eduggs

PHL sounding at 15UTC Monday morning when the GFS shows moderate snow. If this sounding is reliable it would not be snowing at this location. That's a virga storm.

It's possible the problem is mostly confined to the QPF parameter. It could be nailing the synoptics but just not properly accounting for dry air interaction with precipitation. I am a little intrigued by its H5 depiction. A closed low at H5 gets pretty far north this run.

The GFS is printing out QPF with -30C dewpoints at 700mb on the NW edge of the precipitation shield for Monday. I'm not buying it. That's virga. H5 looks relatively impressive for sure, but I think something's wrong with the GFS's QPF algorithm.

Something looks wrong with the GFS's QPF algorithm. There's a pronounced dry layer around 700mb on the sounding throughout NJ and EPA etc. on Monday morning. Dewpoints are like -20 to -30C. And at the same time, the GFS is printing out QPF. That's virga. No way snow is reaching the ground through that dry air if the sounding is right. Granted, H5 looks pretty decent for maybe SNJ to get clipped, but the GFS looks way off with QPF here.

The most IMBY poster on the entire site who lives much further away from the sub-forum majority than NYC or PHL posters, complaining about people posting from other sub-forums...

I remember plenty of rain that year. Wall to wall has never existed at our latitude in recorded history. Wall to wall warm is becoming increasingly possible, but there will continue to be intrusions of cold air following wound up storms regardless of CC.

The GFS is almost certainly too far NW with the precip. shield for Monday. It has placed too much QPF into dry air a few times this winter season.

There will probably be an ultra-plinian volcanic eruption in the next few hundred years that cools global temperatures for a year or two.

I think it's a big red flag for anyone in coastal VA, MD, DE, NJ hoping for snow that the NAM continues to be so flat at this relatively short range.

Then there's the 0z NAM.

Somebody should tally how many times that's been said in the past two months. You're not wrong though.

I feel like we're due for a cutter period. The mean longwave trof should shift more towards the center of the country. That would finally get the midwest their snow and the Lakes region their lake effect. Probably more mixed events for east coast ski country.

That was flukish and only very light snow. The 12z EC is further SW and more wrapped up at H5. It produces a stronger storm and heavier precipitation right near the coast. If you want something more than a trivial snow event locally, IMO this run was much closer than last night's. It's still not there yet, however.

Looked much closer than last night's 0z. I didn't see 06z.

GFS lost the Monday event like the NAM. The southern shortwave is clearly a very sensitive feature. The wide ensemble spread supports this sensitivity too. Since the majority of guidance for several runs says we don't get any snow out of this, that is clearly the most likely outcome. But based on the individual ensemble members, we should probably expect something like one or two out of 10 operational runs to be hits or near misses. And maybe that's the approximate likelihood of getting some snow out of this in our region.

The RGEM is not nearly as sharp in the SE as the GFS/NAM, but it still managed to get a little backside snow to EPA, CNJ, NYC etc. Maybe the start of a trend? I find the RGEM much more believable with a more strung out look instead of the wound up look. Not sure if that's just pessimism.

The GFS is has a pretty wound up southern stream shortwave. It looks a lot like the NAM, just about 8 hours faster. That's gotta be a good hit for parts of the mid-Atlantic. Nice trend at 18z with the American guidance.

18z NAM looking surprisingly threatening for some of you guys. Pretty noticeable change from last run. Much sharper southern stream shortwave. I hope it's real.

The 18z NAM looks a lot more threatening for Monday than the previous runs. Significant changes. Southern shortwave is much sharper this run. That looks like it would produce a decent snowstorm in the mid-South through parts of the mid-Atlantic. We'd still probably need a little help to get snow to our region, but if this run is onto something real, it's something to watch for sure.

I've seen plenty verify as snow, especially in the higher terrain of VT and NH. Low level temps in the coastal plain are often problematic. Ana's are kind of what we call the rare scenario in between the full cyclone and frontal crossing. I agree most do go one way or the other.

That's good advice. Analfrontal is deviant, especially for sucked weenies. What the 18z GFS is showing isn't really anafrontal. If you only look at the surface graphics, if looks like that. But if you look at H5 and H3 you see there is a legitimate southern stream wave. Problem is there isn't enough support for this robust look right now.

I recall a few times this year when the GFS wrapped up a southern stream wave and produced backside snow in the medium range when most other guidance did not. In every case, the northern stream ended up being too fast and the southern stream vortmax never made it to the downstream side of the longwave trof. The result was a positive tilted trof, squashed southern stream wave, and a frontal passage. Nobody trusts the GFS showing snow with this and probably for good reason. But there's just enough support from the EC, UK, previous CMC runs, ensembles, and even the ICON to completely dismiss it.

We know individual model runs are not accurate in the long range. Ensembles are better but still not very good beyond 7 days. We look mostly for hope, but I don't think we should expect consistency.

The CMC is not close for the Monday coastal. And it trended in the wrong direction.

Yes. The 500mb vorticity charts would support a light to moderate snow event right along the coast. A few individual ensemble members sharpen the trof in the SE like the 6z GFS did, but the other global models mostly keep the trof positively tilted and slide a harmless front through the area. We need to see more model support to believe it.