Winter Weather

Winter Weather Outlook

Happy New Year!

As mentioned in last week’s “commentary” post, the weather pattern for January starts off similarly to December- with a very broad jet stream troughing, giving us cold weather with a storm track that misses us to our east, followed by a flattening of the jet, with milder temperatures and a storm track to our west, giving us rain.

Also mentioned, the numerical weather models have been inconsistent and forecast accuracy regarding specifics beyond 2-3 days has been unreliable.

That is certainly true this week– a broad dip in the jet arrives on Wednesday and very cold temperatures are expected Thursday through Monday.  Low pressure vorticities that would ordinarily give us snow with a sharper jet dip will likely move off to our south and east with the current broad configuration.

However, with the model’s extended forecasts so inconsistent, the possibility of snow over this weekend needs to be watched. Right now, snow looks unlikely.

Philadelphia Area Weather Forecasts

Philly Weekend Weather Forecast

The roller coaster of this season’s temperatures continues as the current dip in the jet stream relaxes and milder temperatures return for Sunday.

For Saturday, expect breezy conditions and slightly above average temperatures .  Sunny skies in the morning become obscured by mid level clouds in the late afternoon. Highs near 45.  (Average is 40.)

A weak front passes through New Year’s Eve.

Sunday is milder and sunny with highs near 50. Clouds move in Sunday night with showers on Monday.

A broad upper air trough with some very cold air establishes itself midweek with a return of cold weather here. The position and broadness of the upper air trough keeps the deep cold away from our area. It also keeps snow out of the forecast. 

Commentary

Inconsistent Weather Forecasts- Commentary

I’ve been looking at the weather for years.  I can’t remember a previous period of time where the major models have been so inconsistent with forecasts.   The major models, while often showing some disagreement with various features, seem to be in less agreement over the past month or so.

More importantly, the models themselves seem to change with their own forecasts from day to day.  Two examples this week- based on the forecast from the weekend, Tuesday was expected to be mild, but it wasn’t until Monday that it became apparent that temps would be near 60.  Thursday was supposed to be much colder at the start, now  not so until later in the day. What looked like snow is now a rain forecast.

Basically, this season, you can’t count on the models for a specific scenario beyond 2, maybe 3 days in advance.

I’m not sure why this is the case.  I have been reading that temperatures in the Arctic circle are very mild this year, with the cold pools of air being further south, in Siberia for example.  Not the norm. I suspect this is throwing off the models quite a bit.

Either way, weather forecasting so far this cold season has been more of a challenge than usual.

Weather… and Other Things 'Up in the Air'