Moderately Unstable

If that trend keeps up they'll need to extend the warnings....

Yes. No 24k NAM. 12k and 3k are both on Pivotal.

I've been trying to come up with a way to express how excited the NAM caving makes me but I literally can't. Agghhh. Looks like it finally clears philly early Wed am. Weather channel uped philly estimate to 12-18" storm total. Muahahahahahahaha!!!!!!!!

I really like the RPM. Weather channel's parent company's in-house model. 12km res goes to 72 hrs. 4km res goes to 51hrs these days. Almost every broadcast met you know uses it. Do the NE forum members post the maps or no? As of now, it is trending more euro/rgem than nam/hrrr. I think the euro has a good handle on things overall. It does well with headline type miller B's; NAM facing retirement and is known for kooky solutions to a level that "being NAMed" is common meteo vernacular. Looks like the NAM is coming around finally. Wrt the last euro, all I want to say is, that European model looks very plowable tonight .

Sorry guys, I wrote that on my phone. I promise I know better haha. Thanks Jim for formatting.

PSA: A few folks here yesterday made statements like..."under 6-8 WILL NOT happen". Remember not to predict ultimatiums before an event occurs. Weather gods don't like hubris. Mt. Holly is not going w/NAM. If they were, they'd have to majorly cut those totals particularly around Philly. They're just not going into rgem land. They seem to be splitting the difference. Not very weenieish, does seem logical though. The models all show good qpf in Philly and surroundings. The differential in the snow amounts is mostly differences in how much warm nose pushes in and hence how much mixing occurs. My exp is that given the cold air that's been in place, and the high precip rates expected due to the rapid deepening low, you'll get the typical evap cooling effect where the heavy rates keep the column at freezing so long as precip is sufficiently robust. The lull period tnght tmrw am is where the risk is as has been stated. Heaviest rates, 1-2" hr are really only progged for a short time on any of the models, and it's right after precip ramps back up. Some models show that period being sleet for many of us; that cuts the totals. Others keep it all snow. That will be the difference for the corridor though btwn a 6-8-12-15 storm total. Remember that if we got 2" thundersnow type rates for several hours, we'd be talking plural feet in the corridor, not 10ish inches over 3 days. *Most* of this event is clearly NOT heavy snow. So, don't panic if things don't work out exactly as the models project. Expect that they won't be perfect. One thing they all show is that this system is with us for awhile and should produce some snow most of that time. By Tuesday pm, we will probably add up to what this forum expects, but, expect a lot of panic and concern from people here tonight and Monday, beyond the lull..just bc I think people are expecting a major 2"+ hr rate situation and again, outside a few hour window, this is a low and slow burn. I also think based on what I'm seeing live that the models may be underdoing the overrunning totals a bit, and that may also help us get to expected totals. We're going to be fine, folks.

The thing worth considering here, is that, unlike the *December* storm, this storm is sticking around a long time. Yeah, the event starts within 24 hours. But the actual ramp up where we expect to see the transfer and thus, the bigger totals, isn't until Monday (e.g. 36 hours ish out). I think we could safely predict right now what happens tomorrow. The overrunning precip comes through, gives a widespread several inches, semantics dependent on mesoscale details. Hence, we have 12 hours before we'll be at the point where, in December, the models started making everyone cry (they began that trend sooner though) wrt the actual Nor' Easter component to this storm. I think 10-14" is what I'm going with for the city. Someone in the LV will see north of 2". I don't necessarily buy the pie in the sky 3-4 feet. Mixing is a concern for the corridor, but the transfer should probably limit duration. I think the above comments were right vis a vis the NWS was pointing it out as something to be aware of and consider, not buying or not buying it. It's one of those things to keep an eye on. If that signal sticks around and it starts showing in other models, pay attention. If not, just a good-to-know. Wishing all in this forum good luck the next few days, if you're chasing, staying home etc. May the snow totals be forever in your favor.

Does anyone have a link to a website that shows a high temperature verification map for today? Ideally something that compares actuals to the statistical and dynamical guidance?

Not necessarily. The high res and proprietary guidance today has been a bit all over the map. Several typically good short range models are progging the axis being more along the apps with PHL at 6-10. Of course several globals clearly show more. Personally, I'd have called 8-12" for the moment in CC PHL, because it's less jarring for the public to shift up or down a peg from that range. No point in forecasting max possible amount just yet, sets up a lot of room to bust. Too many things have to go right for 12-18. We can't miss the overrunning, fgen needs to be good, transfer of low has to be good. 6-10 is nothing to sneeze at, and model variability is the reason it is useful to wait to go full tilt until I'd say the 00z runs tonight. This IS philly after all. If all the models are honking together then you raise the bar. 12-18 is your best case for phl, 5-8 is your worst case....8-12 is a safe middle. They say fortune favors the bold, perhaps that explains my misfortune. I am genuinely curious right now to see if winds and visibilities end up hitting blizzard criteria somewhere in the mt holly forecast area. Seems possible. Edit: I like the epawa map.

