wxsniss

Yeah was thinking last night we should have been more tipped off by the realtime obs of an overproducer in KY/WV. I'm faulting myself for not weighing that more and being too misled by HRRR/RAP trends. The ML fronto 3-8am was really the main story of the event and saved the higher-end forecasts. Conveyor mechanics were definitely not the best. We saw a little 850 easterly advection in the second half after 12z give a bit of regeneration to radar returns, but it wasn't anywhere like our more organized storms. So, taking out the ML fronto band (boosted with higher SLRs), I think the convective interference did significantly diminish the overall storm outcome. All hobbyist thoughts... you and Coastal and others are great teachers.

Ha I actually was looking through charts of that event last night when Hoth was trying to remember the date of a similar event with runaway convective processes. Yeah (also in response to @40/70 Benchmark) this was not an easy forecast at all, and I definitely was nervous of a Messenger shuffle as guidance started favoring the easternmost low last evening that we had previously minimized as convection-driven. I was steady all week with 3-6/4-8 across eastern SNE that I mostly attributed to advection from a deepening surface low, but those thoughts did not reflect the bigger story of the event which ended being that nearly stationary fronto band overnight.

Lol I too saw that in the PNS. Trigger warning for weenies in our area.

Agree Our area usually gets shafted by an early and/or Winthrop sewage plant measurement that gets propagated in media. But Boston actually got a representative measurement this time. I just put the map up for a synoptic visual.

Yeah brutal for the NW crew... I think reflects how much of this event was carried by that one mesoscale feature 3-8am.

KBOS final 11.7" per NWS twitter Great storm to placate a lot of early seasonal frustrations. As always, a great place to learn from the mets here. The map below I think predominantly reflects (1) 700mb frontogenic band in response to vigorous shortwave and great SLRs, overlayed in 2nd half with (2) deepening of the farther-east-than-could've-been surface low with ensuing advection through 850-700 mb layer

Per Box twitter: As of 1 PM, here are how our climate sites stand in terms of snowfall from the season's first major winter storm: #Boston - 11.2 inches #Worcester - 6.2 inches #Providence - 5.9 inches #Hartford - 5.4 inches

Box in case this wasn't posted earlier: Well, the snowfall has over performed, especially in the mesoscale snow band that developed early this morning. It appears the liquid precipitation aspect of the forecast was quite accurate, however excellent dendritic growth conditions setup in that band, leading to SLRs of greater than 20:1. That greatly exceeded our expectation of SLRs in the 12-14:1 range and are pretty rare around these parts. That fluffy snow is a whole lot easier to clear, that is for sure.

You and others nailed the fronto signals. We were also posting soundings with great crosshair / snowgrowth potential. But the dual low issue and definite (and ultimately correct) trends to emphasize the easternmost surface low, along with the new downtrends on RAP/HRRR, were not easy to ignore. I think only after we were seeing the strong radar returns off NJ entering LI that I posted ~10pm was there some evidence the s/w was enough to overcome the further east surface low. Some cool anatomy of that band from 6z NAM 5-7am:

Interim measurement ~10am near Brookline Village, still getting moderate so anticipate we end up 10-12

Yeah it was a tricky storm to forecast. The Euro/RGEM/NAM also slipped down yesterday evening as emphasis on the easternmost low increased, giving some credence to the HRRR/RAP downtrends. The big driver of 6+ amounts despite the dominance of the easternmost low was that nearly stationary 700 mb frontogenic band overnight, and while there was evidence for it (CoastalWx's posts yesterday), no guidance had it stationary for so many hours with significant minima north and south. Had this system consolidated a surface low closer to the vorticity emerging from Virginia, with better conveyor mechanics, totals would have been more uniform and higher across the board.

Nothing better than enjoying this winter wonderland with my one year old... sheer magic. Boston metro area (and immediate suburbs including Brookline) probably ends up 10-14" Kudos to all the mets and vets (including myself) who recognized that the quorum of OTS / whiff guidance was discordant with synoptics. And yes, Tip has a knack for starting long-range threads that materialize as big events.

Heaviest rates I’ve seen since that 1-3am Dec 17 2020 WAA band I don’t recall a 700 frontogenesis process sustained over so many hours over Boston like this

Hope you can see this Jerry! Heavy snow in this band, gotta be at least 1”/hr

Was about to ask… you’re right under that great early band you had forecasted, stretching all the way to North Haven. Mesos look great for your area, 6-10 seems in reach. Moderate here, everything whitened in less than an hour

6z NAM back to widespread 6-10 eastern SNE! Continues theme of dominant eastern low that itself positions more west No wonder ensembles had so much spread depicting this surface low position.

First flakes in Brookline MA Nice band setting up Hartford to South shore

east SLP appears to be taking over on schedule:

Would not be bad considering people were talking whiff early in the week. Reaches maturity off Nova Scotia. One aspect that could still surprise is duration in eastern SNE depending on how the west->east transfer unfolds.

0z vs. 18z/12z Euro continues theme of slightly faster west -> east low transfer while being a bit more robust for eastern SNE

Good to have you back, Will Yeah 4z RAP and HRRR runs stopped the bleeding, and associated with later west --> east SLP handoff. I posted the robust radar returns off NJ above. I think that's a sign of earlier/better west SLP development, but hard to say it's kind of in between the 2 low centers. In any case, it's appearing 1-2 hours earlier than progged.

Next 3 hours are pivotal resolving this 2-headed coastal 0z 12k/3k NAM actually does not have the west head In next 2-3 hours, HRRR has west head decay, east head dominates and drives the rest of the show

4z RAP stopped the bleeding This stuff off NJ coast is ~1-2 hours earlier than shown on NAM... any earlier or more robust western low development helps us...