January 24-26: Miracle or Mirage JV/Banter Thread!

[Nomz]

Totally meaningless, but it has been depressing to watch the Saturday and Sunday night low temps creep up like 3 degrees.

[mappy]

1 minute ago, TheColtrane said:

Cool thanks. Now get them to label it properly, which was my point in the first place.

Moving this to banter

NWS doesn’t need to label it snow and sleet because sleet counts as snow. 

[WxUSAF]

So ready not to look at model output for this storm anymore…just freaking get on with it and start snowing!

[stormtracker]

@NorthArlington101

Hit the showers.  I'm benching you till after 12z.   You're in a downward swing...it's happening to all of us.  You'll come back up after you get away from this place  

[winter_warlock]

Well whether we get 1 inch or 20 inches. One things for sure.  This coming week is gonna be bone chilling cold!!

[H2O]

[Ralph Wiggum]

10 minutes ago, Nomz said:

Totally meaningless, but it has been depressing to watch the Saturday and Sunday night low temps creep up like 3 degrees.

I remember when for 3 days it has 12 degrees and snowing up my way both sat and sun. Now its just Sunday and 25 degrees. Probably will end up 33 by game time.

[clskinsfan]

Wanted to drop my apologies for last night as well. It is going to snow. Just need to be happy about that. 

[Nomz]

Went from this on Wednesday

To this today (DC)

 

[stormtracker]

4 minutes ago, H2O said:

Altho again, he could very well be valid.  I get it.  But I would have at least waited till after the entire 12z before I came down.   I might join him after that. 

[WolfStock1]

Anyone know why Apple weather is so different than NWS forecasts?   I don't use it but my wife does, and here's what hers shows this morning for Leesburg area for Sunday:

 

 

Umm.. what?   24" of snow?  Only 70% max chance of precip?   Totally different than legit forecasts.

Only thing I can figure is that the app doesn't have the ability to account for wintry mix / sleet, so it just does some kind of "snow equivalent" or something (?).   No clue why chance of precip is only 70%.

[LP08]

Just look at the FV3. Still snow past 18z.

 

its wrong but fun to look at

[Nomz]

Just now, WolfStock1 said:

Anyone know why Apple weather is so different than NWS forecasts?   I don't use it but my wife does, and here's what hers shows this morning for Leesburg area for Sunday:

 

 

Umm.. what?   24" of snow?  Only 70% max chance of precip?   Totally different than legit forecasts.

Only thing I can figure is that the app doesn't have the ability to account for wintry mix / sleet, so it just does some kind of "snow equivalent" or something (?).   No clue why chance of precip is only 70%.

I had the same question and didn't get any answers. I don't think a single model has been close to 24" since Tuesday. I think I could chatGPT an app that produces better precip forecasts than apple weather.

[StormyClearweather]

1 minute ago, LP08 said:

Just look at the FV3. Still snow past 18z.

 

its wrong but fun to look at

Yeah, word on the street is it sucks at thermals, but we can get a dopamine fix out of it at least.

I hate the NAM. It's only right when it fucks us. 

[Nomz]

2 minutes ago, Nomz said:

I had the same question and didn't get any answers. I don't think a single model has been close to 24" since Tuesday. I think I could chatGPT an app that produces better precip forecasts than apple weather.

However, I did see someone who was way in over their head take the h288 GFS from 12z yesterday verbatim (the one that showed like 40" in DC) so maybe we're not ready for that

[H2O]

4 minutes ago, stormtracker said:

Altho again, he could very well be valid.  I get it.  But I would have at least waited till after the entire 12z before I came down.   I might join him after that. 

This was in response to the overall mood this morning.  From snow/sleet maps to maps to warm noses.  People are wore out.  Critical times.  Knifes edge.  People staring at models like this 

[paulythegun]

FV3 buries DC with snow. Very late changeover. NAM3k brings a very early changeover. NWS' forecast looks much more like FV3 (high snow totals). See the other thread. I asked ChatGPT to discuss the models' strengths and weaknesses (LOL). Here's what it told me (EXACTLY WHAT I WANTED TO HEAR, SHOCKER! but an interesting read):

 

This is a classic Hour-40–60 Mid-Atlantic fork, and the way you described it already hints at which solution is more plausible versus more diagnostic noise. Here’s how forecasters would parse exactly this setup.

---

What the disagreement really is

NAM solution

• Introduces a 700-mb warm nose after ~40 hr

• Overruns CAD → sleet/freezing rain inland

• Produces a fall-line snow cliff (DC ~4", south much less)

FV3 solution

• Keeps the column colder

• Maintains deep isothermal profiles

• Allows widespread synoptic snow, including south of DC

• Matches the current forecast thinking from National Weather Service

This is not subtle disagreement — it’s a structural difference in storm evolution, not just a few degrees.

---

Why the NAM solution is suspect at 40–60 hr

The NAM’s warm nose is a known bias

At this lead time, the NAM often:

• Over-advects mid-level warmth ahead of strengthening southern stream systems

• Especially above CAD, where it erodes cold air too early

• Invents sleet/freezing rain before the synoptic forcing is mature

This is textbook NAM behavior in overrunning setups.

