An Alberta clipper system will bring a chance of light snow late Tuesday afternoon .
As always, there are differences between the NAM and GFS models with the NAM showing about .15 inches of water and the GFS showing about .03 inches of water(QPF). Both models have the upper atmosphere cold enough for snow but both models also show surface temperatures to be above freezing.
With the QPF values in this low range, it is not out of the question for the precipitation to miss us or only affect northern areas. Either way little or no accumulation is expected due to temperatures being too warm.
The afternoon NAM has backed off on the QPF. It’s down to .01 inches. So maybe a flurry in Philadelphia, maybe not.
It is expected for temperatures to drop behind the clipper so any moisture lingering may freeze later Tuesday evening. I’ll update later tonight.
Tonight’s NAM QPF is again 0.01 inches water, the GFS has 0.04 suggesting a snow flurry or quick snow shower at most.
An easterly surface wind preceding a warm front will keep mostly cloudy skies over our area on Saturday. There’s a chance of a light sprinkle in the morning, but most of the day will be just cloudy, maybe some bright spots early afternoon. High temp around 50.
A low pressure system moving up through the Great Lakes will pull a warm front through Saturday night into Sunday morning with rain, possibly heavy. The warm front moves through Sunday mid-morning, the showers end and skies may brighten early afternoon. Very warm. High 63. Winds pick up also in the afternoon as a cold front approaches with cloudiness again thickening. The cold front moves through Sunday evening. Temps will plummet to the low 30s Sunday night with windy conditions.
Updated Sat 1/9
It looks like it’s going to be cloudy today (Saturday). The light sprinkles expected in this morning are developing. A sprinkle possible early evening but the moderate rain starts after midnight. The rain ends around noon Sunday. Very warm and very windy. We may see some sun in the mid to late afternoon Sunday. Temperatures begin to fall. Doesn’t get cold until Sunday night.
The quasi -stationary frontal boundary moved through as a cold front this evening, causing the showers.
A northeasterly flow of air behind the front will cool things down for Saturday. Saturday will be mostly cloudy but skies may brighten mid day (as happened today). Highs on Saturday low 50s.
Late Saturday afternoon, the same frontal boundary will move back as a warm front and showers will return late afternoon into evening.
Sunday will bring dry conditions and possibly some sun breaking through. Very warm with temperatures in the low 70s and possibly higher if the sunshine materializes. Enjoy it while it lasts.
Clouds return later Sunday with as low pressure develops and moves towards us on Monday through Tuesday. The latest NAM model suggests the possibility of icy precipitation Tuesday morning.
For those people who miss winter, cold weather, with possibly below average temperatures, returns next weekend.
A stalled frontal boundary to our south will advance slowly northward as a warm front as waves of low pressure develop along the boundary, causing rain and showers.
As is often the case in these scenarios, timing of the waves and exact placement of the front varies from model to model and there are divergences in timing and placement of the front as the timeframe goes forward. Large difference by Sunday.
For today, Friday, we will have cloudy skies and damp conditions. The GFS and NAM bring showers back into PHL between 4 PM and 7 PM with rain, possibly heavy during the evening hours.
For Saturday, the morning looks to be damp without showers, but with increasing chances of showers in the afternoon and especially by evening.
Sunday is a big unknown- the GFS has the front to our north with high temps near 70. The NAM has high temps in the mid 50s with the warm front stalled to our south.
Both models have a deep low pressure system bringing rain, possibly heavy, on Monday,
Temperatures still look to return to normal winter temps by New Years Day and even below average temperatures for next weekend possible. The possible storm for Jan 4-6th timeframe has again disappeared from the latest GFS.