Category Archives: Weather Updates

WINTER WEATHER UPDATE

Just a quick update,based on tonight’s NAM model data that just became available.

Much of what I wrote about earlier today still holds.  While the lower levels of the atmosphere remain below freezing for an extended period on Thursday due to “cold air damming”, the upper levels of the atmosphere are forecast to be too warm to support snow Thursday.

I believe this will be a sleet event, eventually changing to sleet and rain; rain possibly heavy in the afternoon. While some early snowflakes are possible, it should quickly change to sleet.

I’m sure there are forecasts out there for snow, based on preset precipitation type algorithms. But thermal profiles have worked well for my forecasts in the past and I’m going to stick with it this time. This forecast is for Philadelphia and immediate suburbs. Areas far north and west may have more freezing rain and sleet accumulating.

The scenario with the upper low enhancing a secondary surface low Thursday night into Friday morning is also supported by tonight’s NAM.  However, it’s looking less likely that enough cold air will allow a changeover to snow .

Things will clarify by tomorrow evening.

 

WEATHER FORECAST UPDATE

Today’s weather featured a bit more cloudiness than had been forecast and the temperatures weren’t able to reach the predicted high.  The front has stalled just a bit further north and over-running of moisture has to occurred today giving us the clouds.

As mentioned yesterday, it wouldn’t take much for the amount of rain expected on Sunday to increase, based on further intensification of the wave expected to form along the stalled front to our south. Indeed, the GFS and last night’s NAM suggested that rain might continue through the day on Sunday.

So while Friday’s model forecast had Philadelphia on the very northern fringe of precipitation on Sunday, things are now looking wetter.

This afternoon’s models are predicting a very cloudy and rainy Sunday. Rain starts in the morning and continues into the afternoon. High in the mid 60s.

Autumn, which begins tonight, continues with the rainy pattern we have had for much of this past summer.