Monthly Archives: January 2017

Philadelphia Area Weather Forecasts

Winter Weather Update- Philly Weekend Weather Forecast

10PM Update:  Latest NAM shows QPF values back up to 0.15 inches water.   The atmosphere warms a bit in the upper levels towards evening.  Here are the latest changes:  Light snow starts in the afternoon, mixes with sleet and possibly some freezing rain after 6pm and ends during the evening.  Accumulations less than an inch. Temperatures fall below freezing later Saturday night.

Today’s NAM has really backed off from the higher QPF values showing yesterday and this afternoon’s 1 PM model run (18z) has the QPF down to 0.06 inches water.  This falls into the category of a dusting or coating and at this low QPF level, this sometimes can translate into a complete zero.   The GFS has been in a similar range of QPF values.

The NAM has any precipitation occurring during the afternoon and early evening.

So this “snow event” (to use the TV people’s jargon) is looking like it’s not worth talking about.

The next data (NAM) becomes available after 9 PM and the NAM FOUS (Forecast OUtput Statistics)  about 9:40.   I’ll update only if there’s a significant change.

Saturday looks to be cold and cloudy with some light snow coating possible, per the discussion above, in the afternoon.  Light snow , sleet and freezing rain into the evening.  Highs about 32-33.

Sunday will be mostly sunny and milder.  Highs about 45.

Winter Weather

Saturday Light Snow Update

10 AM Friday: Latest NAM has further reduced the QPF to 0.07 inches water  should be a minimal snow or dusting

 

Light snow is still forecast by the models for Saturday afternoon. This morning’s NAM had been forecasting a QPF of 0.26 inches water falling as snow, but tonight’s NAM has backed down to 0.17 inches water.

Additionally, tonight’s NAM has the upper atmosphere warming during the afternoon, so some of the snow will be very wet and won’t accumulate very much. Surface temperatures will be close to 32, also reducing accumulation.   One inch is the current best guess.

Still too early to nail this down, but this light snow will be much less of an issue than last weekend’s snow.

Philadelphia Weather Outlook

Winter Weather Outlook

After we enjoy some more above average temperatures on Thursday and Friday, a cold front is expected to slip south of us on Saturday and become somewhat stationary.  Enough cold air is expected to move in to keep temperatures in the low 30s.

A small wave is expected to form on the stalled front and move just to our south Saturday afternoon and Saturday evening.   About 1 inch of snow is currently expected, possibly mixed with sleet.

Here are the trends– temperatures are trending a bit colder with the front just a bit more to our south.  The small wave is trending somewhat stronger, possibly meaning more than 1 inch of snow is possible.

This season, things don’t really come into focus until the 24-36 hour time frame.  With this system, we really won’t know specifics until Friday.

By the way, much of next week looks to have more unseasonably high temperatures.  We may be getting our January thaw significantly early this year.