OceanStWx

3 minutes ago, dendrite said:

SW flow aloft yes. It was N-NE flow at the surface. 

But in the knickers days they wouldn’t have really known the difference between a coastal and a strong overrunning event like 1/25 unless someone had access to a barometer and pressure readings in the region. 

Scrawled across the desk journal of Ekster’s great great great great grandfather:

“The snow, mark my words, doth ever arrive sooner than one might reckon, and the sleet likewise.”

11 minutes ago, CoastalWx said:

I think we thought there would a band to the NW. I did. But I think that night I saw the 3K Nam show the western CT stuff and then that firehose into SE MA and RI. That had tremendous front despite lacking big convergence. You also rode the dryslot which steepens lapse rates and aids in that too. I felt pretty good about that area. Actually was hoping it would be more north but it was modeled well.

I admittedly did not participate in the office run up to the storm, but from conversation I can say our post mortem caution flags should’ve been the dry air eating the northern edge versus the pretty simulated reflectivity and QPF maps presented, and falling for the NBM snow ratio trap. That second one shifted the heavy snow at least a row of counties north.

18 minutes ago, dendrite said:

A on pack (mostly semi deep since 12/2)
B on cold (consistent but nothing high end)
C on snow (basically running near avg)
D on intangibles (too much nickle and diming…missing the biggies…little rain is a plus

B-/C+

I'm not usually a pack retention kind of guy, but it's been impressive this season. I've had 6 days since 12/3 with a T or less on the ground. And I've been over 10 inches on the ground since 1/26. 

Chuck in a normal March snowfall and I'll be at the best snow season since 2018-2019.

1 minute ago, 40/70 Benchmark said:

Thanks so much. Where is that fronto option of TT? Having trouble finding it...does it require subscription? 

Nah, it's under the "Lower Dynamics" section of most models (including the Euro!) but the FGEN is the last variable listed. Temp advection comes first so it's easy to miss.

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=temp_adv_fgen_700&runtime=2025112912&fh=84

8 minutes ago, CoastalWx said:

Some of the video I saw from Plymouth is ridiculous. All out blizzard. 

Can't tell whether Cantore had pants on or not because snow was over thy knickers.

6 minutes ago, tunafish said:

That 6.5" for South Portland is a mile up the road.  Must've had about .20" more QPF than me .

4.8"/0.43"

Easy to spot the drift measurements in a storm like this up here.

1 hour ago, tamarack said:

Other than the town of Oxford (western Maine) which had only a trace, our 0.2" is the lowest amount reported to cocorahs, as of 11 this morning.     
(5-6 sites reported precip but left snowfall as NA.  Other sites in those areas all had at least 1" snow and up to 5".  Tops in Maine is 11.3" in Washington County.)

Thank you for your service though, that 0.2" helps to define the edges of our snowfall map. 

7 minutes ago, weatherwiz said:

Very annoyed with myself because that was a glaring signal on all guidance...extremely glaring signal but for some reason I didn't want to buy it and buy into exactly how bad the potential for subsidence would be in the valley. The signals were all right there, laid out right there and just totally overlooked. 

Great stuff on the differences in alignment regarding 850mb fronto and 700mb fronto and what happens when the two become stacked. Moving forward I am going to give stronger attention to this. Anytime there are situations where models are big with the 700mb fronto, I've disregarded what's happening at 850 in terms of fronto. I wonder if this stuff would be covered in my course this week focusing on isentropic analysis. 

The other challenging part when dealing with the potential for subsidence zone(s) is how to portray that on a snowfall forecast map without making the map look stupid (Speaking for myself here). I guess maybe one way to do this is don't go crazy with the ranges and then add some text or an outline indicating where max totals may be. It's much easier to highlight max zone versus min zone I think anyways

Part of me kind of misses the days of broad ranges with highlighted zones for "locally higher amounts"

The problem these days is that you can try and forecast the band from PVD-GHG on this run. But then the next run it's ORH-BOS, so you increase the snow there. But you don't want to drop it from PVD-GHG just in case that was actually right. So the snow amounts are forever only going up until it's too late to recover from the messenger shuffle.

2 hours ago, dendrite said:

Yup…wind failed at TAN. Interesting. Still they had a stretch with frequent gusts over 40 before it crapped out. 1045-1252z…lame. I’d count it.

I wouldn't be surprised if post analysis counts it for Storm Data anyway. Some of it is a bit subjective, but if DAW, PSM, and PWM all hit blizzard up here how could I say coastal York wasn't also a blizzard.

9 hours ago, 40/70 Benchmark said:

This, combined with the 50-75 shift south, is what killed me. This is a lesson that I'll take from this.....that band set up over ORH CO into S NH just like I thought it would, but it just wasn't very impressive. I think jan 2022 was like that , too. Could you provide a graphic to illustrate this?

Thanks in advance. I need to get better at band/fronto diagnostics. I am too weak with that.

In a typical developing (i.e. not peak intensity) storm your frontogenesis is going to be sloped towards the cold air. 850 is farther southeast than 700 mb, and so on. Lift tends to be maximized around 700 mb, hence congrats Dendrite.

This storm bombed out a little farther south, so one of the first things I noticed was the position of the forecast 700 and 850 mb frontogenesis.

While still sloped a bit, it's far more collocated/vertically stacked. That signaled to me that one major band would develop. And that look at 700 mb with a secondary band farther north suggested to me that it wasn't going to be a uniform precip shield. That a subsidence zone was possible between the two. I may have sent a text about toaster baths in the LWM area to @CoastalWx and @CT Rain Sunday.

I made a little gif too, so you can see how the forcing is overlaid.

