Monthly Archives: August 2020

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

Sat 07:43 PM Update — Today’s HIRESW along with other models do support more shower activity on Sunday. Showers and thundershowers are possible anytime between 11 AM and 5PM Sunday. It appears that many areas around PHL will see some shower activity.
Sat 09:18 AM Update — Later runs of the NAM-NEST and two pre-release versions of the HIRESW do not support the heavy showers predicted by the HIRESW-ARW last night, as mentioned in my previous ‘update’.  The latest model blend (NBM) still includes the Sunday showers.

So there’s uncertainty in the forecast for Sunday.   I’ll keep an eye on this.

Fri 11:20 PM Update — Tonight’s HIRESW-ARW models show significant showers and thunderstorms on Sunday. This is a significant change in the forecast. I’ll update again over the weekend.

A Bermuda high pressure system off the southeast coast will bring increasingly warm and humid weather to our area. Weak disturbances moving around the periphery of the high pressure system will bring occasional clouds and slight chances of widely scattered showers and thundershowers.  Most of our area this weekend will be dry.

Saturday—

  • Cloudy early morning with a slight chance of a light shower. Clouds break for partly sunny/partly cloudy skies by late morning or early afternoon.
  • High temp 86.2º sd 1.3º. Dew points 66º-70º
  • Calm to very light winds from the SW 3-5 mph
  • Slight chance of a widely scattered shower late afternoon. Most areas are dry.

Sunday —

  • Some fog and clouds early.
  • Sunshine breaks through after 10 AM
  • High temp 87.8º as 2.3º.   More humid. Dew points 68º- 70º
  • Calm winds in the morning.  Light winds up to 10mph in the afternoon.
  • Chance of thundershowers late afternoon, far northwest areas. Philadelphia is expected to be dry.
Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

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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.