Saturday, December 10, 2011

The Next Shot Of Rain Comes Later Next Week

Tranquil weather is in control through the weekend and into the early parts of next week. Tomorrow is shaping up as our coolest day since Snowtober and the coolest non-precipitation day since March so yeah, winter's sorta here although old man winter is merely dipping his toes into Philadelphia's climate. Colder core of air has over Canada and will retreat out pretty quick as the main pattern aloft doesn't support blocking quite yet. The cool air, however, is at least a sign that we can get somewhat "typical" for December around here!

The next storm system will impact us between late Wednesday and Friday -- and will be a rainmaker for the region as the Nina Southeast Ridge flexes up and a storm system organizes in the Plains, riding northeast through the Great Lakes. An initial shot of overrunning light rain could start off the rain event on Wednesday afternoon.   The low that brings this first shot of rain lifts north into Canada, pushing a cold front through the region early on Friday.   Rain is expected along the frontal boundary passage as it moves through, with the potential for a wave of low pressure to ride along the boundary and possibly enhance rainfall a bit.

There's some question as to what happens after the front clears through.  The GFS suggests the front bogs down, similar to what happened last Wednesday, with a second storm system riding northeast along the front next Saturday with a round of heavier rains for the region.  The Euro pushes the front through and delivers a cold shot for next weekend before low pressure organizes in the South and pushes northeast around December 20th.  If the GFS' scenario from early this morning is correct, we could be looking at the potential for another soaking of rain that could lead to more stream/river problems around the area before we cool off.   Wishful thinking is that this doesn't happen but wishes and dreams don't get you too far sometimes!  

There's lots to be settled in the coming week so the potential for another heavy rain event could merely be a model hallucination and not reality...but the potential for more rain in the late Wednesday through Friday timeframe is real.  It does not look quite as bad as what we went through last week but it will keep the mud moist and the yards soggy.