Friday, January 24, 2014

Snow Storm Potential for Eastern VA/NC/SC

Over the past few days, the risk for a major snowstorm for areas of eastern Virginia/North Carolina/South Carolina has really increased.  We will have a clipper system move through during the day on Monday.  Behind this system, very cold air will push all the way into the south-east.  This air mass will be just as cold as the one we've seen this week.  The maps below are from today's 12z European model. I highlighted the piece of the piece of the polar vortex (or polar low) that has been responsible for continuously slinging northern stream energy into eastern section of the country.  This has been why we have seen so many clipper systems over the past few weeks and a persistent trough across the east coast.

This clipper will rotate through, dragging a cold front in its wake.  This will deepen the trough over the east coast.  The front will eventually stall out.  A piece of energy coming out of western Canada will dig into the southern plains.  Once it rounds the base of the trough across the east, we will be watching for an area of low pressure to form off the Georgia/ South Carolina coast.  Instead of this low taking the more typical track right up the eastern seaboard, yet another piece of energy will be coming out of Alberta.  This is known as the "kicker".  This will force the coastal low to stay well off shore.  Not only will this keep the best chances at precipitation along the coast, but it will also lock in the cold air.

As a result. here's what the 12z European looked like at the surface.

Now switching gears and looking at the 12z gfs, the "kicker" comes much farther south...forcing the trough over the east to get kicked east and in turn the coastal low to form farther east and out to sea.  

As a result, the precipitation barely graze far eastern areas of the Carolina and Virginia (shown below).  One of the biases of the gfs is to be too strong with the northern stream so I'm leaning more towards the Euro at this time.


This seems to happen with nearly every significant east coast storm involving any kind of disagreement between the Euro and the Gfs in regards to how strong the northern stream will be/ deciding how close to the coast a low will track, especially in the 4-6 day out range.   The gfs will likely continue trending towards the euro over the next few days.  The Euro even has agreement from other global/ensemble members right now.

The 12z CMC

12z euro ensembles

12z JMA

It will be interesting over the next few days to watch just how far west the coastal low comes.  It will come down to tracking how deep the trough over the east gets and how strong the piece of energy ("kicker") is coming out of Canada.  Right now...here's my early, early, early thoughts at who has the best chance of seeing snow.  I'll adjust over the next few days as we get better sampling of the pieces of energy involved with this system.


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