wxsniss

An example of what I and others posted earlier... 0z ICON last night showed this as well (but backed off at 12z today). This is from 12z UK, keeps low level easterly flow into 0z-6z Tuesday... this is what we'd need to get us closer to 20": (EDIT: this is 850, 0z Tuesday, from 12z UK run Jan 22):

Without digging deeper for a better example, 0z ICON last night had the closest depiction of this we have a closed low 925-850 just southeast-east with easterly flow well into 0z-6z Tuesday Not totally outlandish either for these lower levels... Higher up 850-700 probably not happening fast enough

Agree, one of the more suspenseful remaining aspects of this imo if we're looking for the more "exotic" "nirvana" solutions of SWFE + CCB to get us to 20" and over I think ICON has had some of the better depictions of this, by virtue of faster infusion of energy and tilting of the trough

Agree Jerry I think 10-16" is a lock for most of SNE... but a few model runs flirting with better coastal development and capture... that would get us to 20" and more 13z Jan 22 NBM output...

Agree, exactly why in the cold vs. qpf debate about what's more important for a snowy winter, I always go with cold, even if it risks cold dry runs. The historic ones are often preceded by an anomalous cold dome... 2-14F, –2-27 Jan 21,22, 2005 3-19F Jan 6, 1996

12z ICON is great, but did back off a bit on the coastal development and capture... you can see at H5 the energy is slower to infuse and tilt the trough compared to the 0z ICON Just something to watch if we're looking for the more "exotic" "nirvana" solutions of SWFE on steroids + CCB to get us above 20"

NESIS 4-5 likely... these geographically massive ones you can see a mile away https://www.ncei.noaa.gov/access/monitoring/rsi/nesis

Very similar to 12z run at H5 and surface Doesn't quite develop and capture coastal like 0z ICON, but still would deliver 10-20" all of SNE assuming better than 10:1

Yeah EC AIFS followed same pattern as GFS... 0z and 12z similar, 18z outlier 0z and 12z better phase, coastal redevelopment, big hit SNE especially east

I like the comparisons, was lucky to experience both In terms of phase interactions, 0z GFS resembles 12z GFS as well as 0z ICON (ie., 18z GFS disconnect was hopefully an anomaly)

12z CMC and UK also had hints of more potent backend vorticity rounding the trough which would improve coastal development Just catching up... been a while since we've been staring at a region-wide foot+ with lots of buffer. Quick look, key variables determining 12"+ vs. 20"+ in SNE include • proficiency of coastal development, and how well it can vertically stack and better develop a comma head • ratios: 12-15:1? • CF enhancement for eastern areas? Thanks @MegaMike for that link earlier... here's an NBM product I haven't seen before, run 13z Jan 21:

0z EPS jumped ~150 north compared to 12z EPS mean QPF now 0.7-1" all of SNE

Agree I've been browsing through NARR there are H5 similarities to Jan 1994 and Feb 2013... it's nice to be in a favorable setup for a change... in the what's-more-important cold vs. qpf debate for optimizing chances, we're rolling with cold for a few weeks and I think we do well

Quick glance and thoughts, sorry if posted earlier: • GFS / AIGFS alone in terms of timing of stream interactions, too little too late for SNE... can't be certain it's wrong, but I favor this having impact on SNE, and potentially very big impact if we can get northern stream interaction sooner rather than a later infusion of trailing energy at exit • some similarities to Feb 15-18 2003 aka PD2 at H5... https://www.meteo.psu.edu/ewall/NARR/2003/us0217.php • interesting that AI-GFS vs. AI-EC very different from each other compared to their strong consensus for Jan 18 event • lost in the trenches of forecasting an upcoming event... this definitely feels like we're turning a corner in SNE compared to last 4 years

