Philadelphia Weather Outlook

THIS WEEK’S WEATHER

Perfect Weather

Update Thu 11/03 @ 5:47 PM — Not much happening since my last update. Just perfect weather! Expected to continue! High pressure remains in control off the coast—

Today’s 12z NAEFS Forecast for Thursday. High pressure off the coast. A strong upper ridge over us (as shown by the red 540 thickness line) and a sharp trough in the West. That cold trough never makes it into our area. (Click on image for a larger view.)

The push of colder air in the West never makes it into our area. A front falls apart as it approaches later Sunday—

NAEFS forecast for Sunday at 7 PM. High pressure remains stationary in the Atlantic. The weak cold front falls apart in central PA. A tropical like storm develops near Florida, that needs to be watched. .

Mild Weather— Little Chance of Rain

Update Tue 11/01 @ 5:25 PM — A strong ridge of high pressure will maintain a southwesterly flow of mild air through the weekend and perhaps well into next week.

My caption on the NAEFS graphic below explains—

12z NAEFS forecast for Friday morning. A Bermuda-like High (1) off the coast will maintain a southwesterly flow of mild air into our region. A cold front (2) will lose its punch as the push of cold air (3) diminishes. The front shears off to our north and east on Sunday. For next week, a flat zonal flow will continue generally mild dry conditions .

Updated Mon 10/31 6:55 PM — So game 3 is officially postponed. It’s not clear to me why MLB waited so long. By this afternoon, there wasn’t a single model that wasn’t forecasting rain, if not by the start, by 9-10 PM.

So which model, if any, did the best with this forecast? Well, the ECMWF would have been the clear winner, but this morning’s ECMWF had the rain starting early in the afternoon. Clearly not correct and the model run last night had very little falling right along I-95 and the stadium.

The high resolution HREF, HRRR and NAM-NEST all kept the heavier rain off to the west of the city until later this evening. Clearly not correct.

Last night’s new GFS had the rain starting about 9-10 PM at the stadium. A little slow with the start time, but the general axis of the rain right now is just as predicted. Still, not a winner.

The German ICON model from this morning wasn’t bad. Some rain at about 7PM and increasing afterwards. Axis of rain isn’t what we have on radar.

Yesterday’s Canadian HRDPS, as was this morning’s, was surprisingly good. It had the rain starting about 7-8 PM and the rain axis is pretty much what we have right now. Not sure that it’s a winner, but close.

The bottom line — models rarely capture reality exactly, especially with precipitation placement and timing. This is something we get reminded about each winter with snow storms.

Update Mon 10/31 @ 4:58 PM — The lastest HRRR still keeps the heavier rain to the west of the stadium at 9 PM, but the rain moves in and increases in intensity after that time—

The earlier forecast that Trick-Or-Treaters would be OK before 7:30 – 8:00 PM probably is too optimistic.

Current Radar (5:10 PM)—

Radar with RAP model jet stream wind streamlines (red) at 5:10 PM (Click on image for a larger view.)

A radar image with motion captures that the rain is moving in rapidly—

Latest HRRR model forecast total accumulated rain by 9 PM—

18z HRRR Total accumulated rain totals at 9 PM. the HRRR shows only light rain at Citizens Bank Park at 9 PM, but rain increases afterwards. If the Phllies play tonight, they will play in increasingly heavier rain. (Click on image for a larger view.)

The NAM-NEST cranks out more rain than the HRRR. Here’s the Total Accumulated Rain forecast by 10 PM—

18z NAM-NEST forecast Total Accumulated Rain by 10 PM. Significant rainfall by then. (Click on image for a larger view.)

Previously Posted Mon 9:49 AM —

First order of business this week is the forecast for Trick-Or-Treaters and the Phillies World Series game this evening. I’ve been waiting for the latest ECMWF and NBM to become available before posting this.

Those of you following the weekend postings will know that the ECMWF has consistently forecast some light rain during the Phillies game this evening.

Here’s the latest ECMWF accumulated rain forecast for 9 PM—

06z ECMWF showing very light precip at 9 PM. By 11 PM, it increases only slightly to 0.02- 0.03″ (Click on image for a larger view.)

However, many of our high resolution models (HRRR, RAP, HIRESW, NAM-NEST) have all kept light rain in the western suburbs during the evening hours while keeping the immediate PHL area mostly dry until after 11 PM.

The new GFS-v 16.3 continues to have light rain move in between 9 and 10 PM. The high resolution Canadian model is similar to the GFS.

New GFS for 10 PM—

06z GFS (new version 16.3) showing considerable rain near stadium (0.11″) accumulated by 10 PM tonight. (Click on image for a larger view.)

The latest model blend (NBM) just became available and it captures the majority consensus —

12z NBM shows similar ot the ECMWF at 8 PM but increases accumulated rain to 0.07-0.10 inches of rain by 11 PM. Not great for baseball. (Click on image for a larger view.)

Based on the NBM, Trick-Or-Treaters should be fine in most of the area before 7:30 to 8 PM.

For the World Series Game 3, some light rain expected by 9 PM which will increase by 11 PM which may require some decision-making by MLB.