wxsniss

upstream returns looking really healthy for eastern MA 1-5 am should deliver some good stuff:

0z HREF looks great for most:

Mesoscale Discussion 1856 NWS Storm Prediction Center Norman OK 0912 PM CST Wed Dec 16 2020 Areas affected...Extreme northeastern PA...parts of southern/eastern NY...northern CT...western and northern MA...southern NH/VT Concerning...Heavy snow Valid 170312Z - 170915Z SUMMARY...The primary band of persistent heavy snow will orient from southern/east central NY across northwestern MA to southern VT/NH through the early morning hours, with 2-3 inch per hour rates expected through 09-12z. DISCUSSION...A 1002 mb surface cyclone along the MD coast will continue northeastward through early Thursday morning, just off the southern New England coast. Very strong low-midlevel warm advection has contributed to heavy snowfall the past several hours across parts of PA/NY into southern New England. A warm nose in the 850-700 mb layer (temperatures near or just above 0 C), and ocean influences near the coast have resulted in mixed precipitation spreading northward across NJ and Long Island, and this trend will continue into coastal areas of southern New England overnight. Additionally, the midlevel dry slot has reduced saturation in the dendritic growth zone (generally 600-500 mb layer) from south to north, which has reduced snowfall intensity and also contributed to mixed precipitation types. Northwest of the dry slot, the longer-duration heavy snow is expected, with some banding structures and embedded convection in association with weak static stability and focused frontogenesis in the midlevels. Here, ascent will be maximized in the dendritic growth zone for several hours and temperature profiles will remain well below 0 C, which will support snowfall rates of 2-3 inches per hour through about sunrise.

First flakes Brookline!

Yeah this will actually take a bit of strategy lol... For our area, I'm thinking best rates from WCB portion will be 1-5am... also will be fun to nowcast the CF flirting with the Boston metro for several hours, should see some enhancement north of that

2am-7am will be a blast for much of SNE...

Upstream obs... Philly area was getting 40-50+ dBZ, heavy snow WAA thump will rock tonight... might take some creative sleep strategies to be up for the best of it

6z HRRR steady as she goes, slightly more robust than 0z HRRR... 6z NAM same Widespread 10-16" most of SNE, spots higher CF gets to just barely past Boston

Better for much of SNE More uniform... maybe better warm conveyor belt into MA, less robbing from that convective blob, and as a result more uniform spread between the WAA and midlevel banding

The issue we were talking about yesterday... that next-in-line shortwave digging more is interfering and de-amplifying our trough You can see it's less an issue on the 12z NAM

Yep... while ptype and dryslot issues starting to creep into southeast MA Great banding signature to MA/NH border Ukie and NAM now more alike than Euro

Yeah this is not done trending... 6z NAM looks even more amped and further NW than 0z

Yeah you might guess the shortwave got shredded on approach if you just looked at the QPF maps, but it's definitely better than 12z

This is a much better solution than 12z for SNE than the QPF maps would suggest

H5 closed already at hr 54... this is a big jump NW

Thru 48 already looking better Better looking shortwave Downstream ridging is better Better spacing from upstream shortwave This will be tucked more NW

Thru 36h better digging trough and downstream ridging Watching the following energy over Saskatchewan... it's digging a little more than 18z, may not make any difference but we want that to remain flat and inconsequential... that's the piece that muffed a better SNE hit on today's12z Euro

Huge hit well into NH and VT

Crazy weekend at work but lurking... 0z NAM way further west and the H5 changes were apparent as early as 24 hours... significantly more amped than 18z NAM and Euro Whether this represents new sampling off Pacific vs. NAM in laughable range remains TBD... maybe only takehome point is further lack of support for GFS

Yeah I see it now, thanks all, it really was that simple. The changeover had transiently good lift through the DGZ, I guess enough to cool soundings to keep it snow thereafter. But lift dropped and stayed low while we were supposed to be rocking in a comma head. These are from 12z 3k NAM, before (21z), ~during (00z, I know in reality changeover was around 21z), and after (02z):

Thanks man! Great disco here between you, Will, Tip, OceanStWx, and others... One question that's been bugging me because I'm sure the answer is simple: All the red flags granted --- lift way lower than DGZ, DGZ so high up that there's a longer 32F path of descent and the "snow" is more ready to melt, lack of drier dewpoints, garbage airmass --- but none of these were an issue during the changeover. I made a timelapse (I can't figure out how to upload) showing we went from rain bare ground to white coating on most surfaces in < 5 min! And people everywhere metrowest down to northeast CT were reporting the same. At 4pm, extrapolating that for the next 4+ hours, even if intermittent, it looked like much of eSNE would easily reach the NWS totals as the bands pivoted. Anyone know why was that 30 min period during the changeover able to overcome all the red flags, in contrast to the subsequent 4+ hours?

Boy, 7 months old Thanks for the nice words, Jerry. Yes, it's more exhausting and more magical than I had ever imagined. I've already had my first instance of getting all ready at 12:50am to geek out over another most important Euro run of our lives, only to be drawn away because he wakes up crying. Maybe he didn't like the solution October snow was his first!

Thank you for that. That is so refreshing. Only the best here, including you, Walt, and some others, are confident enough to admit when they were wrong and understand why. Attributing incorrect forecasts to weenie maps across the board is a tiresome narrative. Career NWS mets, actually putting up concrete maps, and to an audience of hundreds of thousands, got this and other storms wrong, and it's not because they were rip-reading weatherbell maps. There were plenty of red flags that we can point to in hindisight. As always, a confluence explains the bust. Last night we actually mentioned that the best omega was well below the DGZ in eastern SNE throughout most of the event --- but maybe we dismissed that as generating poor but not inadequate snowgrowth. We've certainly overcome that in other storms. A stinger never really materialized. We've certainly had past storms overcome marginal airmasses with good dynamics, and maybe this just did not pack enough punch. Not a single person here would have said Northborough would end up with 1.5". Even Lunenberg managed only 6.5" lol.

Thanks Jerry I’ll find out soon enough if love of weather is inherited or learned