Upcoming Cold Weather Outlook

If you’ve listened to any weather forecasts recently, you’ve likely heard that [several] oubreaks of cold air will be affecting us over the next week.

The models are in reasonable agreement that a deep upper air trough will develop over the eastern US, probably in three different stages. The first influx of cold air will enter Thursday afternoon.  Another will move in Saturday night.  A third will likely affect us next Tuesday into Wednesday.

What is less clear is the amount  snow (if any) that will accompany each of the clipper distubances that herald in the cold outbreaks.  Right now, the amount of snow expected in PHL for each of these disturbances looks to be less and less with each model run.  Thursday will likely just have some snow showers.  Saturday afternoon’s clipper also appears to be trending towards less snow here.   Additionally, the sharpness of the trough appears to be somewhat less, meaning less cold air in Florida.

The only real threat is next Tuesday, where a low pressure system from the southwest (not a clipper) may interact with the re-developing upper trough.  Of course, much can change in a week, but these are the current trends.

Philly Winter Weather Update

Over the past day, the NAM model has done well with the temperatures and the precipitation predictions.  The freezing drizzle and very light rain should continue on and off this afternoon.  Just a few snow flakes this evening.   The NAM only cranks out 0.01 inches of water every 6 hours, ending late evening.

During the daylight hours, solar insolation through clouds may keep some dark roadway surfaces just wet, but towards evening, more icey conditions are possible.

Winter Weather Update

The afternoon NAM model continues to show colder surface temperatures around PHL.  Chances of freezing rain or drizzle appear more likely for later tonight and Monday closer to PHL.

I don’t think the models are capturing this low pressure system well.

A small  cyclonic surface wind circulation is developing off the NJ coast.  Could an unexpected secondary low be developing?   Stay tuned.

Weather… and Other Things 'Up in the Air'