[su_note note_color=”#bceaed”] During the Covid-19 Pandemic shutdown, I’ve been doing daily forecasts.  I’ll be returning to the office and this blog now returns to its regular Weekend Weather Forecasts & Outlooks along with its Significant Storm Forecasts focus.

I hope you’ve found the daily forecasts useful and informative. [/su_note]

Monday forecast—

  • Clouds in the morning break for sunshine between 12 and 2 PM on Monday
  • High temp   76° sd 2°    76.9° (HRRR)
  • Winds light 4-8 mph E —>SE late afternoon


[su_note note_color=”#ffffff”]Updated Sun 09:44 AM — Latest HRRR keeps the sunshine to just west of the Delaware by 3 PM.  The clouds hang tough east of that line.

HRRR (High Resolution Rapid Refresh) Model 3 PM low cloud cover forecast.   Darker= more clouds  (Click on image for a larger view.)

However, the experimental FV3-SAR has more extensive clearing and sunshine. [/su_note]

The forecast for Sunday hasn’t changed appreciably from what had been posted Friday evening.    High pressure noses down from the northeast as an upper level ridge begins to build in.

The northeast flow from the high will bring us cloudiness and somewhat chilly temps for this time in May.

The high resolution models (NAM NEST and ARW MEM2) have some clearing after noontime.  The experimental SAR model has considerable clearing during the early afternoon.  The model blend (NBM) is more pessimistic about the cloud cover.

Sunday —

  • Low clouds in the morning
  • Clouds lift late morning and break for a mix of sun and clouds  into the evening.
  • Winds NE 10 mph with gusts to 18.  Gusts diminish in the afternoon.
  • High Temp 65.3º sd 3.3º (higher than average spread!)
NAM NEST Cloud forecast 12 PM Sunday  (Darker = more clouds)      (Click on image for a larger view.)

A similar forecast for Monday… warmer in the mid 70s.


[su_note note_color=”#ffffff”]Updated Sat 05:23 PM — It’s difficult (read impossible) to time the showers and clouds with this sort of instability setup, but it doesn’t keep me from trying. [/su_note]

[su_note note_color=”#ffffff”]Updated Sat 08:34 AM —Several of the short range models suggest some bright skies and even some sun breaking through between noon and 3 PM Saturday. More showers possible later today, although the rain this morning may be the heaviest we’ll see. [/su_note]

Less than ideal weather will affect our area this weekend. Things will improve by Monday.

An upper closed low pressure be directly over us on Saturday. The exact placement of showers and the degree of cloudiness is difficult to accurately model with upper lows.

Any sun that manages to break through the cloud cover on Saturday will trigger instability showers and thunderstorms.  Here’s the NAM forecast for noon on Saturday showing the the low pressure system (blue line) at 500 mb (~18,000 feet)—

NAM forecast 12 Noon Saturday.  (Click on image for a larger view.)


  • Mostly cloudy, breaks of sun possible at times.
  • Showers and thunderstorms possible any time, especially late morning and in the early afternoon.
  • High temp 75.7º sd 2.3º
  • Winds light from the W, increasing and shifting to the NE later in the day.


For Sunday, the upper closed low moves off to the east, as surface low pressure maintains clouds.  Some models have considerable breaks of sun, some show very cloudy conditions  —

NAM forecast for Sunday noon  (Click on image for a larger view.)


  • Mostly cloudy, then breaks in the clouds possible later in the afternoon.
  • No precipitation
  • Cool. High temp 65.7º sd 3.3º
  • Winds gusty from the NE in the morning, decreasing in the late afternoon.


For Monday, skies still fairly cloudy with breaks of sunshine developing during the day as high pressure builds in—

NAM Forecast Monday noon (Click on image for a larger view.)


  • Clouds break for sunshine by late morning.
  • No precipitation
  • Milder- High temp 73.1º sd 2.8º
  • Windy and gusty from the SSW




[su_note note_color=”#ffffff”]Updated Fri 10:35 AM — This mornings models continue with showers moving in about 12-1 PM.  While most areas will receive about 0.2- 0.4 inches of rain, there will be isolated areas that have downpours of much more. These areas will be west of Philadelphia.

NAM-NEST Accumulated Rain by 5 Pm Friday  (Click on image for a larger view.)


An upper air low moves towards us as it weakens.  Rain moves in about noon.

Friday —

  • Cloudy
  • Rain moves in about noontime. QPF  0.2-0.4 inches, more west of the city
  • High temp 69.4° sd 3.2°      68.6° HRRR
  • winds ESE 7 mph, gusts to 15