Category Archives: Weather Outlook


Most models have the remnant moisture of Hurricane Laura moving into our area on Saturday.  It currently appears that the storm’s energy and moisture will become incorporated into a non-tropical low pressure system moving through to our north.  A cold front moves through Saturday evening.

At this stage of things, there’s little agreement where the maximum dynamics, moisture and precipitation will fall.

The GFS model, along with the statistical ensemble version, the GEFS, have the maximum precipitation falling in New England—

GFS precip forecast 8 PM Saturday  (Click on image for a larger view.)

The NAM-NEST has a very different scenario, with much higher amounts falling closer to home—

NAM-NEST precip forecast 8 PM Saturday(Click on image for a larger view.)

Most models agree that rain starts Saturday morning and becomes heavier during the afternoon.  It’s likely that the NAM-NEST is over-forecasting the rain here and we’ll likely get only 0.5 to 1.5 inches of rain.


Last night’s HIRESW-ARW-MEM2 came through, accurately forecasting the showers that moved through around 12 – 2 PM.

Here’s last night’s HIRESW—

Last night’s HIRESW-ARW-MEM2 forecast for 2PM Sunday. (Click on image for a larger view.)


Here’s the current radar at 1:39 PM—

NEXRAD radar 1:39 PM Sunday. Courtesy of (Click on image for a larger view.)

That’s about as good as model forecasts get. 

There’s been uncertainty regarding the shower/thundershower potential on Sunday.  High humidity, heat and instability suggests that some showers and thundershowers are likely during the day.

Tonight’s models just becoming available have the greatest dynamics just south of Philadelphia and the majority of the models keep the showers just south of our area.

The exception is the HIRESW-MEM2, which continues to forecast showers and thundershowers further north into our immediate PHL area, from 11 AM through 3 PM.  As someone who looks at the models as my daily crossword puzzle(s), the HIRESW-MEM2 has been particularly impressive this summer in predicting these sort of convective storms.  So, I’m betting on its forecast for Sunday.

The models have more consensus about another period of showers/thundershowers around 10 PM Sunday evening, as another wave moves through.



Today’s weather (Thursday) was nothing less than spectacular.  Low dew points, temps in the low 80s and clear skies, very light winds.  It doesn’t get any better.  Those of you, like me, who enjoy looking at the sky may have noticed cirrus clouds in the southern horizon —

Cirrus clouds on the southern horizon with some fair weather cumulus

These clouds are the result of moisture that is moving in for the weekend.  This morning’s HIRESW captured this border of high level clouds very nicely (light brown shading)—

HIRESW-FV3 pre-release forecast -clouds high level  (Click on image for a larger view.)

This moisture will gradually make inroads into our area for the weekend.

Earlier this week, the statistical models had a fair amount of clouds and showers.

However, the weekend forecast period is coming into range of the higher resolution models which show significant sunshine for Friday, Saturday and Sunday, albeit with some periods of cloudiness on Saturday and to a lesser extent on Sunday.

Scattered showers appear to be possible on Saturday, especially very early morning and again late afternoon.   These will be widely scattered; many areas will not see any.

HIRESW-FV3 1 hour precip forecast 6PM Saturday.  (Click on image for a larger view.)

Sunday appears better, with a lower chance of showers in the immediate PHL area.  

Dew points will gradually rise into the upper 60s to near 70º (more uncomfortable) by late Saturday into Sunday.

NAM Temp Dew Point Forecast  (Click on image for a larger view.)

Things will probably need to be more fine-tuned, but right now a pretty good weekend weather-wise is on-tap.


Updated Thu 08:34 PM — Apparently, the huge difference in the weekend forecast is the result of a big difference in the European model and the our NOAA models.  It’s difficult to ignore our own models here.  So we’ll have to see how “beautiful” the weekend weather turns out to be.

I was watching the 6 PM news last evening and I heard the weather entertainer say it was going to be a “beautiful weekend”.   I said to myself,  ‘Gee, what is she talking about??’

An upper air trough and high pressure to our northeast will bring an easterly flow of cooler temperatures, but low pressure is expected to develop on the stalled boundary that is expected to sink to our south.

We will get some dryer air  on Saturday, but it’s not a sure thing how much sunshine we’ll see.  The statistical models, (the GEFS, SREF) along with the Model Blend (NBM) maintain a fair amount of cloudiness on Saturday.   Rain/showers are returning on Sunday.

Saturday  forecast SREF model—

Short Range Ensemble Forecast (SREF) for 2 PM Saturday (Click on image for a larger view.)

Sunday forecast GEFS model—

Global Ensemble Forecast System (GEFS)  for Sunday 4 PM (Click on image for a larger view.)

It’s still a bit in the future and things could change, but right now a beautiful weekend isn’t in the cards.