OceanStWx

Any warm near surface air is expended to melt the snowpack, keeping surface temps colder. This sets up an inversion which makes winds harder to mix down.

More for the higher terrain than Wolfeboro proper, but a 4-7" thump before a flip is not out of the question. The tough part about the watch text is that this is a grouping from Carroll County up through the Maine mountains and AUG. So it's a large area and the formatter just averages the totals out to 8-12". Much of that watch will be more like 4-7" or 5-8".

I was 12.5:1 in the morning, dropped to 10.5:1 by 1 pm, and the final measurement 9:1.

Yeah, that area of NH is a tough call right now. But none of the wind or flooding threats appear high enough for a headline right now, and snow is likely to remain advisory level so it doesn't need a watch either. So HWO is all you get. Bufkit is all over the place for LEB too. GFS 8 inches, NAM 5, HRRR 1.5 (but the HRRR is awfully close to a blue bomb profile).

I don't know if the threat is widespread enough for SPC to take notice, but CSU machine learning does have a little 5% wind tickling CT.

We can always catch the next cutter.

Really good consensus around GYX of 4-5 inches before a flip. I'm a little wary because the snow growth zones is so elevated that we can hang on to 15:1 ratios.

I think this one is going to need convection to help mechanically mix, because I don't see a lot of support for the LLJ alone doing it.

I'm seeing pros and cons. So far the magnitude of LLJ is not as high and not as consistent across the model suite. We have CAD in this event that just wasn't present on 12/18. It's a much more inverted sounding, so mixing will be more difficult. However, this event has more convection modeled that 12/18, and it could be all it takes to mix out the inversion briefly. We've also been discussing the impact of where those 50-60 mph winds occur. Relatively speaking we had fewer outages along the coast, where 50-60 mph happens a few times a year. But from I-95 into the mountains the grid was wrecked, because those kinds of wind speeds are not common.

Well a dog fart in Moosup can knock the power out in CT.

All dug out from 16.9" on 1.60" liquid.

My threshold is below zero at 950. If you have that you'll snow unless it's just mood flakes. So -1 at 925 will usually leave 950 too warm.

It's also so cold aloft that unless you've absolutely scorched the boundary layer on easterly flow, it will snow. I mean 950 mb temps around -3 for the GFS and NAM, it's hard to get rain that far away from the shore break.

The strangest part of the actual image is that it looks like they hit "smooth" with the CWA borders on and blended in a bunch of zeroes because all their neighbors don't have QPF out that far. That's why it goes from 6 inches to nothing so fast as you approach ALY and OKX CWAs.

That's a box roughly north to Juneau, west to the Aleutians, south to SFO, and east to the CA coast.

https://www.nhc.noaa.gov/text/MIAREPRPD.shtml Well there we go. Edit: Now I see that's for Friday, which is probably too late to help with this storm, but will help the 10th.

I mean sometimes we mess around and create storm total grids to see what we have in the forecast as a baseline. But the automated scripts can grab them and send them without someone physically pushing the button. That's why we have a "work" grid we can create at GYX. Those don't go anywhere, and I'm not sharing the image.

Capital H hate going with a deterministic snowfall forecast at this range. We know it's going to change, we've shown we have low skill getting amounts right this far out, and we just don't have a lot of data to build that forecast with. I have to think this accidentally slipped out to the winter page. We aren't even required to have QPF this far out, and WPC doesn't even provide the probability information to produce the rest of the graphics on the winter page.

It's happening more often, but I don't know for sure where to find reliable information on plans.

The sensitivity is highest tonight around CA and NV, so those raobs will be important.

Toaster bath for the chickens?

I don't think so. The NBM is pretty sophisticated, bias correcting a lot of variables at each individual grid point. But it can have limitations when ensemble make big swings or you have dramatic pattern changes. It also struggles with mesoscale features at longer ranges (obviously), but that is what the forecaster is for. Make the right adjustments vs messing around with day 7 sky cover and dewpoints. The problem before the NBM was that each office was starting with whatever they felt like, and for people who live close to the border of two offices you could have wildly different forecasts. It was also pretty poor practice to try and cherry pick the model of the day, nobody is actually any good at that.

It will also be interesting to see how the NWS forecasts go today. Primarily starting with the NBM is producing better and more consistent forecasts, but the data is a cycle old. So the afternoon forecasts today will be using mostly 00z data fed into the NBM. That means chances of snow will be lower with this NBM run because of the inclusion of the paltry GEFS/GFS (and at this time range it is almost entirely GFS/Euro based). Blindly populating with NBM may lead to artificially lower snow forecast if the 00z guidance was indeed a burp.

I meant what I said. When you have your mean sitting higher than the 50th percentile, you're dragging the mean up. We've actually seen in the regional verification that quite often our (the NWS') forecast is closer to the 90th percentile than the 10th of the forecast spread. We almost always forecast too much snow, except for the picnic tables and First Connecticut Lake.

Those are pretty tight ranges for 25/75 too. That would suggest high confidence from the Euro. However, we've seen in the past few years how the ensembles can be underdispersive (i.e. not capturing the true spread of potential outcomes). It's why we tend to see the ensemble mean shift in tandem with the op so often.