December Medium/Long Range Discussion

[NorthArlington101]

3 minutes ago, mitchnick said:

That's odd. Operational shows this on Pivotal. 

I’m showing the ens. I keep hearing random chatter that they’ve got a broken output but nobody has offered any proof, so I’ll choose to ignore it. Looks plausible to me… 

[TSSN+]

Only model that far south so it’s an outlier. 
 

 

[Eskimo Joe]

9 hours ago, winter_warlock said:

Gfs hr 126

High is in a bad spot. Southeast winds just eroding the cad.

[SomeguyfromTakomaPark]

Wow ai ensembles lol.  Absolute eye candy.  Do I fall for it? Hook line and sinker!!! U know the drill. 

[mitchnick]

41 minutes ago, Heisy said:

The one posted is the Ai ensemble mean


.

I know, it's odd that the operational would have to clearly be a huge outlier.  Hasn't it learned anything? 

[Ji]

i saw the individual panels for the Euro AI ensembles. Just wild lol

[TSSN+]

4 minutes ago, mitchnick said:

I know, it's odd that the operational would have to clearly be a huge outlier.  Hasn't it learned anything? 

Nope, it’s just like us. Ain’t learnt nothin. Haha 

[MillvilleWx]

Caution when assessing the AI model at range, especially for setups that lean more delicate and have greater emphasis on energy ejections and thermal gradients involved. AI is a great model and actually performs very well inside 72hrs when it comes to 5H progression and MSLP characteristics. It can still be semi-erratic and off beyond the 72hr mark, although I will add that if the model doesn't waver much and it maintains credence inside 72hrs, it probably will be right more often than not. It's something to keep in mind when looking at the AIFS/AIFS-ENS package. It's a tool like any other piece of guidance, and it's verification is pretty damn good right now because it doesn't utilize the typical thermodynamic and dynamic functions that allow for greater swings in output compared to dynamical models. You'll know it might be on to something when it doesn't waver for a while and we begin reaching that critical point inside 48hrs. 

[NorthArlington101]

CMC ens last night were also good… for the little it’s worth. 

[poolz1]

Give me the set up at the end of the Can run last night.  Endless overrunning into a stout HP.  I think these set ups only occur on model runs though.  

[Chris78]

2 minutes ago, poolz1 said:

Give me the set up at the end of the Can run last night.  Endless overrunning into a stout HP.  I think these set ups only occur on model runs though.  

That was a perfect set up. Cold High anchored NW of us in Canada and a huge slug of moisture running Sw to NE.

As the run ended we had 6"+ on the ground and several panels of snow left to go past 240 hours.

North of DC would of been easily 12+ amounts.

[Eskimo Joe]

5 minutes ago, Chris78 said:

That was a perfect set up. Cold High anchored NW of us in Canada and a huge slug of moisture running Sw to NE.

As the run ended we had 6"+ on the ground and several panels of snow left to go past 240 hours.

North of DC would of been easily 12+ amounts.

 

10 minutes ago, poolz1 said:

Give me the set up at the end of the Can run last night.  Endless overrunning into a stout HP.  I think these set ups only occur on model runs though.  

Yes, THAT is how we win and its inside an established pattern. Not a wave breaking into something as we're setting up. Really would like to see at least a slightly -NAO to help lock in our cold air though.

[poolz1]

7 minutes ago, Chris78 said:

That was a perfect set up. Cold High anchored NW of us in Canada and a huge slug of moisture running Sw to NE.

As the run ended we had 6"+ on the ground and several panels of snow left to go past 240 hours.

North of DC would of been easily 12+ amounts.

I dug into the details too! lol  I'll live in fantasy model land as much as I want.

[mitchnick]

You guys made me look at the Gem. Dang, that's a dream. 

[mitchnick]

12z Icon went bad on us. 

Nothing. Big shift north.

[TSSN+]

1 minute ago, mitchnick said:

12z Icon went bad on us. 

Nothing. Big shift north.

Good thing it’s the icon and worth about 1 cent 

[87storms]

1 hour ago, MillvilleWx said:

Caution when assessing the AI model at range, especially for setups that lean more delicate and have greater emphasis on energy ejections and thermal gradients involved. AI is a great model and actually performs very well inside 72hrs when it comes to 5H progression and MSLP characteristics. It can still be semi-erratic and off beyond the 72hr mark, although I will add that if the model doesn't waver much and it maintains credence inside 72hrs, it probably will be right more often than not. It's something to keep in mind when looking at the AIFS/AIFS-ENS package. It's a tool like any other piece of guidance, and it's verification is pretty damn good right now because it doesn't utilize the typical thermodynamic and dynamic functions that allow for greater swings in output compared to dynamical models. You'll know it might be on to something when it doesn't waver for a while and we begin reaching that critical point inside 48hrs. 

Weather model evaluation seems similar to machine learning on just about any dataset.  Want to reduce variance and have a more generalized prediction (it'll probably snow, but not sure how much)?  Random forest classifiers can help.  Want to reduce bias and get more precise with potential overfitting (don't worry about downsloping, it's gonna snow 9.8")?  Gradient boosting.  Want a mixed bag, but high cost and a potential black box (it's gonna snow somewhere between 1 and 15"), go with ensembles that have a variety of algorithms.

Judging by the median (which I'm assuming is the wise thing to look at lol), looks like the AIFS ensembles are leaning towards snow tv, which is still a win in early December.

[TSSN+]

Gfs still on car topper alert for northern Maryland crew sunday morning.

 

 

[Ji]

21 minutes ago, TSSN+ said:

Good thing it’s the icon and worth about 1 cent 

you still dont want any model being that warm/north

[SnowenOutThere]

GFS looks to have a bit more confluence so may be a bit cooler

[Ji]

1 minute ago, SnowenOutThere said:

GFS looks to have a bit more confluence so may be a bit cooler

it should at least hold from 6z

[NorthArlington101]

Nice thump at 117. Looks better

[NorthArlington101]

Still all snow at 120

[Ji]

1 minute ago, NorthArlington101 said:

Nice thump at 117. Looks better

thats the problem...its 117 and not 17 and its the Gfs lol

[winter_warlock]

From sterling this morning....

 

Forecast confidence remains very low Tuesday into Wednesday. On the
synoptic scale, a shortwave embedded within a much broader longwave
trough encompassing much of the CONUS is expected to lift
northeastward out of the base of the longwave trough and interact
with what should be a sharp baroclinic zone in place along the East
Coast. Various sources of both deterministic and ensemble guidance
have shown a large amount of spread with respect to what will ensue
with this system. Some solutions have shown large precipitation
totals, while others have shown little precipitation at all. Some
show snow, some show a wintry mix, and others show plain rain. As is
typical, temperatures look to be colder the further north and west
one goes, so those locations have a greater chance to experience
wintry precipitation if it were to occur. It`s still too early to
get into details at this point, but this system will be one to
monitor over the next several days, as it has at least a chance to
bring portions of the area their first wintry precipitation event of
the season.

[Cobalt]

12z GFS shows -4C 850 temps at 6z Tuesday for DCA. 0z had +2C during the same timeframe.

[TSSN+]

We back 

 

[NorthArlington101]

Just now, Ji said:

thats the problem...its 117 and not 17 and its the Gfs lol

it's a WSW for you verbatim though

[bncho]

winter is uncancelled again! yay!

[NorthArlington101]

Flips at 123 for DC but been solidly thumped before that. Waiting til the end but ~4" DC - 6" Loudoun, ~8" Frederick