Pattern Jammin January 2024

[weatherfide]

The PNA being negative is not good. I know there will be folks that talk about the strong negative NAO. But I read somewhere in most cases it only helps the mid-Atlantic and NE. And from everything I've seen over the years, we need the PNA positive (...in most cases).

CPC - Climate Weather Linkage: Teleconnections

www.cpc.ncep.noaa.gov

If we have a -PNA, all but NC will be out of luck with a -NAO. If we have a +NAO/-PNA, we can get out the shorts and turn off our heaters for a month.

 

[J.C.]

If we have a -PNA, all but NC will be out of luck with a -NAO. If we have a +NAO/-PNA, we can get out the shorts and turn off our heaters for a month.

The favored CAD areas can score with the ladder, but there needs to be a nice cold source up in the northeast at least.

 

[Billypg70]

So the best sub-seasonal forecasting is "poor"? and seasonal forecasts are fair? why even perform sub-seasonal forecasts?

I liken it to a dog chasing a car,
What is the dog going to do when it catches the car?
Bury it? ??‍????
It's just in our DNA and there's not a soul that comes in here that doesn't have it or you wouldn't be here at all.

Also looking for the Holy Grail of Patterns that leads to Board wide glory with a Big Dog.
??️

 

[iGRXY]

The PNA being negative is not good. I know there will be folks that talk about the strong negative NAO. But I read somewhere in most cases it only helps the mid-Atlantic and NE. And from everything I've seen over the years, we need the PNA positive (...in most cases).

CPC - Climate Weather Linkage: Teleconnections

www.cpc.ncep.noaa.gov

It depends, usually a neutral PNA is pretty good with a -NAO. You don't want to unload the whole arctic either and a +PNA can do that, especially if you're getting CPF and moving high pressure out of Siberia. -PNA/-NAO combos work for my neck of the woods because they mean Miller B/CAD. These days expecting a total EC trough with the TPV slid underneath a Greenland block and ridging poking into Western Canada and north of Alaska is a fairytale. Best you can hope for snow wise is to get the TPV to be situated over the Hudson/GL or a bombing 50/50 low with good snowpack in SE Canada/the Northeast to deliver the goods down this way.

 

[iGRXY]

Likely going to see more icing this run on the NAM

 

[iGRXY]

Yep

 

[SimeonNC]

Yep

NAM was way colder, keeps icing in the foothills till mid-morning. Honestly the thought of seeing the RGEM scares me now lol

 

[JHS]

Close to warning criteria above I-85 from Greenville to Cherokee counties in SC now, with up to .35 of ice in parts of the foothills of NC.

 

[SimeonNC]

Also, isn't the CAD with this more of a hybrid than an in-situ because of the HP in Canada providing the cold source? Or is the HP too far from us to have any meaningful effect?

 

[griteater]

So the best sub-seasonal forecasting is "poor"? and seasonal forecasts are fair? why even perform sub-seasonal forecasts?

Yeah I don't have the specifics regarding how this chart was made, but with the skill on the y-axis, you have to factor in the type of forecast data being produced. A seasonal forecast is, of course, going to be more broad-based (e.g. slightly above normal temperatures) vs a 5-day forecast of specific temperatures / precip chances etc....so, a 'successful' forecast isn't the same for both

 

[ILMRoss]

So the best sub-seasonal forecasting is "poor"? and seasonal forecasts are fair? why even perform sub-seasonal forecasts?

energy markets

they're not useless. for example it seems clear 'somebody' is going to get whacked by a cold air and traders/energy providers would like to know that. just as one example.

but also it's way easier to make crude forecasts like "colder than normal" or "wetter than normal". predicting the storm track- way different animal. only so much we can ascertain using convection in india and heights over greenland

 

[BullCityWx]

NAM has at least some icing down to NE Richland County.

 

[Blue_Ridge_Escarpment]

NAM has at least some icing down to NE Richland County.

If you start seeing wedging/icing into the Sandhills you better start paying attention in immediate CAD zones.

 

[iGRXY]

Could be even worse. The NAM is drier compared to the Globals by almost half. NAM dry bias might be showing it's ugly head right now.

 

[Nomanslandva]

Nam is ZR the whole event here and even north all the way to Winchester. OK...

 

[BullCityWx]

 

[iGRXY]

Also, isn't the CAD with this more of a hybrid than an in-situ because of the HP in Canada providing the cold source? Or is the HP too far from us to have any meaningful effect?

Yes to an extent. Not a super strong HP but it's there supplying an addition push of cold air on the retreating Mid Atlantic HP.

 

[JHS]

If you start seeing wedging/icing into the Sandhills you better start paying attention in immediate CAD zones.

You are in the worst of it on the NAM right now. It has close to a 3rd of an inch of ice in HKY.

 

[iGRXY]

Could be a lot worse honestly if the NAM is underdoing the amount of precip. Still has almost 0.25" of accretion along Highway 11 and 0.1" along 85.

 

[Tarheelwx]

Is that high up in Ontario going to have any impact on the wedge? It went from 1027 on the 06z run to 1030 on the 12z run. Seems it could be a source. Usually we want to see the high in NY or PA.
TW