psuhoffman

for those that want to feel better, or worse, for a few hours

Then what are ensembles? What's the NBL? Why do we look at ALL the guidance and not just one model run? If we could create one perfect model that predicts the weather with 100% accuracy down to the second like in BTTF2 then yes, we could just program that one model, sit back, and let it forecast. But we don't have that ability. We know the best models we can currently create are flawed and will not perfectly predict at range. If you are taking them as they are and using them as a forecast that is user error. The skill is seeing all the permutations shown by the various models and interpreting what is most likely to happen within that envelope. The best are better at that...the rest post 300 hour model plots on twitter and facebook.

IMO it probably will be a pretty tight gradient in this type of evolution, which the Euro/RGEM/GFS now all show. The bulk of the precip falls in just a few hours in an incredibly intense bad. Once the thermals go isothermal under that band its unlikely the rain/snow line moves much. The temps surge north as that band arrives then the dynamic cooling stalls it and that is likely where the rain snow line sets up for the duration of that period. So if you end up on the snow side you can quickly pile up 3-6" (I think the higher totals are unlikely) where as just on the other side...womp womp. There isn't that much precip out ahead of it and none behind it where some frontrunning snow or band on the backside could cause some consolation snow for places on the rain side during that main show. It's all or nothing really.

This one is more complicated IMO than some of the clearer examples of storms in the last 5 years or so that I am convinced we lost a 1-3 or 2-4" snow around DC due to warming temps. Plus its not over yet, maybe things trend colder again, I was just pointing out that synoptically I don't see much other to root for than "just be colder". Plus I am not in the mood to argue with the "don't talk about that" crew anymore.

Yea, but isn't that what partially is responsible for the very heavy precip under that trough? The GFS hints at it too but its colder so its ok. But if the Euro is right about the warmer thermals overall, not sure what the win path is there. No trough, no heavier precip, trough, warmer. What are we rooting for there? I guess just the colder GFS thermals to be correct?

Euro and RGEM today kind of made me a little less optimistic. I was thinking that but they both have 6 hour QPF bombs and are still really really warm.

What are you talking about? You use them to make your forecasts. You were asking me what the MSLP and location was just the other night on the euro where it passed our latitude and talking about what we need that to be in order to get snow. You're taking the model output, and adjusting with experience. Using it as a tool. You would have had no idea there was going to be a low anywhere near Ocean City on Saturday evening from that range without the models. We can extrapolate for a day or two using current observations but beyond that we would have no idea what the features important to make a forecast would look like 4, 5 ,6 days from now! You have to look at all the guidance, decide how its likely in error, apply your knowledge of what usually happens to adjust for that error and make your best educated guess. How else do you propose you put out a forecast for something more than a couple days away? If they could make them better they would, its not some kind of conspiracy to hide the real weather from us. It's just the limitations of our current scientific and mathmatecal ability.

@WxUSAF @Terpeast I'm not too worried about the too amped or sheared out options. I think it will end up with the more favorable in between solution. But I am concerned the thermals might bleed the wrong way anyways and even with the more favorable track/intensity it just ends up too warm.

A model output isn't a forecast. It's a tool to be used to make a forecast.

Can we take the colder airmass on the NAM and apply it to the euro precip?

PNA values from that time period 1966 1 15 -1.725 1966 1 16 -1.642 1966 1 17 -1.534 1966 1 18 -1.542 1966 1 19 -1.654 1966 1 20 -1.739 1966 1 21 -1.622 1966 1 22 -1.402 1966 1 23 -1.269 1966 1 24 -1.26 1966 1 25 -1.204 1966 1 26 -1.255 1966 1 27 -1.369 1966 1 28 -1.562 1966 1 29 -1.333 1966 1 30 -0.903 1966 1 31 -0.927 However, I agree that while the numerical value is a -PNA there is a HUGE difference between a -PNA linked up with the NS in a full latitude trough and a -PNA due to cut off STJ energy crashing into the southwest with ridging over top of it. But technically it is still a -PNA. I was just trying to see if you think that setup can still work. It appears you do.