Appreciate it Vortex The flaws of KBOS/Logan snow reports (at some point near a water treatment area? jutting out into the ocean?) and poor representation of the downtown area such as Boston Commons are very familiar to this board lol In this specific case, my own measurement of 5.5” in Coolidge Corner area and neighboring PNS reports are validating… even with some margin of error, the city probably has not yet broken 6”: 1 S Brighton 5.5 in 1015 AM 01/19 Public Logan AP 5.3 in 1041 AM 01/19 Official NWS Obs Chelsea 5.2 in 1043 AM 01/19 Trained Spotter Boston 6.5 SW 5.1 in 0700 AM 01/19 COCORAHS West Roxbury 5.0 in 0940 AM 01/19 Trained Spotter Chelsea 4.9 in 0848 AM 01/19 Trained Spotter Boston 3.1 SW 4.7 in 0700 AM 01/19 COCORAHS Logan AP 4.6 in 0703 AM 01/19 Official NWS Obs Chelsea 4.5 in 0800 AM 01/19 Trained Spotter West Roxbury 4.3 in 0815 AM 01/19 Amateur Radio Logan AP 3.4 in 1200 AM 01/19

Quoted the above to help consolidate our tallies and impressions into the same thread for rolling reference... I agree: for Jan 18-19 2026 event, my impression was the AI models crushed legacy physics models in the 2-5 day range... we had multiple legacy models and cycles showing 0 QPF beyond far southeast MA vs. AI models showing with remarkable consistency solutions like those below. Within 24-48h, legacy models including EC/GFS and hi-res models NAM/HRRR etc were helpful to refine details. Can anyone suggest an objective and easily accessible measure of verification if not QPF? Here are CoCoRaHS QPF estimates for 7a-7a, compared to guidance below, all 24h ending 12z 1/19/2026:

Nice little event to help get us off the mat... My neighborhood near Coolidge Corner measured around 5.5". Logan AP 5.3", so still haven't gotten the 6" monkey off our back... almost 4 years since the Jan 2022 blizzard. Just came back sledding with the kids. Feels like winter should! Another relatively windless event producing beautifully rimmed trees.

Good map. Yeah this is a tough forecast. My reasoning: I figured mid level forcing would be best further southeast, so I thought 3-6 more likely further southeast MA maybe into northeast RI. And best stuff there after 7pm when BL temps and ratios are improved. But maybe if the pre stuff early afternoon and better ratios deliver, I could see 3-6 expanded further northwest.

A beer on me whenever I can make it to a gtg… I think you’re misreading, relax man was completely benevolent and earnest. Quick glance at 0z NAMs and RGEM, I see no reason to change my call from earlier: generally 2-4" eastern SN, spots 3-6" on south shore and Cape, 2-3" around Worcester area and less further west and an awesome snowy atmosphere at Foxboro

Relax man, this feels a bit like amplifying a disagreement out of thin air... (a strength of this forum is the enrichment of ENTPs?) Preponderance of legacy physics models Wed-Friday last week had Jan 18 a graze or completely out to sea vs. AI guidance almost invariably had a substantial advisory-warning hit across the southeast and more. The move of legacy models towards the AI guidance at 12z today suggested AI guidance could be correct, obviously with verification TBD. You're reiterating the point I made multiple times: a major weakness of AI guidance is that how a solution is achieved is opaque, and we can't point to a physics-based mechanism for why they are consistent or change. In any case, this field is at least something kind of evolving and cool to distract us from the latest of a series of disappointing winters. I haven't looked at guidance since 12z, but my current take for Sunday: generally 2-4" eastern SN, spots 3-6" on south shore and Cape, 2-3" around Worcester area and less further west Hoping at least for some Foxboro snow mojo of yore...

Also agree with this I think @CoastalWx posted... now that AI guidance has gotten us here, I'd weigh physics / deterministic and hig-res models to take us the rest of the way. Finer (and physics-based) details like rates and BL temps will be critical for eastern SNE accums.

I wouldn't go that far. These are empiric in the sense of being based in historic data and probability. Obviously verification TBD, but through 12z today (with major deterministic models shifting towards AI), I agree with Jerry this is shaping up to be an unambiguous win for AI guidance. I agree a major weakness (see my dedicated thread on the topic) is that reasons for a solution are opaque. We have to reverse engineer how a particular solution is reached. Also mentioned in the dedicated thread, and eager to watch how this unfolds in the next few years: physics-AI hybrids are in development.

0z EC AIFS actually small tick NW compared to 18z, but did not regain the big hit that was 12z... still advisory most of SNE, warning southeast of Plymouth 0z EC also small tick NW... but mostly nuisance low-end advisory outside of Cape

I’ve always wondered why Polymarket doesn’t have weather events

Preferred... for the sake of having a clear answer about the current utility of AI guidance, I want a decisive victor, not gradual ticks towards a compromise.