and Schuylkill counties meet there is a winter storm advisory, watch and warning within miles of each other.

Off we go.

In technical weather terms there is a boat load of moisture to work with.  See model image below for amounts according to the GFS.

You can see a large area of 1-4 inches of precipitation.  Now the GFS has been consistent in doing something interesting.  Take notice of that darker shade of orange centered by Berks County.  I'll get back to that later.

Here we get the snowfall prediction from NCEP. 

Logically this makes sense.  The snow is confined to the interior and in places that are naturally hillier.  Have to remember a decent amount of warm air is being kicked back in from the ocean which plays against having snow close to the coast. 


The GFS becomes an entire different story.  I'll post a few images.  Remember that bright orange spot from above.

This is after the brief transition from an icy start.  Temperatures have risen and we are in the heaviest part of the rain.

Now this model and in older runs of some others, there has been this massive amount of moisture thrown back

As the warm winds change direction from coastal to winds out of the north, temperatures quickly drop back down.  In my experience though this usually happens after the moisture has is already passed.  This storm set up is allowing for another low to form and contribute to this extra moisture that if the models are correct tends to place the heaviest of this banding back over the Lehigh Valley as you can see above.

This is the very next image from the GFS.  Remember, we are talking a six hour difference.  Notice the dark blue is still over our region.  In this image you can also see the two lows that have formed.  If I'd post the next image it would still show us in a heavy band.

Now is all of this a possibility?  It's hard to predict what's going to happen when one low bombs off the coast let alone two.  I'll give you possible but extremely far fetched at least to what this shows.  If I recall I believe there was a storm last year that provided a decent amount of wrap around snow in a narrow band.  Otherwise it doesn't happen often.   And when I say doesn't happen often I mean not in the sense that the GFS shows.  My theory is that 9 out of 10 times it doesn't happen.   

This is where it gets either funny or awful.  I can't be the judge yet.  Last storm I used the GFS model for NYC to show our own potential snowfall.  After all the crap the GFS produced leading up to the storm the totals the night before ended up being more accurate than I was guessing.  I kid you not, this is what it shows for the system moving through tomorrow and tomorrow night.

There you have it.  Apparently we are looking at somewhere between 10 and 16 inches tomorrow.  Odd how extremely centralized it is too.  Really not even sure what to say.  If we got a quarter of this I will never make fun of the GFS again.

Moving on to reality.

The NAM just updated and it too kicks back snow which again I'm not doubting.  The amounts though with the NAM are far more realistic.

Looking at this one it resembles the first snow map I showed.  By the way the Euro is also very similar with a slightly larger area of pink shades but otherwise very close.  I tend to think this will be very close to the final totals.  All of our snow comes from whatever is able to wrap back around.


The call.

The temperature was far colder today than I thought it was going to be though I also didn't pay much attention.  That should help any early moisture fall in a frozen form.  I still think rain wins out quickly with the way the storm is tracking so I'm not very concerned about morning issues aside from the normally tricky spots.  Rain and wind is the primary player tomorrow.  The snow is the most challenging aspect of the forecast.  There are a lot of variables.  If the temperature drops fast enough and there is enough heavy precipitation it won't take long for snow to stick.  I have trouble seeing more than a coating for most areas so giving an exact figure is tough.  Since I don't see much anyway my only guess will be for a place I know will report.

Allentown - 0.7