eduggs

The 12z NAM is west of the 6z GFS and a few mb deeper. H7 does not look great on either of those runs if you want a significant snowstorm.

Not a big surprise the NAM shifted towards model consensus. Subtle changes aloft make big differences at the surface.

Guidance has been really consistent for days now targeting EMA. We haven't really had big swings with one run wrapping up into NH and then another skirting coastal NJ. I like that consistency.

Interesting that the RGEM has flattened the trof for several runs now... slightly lowering the amplitude but with similar tilt progression and evolution. The vortmax was modeled in SVA, then NVA, then central MD. Higher amplitude is often better for stronger, tucked solutions, but in this case that puts the resulting SLP closer to our latitude. I'm still suspicious of the really close tuck on the RGEM, but the consistency is great to see. It's too bad all the precipitation is north and northeast of the SLP. The mid-level lows are still immature at our latitudes.

You suck at reading comprehension

The CMC is west of 12z, but not so much west of 18z. And if the upper levels on the CMC match the RGEM (can't view them yet), they may actually be less sharp than 18z. Nice run but unlikely to be indicative of a significant trend IMO.

That would be pretty solid if it didn't include tomorrow's rain/ice. I'm seeing more like .2 - .3 for early Friday.

The RGEM is the best looking of 0z. It looked pretty solid. But at H5 it was actually surprisingly a touch flatter than 18z. I don't completely trust the tucked look with the flatter H5, especially considering the rest of 0z. Regardless, it was a comforting run.

I'd call this pretty decent model consensus and also pretty decent run to run consistency. I wonder if that means we won't see huge short term changes.

That's a great looking run from the RGEM. With >12:1 ratios, arguably warning snows for all of SNE, plowable back to the west into NY, NJ, PA and also well up into NNE. Significant snows are still very possible, particularly for eastern SNE. One negative, however, is that this run actually looks a little less sharp aloft than 18z. I don't like the trend of flattening the trof, but I suppose it could also be indicative of the possibility that a tucked solution is possible without a strongly tilted trof. I trust the RGEM with tucked SLP positions a little less than the EC or GFS.

I like the RGEM a lot. Definitely in the top 3 at 48 hours. The ICON is useful for trends. I wish they would release a hi-res version of the ICON like they have in Europe.

Sneaky inch tomorrow morning somewhere in WMA or NH?

The ICON is a touch flatter and therefore weaker/SE at the surface compared to last run. But 18z was pretty solid. Still a widespread plowable event and close enough to trend better.

Agreed except we can't do an outlier test with so few data points. OK maybe you could with the HRRR. But the other models aren't run frequently enough. It's risky to disregard outliers when they very often end up being the most accurate runs of a suite.

On a microscale, no. We still can't pinpoint precipitation boundaries at the scale of individual towns and cities 3 days out. That's why I think it's best to take everything into account. Based on GFS and CMC trends several days ago, some thought good snows would get to PHL and NYC. The NAM was stubborn and resisted the trend. In the end, a blended compromise would have been right. It doesn't always work that way, but it's still almost certainly best to weigh all model outcomes at least a little.

I think it's significant that the NAM has decreased the sharpness and amplitude of the 500mb trof for several successive runs today. That's doesn't mean I can predict the future or change your mind if you disagree. It's just an opinion.

EPS didn't do so great for the Mid-Atlantic snowstorm from 48 hours out. It was 40 miles too far NW with accumulating snow. The NAM correctly kept the meaningful precipitation further south. All of the major models lead the pack for some events and on some runs.

From a forecasting perspective, discarding individual models runs - without obvious cause - will lead to forecast bias. From a hobbyist perspective, it will lead to false expectations and disappointment. We've seen it a million times. If it's an outlier run, is it unreliable or the first to sniff out a trend? Without knowing the final outcome we cannot know which model runs to consider or discard. That's why it's best to consider all the major model outcomes as plausible and deal in probabilities, not absolutes.

The surface isn't the problem. Weather isn't generated at the surface. Ls and Hs don't do anything - they have no causal effect. They form and evolve in response to what happens in the upper levels.

So now there's a bit of a discernable trend with the NAM. Wonder if the rest of 0z will confirm or deny.

It's definitely relevant. You can't just discard major model runs. Every "bad" run makes a "good" outcome a little less likely. But that doesn't mean it can't come storming back tomorrow... just that it's slightly less likely.

They had a massive push of GOM moisture out ahead of a robust and sharpening southern stream wave. The Thursday night event will not have that. We'll have to do more with less. Ratios should be much better, but we shouldn't be expecting .3" liquid hourly QPF totals this go around.

Some people are thinking whiff or bomb, but a light, plowable event is another plausible option. The initial mid-level fronto could setup fairly far NW and slide through most of the NE even if the the trof never sharpens up and the coastal misses mostly offshore.

1. Smaller events are usually shorter events and that means you might not be able to enjoy them due to work or sleep. 2. In places that don't get snow events very often, there can be a feeling like you have to cash in on every chance that you get because you can't count or another to look forward to.

That actually sounds like a pretty good handle. No discernable trend - take the average. It's not really possible for them to show exactly the same surface weather 3 days out.