I do think part of the problem with the secondary band was that it was advecting so much dry air into the storm. @dendrite posted somewhere along the line the map of RH, and 50% across central NH just wasn't going to get it done for that northern extent. It was like a dry wedge in the usually CAD spots. 

One of the weirdest storms I’ve ever worked up here. Huge bust on snow totals - I have nothing on my snow board and snow depth went down a half inch today. I would guess I have around 2”. BUT PWM did verify a blizzard warning. 

4 minutes ago, Greg said:

That's the general sense but what I wrote above is mostly because of inaccurate or lots of snowfall data metrics that are all over the place. In other words, too many cooks in the kitchen using different methods than using a single one. Coops with the settled snowfall is more trustworthy data. As long as the CoCoRaHS match or come in within reason to the Coop data, it is accepted. If it looks way off it is not recorded or data cleaned. Sometimes as people can see some bad/off data gets though on the PNS reports.

The reality is that outside of some real fluffy lake effect type stuff, measuring every 24 vs every 6 hours is only going to move your SLR from 12:1 to 14:1 not 12:1 to 20:1. 

1 minute ago, The 4 Seasons said:

airports, climate sites, i am assuming are clearing every 6? I notice they are usually higher in these big events than surrounding reports that are taking one depth measurement (most of them anyway).

BDR just came in with 20 

I think it's only required if they are paid observers. Either a volunteer near the airport or a FAA contracted observer at the airport.

2 minutes ago, Chrisrotary12 said:

Time to go clean the driveway and dream of ripping 300 yd bombs down the fairway. 

Just now, dendrite said:

I think the only reason it’s 24hr is because they don’t want to force their volunteer observers to take readings more than once per day. 

Correct, last I saw officially you only need once in 24 hr measurement, but can clear up to every 6 hours.

7 minutes ago, The 4 Seasons said:

Is the V5 experimental going to overtake the current version 4.3? I noticed its significantly lower in the snowfall mean than the operational in almost every event. 

At some point this year I would imagine, the evaluation period ended 12/1.

3 minutes ago, 78Blizzard said:

I don't know all the models that go into the NBM, but given the projections from the GFS, Euro, and other standard models which appear to have missed the mark by a substantial amount, perhaps we should start looking at some of these other models, especially for storms like this. 

The NBM includes just about everything. In the extended it's primarily the ensembles members and then starts to bring in meso models in higher weights as you get inside 36 hours.

There is dynamic weighting based on recent model performance (which is great when the pattern is stable, not so great when big changes occur). And some NBM fields are bias corrected on a grid by grid basis.

Overall it's pretty good, but there are blind spots that humans can still improve on.

4 minutes ago, dendrite said:

Too bad the water equiv at the ASOS is useless. Hopefully they augment that by melting the w.e. down.

1 minute ago, The 4 Seasons said:

but we've learned they never do...

Unfortunately ASOS is king, and that liquid is what goes in for the climate. Even if the snow observer reports more (or less). 

3 minutes ago, ORH_wxman said:

As a rule (I had mentioned this before the mega SWFE on 1/25-26), I try not to stray over 13 or 14 to 1 even in cold events that look “decent” in the soundings. That’s basically the cold snow climo in a lot of New England (outside of the upslope zones).

Unless you have overwhelming model consensus on strong crosshair sigs in an event that isn’t super complex or long-duration….that might be the exception. 

You can see from the study that only 1 in 4 obs is greater than 13:1 in SNE, maybe 1 in 10 greater than 20:1.

Even factoring in people who measure once when the storm is done or the next morning with compaction, you're maybe moving the SLR 2 inches, not 5+.

1 minute ago, HoarfrostHubb said:

Yeah the NBM was way overdone in a lot of the region.   

We're still getting used to the forecast process now, and the NBM is good, but it still has some big holes.

One is that it provides us with snow ratios, but it nearly always too high. It is too frequently in the 15-20:1 range. 

As an example for BOX's CWA, if you just had your extended forecast living in the 8-14:1 range you would be a lot less susceptible to these kinds of NBM busts.

Just now, acoolerclimate said:

Who is Will and can I get the data from him? 

@ORH_wxman

Honestly he may have even done the work 20 years ago. 

4 minutes ago, DomNH said:

Not staffed 24/7 so probably missed a couple measurements. 

They are just like a coop, once daily measurement in the morning. But they will report to us on the 6 hours when they are in the office.

4 minutes ago, Chrisrotary12 said:

 

Are you really going to F’ng kick me while I’m down? Have some respect. Lol. 
 

I got that from GYX report. 

1 minute ago, DomNH said:

Could be wrong but I think that came from the CWSU at the Boston ARTCC. I absolutely believe that 33'' total.

2 NNW is Pennichuck water. Their data is pretty meh overall, they do us a free service but there are occasional mistakes and they like their "round" numbers x.0 and x.5.

The Hudson coop had 28.6" and is a former met, so pretty reliable obs there.

2 minutes ago, RCola said:

The echos look lighter but it’s just as strong as it has been. I think we push 38”.

This is a full corpse rotting in this band. Never in my years studying weather have I seen a mesoband this persistent outside lake effect or ocean effect snow.

It won't necessarily get weaker, but you will see the band contract in size as the warm advection moves north and it becomes more driven purely by deformation. 

20 minutes ago, acoolerclimate said:

Thanks. Depressing, but thanks. Weird they wouldn't just put that data into the Local Climatological Data. 

Once a certain amount of time passes it is no longer a local WFO thing. Only NCEI can change it, so IIRC when Will pieced together the missing records it was too late for BOX to change things. And NCEI is notoriously unwilling to change data (with good reason, don't need ulterior motives driving data changes).