psuhoffman

Yea...no real reason for it...it’s nearly an identical run to 6z in the progression of all the various waves. Impressively so for the complexity of this setup. But it simply adjusted the thermal profile a few degrees colder. At that range that isn’t rare.

Gfs seems more amplified than the icon early on. Slower too. Of course we might need slower now. Without the NS phase it’s likely to be too weak to work with all the shortwaves knocking down heights on top of it. A fast moving weak stj wave ends up like the icon. Of course the slow phase bring temp issues. So would you prefer the rock or the hard place?

Fog fail

The simple idea might be a lost cause now. You only have to go out 72 hours to see all the various shortwaves clearly. They are real. And all over the place. And that probably means without a phase nothing can amplify enough. Too much splitting and competition of the energy. Even if it made it here a weak strung out wave won’t work. So were left rooting for a phased bomb now as the only option. Good luck with that both getting it and figuring out all those shortwaves at range.

Excellent point. In a better year when we aren’t always looking at day 10 ghosts by the time one threat either fizzles or is over the next one we turn our attention too is only 5 days out. We don’t even notice the day 7+ shenanigans. Plus 10-20 years ago we didn’t tend to look that far out. 20 years ago nothing even went that far. When I started analyzing guidance in the late 90s at PSU the MRF/AVN (what became the GFS) ran to 10 days at 0z and 5 at 12z. The euro was only once a day to 7 days. The eta and ngm ran to 48. Nogaps to 6. And that was it. And when we would have our daily model analysis meetings at the weather station day 5 stuff was considered the same way most think of day 15 now. We barely paid it any attention beyond general pattern trends. So the euro probably seemed less jumpy when it ran once a day and only to 7 but most didn’t even pay attention past 4/5 days.

Gefs makes no sense with its mjo forecast. The geps goes crazy into phase 5/6. Cfs and eps are meaderong in the COD. The gefs goes strong into phase 2/3 which are cold phases in the east February. So the guidance with the worst mjo looks best. The one with a good mjo looks like dog crap. Go figure.

The eps and geps both have a very workable pattern at the end. Neutral AO. EPO ridge. Gefs is a train wreck. Reloads the same +AO. Pac ridge north of Hawaii pattern. Normally I would say with the CFS, EPS, GEPS all showing a similar progression toss the GEFS. And science would say that’s the way to go. But would anyone be surprised if in this one case the gefs schools all the other guidance?

That’s a definite degradation

Furthermore “the euro is rock steady” isn’t a thing anymore. I don’t know if it’s because it runs 4 times a day now vs once back in the day. Or if it’s higher resolution made it more accurate but also more prone to tangents. But it definitely jumps around with specifics run to run the last several years. But usually it’s goalposts are closer to the reality and it tends to catch on first. But it’s not 100% and you can’t just rip and read it’s long range output as a gospel forecast.

Ignore the low off Norfolk and look at the whole picture. Everything else is pretty much the same. That low is tenuous based on exactly how the stj wave ejects. If it leaves too much behind and doesn’t phase it ends up suppressed. If the wave ejects healthy enough it phases and we end to with stronger storm. It’s a minor detail that leads to one major difference but on a pattern level the euro isn’t flopping around in the larger sense.

They wash out the MS and SS vorts there and so it’s all northern stream. The gem tries to kick up a NS dominant system the euro simply suppressed the SS wave.

It’s the surface temps. 38-40 might not be a torch but it’s not gonna work for snow. Verbatim that’s the look of rain mixing with slush bombs during heavy precip. Not saying it’s correct but those surface temps don’t support snow.

Not worth it. Either he is in here regularly and he knows that...in which case he is trolling, or he never reads this thread and he just dropped in to post that, in which case he is trolling.

It’s 7 days away. We wouldn’t even know there was a storm threat there if not for NWP. You can’t extrapolate the atmosphere to 150 hours with barometric pressure rules and wind plots.

Right now it’s in last place among major globals...and that was even before the major cmc upgrade last week. If that continues I wonder will there come a time the gfs becomes just a teaser like the icon as we wait for the big boys (cmc/UK/EC) to come in?

Oh well I thought the quicker would be better...didn't expect cutter again lol Upper levels amplified way too far west given the lack of blocking or cold in front. It was another solution where if we had a truly cold airmass or some blocking that progression would be a 3-6” snow to mix solution but with what we are working with just rain.

Yea but the mid and upper level trough is going neutral and amplifying west of where I want given our thermally challenged situation.

I added a simplified explanation of mid latitude cyclone development and how the "CCB" works in the snow climo thread if anyone is interested. I know bad timing with the 0z runs coming in. But you can check it out later.