Mt holly has hoisted initial warnings.

1) Yes Mt Holly write up was good. 2) I'm refraining from posting right now, or getting excited, as I've learned the very hard way (as have all of you) that we've been burned SO MANY TIMES on winter setups. There's an excellent article the inquirer put out earlier basically making the point by talking about the improvements in modeling coupled with myriad high profile busts over the last dozen years. Moral of the story is, Philly weather is hard to predict wrt snow. Complex almost always. You've got an elevation change, variable coastal effects (sometimes intrastorm), etc. I'll try to make a call tomorrow night just to be part of the bandwagon bc yolo. The things I DO like about this setup are its long duration, the favorable teleconnection pattern, the existing cold air "cold air is the bully"--> meteo refrain referring to cold air being more dense, thus if you want to bet on something, bet that cold air sticks around longer bc it takes longer to dislodge. The long duration aspect means that if one element underwhelms, say, overrunning, or fgen, there's 2 other components that can make up for it. Much better than a quick hitter that is progged with 2" rates. If you miss an hour, or 2, of those 2" rates bc the low tracks differently than you expect or the column takes longer to saturate than you think, you're sol. With a storm like this, it's kinda lumbering and that makes it harder to bust. The PG is impressive--will be interesting to see what type of warning (*ahem*, if a warning) is hoisted. That all said, this is Philly, my above axiom stands vis a vis the models' ability to prognosticate a major event that doesn't happen. A lot of historical data points to this being a good setup. Air travel is still down though (# flights): weather data from aircraft are fed into the models as part of their initialization. I also tangentially think that climate change may be (possibly) hurting model performance. Your basic assumptions have to change a bit when the energy budget shifts (e.g. less energy coming through atmos can get back out to space). I'm sure modelers are factoring that in, but, cursorily, I have noticed a trend for models to be more finicky the last several years than in the past, and I do wonder if climatic effects are partially responsible. Anyway, looks promising, but I'm not gonna start letting model variability and run to run updates consume my life till tmrw night.

I'm almost certain everyone knows this, but the "precipitation depiction" pane on RadarScope also shows the R/S line as well. Similarly, hydrometeor classification is very helpful. I know everyone has their own "go to" radar services for different events so I just want to share in case anyone reading this (member or not) wanted another tool to look at.

18z nam is definitely an improvement for my area. 500 mb heights down substantially, better CCB positioning.

Well, yeah, I *do* agree that if a model is showing a 1:10 ratio for SEPA for this storm, regardless of which one, that's not credible. Sometimes, Kuchera does go ham --when the conditions aren't so marginal--and can indeed overdo things substantially. Here though, I honestly think the "main story" is, the models are, collectively, shifting the storm North. They're doing that due to the Canadian HP traveling more E than previously forecast, so the expected strong block in place that would preclude a negative NAO from shoving a low into the coast, is not progged as being as influential, so the tucked in solutions end up working more. I don't think the Kuchera ratios were wrong relative to the dynamics the models in question forecasted earlier on. They weren't 1:10. The maps I have with 1:10, and in this thread, show 18-20+" in Philly consistently. Kuchera is more in the 10-15 range. Both seem high now, but Kuchera was lower. The thing I am disputing is that "kuchera inflates the totals". At best, it isn't deflating them enough. Euro may have incorrectly parameterized the column temp, sure. Again, not an issue with the method itself though, and the theory behind it. Final point (unrelated to Kuchera): the storm isn't here yet, and won't peak until tomorrow night for this forum's area. The trends are bad, the fat lady has left her dressing room, but she is not yet at the microphone. In other words, trends are bad. They will keep oscillating, one way or another.

