Thursday, February 09, 2012

Talking About Saturday's Snow Shot

We've talked for a couple of days about the potential of a coastal storm developing off of the Carolinas on Saturday. While this storm will not directly impact the region and will not bring epic amounts of snow, it is close enough to interact with a cold front that will push down into the region Friday night and early Saturday morning. That interaction will result in the development of at least snow showers, perhaps some light snow, across the region late Friday night and continuing into Saturday morning.

The Euro has been talking this potential up for a few forecasts now and we were highlighting it on our Facebook page on Monday (hence the chance of snow showers you've seen in our forecasts for a few days).  This interaction of low pressure with a frontal boundary that's moving towards the low in the winter can sometimes produce a "norlun" or a norlun type event where a band of snow sets up and drops a few inches or a deformation zone (which is similar in that precipitation is enhanced but the mechanics are different and sometimes less pronounced as a norlun).   Regardless of what ultimately pops on Saturday, the potential for a band or two of precipitation to fire up is there.

The Euro (above) is slightly less pronounced with this precipitation potential in last night's run compared to the GFS (see below) and the NAM (not shown) as the Euro simply shows a bunch of snow showers, flurries, and light precipitation lingering around early Saturday morning while the other two models show a bit more pronounced band of precipitation shooting through the region in the pre-dawn hours or early morning hours of Saturday.   With that said, the Euro does develop this similar type trough band later in the day.   In terms of timing, the NAM is the fastest, Euro slowest, GFS is the "middle ground" on timing.

The good news is that the atmosphere above the ground will be sufficiently cold enough for snow...but the surface might not be initially along the coast.  This could be a similar type event to the one we just dealt with in South Jersey -- starts as rain along the coast before a changeover...especially if this event gets in early enough a la the NAM's thinking before the cold front can nudge temperatures down towards freezing.

The rest of the region should be cold enough for snow.  The big question is timing -- will this be more of a Saturday predawn, morning, or daytime event -- as well as where this trough band sets up.  Most computer guidance suggests it will set up across South Jersey and Delaware but these band placements are fickle on modeling and may shift around a bit before reality sets in.

A couple...perhaps even a few inches of accumulation are not out of the question with Saturday's event, with the "few" falling where that band sets up.  It might be a situation where the highest totals are 4" but it is a localized, narrow band somewhere in the region while everyone else gets an inch or two.   Don't expect four inches to fall in your backyard but be happy if it does...but odds do favor an inch or two as of now.   We'll continue to keep an eye on this though as a lot of moving parts abound with this system and it may shift a bit before Friday night and Saturday.