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Everything posted by OceanStWx
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1/9-1/10 Now Morphing to Less-Than-Exciting Power Cutter
OceanStWx replied to Torch Tiger's topic in New England
We can always catch the next cutter. -
1/9-1/10 Now Morphing to Less-Than-Exciting Power Cutter
OceanStWx replied to Torch Tiger's topic in New England
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. -
1/9-1/10 Now Morphing to Less-Than-Exciting Power Cutter
OceanStWx replied to Torch Tiger's topic in New England
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. -
1/9-1/10 Now Morphing to Less-Than-Exciting Power Cutter
OceanStWx replied to Torch Tiger's topic in New England
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. -
1/9-1/10 Now Morphing to Less-Than-Exciting Power Cutter
OceanStWx replied to Torch Tiger's topic in New England
Well a dog fart in Moosup can knock the power out in CT. -
All dug out from 16.9" on 1.60" liquid.
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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.
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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.
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Toaster bath for the chickens?
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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.
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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.
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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.
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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.
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It's important to look at these panels like Ginxy has here. The ensemble means may look nice, but don't tell the whole story. Like for Mount Tolland for instance, the EPS mean is about 5.5 inches. But the 25th/75th range is 1.5 to 8.5 inches. So some bigger members are dragging the mean up, while the floor still remains quite low. When you can start setting the floor higher, that's when you can start honking for a storm.