psuhoffman

The EPS did improve slightly which was enough to pretty much keep the probabilities the same from 0z since the EPS is the highest weighted in my calculations. The GEFS and GEPS got worse. GEPS is still the best of the 3 but it was even better at 0z. Remember this is through 0z Feb 6 Odds of 1" ,3", 6" 1/28 0Z: 51%, 27%, 9% 1/28 12Z: 51%, 28%, 11%

I'm putting together a bulletin board of what we need to go right for visual support

Sorry guys...I really want this to go the other way here. I am honestly not trying to be a downer, if I liked what I saw today I would say so. But I honestly think today things trended away from what we wanted after the last 24 hours we did see some progress. I will update the numbers for a combined ensemble snow probabilities when the EPS rolls out soon but just warning you the GEPS and GEFS both took a step in the wrong direction so unless the EPS looks a lot better the numbers probably moved the wrong way from 0z.

I cant really relate to tiny things

@brooklynwx99 so far today the trends are opposite what we want. I don't think seeing the confluence relax is a good thing...what we actually want is MORE confluence but also a more amplified wave. We want them to slam into each other and fight it out. That is the snow solution with upside. A weak wave has very little potential here. If the confluence remains strong it gets squashed. IF the confluence relaxes you get this euro result. Either way we lose with a weak wave. Today the confluence trended weaker and the wave trended weaker across guidance. A lot of time to turn those trends around but they are going the opposite way of what I want to see right now.

ya it wont be squashed but that looks like a setup for rain imo. Again, the "win" scenario is very very very narrow here. The ridge axis at the mid and upper levels is right under us so the only way to suppress the boundary is with the TPV. But that leaves no room for a system. We need the perfect combo of a strong wave and perfectly timed TPV/High for it to work. Weak wave, squashed. Strong wave, TPV relaxes too much...rain. If you run all the scenarios the odds favor either squashed or rain. That's why we keep seeing MOST runs flip back and forth between those 2 extremes with very few actually showing that in between snowy solution.

Just enjoying a couple of board residents going at it again...

lol

I’m not necessarily saying this is related to anything else. Two things can be true. But it’s been a repetitive issue in recent years. I’ve pointed out over the last several years often there is very little frozen precip associated with mid latitude waves.

Hope so, the snow it shows falls at ~35*. But the larger issue remains. Even when there is snow with these waves it’s a relatively small geographic area with marginal temps.

Today's guidance took a step back towards a problem that to me is the biggest limiting factor in this setup and has been a repetitive issue recently. Lack of interaction between moisture associated with the southern stream and the cold associated with the northern stream. I've been mentioning this for years...it was a HUGE problem in 2021 when we had blocking and storm after storm took a perfect track. I think it gets less attention when we are in periods with a bad storm track because so much else is wrong that we don't pay attention...but this has been a theme for a while now and its a big problem. Last night we saw some improvement with this but today the guidance seems back to not having any interaction between streams. That is what leads to this.. Wave 1 Where is the snow??? look at the pathetic "win" zone Wave 2 Again where is the win there? Wave 3 And its not just a here problem...the next wave isn't even close for us but it wouldn't matter what the track was because look... There is really very little to no snowfall with most of the waves, and this has been a theme a lot of the time recently. The GFS shows a bit more snow but if you look closer its probably a faulty artifact of its faulty cold bias in the thermals and a liberal precip type algorithm. Because look at the surface temps on the GFS when that 2-4" of snow is supposed to be falling to our south. It's 34-38 degrees and that is on a model with a cold bias. The CMC precip type output is likely closer to reality if that is the actual track and interaction between streams. Not enough attention is being pain, IMO, to this. It's a big part of our struggles in recent years. We should not see wave after wave in January and February with virtually no snow on the northern side of the track at the mid latitudes. When there is almost no snow until you get north of 40* with any wave...well...thats kinda a problem for us given our latitude!

