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Central PA Winter 23/24


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14 minutes ago, Bubbler86 said:

Not going to extrapolate too much and I think the GFS had more than one lowest point of pressure for quite some time leading up to the storm on the 12th (on the 12Z run) but the 18Z Nam low position is pretty far north at 84.   It did slow down a bit from its 12Z run though. 

Slowing is the key imho as I posted last night. Plenty of time to go either way, but day 4.5 most assuredly will  not accurately represent the final outcome. 

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17 minutes ago, Mount Joy Snowman said:

I have a few takeaways from this.  Firstly, is that the Euro is still the top model, and not simply because it has the highest average correlation coefficient, but also because it seems to have significantly less variability than the other models and avoids some of the wild swings and misses.  Steady as she goes, some would say.  Secondly, the Ukie is still a very solid model in terms of large scale pattern recognition.  Thirdly, these data are only taken from the 0z runs over a one-month period, not exactly large sample and prone to some skewing if you have a couple of bad singular runs.

I also looked at the same scoring but as an annual average over the last 40 years, https://www.emc.ncep.noaa.gov/users/verification/headlines/acc_annual/ which shows that, while the gap has narrowed, there has never been a year when the Euro didn't lead the way over the other major models.  Also, for almost the last 20 years, every single year the UK has outscored the GFS, which I think would be a surprise to many, and in fact, even the CMC outscored it the last couple of years.  In total, all of the models perform much better these days and the gap between them is mostly negligible.

Now, these scores only relate to H500 placement and there is obviously more to predicting everyday on-the-ground weather than that, but they seem as good a place as any to start.  Mostly these are fringe differences that would be hard to detect by an observer casually checking all the models on a regular basis.  Just my thoughts.   

I recall seeing that years ago when the Euro was much better. But that is based on a forecast 5 days in advance. Which begs the question, how about 4.5 days which is where we are today. Or 3, or 2, etc. I don't know the answer, but it seems to explain how the Euro, or any other model, get beat by a lesser model.

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6 minutes ago, Bubbler86 said:

Model PBP is all above the enjoyment of finding the differences which lead to the changes. 

Yep. And compare the 18z Rgem at 84hrs to 18z Nam at 84hrs then 12z Gem at 90hrs. Rgem much further west/south.

https://www.pivotalweather.com/model.php?m=rdps&p=prateptype-imp&rh=2024020818&fh=84&r=conus&dpdt=&mc=&pwplus=1

https://www.pivotalweather.com/model.php?m=nam&p=ref1km_ptype&rh=2024020818&fh=84&r=conus&dpdt=&mc=&pwplus=1

https://www.pivotalweather.com/model.php?m=gdps&p=prateptype-imp&rh=2024020812&fh=90&r=conus&dpdt=&mc=&pwplus=1

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1 hour ago, mitchnick said:

I recall seeing that years ago when the Euro was much better. But that is based on a forecast 5 days in advance. Which begs the question, how about 4.5 days which is where we are today. Or 3, or 2, etc. I don't know the answer, but it seems to explain how the Euro, or any other model, get beat by a lesser model.

From that site, you can go into the archives and change the forecast lead time to whatever you’d like. I briefly looked at <5 days and it seems to pretty much show the same results, with the major difference being that the gaps between the models are significantly narrowed as you reduce the lead time, as expected. Admittedly, I did not spend much time analyzing it. 

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Some positive moves back the other way by the models today. Certainly still some disparity. Canadian still largely uninterested (rain) but did come back towards the other guidance some. Last night at 0z it had the rain/snow line in the NE pretty much where the GFS had the northern edge of its snow shield, so we’re zeroing in a bit. I think the GFS/GEFS is a bit generous getting a pretty significant snowfall swath thru the Mid-Atlantic.

