Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST- FRI EARLY EDITION

[su_note note_color=”#d9f2da”]The weather is looking better for Sunday morning. Details later[/su_note]

A series of weak disturbances emanating from a low pressure system in the Midwest will pass through, mostly during the nighttime hours Friday through Saturday night.

For Saturday, showers Friday night will move away, allowing partial clearing, some sun and dry conditions for much of the daytime Saturday.  High temperatures 76-80 (EKDMOS) or 75 (NBM). Light winds.

The main surface low pressure system approaches late Saturday into Saturday night. Rain develops, possibly heavy before daybreak Sunday.

There remain some differences in the forecast for Sunday and the Broad Street Run

The GFS has the low pressure system exiting by mid-morning with rain decreasing considerably.

The latest FV3-GFS and the NAM show an upper air disturbance causing a slowing of the exit of the surface low with considerable rain for much of the day, tapering in the afternoon. High temperatures 65-68 (EKDMOS- with large statistical spread)  or 63 (NBM). Fairly windy in the morning.

I’ll update this evening about 11 PM.

Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

[su_box title=”Weather Outlook Update Thur PM” box_color=”#defcdc” title_color=”#000000″]Tonight’s NAM has joined the FV3-GFS in predicting moderate rain for Sunday morning. See forecast below for context.[/su_box]

Significant differences exist between the models for this weekend’s forecast.

(Not surprising, since the forecast– predicted high temperatures (86) and the predicted thunderstorms for today, Thursday, weren’t too accurate – only the GFS had the high temperature near 86 and the higher resolution models had the thunderstorms suppressed to our south today and predicted the 80-83 we actually saw.)

Back to the weekend-

Updated with GFS: For Saturday, cloudy but dry (perhaps some light drizzle in the morning)  with an easterly, cooler wind.

For Sunday, large differences between the models.  The latest GFS, NBM, and NAM suppress most of the showers and rain to our south.  The still experimental FV3-GFS has heavy rain on Sunday.  I’ve liked the FV3-GFS over the winter, but it’s currently an outlier.

I’ll update Friday evening, as usual.

Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

This post will be a ongoing collection of observations and thoughts about the upcoming weekend weather.

Wed PM – Tonight’s NAM shows no thunderstorms for Thursday and highs near 82. Tonight’s NAM has the rain tapering early Sunday morning.

Wed AM – Very warm on Thursday. Looking towards the weekend, it looks like an easterly flow will keep temperatures not as warm as previously expected. It appears that most of the periods of rain will occur during the nighttime hours, although it may linger into Sunday morning. 

Tues PM – Tonight’s NAM shows a change of forecast -The warm front that moves through Wednesday returns as a backdoor cold front Thursday night. Friday not as warm as previously thought.

Tues AM -A warm front will slowly move north of our area on Wednesday, opening up a flow of  moist, warm air from the southwest. Weak impulses embedded in this southwesterly flow will give us a chance of showers Thursday through Sunday morning.   The main low pressure system is expected to move over our area on Saturday night.

So, there’s a chance of showers almost every day, according to the EKDMOS.   We are getting into the season where the normal “background probability” is about 20-25%, but this is looking higher.

EKDMOS 6 hour rain probability

Temperatures may reach into the mid to upper 80s on Thursday.    Reviewing the FV3-GFS, we may be lucky and the showers occur mostly during the  evening and night time hours.

Weather… and Other Things 'Up in the Air'