Update Sun 01/22 @ 2:58 PM — I wanted to update on the possible coating of snow early Wednesday morning before it all changes to rain.

Surface temperatures will be over 32º by 9-10 AM in most of the the immediate PHL suburbs.

Reviewing the models from last night and this morning, I think the ICON model captures the gist of the likely ‘snow’—

Significant rain will follow any snow that does fall, so final accumulations in our just about all of our area will be zero.

The NWS has daily “extended forecast discussions” Here’s a quote which sums up the lack of jet stream amplification and snowstorms here-

“Although a colder pattern is coming, there is no imminent sign of any major arctic air masses surging south from Canada.”

Update Sat 1/21 11:23 PM — No change in Sunday’s forecast. Rain moves in about 2-4 PM.

Update Sat 01/21 @ 9:25 AM — I looked out the window this morning expecting to see sunshine and said to myself, “something ain’t right”.

Here’s the latest NBM (12z) just released, showing a lot more cloud cover than it had forecast yesterday with much more range of uncertainty—

The latest HRRR just available also shows mostly cloudy for today, although the latest GFS (06z) shows no clouds, as does several other models.

So here’s the updated forecast—

Saturday

Considerable cloudiness, some breaks of sun possible in some areas, especially late afternoon. Winds decreasing throughout the day. Little wind at the time of the Eagles start. High 42 ± 1.3º

Forecast for Sunday (below) remains unchanged with rain moving in 3-4 PM.

Previously Posted Fri 6:10 PM —

We had the predicted cloudiness today and even some scattered light rain drops that passed through much of Montgomery county. (I went back and I couldn’t find a model that predicted these convective showers.)

High pressure builds in for Saturday. A strong coastal low will affect our weather on Sunday through daybreak Monday.

Saturday

Mostly sunny, some clouds at times. Windy. High temperature 42.3º sd 1.4º NBM model for location Blue Bell, PA. Winds begin to drop off during the Eagles game.

Sunday

High clouds in the morning thicken and lower towards noon. Rain moves in about 3 PM. Becoming windy. High temperature 43.7º sd 1.3º NBM model for location Blue Bell, PA.

Update Fri 01/20 @ 10:18 AM — Low clouds are moving in, as forecast. Wind gust forecast is somewhat reduced but still quite windy.

Update Thu 1/19 10:11 PM — We had a lot more rain today than had been forecast by the models. Almost twice as much.

Previously Posted Thu 5:54 PM —

The deepening double-barreled low pressure system that brought us rain on Thursday will slowly move off to the northeast. A cyclonic flow will result in cloudiness afternoon and the pressure gradient will give us very windy conditions.

Friday: Sun in the morning will be followed by considerable cloudiness and with very windy conditions. High temps in the mid 40s, but apparent temperatures (wind chills) will be in the upper 30s.

Monday

Update Sun 1/15 4:55 PM — Monday will be sunny and milder. Still somewhat breezy.

High temperature 46.3.º sd 1.6º NBM model – for location Blue Bell, PA

Sunday

Update Sat 01/14 @ 4:34 PM — The clouds hung in today.

Skies clear early Sunday morning. Sunday will be sunny, continued cold and still quite windy. Here’s the latest NBM wind meteogram—

Update Sat 01/14 @ 10:25 AM —

Update Sat 1/14 8:08 AM — I often don’t watch the TV weather at 10 or 11 PM, but last night, I was curious how they were handling the uncertainty in the cloud cover for Saturday. Now I know how they handle it— they basically avoid the subject. I listened carefully; it just didn’t come up. On the ridiculous single weather picture summary at the end, they had the words, “some sun”. Yeah? When? How much? Where? If you weren’t really thinking about it, you didn’t realize that they didn’t tell you anything beyond it was going to be cold and windy.

So let’s jump to the chase: there’s still uncertainty and wide differences in the cloud cover forecast for today, Saturday. I’m leaning towards cloudiness until about 2-4 PM, where we may see “some sun” in some spots. I’m leaning on the new NBM version 4.1 for this forecast. (The new version 4.1 goes into operational service on Jan 17th).

Update Fri 1/13 9:18 PM — Tonight’s models, just coming in, continue to emphasize considerable cloudiness for Saturday especially from the city and eastward, and even a slight chance of scattered snow flurries.

Current water vapor image correlates to the western extent of the cloud cover forecast from tonight’s NAM and HIRESW models—

Previously Posted Fri 5:46 PM —

A cold front moved through on Friday, and a highly amplified jet stream trough will have us in colder weather for the weekend. The sharp trough will induce a low pressure system in the Atlantic. This system will be too far east to affect us, except for some cloudiness, especially at the Jersey shore on Saturday.

Saturday

Cold air with the trough along with the coastal low will bring more cloudiness than originally expected in many areas, especially into New Jersey. It will be quite WINDY and cold. Cloudiness lifts during the afternoon hours.

High temperature Saturday 37.8º sd 1.7º NBM model – for location Blue Bell, PA

Sunday

Sunny, continued quite WINDY and cold.

High temperature 42.0º sd 1.5º NBM model – for location Blue Bell, PA

Monday

Sunny and milder. Still somewhat windy.

High temperature 45.2º sd 2.3º NBM model – for location Blue Bell, PA