Philadelphia Area Weather Forecasts

THIS WEEK’S WEATHER

Rain New Year’s Eve

Update Wed 12/28 @ 8:34 PM — So, it’s increasingly likely that New Year’s Eve will be quite rainy and warm for December. What about earlier on Saturday?

Unfortunately, the models have the rain moving in late morning or around noontime. Here’s the ECMWF forecast for Saturday at 1 PM—

Wednesday’s 18z ECMWF forecast for 1PM Saturday. Some light rain already moved in. By 4PM, it’s raining for sure. (Click on image for a larger view.)

The skies gradually clear out New Year’s Day (Sunday). It will be mild but VERY WINDY.

The best day for outdoor activities this week might be this Friday.

Today’s NBM model wasn’t forecasting as warm temperatures for next week as discussed immediately below, but still temps above average.

No snow in the current forecast, but there’s plenty of cold air in Canada and quite a moisture stream into the continental US from the subtropical jet stream.

Gradually Warming Temperatures

Update Tues 12/27 @ 8:54PM —The main focus for this week’s weather is the gradually increasing temperatures. Here’s the latest NBM model temperature forecast through early Saturday —

Tuesday’s 19z NBM Model forecast Temperatures/Dewpoints with standard deviation for Blue Bell, PA . (Click on image for a larger view.)

By the weekend we are moving into the 50s and near 60º. And next week will be even warmer—

Tuesday’s 19z NBM Model forecast Temperatures/Dewpoints with standard deviation for Blue Bell, PA . (Click on image for a larger view.)

Unfortunately, there’s fairly good model agreement that New Year’s Eve will be very rainy here although timing varies with the rain—

Tuesday’s 18z GEFS shows some heavy rain around midnight Saturday. (Click on image for a larger view.)

Update Mon 12/26 @ 7:57 PM — The clouds that moved in mid-afternoon will move out on Tuesday. Expect temperatures to remain cold on Tuesday.

The trend is towards warmer by Thursday and especially Friday through Sunday.

A Bermuda high builds by Thursday…is this summer??

Monday’s 18z GFS forecast for Thursday at 9 AM. Bermuda high off the coast and increasingly warm air will start moving in. (Click on image for a larger view.)

High temperatures will be near 50º on Friday and near or above 60º on Saturday. Unfortunately with the warm temperatures, rain is expected for New Years Eve and possibly lasting into New Years Day.

The current outlook is for warm and wet next week.

Forecast Outlook through New Years Eve

Posted Sun 8:46 PM —

Overview

This week’s weather will transition from the current cold upper air trough—

00z ECMWF 300 mb winds (jet stream leavel) forecast for Monday 1 PM. Upper level trough in the Great Lakes along with southern jet stream across Florida. (Click on image for a larger view.)

….. to a much warmer upper air ridge over our area by next Saturday, New Years Eve—

00z ECMWF jet stream level wind forecast for Saturday 1 PM and New Years Eve. Upper level trough will bring warmer temperatures, but also some rain is possible. (Click on image for a larger view.)

In the interim, daily high temperatures will gradually increase each day.

Monday

An upper air disturbance along with a surface low pressure system will approach our area during the day. Increasing cloudiness late morning and mostly cloudy by mid afternoon.

Today’s 21z RAP model forecast for Monday at noon. Low pressure will approach, but little moisture for any precip. (Click on image for a larger view.)