8:32 AM

A mesoscale convective system or MCS formed over North Carolina last night and will have a significant impact on the forecast today.  

moisture-robberAn MCS is basically a large complex of thunderstorms with a mesoscale low pressure system.  These thunderstorms can produce very heavy rain, strong damaging winds, and frequent lightning over a location, but they can also limit moisture advection for locations to the north of the MCS development.  

That’s exactly what is happening this morning.  While rain is racing through the forecast area via the warm front, the significantly heavy steady rainfall ahead of the cold front will not materialize due to the lack of moisture which is bottled up over the Southeast coast.  This also means the atmosphere is more stable and lacking the “high octane” moisture which would have made strong to severe thunderstorms possible over the southern Philadelphia metro and central/southern New Jersey.  So what can we expect for today?

Well, showers and thunderstorms will impact the forecast area as the cold front moves through the region this afternoon, generally around 12 PM to 4 PM from west to east.  The thunderstorms will be capable of heavy downpours, isolated lightning, and strong wind gusts up to 40 mph.  

High pressure will build into the Mid Atlantic tonight through tomorrow morning, however the strong gradient between the high over the Ohio Valley and the low over New England will lead to a windy Monday with sustained winds around 15 to 25 mph from the northwest.  

High pressure will remain in control on Tuesday with clear skies, light winds, and near normal temperatures.

So to wrap things up.  MCS limits what was suppose to be a strong moisture advection into the forecast area.  A strong cold front will still move through this afternoon.  A windy Monday will follow with a much more tranquil day on Tuesday.