Wednesday, March 13, 2013

A Fast Pattern Ahead

Modeling is hinting at the possibility of three systems over a 96 hour period of time -- those three systems tracking through the region between Saturday and Tuesday -- in what is shaping up as an active and fast moving pattern for the end of this week and the beginning of next.

The first of these systems will move through on Saturday -- low pressure or a trough diving southeast through the region.  Most of the modeling out there suggests showers for the region as it moves through due to timing (daytime), temperatures aloft being above freezing, and low pressure track.  This does not look like a big deal at this point -- merely a reinforcing shot of chill from Canada.

The next two systems have a bit less certainty in track and detail.  Sunday night into Monday offers the possibility of a wave of low pressure pushing east through the Mid Atlantic. Modeling varies on track and detail for the region -- with the Euro offering a rain and snow solution depending on location.  The GFS pushes this wave of energy farther to the south and bring us nothing as the track of this wave of energy is about 200 miles south of Philadelphia and along the Virginia/North Carolina border.  The Euro in past runs had produced a swath of steady to heavy snow along and north of the PA Turnpike. The city would be on the rain/snow fence.  While detail is still waffling on the exact evolution of this, the Sunday night and Monday timeframe does offer a potential for some snow...especially north of the city...and a few to perhaps several inches of snow can't be ruled out across Pennsylvania and Central into North Jersey.  Odds favor the most snows north of the city...there's still plenty of time to watch this one.

The third system is timed for Tuesday.  As of now, modeled in many respects like yesterday's rainfall in that it would be a largely "mild" system with a period of rain moving through.  A few past runs of the Euro had dried this system out a bit and made system #2 the stronger of the two.  Given how closely spaced these two systems are, it's likely one of the two ends up stronger and the other weaker in the end.

The Sunday Night/Monday system (the middle one) is the one with the best chance of bringing snows to parts of the region and is dependent largely on track.