Monthly Archives: February 2023

Philadelphia Area Weather Forecasts

WEEKEND WEATHER FORECAST

#weather #paweather #wx #pawx #philadelphia

Back where we started

Update Sun 2/12 10:53 AM — This morning’s NAM has reverted back to the rain moving into Philadelphia. Now about 8-10 PM and continuing into the night. The Eagles win forecast hasn’t changed.

Forecast change

Update Sat 2/11 10:22 PM — Tonight’s high resolution models (NAM) keep the rain well south of our area Sunday evening. A significant change in the forecast.
Update Sat 2/11 11:18 PM — BTW, the GFS and tonight’s Canadian RGEM still have the rain here, as previously forecast. My bet is on the NAM and the Eagles.

Update Sat 02/11 @ 5:56 PM — No major changes in the forecast for Sunday. Rain moves in from the south between 4-6 PM. In the city, it will be very light and there will be a sharp cutoff just north of the city’s northern immediate suburbs. This has been a boundary or edge condition for the precipitation shield for days and some models are further north, some are further south.

The HREF forecast provides a good compromise—

18 z HREF simulated radar with accumulated precip contours (light green) . Total amounts range from 0.02” to as much as 0.10” in the immediate PHL area, more south, less north. Click on image for larger view

One change is the precip moves out as early as 11 PM to midnight, just in time for the Eagles victory celebration.

Still no signs of any snow here for the next 10 days!

Update Fri 2/10 10:43 PM — Tonight’s models are trending towards a bit earlier start of the rain on Sunday in Philadelphia, perhaps as early as 4-6 PM. Unfortunately, it appears that it might advance further north with somewhat heavier rain making it into the city than previously forecast. Stay tuned.

A secondary cold front will pass through Friday night and Saturday will be much colder than previous days.

A coastal storm with a closed low will be blocked from moving north. The precipitation shield will affect NJ and Delaware during the day Sunday. Light showers will move in to the immediate Philadelphia area Sunday about 5-7 PM

Saturday

High pressure will bring mostly sunny skies. Windy conditions in the morning will gradually subside during the afternoon. Some clouds towards sunset.

High temperature 45.1º sd 1.5º ( NBM model- location Blue Bell, PA)

Sunday

The coastal low will move north but be blocked by high pressure. While the rain will be significant in South Jersey and Delaware, only light rain is expected to move into Philadelphia early evening.

Here’s the northern-most extent of the rain by 7 PM, according to the high resolution NAM-NEST —

Today’s 18z NAM-NEST simulated radar forecast for 7 PM Sunday. The NAM-NEST forecast is very similar to several other models, perhaps just a bit further north with the rain than several.

High temperature 45.6º sd 2.5º ( NBM model – location Blue Bell, PA)

Philadelphia Weather Outlook

WEEKEND WEATHER OUTLOOK

#weather #paweather #wx #pawx #philadelphia

Update Fri 2/10 4:35 PM — A quick mobile update. The precipitation on Sunday does now appear to move into Philadephia between 6-8PM. It doesn’t appear to move much further north than the immediate suburbs. The regular Weekend Weather Forecast will be posted later.

Still Some Uncertainty

Update Thu 02/09 @ 8:04 PM — So while the NAM, GFS and ECMWF posted below keep the rain to our south until midnight or after, the statistical models are not all that sure.

Here’s the NAEFS that just became available. The NAEFS combines the Canadian ensemble model with our GFS ensemble (GEFS).

Here’s its forecast probability of light rain before 10 PM Sunday —

Today’s 18z NAEFS shows a 30% chance of rainfall greater or equal to 0.10 inches by 10 PM for the preceding six hours. (Click on image for a larger view.)

If we set the threshold for any rain lower, as little as 0.01 inches for the six hours preceding 10 PM Sunday, here’s the probability—

Today’s 18z NAEFS probability of greater or equal to 0.01 inches of rain before 10 PM Sunday. It’s 45% in Center City and for a six hour period, that’s relatively high for a six hour period.

This NAEFS is more in line with the latest Canadian regional GEM, the latest German ICON model and the SREF.

So it’s going to be a close call. Some sprinkles and light rain possible here during the Super Bowl, but not a sure bet. My regular readers know my mantra, “never ignore the NAM” which currently keeps us dry.

I’m still keeping an eye on the weather for Sunday and based on today’s ECMWF along with the latest GFS , it appears that the rain will stay south of Philadelphia until after midnight Sunday. Indeed, currently there’s remarkably good agreement in the models today, considering how far apart their forecasts were just a few days ago.

Here’s the latest GFS, just available—

Today’s 18z GFS forecast for Sunday night (actually midnight Monday). The rain stays to our south at that time (Click on image for a larger view.)

The forecast period in question now falls within the forecast horizon of the latest 18z NAM model (84 hours). The NAM forecast is remarkably similar to the GFS —

Today’s 18z NAM forecast for 1 AM Monday morning (Click on image for a larger view.)

Even today’s ICON model (posted earlier today) has fallen in line with the other models.

So things look good weather-wise for the Eagles victory celebration.