Timing/position of the low transfer will be a big factor. Most guidance seems to suggest pretty robust strengthening of the coastal low, so those dynamics will help with cooling the column. Primary up into WV before the coastal takes over isn’t necessarily a bad evolution, but we’ll have marginal cold in place.. so I’m leery of LSV spots yet. Something closer to the colder overall GFS solution would be ideal, because I think a rain changing to snow scenario has a high potential to disappoint in Sus Valley spots. Obviously don’t want to drive the primary up too far either, because aside from initial warm air push you drive north the best precip when the precip shield sets up with the coastal transfer. 

EC ensemble blend seemed to be the best middle ground for the 12z suite, which looked like this. 

3”+ probs

image.thumb.png.9153cc74a28da917e1aef50929bbcc46.png

Individual members at MDT (24 hr snow)

image.thumb.png.1b9d7dce12b8e2cae2eff036109a64fd.png

EC ensemble multi-run trend since 0z Feb 4, 24hr snow mean (MDT) 

image.thumb.png.af8c0b001d55d49ccf7ace8bbbf53607.png

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34 minutes ago, mitchnick said:

The differences between the 12Z and 18Z Rgem are indeed quite significant.   Leery of too much put into where the model places the "L" but definitely a fluid situation to have it that much slower.   

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1 hour ago, philliesmd said:

The airport, as of 5pm yesterday, had already recorded 23 inches. The railcam is snowing pretty good right now.

 

 

I forgot about the rail cam. My niece just messaged me and said she got another 14" today so far. So that's 37" between yesterday and today. Now she lives in Flagstaff proper. South of Flag on I-17 (Munds Park and Kachina Village) gets more usually. I'll bet those areas are 40" or better.

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9 minutes ago, AccuChris said:

18z GFS kuchera

IMG_4272.png

@Atomixwx @2001kxand I endorse that run haha. 

GFS has been illustrating a very well timed handoff to the coastal low underneath PA which sets up some of the best QPF in C-PA and also minimizes any issues with initial rain changing over in our region. 

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7 minutes ago, MAG5035 said:

@Atomixwx @2001kxand I endorse that run haha. 

GFS has been illustrating a very well timed handoff to the coastal low underneath PA which sets up some of the best QPF in C-PA and also minimizes any issues with initial rain changing over in our region. 

Absolutely!!! 

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21 minutes ago, MAG5035 said:

@Atomixwx @2001kxand I endorse that run haha. 

GFS has been illustrating a very well timed handoff to the coastal low underneath PA which sets up some of the best QPF in C-PA and also minimizes any issues with initial rain changing over in our region. 

I think all of us would sign now for this 18z GFS run.

IMG_4974.png

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2 minutes ago, DDweatherman said:

Can the euro come down south some more to meet the gfs? 0z is actually arguably most important suite of the winter so far given the circumstances and this storm is only 114hrs out now

18z will be out in an hour and a half and Eps in 2 and a half.

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Did you know the Icon has ensembles? As if we didn't have enough! Lol

Anyway, the slp is about 6 hrs slower than 12z and mean slp location is south a bit of 13z and definitely a fair bit south of the operational. Here are 3 panels.

sfcmslp-meanmem.conus (7).png

sfcmslp-meanmem.conus (8).png

sfcmslp-meanmem.conus (9).png

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52 minutes ago, mitchnick said:

Did you know the Icon has ensembles? As if we didn't have enough! Lol

Anyway, the slp is about 6 hrs slower than 12z and mean slp location is south a bit of 13z and definitely a fair bit south of the operational. Here are 3 panels.

sfcmslp-meanmem.conus (7).png

sfcmslp-meanmem.conus (8).png

sfcmslp-meanmem.conus (9).png

They added that to pivotal about a month or two ago from what I remember.   I get mocked for putting up the Icon so did not want any extra back lash but thanks for bringing them up. 

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Elliott not backing down from his "no snow" this upcoming week stance:

model solutions of the storm's track and intensity will continue to change, and in some cases drastically, from run-to-run. Using large-scale pattern recognition, interior New England has the best chance for accumulating snow. I'll have a full update tomorrow!

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