Large Storm to Lash East Coast Midweek- Southern New England Impacts

A snowmaker moving through the Upper Plains and Ohio Valley will meet up with southern stream energy off the North Carolina coast to spawn a large and powerful ocean storm.  While a direct hit is unlikely, it cannot be ruled out yet as the American GFS is showing a foot of fresh snow falling on the region.  Instead strong gusty winds will be a big threat especially SE New England.  Big waves will also pound the beaches for days, further damaging areas struck hard by Sandy in the Mid Atlantic and the Blizzard of 2013 in New England.  Light snow, moderate at times will be possible Wednesday night especially SE MA.  Thursday night will see greater potential for accumulating snow from Boston to Worcester south and east.

Current Conditions/Storm Evolution

Surface

HPC surface chart 521 AM EST

A strong system is producing snow across North Dakota, Southern Canada, into Minnesota.  Low pressure over Oklahoma is also slowly pushing east.  These will combine near the Mid Atlantic Coast.  At the upper levels we still are dealing with an upper level low.  

06z NAM 500 mb vorticity 

Today should feature a bit more sun than the past few days.  There will still be clouds around but temperatures will climb to 40 from Worcester County South and east.  

10z RAP 2 m Temp 2 PM (image weatherbell)

Winds today will be breezy at times out of the northwest

06z NAM 15 hour 10 m wind speed valid 4 PM (image weatherbell)

By tomorrow our 500 mb charts look like this

06z NAM 500 mb vort valid Tuesday 10 am 

Our ULL is still off the New England coast.  This low cannot go anywhere, it is blocked.  This will play a role on Wednesday .  The low will keep the same pattern in place; some sun, mostly clouds.  There will be isolated snow/rain showers due to the instability an ULL creates in the lower atmosphere.  Temperatures tomorrow look like this

00z EPS t 2 m max, Tuesday afternoon (image weatherbell)

At the same time here is the projected surface chart

HPC surface outlook Tuesday 7 PM 

Moving along to Wednesday

06z NAM 500 mb vort valid Wednesday 7 am EST

The ULL backs away slightly and our storm deepens at 500 mb.  It starts to take on a slight negative tilt.  This is important because there is no pure Arctic air mass in the lower 48.  A negatively titled trough will allow the storm to become more intense and thus help create its own cold air.  The projected surface at the same time

HPC surface outlook Wednesday 7 am EST

No doubt this storm slides to the east northeast but the question is how far north will it come?  What type of interaction will the storm have with our ULL and high pressure to our north?  We may see just high winds and high surf Wednesday into Thursday.

06z NAM 10 m winds Thursday 4 am EST (image weatherbell)

These are sustained winds of 25-30 mph.  Wind gusts will be over 40 inland, will approach 50-60 on the Cape.  

06z GFS 900 mb winds, mslp Thursday 7 am (image weatherbell)

This is at 900 mb, or about 3500 feet above the surface.  Those are hurricane force winds across SNE and a battering fetch of winds blowing directly onto the New England shore.  

HPC 5 day precipitation forecast

HPC is still looking at a quarter inch of precipitation for most.  A half inch is creeping towards the Cape and Islands.

Summary

I am more concerned about strong winds than snow at this point.  The GFS, its ensembles, and even the EURO Ensemble is bringing some snow into SNE.  We shall see, what is clear is an impressive coastal storm will be offshore during midweek.  Updates will be issued as needed, have a good day!