That’s playing with fire though. With the upper ridge directly under us no matter how weak the wave is if the confluence lists we risk the whole boundary lifting too much. Also we risk the wave simply being weak sauce and not a significant snow for anyone. Ideally we want more amped and more confidence. That’s the combo with upside.

@Maestrobjwa don't overthink this. Keep it simple... our snowiest enso state is el nino. Second is la nina. Worst is neutral. There is variance within all 3 and you see the stats I posted above. Set your rooting interests and expectations accordingly.

The consensus last year at this time was for a Nino this year.

It's close to a good setup, but the real limiting factor on this whole period is the fact the true mid latitude ridge axis is about as horrible as you can get, look at that heat bubble in the gulf. There is no blocking, the pac ridge is too far west, the only thing suppressing the SE ridge is the TPV. But that is a double edge sword because the thing that will prevent the SE ridge from going ape is also a suppressive factor. So we are left with very small margins for error. On wave 1 we need to cold to press but not so much that is shunts the wave south. IOW we need perfect timing. Cold press too slow it goes north, too fast it goes south. With wave 2 we need perfect timing with the TPV movement and associated high pressure. There is a very narrow window where something can amplify enough to get precip to our latitude but not press the boundary too far north. Really only like a 12-24 hour window where the flow is relaxing but has not relaxed too much. It's a real threat, which is more than we have had...but there is a serious cap on the probabilities here unless we get perfect timing with these features.

@Terpeast made an astute observation last night in another thread. This year looks more like an esno neutral v nina. all Enso Neutral in the last 30 years H5 Composite Nina Composite Obviously no one year is going to match a composite exactly but we have had a more typical enso neutral pattern overall than nina. I've said before I don't understand the obsession with rooting for a nina to fade during winter since there is no objective evidence it helps improve our odds later in a season AND enso neutral is even worse for snow here than la nina. But the good for next year could be the atmosphere is already transitioning away from the nina base state and maybe that could be helpful if we do get a nino by next year. Just a warning though...enso neutral following a nina is actually WORSE than a nina. So hopefully we are getting that out of the way this year. But if the projections of a nino fail and next year ends up enso neutral...well historically we are probably looking at another dreg awful snowfall year. Pray for a Nino. Do a dance. Light the candles. Sacrifice whatever and whoever it takes. Do it now.

You better hope next year isn't enso neutral...those are even worse. This is BWI snow data by esno the last 30 years. Neutral Nina Nino Avg 13.1 Avg 17.2 Avg 28.6 Median 11.7 Median 14.4 Median 18.3 % above mean 12.5% % above mean 25% % above mean 44.4% 1994 17.3 1996 62.5 1995 8.2 1997 15.3 1999 15.2 1998 3.2 2002 2.3 2000 26.1 2003 58.1 2004 18.3 2001 8.7 2005 18 2013 8 2006 19.6 2007 11 2014 39 2008 8.5 2010 77 2017 3 2009 9.1 2015 28.7 2020 1.8 2011 14.4 2016 35.1 2012 1.8 2019 18.3 2018 15.4 2021 10.9 2022 14.4

