wxsniss

KBOS 15z-21z looks even better, temps down to -12 or so in 900-850, saturated, with good easterly fetch off ocean in the 900-850 level, and hopefully (I guess depending on where IVT convergence sets up?) we get some lift. Not the surest mechanics for snowfall but this isn't the season to be picky. The bulk of our accumulation would come before dawn.

Agree, posted the same. Looks like things get more showery and snowgrowth worsens after about 12z Mon. Some of the accumulation depicted thereafter comes from more showery activity with poor snowgrowth unless lower level lift can produce something, so the 6+" spots in the 4-8" range will be rare I think. As currently depicted...

Soundings still on the dry side in the DGZ 15z-18z during the IVT stuff

Not just more juiced... the surface low tucks in closer and a little later... verbatim that would be 4-8" for a good chunk of SNE

BIG hit on the NAM And it's doing what you might anticipate from H5... the best vorticity is further back west rounding the trough, not the crap exiting the coast before, so the low tucks a little closer and later

Why this has no semblance to the firehouse analog. There is no prolonged easterly fetch at any level. Also, the mechanics, whether overrunning / CCB / IVT event are not solid and long-lasting... the mesos look more spotty and showery but the hope is it will add up.

Paltry but trend is definite... if it holds, another cave by Euro towards others Unfortunately we have a pretty low ceiling: the flow is too progressive and there is no space or time to amplify. But that low ceiling might still be Boston's biggest single snowfall of the winter season. In contrast to NAM, I'm favoring eastern SNE given both the weak CCB and maybe prolonged IVT as storm departs.

Maybe I'm seeing this wrong, but this doesn't strike me as a firehouse analog... easterly fetch at all levels looks pretty fleeting, and the event is prolonged by some IVT convergence in its wake

Also key: Southeast ridge has been improving steadily... as a result this system develops more northeast than east, and the Norlun vs. departing Miller B blend of impacts that Tip described shifts more to the latter Unfortunately not much room or time to amplify once it exits NJ, but with current guidance I could see this reaching 4-6” in parts of SNE if ridge continues as is and shortwave holds until it reaches us... Of course we are threading the needle and don’t want that shortwave too strong over IN/OH

The squalls have stolen the show this season... A busy Beacon St intersection whitened in minutes:

Horrible. And I hate the relative weather boredom too. We waited all year for this? Outside of November, the squall was the best 10 minutes of the season. I’ve waivered on rooting for futility... Maybe the Super Bowl sets the season tenor (like 2015) with shutout for 3 quarters and then late TD to redeem the SNE season.

Yep... I was riding NAM hard the entire time and posted just that... but even it had 6”+ in northwestern MA on several runs More like the RGEM was not so off with aggressive warmth

KBOS has not cracked 5” total on the season, ridiculous Less snowfall than I expected in northern MA ... No official site in MA reached 6” in this storm

Is it really so rare? I vaguely / anecdotally remember SWFE's with extremely heavy opening thump and excellent snowgrowth before changeover. And how is this impacted by the level/shape of the warm advection in mid-levels that determines where the best lift is...

Yeah roughly eye-balling HRRR soundings we were under 10 ub/s most of the event, brief maxima at 15 and that was well under the growth zone. Not screaming big thump. Never really got excited about this event (as evidenced by 0 post count in lead up). I took this more as a quick exercise to refine forecasting of onset / changeover / total accum. An attempt to make lemon juice out of this lemon of a winter. I expected 3-6" in Boston area based on a NAM/Euro blend, but I'm not sure KBOS even scraped its way to 3". Logan reported 2.2" at 6:49pm. I was counting on more intense rates based on some guidance in the 22z-0z timeframe just before the changeover, but that didn't materialize. You guys and others had all the caution flags going, and just about everyone in here was tempered. Gotta love the TWC map (? Storm Maya), last night it had something like 5-8"/8-12" for most of SNE/CNE.

Agree I think 2 other variables that meh-ed this event, even with H75 advance and timing of sleet changeover as it was: 1) the poor snow growth: it was baking soda just about the entire event... the lift was always significantly displaced from the DGZ... decent dendrites for the past 6 hours and we'd have a different tune in here 2) the initial thump was actually kind of meager: guidance last night was hinting at a more robust thump, ~0.5+ qpf for parts of SNE before a changeover... and then it kind of back off today. It came in like a wall but then was pretty meager the middle 3-4 hours.

Wonder if KBOS season cracks 5" tonight Yep pings arrived in Fenway ~ 6:20pm. NAM was spot on. HRRR was always 30min-1hr behind in sleet advance. Euro was my reason for the higher end of 3-6" range in Boston area, but that too was too cold. RGEM... has been off this season, I didn't give any weight. And most importantly: 18z GFS still has snow/sleet line at MA/CT border at 0z lol

Dualpol line has breached the outer 495 ring and midway to 128, ticking northeast HRRRs have been a touch behind ground obs all afternoon... Boston area flirting with and completing changeover 23z-0z. 3", maybe 4" in spots, should do it. Yeah NAM schooled the other models here. 40 disco + 14+ obs pages of posts... in a more typical winter, this event would have received more like 20 total pages of posts.

...but... but... the most recent GFS had sleet line only to coastal RI/CT at 0z NAM handled this event well. Yeah sleet line is on the move, but looks to have some resistance north of MA/CT border. 23z-1z is critical if Boston area is to reach 5-6"... mesos bring in heaviest rates around 23z and changeover 0z-1z

19z HRRR shows a good fight resisting sleet advance near the CT-MA border 22z-23z Still reaches Boston area between 0z-1z

Best lift is below DGZ... this looks to improve somewhat in the next few hours

Yeah at 20z, 18z HRRR might be a tick slow (?30 min) vs. dualpol But meeting some resistance entering RI, looks like it washed out a bit near WesterlyCT/KingstonRI

Yeah I'm pinning 0z-1z as changeover per good agreement on NAM / HRRR / RGEM. (Obviously ignored the GFS days ago) And that hour could make a difference of 1-2". 18z HRRR sleet line looks maybe 30 min behind dual pol? This winter hasn't given me much excitement to post, but at least pinning down these details can be some fun.

18z HRRR pounds Boston area from 23z-01z... 5-7pm will be fun, one interesting evening commute ahead. And any delay in the sleet changeover 0z-1z could add another 1-2".

Fenway area: Onset ~ 1:30pm, ramped up quickly and sticking to everything. I was calling 3-6" here and Boston metro, riding the NAM, and the HRRR trends make me think closer to 6" is possible. Expecting changeover to sleet between 0z-1z Better snowgrowth soundings look to come in by 21z, will be a fun commute.