January 24-26: Miracle or Mirage Thread 2

[MN Transplant]

Sunday morning 7am per the NAM at DCA

[TSSN+]

It will figure it out by hour 12 maybe 

 

[konksw]

1 minute ago, Weather Will said:

For what it is worth. WB 12Z 12K NAM totals 

lol 2 inches of sleet. That’d be something. 

[BristowWx]

1 minute ago, Solution Man said:

Paging the Icon

the surface 2m temps look acceptable.  melting will limited I believe.

[Stormchaserchuck1]

6z GFS vs 12z NAM, same time

[Terpeast]

2 minutes ago, MN Transplant said:

Sunday morning 7am per the NAM at DCA

Looks like the warm nose starts at 700-750, then later 800-850

[Solution Man]

1 minute ago, BristowWx said:

the surface 2m temps look acceptable.  melting will limited I believe.

I’ll allow it

[adelphi_sky]

1 minute ago, Stormchaserchuck1 said:

6z GFS vs 12z NAM, same time

These 100 mile shifts have to stop. We're 3 days from game time. Sheesh.

[TSSN+]

Just now, adelphi_sky said:

These 100 mile shifts have to stop. We're 3 days from game time. Sheesh.

It’s two different models it’s not a shift of anything. 

[Terpeast]

1 minute ago, adelphi_sky said:

These 100 mile shifts have to stop. We're 3 days from game time. Sheesh.

He’s comparing two different models, not two different runs of the same model.

[Stormchaserchuck1]

1 minute ago, Solution Man said:

Damn Chuck, where’d you get that map?

https://mag.ncep.noaa.gov/model-guidance-model-area.php

[Interstate]

4 minutes ago, adelphi_sky said:

These 100 mile shifts have to stop. We're 3 days from game time. Sheesh.

It is not too much different... The main difference in the low driving up the Tenn Valley

[RevWarReenactor]

6 minutes ago, adelphi_sky said:

These 100 mile shifts have to stop. We're 3 days from game time. Sheesh.

Yeah but its the NAM at 84hours. Thats like the GFS at 144 isn't it?

[StormyClearweather]

I can't help myself - I'm watching column max temps and how they progress. Here's how they compare at HR 60 across the models that PW has with that metric. It's a good sign to me that the 3K NAM is a touch colder. People can hate on it all they want, but I've learned to not bet against 3K NAM temp profiles (good or bad) within 24-36 hours (though this is obviously outside that range).

[mitchnick]

Can't expect the Nam to get all thermals correct at the far reaches of its forecast period. And it's the far reaches where thermals become an important factor in final snow totals.

[Fozz]

10 minutes ago, Stormchaserchuck1 said:

6z GFS vs 12z NAM, same time

I wouldn’t trust the NAM at 84 hours but you never know.

[WxUSAF]

Just now, mitchnick said:

Can't expect the Nam to get all thermals correct at the far reaches of its forecast period. And it's the far teaches where thermals become an important factor in final snow totals.

At the end of the 3k NAM run, it has the snow/sleet line notably south of 12k NAM in Kentucky. Maybe 50mi? fwiw 
 

NAM thermals are definitely worth watching, but like starting with tomorrows 12z or 18z?

[Terpeast]

Main takeaway is the NAM puts itself in Euro's camp, even though it trended a touch colder.

[baltosquid]

ICON hanging back the Baja low this run, thru 36. Don’t know how well it will play with the NS yet.

[Thrasher Fan]

Just now, Fozz said:

I wouldn’t trust the NAM at 84 hours but you never know.

I wouldn't trust the NAM beyond 12 hours. It didn't even sample the current precip over GA correctly at initiation. 

[mitchnick]

Just now, Thrasher Fan said:

I wouldn't trust the NAM beyond 12 hours. It didn't even sample the current precip over GA correctly at initiation. 

Yes, and remember a couple days ago the Nam went hard on an appetizer (1-3") just to the south of the Metros at the end of its run for Friday, and that's Poof!

[Interstate]

Less interaction with the ICON out west

[Eskimo Joe]

3 minutes ago, Terpeast said:

Main takeaway is the NAM puts itself in Euro's camp, even though it trended a touch colder.

E/E rule

[psuhoffman]

17 minutes ago, bncho said:

72 to 75 was.... weird. mix line jumped 100 miles north suddenly?

There is a closed mid level low over Missouri and the winds are screaming out of the SW at h85 and h7 so....  

For us to stay snow south of the MD/PA line we really need less phasing and a less amplified wave to our west.  The 50/50 is sliding out not locked in, the block is centered over northern Greenland, its not suppressive enough to offset a phase system that far to our west like that.  For the amplitude the NAM has we would need a more suppressive look over top.  But...even with this we can get a really nice thump snow before any mix, and the NAM could be overdoing the warming during the heavy precip some...that does happen sometimes the dynamic cooling can overcome the WAA and mix out the warm layer longer than expected...we've seen this so many times.  Dec 2013, Feb 2014, Feb 2015.  It hasn't happened as much recently because we've either been warm or cold and dry the last 9 years lol.  

It is also still possible to get a less amplified wave like the GFS and some of the EPS members show.  And frankly most of the globals are slightly less amplified also.  This primary cutting to our west was my worst case scenario 48 hours ago but I said even in that case we would still be looking at 6"+ of snow to ice...and it looks like that's holding as the worst case we've seen across guidance...which isn't a bad floor to have.  

[Nomz]

From my experience the NAM overdoes low-level response which leads to a stronger LLJ, warmer temps and (for severe weather season) loopier hodographs.

[IUsedToHateCold]

1 minute ago, Eskimo Joe said:

E/E rule

What is the E/E rule? (sorry, I haven't heard this one in my 20 years on the forum)

[Fozz]

1 minute ago, IUsedToHateCold said:

What is the E/E rule? (sorry, I haven't heard this one in my 20 years on the forum)

When the Euro + ETA (predecessor to NAM) agreed on something, some guys like DT would take it to the bank.

[psuhoffman]

It also happened up here in March 2018 with the front running WAA snow....models had that flipping to sleet up here after only a couple inches and it stayed heavy snow through the whole WAA thump and we got about 8" before the dry slot when we got snizzle until the ULL associated stuff that got the whole area with 4-8" the next day.  

[SerialDerecho]

2 minutes ago, IUsedToHateCold said:

What is the E/E rule? (sorry, I haven't heard this one in my 20 years on the forum)

The NAM used be called the Eta model way back when. There was a now rather debunked theory in those days that if the Eta and Euro where in agreement, you could take that forecast to the bank.

Edit:  ninja'd

[TSSN+]

Icon should be significantly improved this run