@Maestrobjwa CCB refers to the cold conveyor belt. I think to fully explain this I should do a quick overview of how most mid latitude cyclones work First of all low pressure typically forms along the boundary of cold and warm air...as air moves across the boundary to try to bring equilibrium to the imbalance. This movement of air creates lower pressure where the air is vacating faster than it is filling in. A low can really intensify when an area of divergence in the upper levels crosses over the surface area of lower pressure. These areas of divergence are typically found in front of either long-wave troughs or Rossby waves or smaller shortwave troughs embedded in the flow. This divergence aloft creates lift below it to "fill" the void and this lift (rising air) from the surface lowers the pressure as the lift outpaces the rate air is filling the surface void. On top of that the rising air cools and condenses causing precip but that process creates latent heat release which causes more lift (warm air rises). This creates a feedback loop that intensifies low pressure. Early in the life cycle of a developing low pressure area they are typically just waves along the temperature boundary Precipitation breaks out along the boundary where the flow ahead of the developing low pressure begins to cross the "boundary" to the north of the wave. The warmer air crossing the boundary has to rise over the denser colder air and this lift creates WAA (warm air advection) precipitation. (rising air cools and condenses creating precip) Showery precip usually exists along the cold front to the south of the low where cold air is undercutting the warmer air cause it to rise...but since this displacement happens much faster the precip there is sometimes more intense (thunderstorms or convective showers) but short lived. Many waves never make it beyond this stage if there are factors inhibiting their intensification. But if a low can amplify and deepen it will develop a circulation at several different levels As it develops this structure...the cold conveyor belt begins to bring moisture that is to the east of the low from the warm conveyor belt to the west of the low. As this happens the storm will begin to develop the classic comma head structure seen below. That precip to the west of the low track is often commonly called the "CCB" since it is a function of a healthy system developing precip in response to the cold conveyor belt transport of moisture west of the low track. Additionally the precip to the west of the surface low track is not driven by WAA as much as other forces and so can have a colder thermal profile, especially in marginal events. Seen above there the dry conveyor belt begins to cause the "dry slot" that you often get near the track of the surface low pressure. Below I have zoomed in on what is going on in the "CCB". This region in the "CCB" develops a deformation zone...a region where the atmosphere is being pulled in different directions at different levels. The convergence of the DCB, CCB, WCB, as well as the sheer at different levels created by the mid and upper level low pressures creates instability in this area. Where the moisture convergence from the CCB bringing moisture in off the WCB meets this instability you can get intense snow bands. This is what they call the "deform" band. One of the best examples of a deform band was from the February 2006 storm. This radar is from the NYC area but this same band impacted our area...I think the Columbia MD area got 20" because they were under this band for several hours. You can see on the radar loop the forces I described above at work. Later in the life cycle of a mid latitude cyclone, because the cold air often outpaces the advance of the warm air...the cold catches up and the low ends up cut off from the warm air advection...at this point we say it has occluded and it looks like this. At this stage the intensification period is over and the storm typically begins to weaken. But during this stage you can often see snowfall wrapped up even under the surface low instead of displaced to the NW of it. Hope this helped some. You can ask any follow up questions also...others feel free to add anything to this.

I will add some stuff about that to the climo thread now

@Bob Chill guidance is off by a few degrees on the overall thermal profile from this range A LOT... usually with a typical airmass in winter the track is more important and that is what we are focused on...and in the end that might be true here also...but it's not at all crazy to think this ends up slightly colder than the guidance things from 7 days away...and if it does suddenly those "perfect track rains" become some big snow solutions. I know last November...from range that snow up here looked like rain...and actually the track ended up even worse but the whole airmass trended colder at the end and that made a huge difference. I can think of plenty of other examples. It could just as easily trend warmer and we end up with no prayer but odds are the guidance won't be dead on accurate with the temps at this range and we only need a SLIGHT adjustment colder...so really its a 50/50 shot we get that one factor to go our way. We would then be back to worrying about track and phase and all the other multitude of factors that can lead to a fail.

models wont often pick up on a 1-3" thump on the back end from 7 days out

It's why if I ever move to a "snowier" climate it probably would be NH over Colorado... I am sure I would be happy in Colorado... but NH can still get massive coastal storms and there is nothing like watching the storm develop and bomb out and looking at radar as the banding heads towards you...or waiting for the pivot... I just don't think I can give that up permanently. And Wildcat/Sugarloaf/Sunday River are "good enough" where if they were close bye and I could catch every powder day I think I would do ok just heading out west once a year... but I would be too bummed out missing every east coast storm ever.

Yea but I’d toss the next 2 weeks to have it look like this Feb 10th yes I know that’s not going to happen but if your going to take the first 15 days verbatim then you can’t toss the 16th.

Depends if you consider low to mid 30s “cold”.