WEEKEND WEATHER UPDATE

[su_note note_color=”#d9f2da”]Sunday morning may be dry with rain starting after noon.

Sunday 7 AM update— Rain looks to start as early as 10-11 AM. The models that leaned towards heavier rain look to be correct.

Sunday 2 PM update— Latest QPF from this morning’s models is closest to that predicted by last night’s NBM – about 0.60 inches of rain, much more further south and east. [/su_note]

Tomorrow’s forecast is of interest because it involves a coastal system that could be considered an analog for future winter storms and forecast dilemmas..

There have been consistent and large differences between the global models (GFS, ECMWF, CMC) and the mesoscale models (NAM, WRF) regarding precipitation amounts.—“QPF”

Today the NAM has been cranking out +1.25 inches of rain for Philadelphia while the global models have QPF’s closer to 0.25 inches of rain.  That’s a huge difference.

The latest National Blend of Models (NBM) unsurprisingly cranks out something in the middle ~ 0.60 inches.

All models have heavy rain in south Jersey.

We’ll probably have to wait for tonight’s models for clarification. If this were a snowstorm, we’d be on the edge of our seats.

The earliest model available tonight is the Rapid Update (RAP)— it is trending towards a later start for the rain and QPF values in the  lower range, except in NJ.

RAP FORECAST for 5 PM Sunday  accumulated rain (QPF)

Just available— Here is tonight’s high resolution NAM Nest, which has rain starting about noon and continues with a QPF of about 0.5 inches by 8pm

NAM Nest forecast precipitation 8 pm Sunday

It will be interesting to see how it plays out .

 

WEEKEND WEATHER FORECAST

[su_note note_color=”#d9f2da”]Tonight’s NAM continues with a westward trend and has fairly heavy rain for Philadelphia on Sunday. [/su_note]

High pressure will move over us on Saturday.

Saturday looks to be sunny and dry with warmer temperatures and less wind.  High 65.  (Some cirrus clouds move in during Saturday late afternoon.)

The remnants of a tropical low moving up from the south will affect our weather on Sunday.

Most of today’s models have the low pressure system moving just close enough to bring showers to Philadelphia and the immediate western suburbs on Sunday.

NAM forecast for noon Sunday

The NAM is most aggressive with the rain and its western track, but the current GFS, Canadian and ECMWF all have light showers in our area either late Sunday morning or early afternoon. (Heavier rain in NJ.)

The NAM has been consistent, but may be over-doing the rain.

An easterly wind flow and clouds will keep it chilly with a high of 57.