12Z runs are underway. One thing I'm noticing on the NAM is the H5 is really haning the energy all the way back into Mexico. We saw this in earlier runs on other models - which ended up a southern miss.
The other point on this one for me is that this isn't a H up north setting up and allowing the L to form and run into it. It's a strong ULL forcing the H down and the L forming, and trying to run into it - resulting in the "slide" with snow mainly coming from over-running.
I simply look at this as two opposing forces head butting versus one gently moving in and the other slamming into it. Always a problem to determine where the line of snow actually sets up.
12Z NAM : http://www.instantweathermaps.com/NAM-php/showmap-conussfc.php?run=2014031512&time=PER&var=ASNOWI&hour=060
If it were the former scenario (H up north, L forms and rides INTO it) then a different story. But we have a slider. Looking at current temps - you can see the airmass that will be pushed down. That is COLD! In this situation the COLD will win, not the warm. That's just my take on it.
So it's about where things set up and how far the overrunning can invade to determine the snow-swath.
Right now - NAM paints a VA/Delmarva/Exterme SJ special. Philly is out. (why does this feel like deja vu?) - A SLIDER.
With this type of system - last minute changes can happen. If the ULL in Canada shifts, weakens, and the H isn't as strong, then a north shift would occur. *ugh* invoking nowcast mode.
But for the next few hours - headed to the Flyboys game. Time to open up a can of whoop-a$$ on those stinking tuxedo birds.....
Enjoy today - looks awesome outside!! LET'S GO F-L-Y-E-R-S!!!!!