Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

[su_box title=”Weather Outlook Updates ” box_color=”#defcdc” title_color=”#000000″]The latest NAM brings the weekend in-range. Saturday looks to be sunny but very windy!

Saturday looks to be dry… cloudy in the morning with clearing and sun in the afternoon. Very windy!

Sunday is looking drier and partly sunny. Uncertain forecast for Sunday – NAM and GFS are quite different.

(This morning’s GFS is more pessimistic about Sunday with showers.)

Today’s models haven’t done well. Neither the NAM nor the GFS had predicted the light showers this afternoon! The weekend forecast is probably low a low confidence forecast. My rule of thumb- if the models are wrong in the short term, they are not reliable in the longer term.

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A series of low pressure systems will affect our area over the next week, following a path of a zonal (flat) jet flow.

The low pressure system bringing rain on Friday is expected to depart and intensify on Saturday over New England.   For Saturday, we will have a mix of sun and clouds and high temps near 68.  It will be windy.

Another low pressure system will affect our area on Sunday.  There are large differences in the track of this low, with the GFS-FV3  having the low move to our north while the GFS has it right over us.  The track will determine the amount of showers/rain we will get.  Right now it appears the precipitation will be light. There’s a large range of temperatures forecast as well.   But too much uncertainty right now in the Sunday forecast.   Stay tuned.

Weather Updates

WEATHER UPDATE- SAT AM

[su_box title=”Weather Update Sat 10:30 AM” box_color=”#defcdc” title_color=”#000000″]Based on the latest NAM, showers have ended but widely scattered light sprinkles are possible. Low clouds lifting to brighter skies may be delayed until 2-3 PM today.[/su_box]

from earlier today:

The gusty windy conditions (Gusts to 35 mph) will continue and diminish later in the afternoon.

The rain ends by 11 AM.

Based on the 2 AM (06Z) NAM and GFS model runs, the low clouds should lift between noon and 1 PM, leaving brighter skies and some sun through a layer of higher cirrus clouds.   Continued improvement in sky cover later in the afternoon. High temp 74-76.

Currently, Sunday looks dry except some showers may develop in far western suburbs in the mid afternoon. High 67-69.

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST-UPDATED WITH LATEST NAM

Updated based on tonight’s NAM data just available.

Those reading my posts over the past few days know that this weekend’s weather will be be influenced by a closed upper low, a situation where the models have trouble in placement of precipitation and timing of areas of vorticity that rotate around the upper low causing instability showers to develop. As a result, this forecast is lower than average confidence.

For Saturday, the general trend has been for the main precipitation to end mid morning west of the city and later east into NJ.

Low clouds thin around noon and some sun through high clouds is likely in the afternoon. High 69-72. It will be windy.

Sunday will have a mix of clouds and sun. Instability in the mid afternoon may allow clouds to redevelop with light scattered showers possible, especially in western suburbs.  Highs 66-69. Light winds.

Weather… and Other Things 'Up in the Air'