wxsniss

Thanks Will That's actually more consolidated than some of the earlier runs that had a separate vorticity lobe further out (like the on the Meh vs. Good GFS comparison I posted last night) As for the upstream indicators of Meh vs. Good...? It seems on the Meh runs, the energy out of the N Gulf emerges further south and shoots more east after it exits Carolinas, whereas on the good runs it tracks more north and curls into the shortwave on the Good runs. This is around 6z Saturday. And further upstream? Hard to identify a consistent difference. Box AFD was commenting that the N Gulf energy was slightly faster than 0z guidance initialized so they preferred Meh, but that was before all the 6z guidance.

Where do people get 6z/18z Euro H5 vorticity? Can’t find it on weathermodels.com I like the 12k/3k 6z NAM. Somewhat more ramped up than 0z/6z Euro, not as coked up as RGEM. I’m surprised there are no watches. Even the worst guidance brings warning SEMA. There’s a good kink in the flow... too much weight on seasonal progressive shred.

For sure, just putting up the verbatim qpf for easiest run to run comparisons This is a good system for deformation banding, maybe roughly northeast MA to between Worcester and 495, obviously will depend on where this tracks I'm still puzzling over the 18z jump, can't be coincidence. And not characteristic of Euro to make such a big jump. I would've expected the progression of Euro solutions to be more like 12z --> 0z --> 18z Still think we end up warning+ most of eastern SNE

Where are you guys accessing 18z Euro H5 / vorticity plots? Weathermodels.com only has surface plots and upper level temps. I don't think so many models jumping at 18z was coincidence, but I haven't traced back what the exact cause might be... I think the shortwaves are ~ over Rockies and Texas at the moment. The solution is very sensitive to handling of multiple pieces of vorticity. Comparisons clipped from GFS... the far southeast vorticity was creating a diffuse / dual low structure on earlier runs:

0z looks more like 12z run rather than a toned down 18z Still a decent hit, verbatim qpf roughly: 3-6 Worcester east 6-12 South Shore to canal ~ 12 most of Cape Cod

I know, I was being sarcastic lol Only consistent outlier is NAM and we have a reasonable explanation for it. If 0z Euro holds serve (and I'd be shocked if it did not given other 0z guidance), I think we are locked and loaded. Don't see this tracking much further northwest (though never say never), and even a correction back southeast tomorrow keeps a big chunk of SNE warning +

That's a misquote... he said it'll stall for 30" 18z Euro verbatim has 2"/hr rates for 4 hours in Plymouth area, 1"/hr rates for 6 hours much of eastern SNE... 0z UK, HRPDS, GFS in same ballpark

Love it

Euro, ENS, GFS, GEFS... that's some legit weight RGEM has been awful unstable this year NAM has had its scores this year, but I think it's now having issues chasing all the little pieces of vorticity And most of all, synoptically a more amped solution (vs. earlier runs) actually makes sense.

Yeah, just too reaffirm that we are being objective... Even before the 18z bonanza, I commented that the GFS was actually realistic and we should not dismiss it reflexively What a prolific pattern this is becoming

Exactly, was mentioning this earlier as a reason for multiple 18z models suddenly collapsing on a big event... Earlier runs for the past day had diffuse / dual low structure chasing pieces of vorticity further east There must have been some new sampling of the vorticity (currently pieces over the Rockies and Texas) or something to make all the solutions jump like that

18z Euro: 6-10 northeast MA to Worcester southeast to Boston 10-20 Boston southeast and all of Cape 20+ jackpot canal area Not just a shift NW, a much more amped system with (finally!) a real CCB impacting SNE

Now briefly closes off H5 at 0z Sunday... and I could see that happening earlier... seriously this may not be done trending What I remarked about 12z EPS/Euro being the only remaining reason to tap the brakes... gone

No joke, Jimmy's map ftw My only surprise with this 18z Euro run is how big a jump it made... Euro generally has more inertia, begrudgingly follows the lesser models

And there it goes, as anticipated... pretty much entire 18z suite except for 12kNAM jumped NW Some new data ingested made everything jump

Funny 18z suite... 3k NAM > 12k NAM RGEM >> HRPDS GFS!!! ICON!!! There's clearly something that made multiple models jump at 18z... I think it at least has something to do with the handling of vorticity I mentioned earlier, and whether we get a diffuse / dual low structure vs. a tighter consolidated closer low. One reason to tap the brakes is EPS / Euro is pretty consistent. But wouldn't be surprised to see that jump by 0z tonight too, or at least the Euro's version of smaller shuffles.

18z RGEM did run... it's a monster hit for Mar 2. It's basically Jimmy's forecast map.

Funny thing (I'm just quickly scrolling through this thread and catching up)... 18z RGEM supports Jimmy's map.

Took a quick look... 18z GFS is not unrealistic. 12z and earlier runs of GFS emphasized a piece of vorticity way OTS so we get a dual low system in the Sat 12z-18z timeframe... 18z emphasizes vorticity closer to coast, so we get a more consolidated single system near benchmark 0z to 12z Euro hints at same struggle in another way: 0z has a consolidated low further out, 12z briefly has a dual low structure that would be much more impactful if everything consolidates around the benchmark low sooner. So I wouldn't toss 18z GFS reflexively... and I would not be surprised to see Euro ramp up due to a synoptically more consolidated and tighter low. Sort of like the 18z RGEM Too bad flow doesn't buckle until later in week, this (and the system after it too, and pretty much any strong shortwave coming through) would have had big dog potential

I and probably eveyone was too exhausted to do a post-analysis... thought I'd toss up some tired and probably incomplete impressions. I went back through model runs in the 48 hour leadup and compared to the obs map above. Thought this was a clear NAM winner. Feel like it's had a good season. Very clear banding signatures that happened. Euro was good too. The old EE rule and ignoring all the other model noise would have given us the best handle of this particular storm. Most guidance wanted to jackpot southeast MA, but between mid-level processes generating bands further northwest and initial boundary layer issues southeast, jackpot ended up in the 495 corridor and extended further north than most expected. RGEM was spastic and more wrong than right. GFS was a national embarrassment, pretty much ignorable. Ok with SLP track, but qpf depictions and thermals were a joke.

Per usual, an anomaly compared to every surrounding site. I'd expect most sites in the immediate metro area (Chelsea, Revere, Hyde Park, South Boston) near 15" after that 5-7pm band. Some other nearby reports: Somerville 19.9 733 PM 3/13 Social Media Revere 15.0 632 PM 3/13

Just returned from a weenie walk around Coolidge Corner... AWT that band did not disappoint! Beautiful out there! Judging from rate of accumulation of freshly plowed pavement, that band reached rates 2" / hr. Amazingly fluffy snow, and notable lack of strong winds. I think we and Boston metro area end up 15-18" when all is said and done.

Nice from Box... this is a healthy and slow band, 1-2" / hr incoming for Boston metro folks... this should get everyone into the 15-20" range:

Finally for Fella / SR Airglo / SBosWx and others in Boston metro... it's been like watching paint dry for improvement in flake size for past hour but we are finally tasting the edge of the meat... she's fading but there are solid 30+ dbz returns... at the rate it's moving, this looks healthy for next 1-1.5 hours at least H7 fronto:

And quickly. You can see how quickly roads get covered after they get plowed. Helps that we cooled to upper 20s too.