Definitive Dennis

Well, today is my twin brothers' birthday.  OK Smitty, what does that have to do with the price of coffee in Columbia?  I'm glad you asked!  When conversing with my one brother today, he reminded me of the stories our father told of toting home his March 12 newborns from the hospital in very deep snow.  That was 1956; and here are the snow totals from that notable storm.

Now that 1956 storm was simply an Alberta Clipper on steroids.  It did not have the same upper air support as what we are seeing for the impending system to affect the upper mid-west, mid-Atlantic and New England.  Nor did it have a low pressure system that emanated from the Gulf of Mexico that this synoptic set-up will have.  When a 500 mb closed low strolls through northern VA as shown below, that is often a south central PA special!  Those screaming winds at 18,000 ft will spin up quite a nor'easter.  Take a look...

And here is another look at the height anomaly for this 500 mb pressure field.  If you are a snow lover, that graphic is a thing of beauty coupled with the surface features!  Also, a ridge over Yellowstone often delivers the goods here as well...It seems to me the stars have aligned for a south central PA special!

I will display just one snowfall model map; the Euro dynamic ratio map.  This takes into account many variables that contribute to dendrite growth; upward motion, upper air temps, and deep atmospheric moisture.  It is essentially a weighted average of all of the atmospheric variables that supply the snowflakes their necessary ingredients to develop.  Check it out...

That heavy band from LANCO to Albany, NY is a combo of a front-end heavy snowfall and the backlash of the deformation of high ratio snows.  Where that backlash band sets up could add an additional 6"+ on the earth below...those are ALWAYS tricky to forecast.  

I also like to look at analogs too.  Here is the top analog based on the GFS...Since this is a February storm below, all of the snow accums are a bit further south; shift this a hundred miles north and east and this looks very close to the Euro output.  Time will tell...

What I do know is that it is quite cold!  Take a look at what should be our max temps for the day!  Temps will not be an issue here at the surface; however, if the storm deepens rapidly and pulls in milder ocean air in the upper levels, a period of sleet could materialize leading to some concrete type accumulations under the fluffy backlash that will blow and drift to some extent!  Warnings might even elevate to blizzard conditions if the wind can become an issue.  I don't believe that will happen here in the KMDT area, but we may see Blizzard conditions and warnings hoisted in the Lehigh Valley of PA.  Brrrrr...

Below is the wind map for Wednesday; a large pressure gradient is setting up across PA for later Tuesday night into Wednesday as high pressure builds in from the NW.  Tuesday's winds will be manageable...

Ok...I think you get the picture; a classic March winter storm is on the horizon.  I guess you could accurately call it Meteorological March Madness!  So my final definitive call; +/- 2" either side of 14; in other words, let's go 12-16".  I'm concerned that I might be a tad conservative, but I am often called "Chicken Little" amongst my friends.  So being the conservative that I am,  I will go conservative with my definitive totals.  After all, the Indigo Girls seem to agree; "...The Less I seek my source for some definitive, the closer I am to fine". Enjoy their take...

And enjoy your Meteorological March Madness!

Smitty

AA:  Looking at a major snowstorm in these parts Monday night into Wednesday.  My final call; 12-16" with cold to follow.  Snow will be around for awhile, too!  Also, keeping an eye wide open for this weekend.  Another clipper to invade with yet another likely accumulating snowfall.  The winter that never was now doesn't want to leave!