During most -PDO cycle ninos we still get a lot of -PNA, but with a block its supposed to overcome it. A -PDO can actually be awesome with blocking if the systems slide east under the block instead of getting stuck out west with a SER linking to the block.

It was kind of doing the same thing the last few runs too. The thing is, as it was coming in, even before that feature, I was noticing its simply warmer. I was toggling between different features. Better high, more confluence, low in the same location...then I would look at the different thermals and it was simply warmer than the GFS and GGEM. Yes that trough doesn't help but there is a hint at that same feature on the GFS also, the difference might just be the GFS is a few degrees colder heading in and so we barely survive it.

But that's like 80% of this sub lol

EPS 6z v 12z. mostly its tightening up the edges and pinning down where that band will be. Unfortunately 95 is right on the edge and might end up on the wrong side.

I don’t know how to categorize it. There is no primary really. It’s nearly identical to the gfs. Better high heading in. More confluence. Same exact slp track. 1-2 mb deeper as it passes us. There is a bit more of that inverted feature. That seems to jump the thermals quick right over us. But maybe in the end it’s just a few degrees warmer and that makes a huge difference here.

Not to be a deb but honeslty the Kuchera map is closer to what I expect based on the thermals. The 10-1 is messed up and counting snow when there are some pretty dubious thermals.

looking at the thermals I don't see how that is correct. There are warm layers everywhere during the whole event. I would be shocked IF the euro is right if anyone east of the BR got more than an inch or two at most. It's not all that dissimilar from the GGEM just warmer. One reason its warmer is the coastal is way less of a defined feature initially until it gets to our latitude. It's more just a wave along an inverted trough with a southerly flow up into our area at the mid levels.

That trend continues at 72, high is MUCH better located on the Euro than the GFS, however that might be offset by more ridging in front of the wave.

Euro has slightly better confluence and High location than GFS at the same time at 63 hours...but the SW is weaker and further north. Not sure which is more important at this point.

NAM had that solution. Ya I know the NAM lol. I think it's likely going to be something from A or B, or maybe a compromise between the two. But C is lurking if there is any additional de amplification trend in the STJ wave.

The models are not "trending" or bouncing around so much as the operationals are simply randomly popping out solutions that fall within the still existing camps if you examine their ensembles. One solution has now been completely eliminated and that was the phased amplified system with a primary into the Ohio valley. That idea is pretty much dead. But within the ensembles there are still 3 camps left. We want the middle ground. But it's well within probabilities for 2 or 3 operational models to pull a solution from the same camp (like last night) but its just random chance. The 3 camps still left A. A little too much amplitude and lingering primary and the main snow shield goes just NW of us. This is a messy one with not a lot of snow for anyone because the primary is weak, the phased amplified solution is gone. But this would take a lighter snow event up into PA. B. The in between option, GFS and GGEM op solutions from 0z and 12z. No primary at all, coastal is just amplified enough to produce a thump snow targeting just NW of the fall line C. A weak sheared out mess with no significant snow anywhere. This solution might target DC south with the best qpf but it won't work with the marginal temps. The 6z EPS took a move towards Camp B but there was still a mix of all 3. GEFS is still a mix of all 3. GEPS is all option A and B. I don't think the models have trended yet, they seem to still just be pulling random options from within these established goalposts run to run.

There was a SHARP cutoff with a storm Dec 5 2003. There was a WAA wave that came out first and thumped NW of 95, the costal developed a day later and mostly missed us and hit New England. But the WAA lead wave had some local similarities to this. I remember I got 7" in western Fairfax county and inside the beltway was pretty much all rain.

That is awesome. This is a pretty good took that has the whole country if you want to waste a lot of time. https://en-us.topographic-map.com/map-hqf3/Baltimore/?center=39.43478%2C-77.33712&zoom=9