wxsniss

12z Euro says still chance of whitening coast, maybe a sloppy few inches 3pm-11pm, temps never really get below freezing

Frustrating morning relative to expectations last night. Heavy rates following changeover stay in northern portion of 495-128. Fwiw, definitive changeover was generally progged for 18z. HRRR/RAP have bands becoming more meridional and pivoting southeast this afternoon, but not sure about intensity.

I'm in Fenway area so can't validate the Corey Hill obs... Heavy white rain Wundermap has had a good handle of line that corresponds well to temps:

Best gameplan imo. Unanimous 0z suite so far (not counting some RAPs and HRRRs) that (1) loop track remains offshore, (2) 925s cool to support snow by ~11a-1p, and (3) we get buzzsawed by the CCB for 6+ hours. Euro will me-too in an hour (18z sort of already did). This is looking much better for us than it did early Monday, with some room to improve even more!

At what point does BOX upgrade the advisories to WSWs... NAM, GFS, RGEM all now reach warning or more in Boston metro

One of the worst handled storms I can remember... major impactful changes within 24 hours on all guidance

That's the 18z run... 0z run was better for eSNE... clear trend to bring that CCB closer

Reggie again also might be snowing by 18z, sooner than depicted, based on 925 temps and up Great trends so far at 0z placing the loop-de-loop just scraping the Cape

Tic

NAM!! keeps hope alive in eastern SNE

It's probably too late and overwhelmed by guidance at this point, but if we're looking potential of a positive bust (at least for eastern SNE), we want the IVT feature to weaken faster and shut off warming midlevel temps... I'm looking at 850 winds here... the less westerly, the weaker the feature: Tues 6z off Euro:

Most relevant portions of 446pm AFD: ...There still remains some uncertainty on exact snow amounts across the lower elevations, including eastern MA and Boston... Still dealing with lots of critical differences in the latest guidance suite. While gaining confidence in some aspects of the forecast, still some lingering questions with the precise details. Among the guidance, we discounted the 12Z NAM, which looked to be a far western outlier with its track. This forecast was based more on the idea of the storm staying just offshore of eastern MA. All the guidance had a little pinwheel effect with the surface low pressure at some point tomorrow into tomorrow night. The critical question is where this happens. The main concern for this will be related to temperatures, which are rather marginal already. A more westward jog to this low pressure will mean armer air and less snow towards the coast. Another complicating factor to the snowfall forecast will be the timing and track of a dry slot in the dendritic growth zone. This looks like it will impact southeast MA and portions of RI. This will limit snowfall simply because the snowflakes themselves will not be as large or well formed.

Ha that's actually not a terrible run for eastern SNE... 925s are like -2C after 15z, that would be something like 36-37˚C heavy snow

High stakes for eastern SNE (among CT and other places with this storm). "non-linear" changes as you put it is so appropriate. It really wouldn't take much for a widespread 8-12" for eastern SNE, but we need that IVT lobe to fade faster. As is, we're now biting nails to see how quickly the main surface low takes over and where it slings up. Trying to figure out things we can pay attention to nowcast... one thing might be 925mb winds over LI pre-dawn Tues... if they have a more easterly component than southeasterly, the bigger scenarios are on the table. If they still have a strong southerly component, not good.

15z Tues actually looks like a big hit once it cools eastern SNE

For eastern areas, actually not bad consensus emerging between 12z GFS / Euro / NAM (more so 3k). RGEM and CMC look on their own with torching the mid levels and looping system inland.

18z Tues that's all snow for much of eastern SNE... 925mb 0C down to maybe Plymouth to Cape

I have so little confidence in any forecast at the moment. The goalposts have drastic changes to forecast. 0z runs NAM-Euro-GFS just 12 hours ago were probably the best solutions in days for your area and a good chunk of eastern SNE... here's hoping we trend back to that later today. 3k NAM and GFS hint that it's still on the table. Not sure what to make of the 6z-Euro-12z RGEM running this so far inland with mostly rain for us. That's a pretty discontinuous jump, but not totally unrealistic.

Reasons to "curb your enthusiasm" are shrinking... You could see since last night that momentum was east, and models just struggled to sort out low consolidation until converging on tonight's consensus among EPS, Euro, CMC, UK. GFS the clear outlier. Verbatim, the B word is warranted.

18z Tues: 925mb winds: Surface:

For eSNE, BEST Euro solution yet!!!! Now a consolidated low by Tues 12z The dual low / disorganized solutions on guidance earlier today were steps in an evolution towards what we're now seeing on CMC / Euro... GFS is the clear outlier

Synoptically and at H5 thru 48h much more like CMC than GFS

Any experience/thoughts on how the potential counterclockwise backing-in would impact snowfall rates? Akin to surge impacted by approach of hurricanes, I'm guessing the west/southwest-ward approach (vs. the more typical northeast-ward approach) might enhance snowfall, but not sure if there's any truth to that.

Agree not sure where the need (?expectation) of precise numbers this far out. Should be perfectly acceptable to put a region-wide alert for potential of heavy snow + winds, stay tuned for detailed TBD. Unnecessarily setting themselves up for criticism.

I’d have more confidence northcentral CT up to ORH than depicted… that area pretty consistently hit