The low begins to develop off New Jersey coast but its still far enough offshore to keep the heavier qpf offshore. On this frame two different distinct s/w's are phasing or coming together to produce this low pressure system. The main culprit is the Polar Vortex over the Hudson Bay. That prevents this from turning the corner sooner.
The OLD GFS:
Notice how the low develops later is has the qpf further offshore and to the north. The main reason why this happens is because the s/w's merge too late for us to get hit. Even more so the second s/w does not dig as much as a result it is forced to meet up too late for us.
I highlighted the two distinct pieces of energy that come together. You can see this happening in the frame above. But as I mentioned before the main player is that polar vortex. In the 12hrs from the older run to the newer run this shifted the PV to the SW. The significance of that is it brings in the s/w in a much favorably trajectory and allows it to dig and phase sooner. Hence the low developing off NJ coast now.
The OLD GFS
PV is an unfavorable spot and shows the s/w at a higher latitude and not as favorable.
If the GFS continues this shift slightly in the coming model runs we could see a nice low blow up right off the coast and give a good snow event for portions of the Northern Middle Atlantic. Something to watch out for, but regardless a light snow event is likely from this system whether it be a plain clipper or a clipper with a coastal enhancement!
Well, my nws sunday forecast takes my snow clipper and turns it
into a rain dripper.........
Rain and snow likely before 3pm, then a chance of rain between 3pm and 5pm, then a chance of rain and snow after 5pm. Mostly cloudy, with a high near 39. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible
There's always a chance for it to POP off the coast but I think right now that is a long shot as well. At least we will see 3 days of white stuff from my forecast a couple weeks ago. We just have to take what we can get. the 2 jet streams just don't want to team up with a storm and a nice blocking HP this year.
Cmc shows nothing Sunday has the storm form way off shore, but has the clipper Tuesday redevelop right off the jersey shore and gives us a "miller b" clipper with front end snow then moderate snow as the coastal pops up. That's Oakland timeframe for a snowfall. So many chances....so little living up to their expectations.
Sigh. Progressive pattern means storm off shore, pretty easy to make a forecast right now for snow showers or very light snow. It's much of the same all winter mike. The chance of this developing close enough to give more then 2" to Philly is probably at 10% right now. It's been 50 mile misses ALL YEAR. Nothing is changing.
Ill put money on it that this pretty decent ridge shown on the 12z gfs is gone by 00z Saturday runs.
I certainly hope I am wrong, very wrong and I want to be wrong. But nothing has changed to give us a decent snowfall.
I wish we could get another November 7-8 storm and get a surprise trend within 3 days and see this thing come west... But highly unlikely.
We're basically missing this by 3-6 hours at the 500mb. The 500 looks pretty decent but it's just a tad late to tuck this closer to the coast. Well see what happens, I expect nothing though =(.