Philadelphia Weather: Chilly, Breezy Weekend, Then a Dry Week With a Steady Warmup, Saturday November 14

Day	Sky	High / Low	Rain
Sat	Partly sunny, breezy	48 / 37	Dry
Sun	Mostly sunny, breezy	51 / 36	Dry
Mon	Sunny	53 / 34	Dry
Tue	Sunny	57 / 35	Dry
Wed	Sunny	61 / 36	Dry
Thu	Sunny	63 / 37	Dry
Fri	Mostly sunny	64	Dry

Today

Partly sunny and chilly, with a high near 48. A northwest wind of 5 to 10 mph will gust to around 20 mph, and the Mount Holly forecast discussion allows for gusts of 20 to 30 mph across the region during the day. No rain is in the forecast.

Tonight

Clouds hang on for the first part of the night, then the sky gradually clears. The low is around 37, with the wind easing to about 5 mph from the west.

Tomorrow

Sunday brings more sun and a slightly milder afternoon, with a high near 51. The northwest breeze returns at 5 to 10 mph with gusts near 20 mph. Sunday night is mostly clear with a low around 36.

The week ahead

The story of the week is a slow, steady warmup under sunny skies. Highs go from 53 on Monday to 61 on Wednesday and 64 by Friday, a gain of about 16 degrees from today. Nights stay cold, in the mid 30s, with Monday night the coldest at around 34. The forecast lists no rain on any day through Friday.

Behind the forecast

Philadelphia sits between low pressure heading into the Canadian Maritimes and high pressure building in from the west. The tight pressure difference between the two is what drives the gusty northwest flow and keeps temperatures a little below normal through the weekend and into early next week, before the air moderates toward midweek. The Mount Holly discussion does not flag any low-confidence periods for our area, and it notes that the growing season ends November 15, so last night’s frost and freeze headlines were the final ones until spring.

The driver that matters most right now is El Niño, the warming of the tropical Pacific. The Climate Prediction Center’s November 12 update keeps an El Niño Advisory in place, puts the Niño 3.4 anomaly at 2.5 degrees Celsius above average, and expects a strong to very strong event to last through January to March. The MJO, a pulse of tropical storminess that circles the globe, has stalled and strengthened over the Indian Ocean in phase 2 as of CPC’s November 13 discussion, and models disagree on how fast it moves east later this month. CPC treats it as a modifier of the El Niño background rather than the lead actor. The outlooks lean mild here: above normal temperatures are favored in the Mid-Atlantic for November 19 to 23 and again for November 21 to 27, with odds above 60 percent in the second window. Precipitation leans below normal in the first window and above normal in the second, and CPC notes extra uncertainty about the storm track heading into Thanksgiving. For November 28 to December 11, CPC favors above average precipitation up the Eastern Seaboard, with troughing across the southern states and ridging over Canada. That fits the usual El Niño tendency toward a more active southern storm track, which NOAA describes as a matter of probability, not certainty.

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Forecast data: National Weather Service, Mount Holly. Point forecast issued 4:08 p.m. Friday, November 13; forecast discussion issued 6:16 a.m. Saturday, November 14. Pattern sources: CPC ENSO diagnostic discussion, CPC 6-10 and 8-14 day prognostic discussion, CPC Week 3-4 outlook, CPC Global Tropics Hazards Outlook, NOAA Climate.gov on El Niño and the winter jet stream.