I have teased before the idea of trying to find a way to calculate snowfall probabilities using all the major ensembles. The mean is always a bad tool to use alone because it can be skewed by extreme outliers. The probabilities are a better tool but the problem with them with any one ensemble is they are susceptible to internal bias error. All the permutations are still based off the same parent model and its equations. They tinker with the initial conditions and the models equations a bit but only within certain parameters. Each model system has to deal with certain problems. One is how to initialize the atmosphere given our incomplete data and resolution limitations. How each model deals with these limitations and how to compensate for them affects the outcome. There is only so much they can perturb these factors within each's parameterization schemes. If there is a bias error for a specific synoptic event inherent in the parent model it is likely to infect the ensemble permutations as well. Another issue is how the models resolve factors that are impossible to actually be accurately depicted in the model either because of the complexity of the process or because of the spatial resolution limitations of the model. Some processes take place mostly at the molecular level and are too small scale for the model to resolve the way they actually occur. Other factors are too complex and trying to actually model them with all the variables would create ridiculous exponential errors. So the guidance comes up with ways to compensate and model the effects of these processes. But each model handles this problem slightly differently. An error caused by these factors in the parent model would also be likely to infect the ensemble permutations. The problem with using probabilities produced by any one model ensemble system is that the whole system is infected with some of the same error biases and the system does not know anything outside the system. In short, the model does not know what it does not know. By creating a probability using multiple systems we can offset some of these biases some. It's still not perfect because at the end of the day we are using a still limited physical understanding to apply the primitive equations to mathematically represent a chaotic fluid system like the atmosphere with nearly infinite permutations based on nearly infinite processes at nearly infinite levels. We're just not even close to being able to do that accurately at long leads. But I do think using all 3 major global ensembles will turn out to be more accurate than any one. The next issue is how to weight them based on their overall accuracy. I decided to go EPS 40%, GEFS 35% and GEPS 25%. Further investigation based on verification scores might move me to tinker with that calculation some but for now lets see how it goes. Using this math here is where we stand based on 0z guidance using BWI as a central location. These probabilities are through day 10, 0Z Feb 6th 51% chance of 1" of snow 27% chance of 3" of snow 9% chance of 6" of snow I will try to update these numbers when I have time after each run going forward (when there is a realistic chance of snow, not wasting time on this during shit the blinds patterns).

After looking across all the overnight guidance, there was a noticeable positive trend. We are in better shape now than 24 hours ago. But expectations should still be low. We are seeing a bit more interaction between the STJ waves and the cold boundary in the last few runs. Not an amazing amount, still most runs are kinda anemic with the intersection of moisture and cold on these waves, but better than it was 48 hours ago when 90% of all guidance pretty much had no interaction until north of our latitude which would do us no good. Averaging the 3 major ensembles gives the DC/Balt metro areas about a 51% chance of 1" of snow through day 10 and a 27% chance of 3" through day 10. That is by far the best odds we have had inside day 10 yet this year. But keep in mind those numbers are still below climo. This is the snowiest period of the winter and average for this 10 day period is actually about 2" so a 50% chance of 1" and a 30% chance of 3" is still slightly below normal. But of course a crumb looks like a feast to a starving man.

@CAPE and @brooklynwx99 have been on this period for a LONG time now and giving detailed analysis of how it could play out. So far they've done an amazing job of interpreting guidance to depict the coming period. Nothing about their posts have been 20/20. Here's a suggestion...why don't you try simply posting your own analysis without including unnecessary digs at others.

One of the reasons I hate progressive wave patterns is not just they are fools gold in that they might lead to a hit or two but rarely will they lead to a truly snowy winter on the whole, but for us they minimize our geographic advantage. SWFE in a progressive pattern really offer us no advantage over anyone else. Our elevation helps in marginal boundary temperature events but these waves the temps are really just a product of where a sharp thermal boundary sets up. And we get upslope enhancement when there is an easterly wind component from coastal storms, a SWFE offers no advantage there either. We really lose most of our climo advantage in these setups. Doesn’t mean we can’t get snow from them. But we really are at the mercy of simple blind luck wrt timing like everyone else.

A big part of our lowered snow climo is this. From 1960-2000 enso neutral years averaged 24.9” and were above avg 53% of the time at bwi. Since 2000 they avg 12” and are above avg 17%. Worse that’s skewed by the only good Enso neutral year 2014. Remove that as an outlier and BWI averages 6.7” in enso neutral years this century!

@Terpeast this is also why I’ve never understood the infatuation with rooting for a Nina to die during winter. There is no evidence it helps and neutral after a nina can be even worse! Frankly neural has simply been our worse base state for a while.

Yup! I pointed this out years ago when I noticed it while putting together analogs but I’ll try to find the numbers again. Actually the biggest degradation to our snow climo has been in enso neutral years. Prior to 1990 a good % were snowy. Since they are mostly duds and some god awful.

Well you seem to be an expert on insanity.