Mkay gotta correct the record here. Kuchera totals are used because they calculate how TEMPERATURE affects RATIOS. Sometimes, that results in greater than 1:10, but NOT always. Here, the Kuchera ratios have been *consistently* less than the 1:10 ratios. Therefore, Kuchera ratios are NOT giving falsely high amounts. If anything, the 1:10 maps do that. Let's check out how: Ratio= 12 + 2(271.16K-T_max), when Tmax is >271.16K. Note, 273.15K=0C; 1 degree increment C=1 degree increment K. Ratio = 12 + (271.16K-T_max), when Tmax is <271.16K. Cool. So, the max temp in the column here is between 1 and 1.5 degrees C. 273.15+1=274.15, 273.15+1.5=274.65. Let's plug that in. 12+2(271.16-274.15)=12 MINUS 2*3...12-6....SIX. 1:6. Kuchera ratios are not the problem. GFS Kuchera ratio for hour 42, 12z run, attached, for PHL. Please note, I am not "defending the models" here, or trying to claim the city will see more snow. I'm mainly saying, there's a lot of claims of Kuchera being pointless. It isn't. It takes 1:10, which is the forecast equivalent of using the 540 line as your rain snow line, and makes it more scientifically precise by calibrating it to the situation. Right or wrong, the Kuchera method itself is not the problem.

They were on point at the time they issued that forecast. Subsequent runs have been more dicey. Some proprietary mesoscale models still show more snow farther south. There is very strong hp. Hard to see the low make it as far inland as some of the models currently take it. Being a good met means looking at the physics, not just the models. Models have utility but they're a tool, not THE forecast. Plenty of times on this forum the models have said BIG STORM and then, poof, nothing, and everyone on here went along with it. Conversely, sometimes situations outperform the models. In closing, unless you are currently working as a paid met, please sitith thy butt down, and stop critiquing those who studied and do this professionally.

Haha, I believe we have but not certain. 2009-2013ish. Larry's friend.. I did the senior project involving northeastern storm chasing.

00z nam maintains snow at least a bit longer over Philly. Also moves the low a touch closer to the delmarva. 540 line unchanged ish. Colder ll air in place though so more snow.

Glen Okono trail was closed several years back. Too many folks getting hurt. I had to help 2 last time I hiked it. Just an FYI in case you didn't know. Not sure if you can still access the parking lot and such or if they blocked it off.

We must find the observer!! *grabs pitchfork*. Jk. I'm embarrassed I didn't know that. I've been to the mt holly office several times...years ago when a friend worked there, and no one ever told me that. Tried to find info on Google but there's nothing. The inquirer itself reported this jan no less that totals were taken from the airport. NjHurricanes point jives with what I was trying to get at though..airport or NJ, there is often some material difference btwn airport and cc. Not hugely so, but it can be a couple inches in bigger storms. The inquirer article pointed out that many areas of phl see significantly more snow than phl airport. Even some inland parts of nj. Only the nj coast sees less. So as to my earlier comment--if I forecasted for the airport, my numbers would be lower than, say, Roxborough, even though both are "in the city". https://www.inquirer.com/weather/snow-weather-philadelphia-winter-phl-measure-20200121.html

Interesting. You're saying the measurements are done across the river...Delaware or Schuylkill? You're saying they *are not* measured at the airport? Sep: confused at what you are pointing out here. Do you mean that phl totals are reflective of reality, or aren't?

Thanks guys, appreciate the words of encouragement/inclusion. Wasn't trying to go emo there, just have been feeling rather self conscious haha. Sometimes I overanalyze things... like when I say something on here and then no one posts for 30-40 minutes I go "is that because I just stopped the conversation or because no one has anything to say right now". Not specifically this thread, just on the site in general. Happened when I was talking in tropical about Iota and internally I was screaming, even though most likely there just wasn't any update to add for awhile. You know how you feel when you go from being the one who knows a lot about something (most on here when talking to other people irl off forum) to someone who is very much NOT at the top of the knowledge tree and your peers can blow your skills to shreds? It's like that, kinda like going from HS to college. Makes me much more reserved.

Welcome back! I hope so too. I know not everyone loves snow, but most folks are working remote these days, its the holidays, it could bring some extra joy to folks who haven't seen snow in a long time. I hear ya on the statistics. One thing to factor in there is that kphl is almost always on the bare low end of the forecast estimates. You have the heat island effect from the city + moderating effect a touch of being next to the Delaware+ farther south + basically sea level. So for every storm in the top rankings list for the city that says, say, 8-9 at the airport, you could realistically have gotten 10-11+ further up but still in the metro area. I also think that from an impact standpoint--you're 100% on the money. Even with sleet or freezing rain, that still causes power outages and makes travel dangerous, perhaps more so. It's just, objectively, cool to have a big full snowstorm with no messy ptypes, in ones own area. I live personally close to the city/burbs line, so I'm especially cognizant of these setups and their gradients. I'm sure my childhood hometown will see 3"+ than me even though the distance is not too far. Either way, fingers crossed.

Posting on here stresses me out sometimes. Trying to "read the room" when you can't see people is nervewracking. Constantly editing and second guessing what I write to avoid saying something dumb & no one mentioning and just ignoring me.