Monthly Archives: April 2021

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

Forecast revisions added Fri 10 PM highlighted
Sunday Forecast updated Sat 11 PM highlighted

The forecast for the weekend has changed (and improved somewhat) from what I posted yesterday for the weekend outlook . An upper air cyclonic flow around the low pressure system near Cape Cod will bring instability cloudiness for Saturday.

Of some concern about this weekend’s forecast— none of today’s models captured this evening’s showers in central NJ. This suggests a lower confidence forecast for the weekend.

The models have backed off on the light widely scattered sprinkles considerably.

Basically, what we have for the weekend is similar to what we had on Friday, but without the light rain sprinkles. Possibly more sunshine on Sunday.

The low moves further east on Sunday, but a weak trough still associated with the same Cape Cod low brings the chance of some clouds Sunday afternoon.

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

Saturday

Mostly sunny skies in the morning will give way to instability cloudiness late morning and in the afternoon. Like Friday, there may be breaks of sun at times. High temp 57.6º ± 2.4º (NBM model, Blue Bell)

There’s a chance of a light sprinkle late afternoon or early evening.

Sunday

The Cape Cod low moves east, but a weak trough will bring some clouds in the afternoon.

A similar forecast to Saturday— sunshine in the morning giving way to clouds, but milder with little or no chance of sprinkles. High temp 62.5º ± 2.3º (NBM model, Blue Bell)

Sunday may not be as cloudy as as Saturday. Clouds move in about 12-2 PM.

Wind forecast

NBM wind forecast Meteogram Blue Bell PA   (Interpretation: Winds from the NW  8-10 mph, gusts to about 15 (NBM) for Saturday.   Similar for Sunday  (Click on image for a larger view.)
Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

An upper air low pressure system will combine with a surface low pressure system off of Cape Cod. This somewhat static pattern with upper air low pressure systems nearby should continue to affect our weather over the weekend.

Saturday

A cyclonic flow around the low will bring instability and cloudiness as disturbances rotate around the low for Saturday. 

GFS model forecast for 11 AM Saturday morning  (Click on image for a larger view.)

Saturday will be mostly cloudy. A quick, widely scattered sprinkle can’t be ruled out, but the day will essentially be dry. Chilly temperatures. High 53º as 2.1º (NBM Model, Blue Bell)

Sunday

The Sunday forecast is more uncertain. The same low pressure system should gradually move eastward, bringing less of a cyclonic flow. However some models are suggesting another upper air disturbance will move through from the west. Some sun in the morning. Considerable cloudiness, especially in the afternoon.

The GFS again cranks out a widely scattered sprinkle around 4 PM. The ICON model is also showing this upper air disturbance and a chance of sprinkles, especially far northern areas. High of 61.1º sd 3.0º (NBM Model, Blue Bell)

Seasonal average high right now is 64º.