A 700-mb warm nose at hour 48 does not mean it will verify — it often means “the model is ahead of itself.”

---

Sharp fall-line cutoffs scream “fake precision”

At 3-km resolution, a knife-edge cutoff near the fall line at Day 2–2.5 usually means:

• Convective or feedback-driven thermal noise

• Poor handling of ageostrophic ascent

• CAD erosion happening too abruptly

Real storms:

• Transition gradually

• Evolve over multiple cycles

• Rarely stop snow exactly at the fall line at this lead time

---

FV3 matching NWS matters — but why matters more

It’s not just that FV3 agrees with NWS — it’s what it agrees on:

• Cold column integrity

• Broad ascent

• Synoptic-scale snow shield

That alignment tells you:

The conceptual model is consistent across guidance.

That’s far more important than any single snowfall number.

---

What’s likely happening physically

Most likely evolution given current signals:

• CAD holds longer than NAM suggests

• Warm nose (if it arrives) is:

  • Later

  • Weaker

  • South/west of DC

• Snow extends well south of the fall line initially

• Any mix issues become:

  • Late-stage

  • South-focused

  • Elevation-dependent

NAM is probably correct that warm air exists aloft eventually
FV3 is probably correct on timing and impact

---

How forecasters would weight this right now

At Hour 40–60:

• Reject the NAM snowfall cliff

• Flag the NAM warm nose as a risk, not an outcome

• Lean FV3 for:

  • Snow extent

  • Cold-air durability

  • Early & mid-storm evolution

If future NAM runs:

• Delay the warm nose

• Soften the cutoff

• Trend colder

That’s convergence toward FV3, not the other way around.

---

Bottom line (plain language)

• The NAM is likely too warm, too fast, and too sharp

• The FV3/NWS solution is meteorologically cleaner

• At this range, widespread snow is the higher-probability outcome

• Mixing concerns are real but premature

This is exactly the kind of setup where:

NAM scares you early
FV3 ends up closer on the big picture

If you want, next we can:

• Walk through what would need to change for the NAM solution to win

• Identify the specific upstream feature that decides this

• Compare this setup to Jan 2016 / Jan 2018 / Jan 2000-style cases

Just tell me where you want to go next.

 

 

 

[NorthArlington101]

9 minutes ago, stormtracker said:

Altho again, he could very well be valid.  I get it.  But I would have at least waited till after the entire 12z before I came down.   I might join him after that. 

Crashouts? Who, me? 

[RevWarReenactor]

LOL, the last page of the regular thread is hilarious.

PSU is like, no snow all sleet on the NAM, and others are like "NAM looks better".

 

I think people are going crazy TBH.

[wxdude64]

34 minutes ago, Ralph Wiggum said:

Hey, can you still be reached at 877-cash-now? 

I wish they'd quit filling my spam email filter with requests for overdue credit card payments! Especially since I've never dealt with them before. 

[LVblizzard]

2 minutes ago, paulythegun said:

FV3 buries DC with snow. Very late changeover. NAM3k brings a very early changeover. NWS' forecast looks much more like FV3 (high snow totals). See the other thread. I asked ChatGPT to discuss the models' strengths and weaknesses (LOL). Here's what it told me (EXACTLY WHAT I WANTED TO HEAR, SHOCKER! but an interesting read):

 

This is a classic Hour-40–60 Mid-Atlantic fork, and the way you described it already hints at which solution is more plausible versus more diagnostic noise. Here’s how forecasters would parse exactly this setup.

---

What the disagreement really is

NAM solution

• Introduces a 700-mb warm nose after ~40 hr

• Overruns CAD → sleet/freezing rain inland

• Produces a fall-line snow cliff (DC ~4", south much less)

FV3 solution

• Keeps the column colder

• Maintains deep isothermal profiles

• Allows widespread synoptic snow, including south of DC

• Matches the current forecast thinking from National Weather Service

This is not subtle disagreement — it’s a structural difference in storm evolution, not just a few degrees.

---

Why the NAM solution is suspect at 40–60 hr

The NAM’s warm nose is a known bias

At this lead time, the NAM often:

• Over-advects mid-level warmth ahead of strengthening southern stream systems

• Especially above CAD, where it erodes cold air too early

• Invents sleet/freezing rain before the synoptic forcing is mature

This is textbook NAM behavior in overrunning setups.

A 700-mb warm nose at hour 48 does not mean it will verify — it often means “the model is ahead of itself.”

---

Sharp fall-line cutoffs scream “fake precision”

At 3-km resolution, a knife-edge cutoff near the fall line at Day 2–2.5 usually means:

• Convective or feedback-driven thermal noise

• Poor handling of ageostrophic ascent

• CAD erosion happening too abruptly

Real storms:

• Transition gradually

• Evolve over multiple cycles

• Rarely stop snow exactly at the fall line at this lead time

---

FV3 matching NWS matters — but why matters more

It’s not just that FV3 agrees with NWS — it’s what it agrees on:

• Cold column integrity

• Broad ascent

• Synoptic-scale snow shield

That alignment tells you:

The conceptual model is consistent across guidance.

That’s far more important than any single snowfall number.

---

What’s likely happening physically

Most likely evolution given current signals:

• CAD holds longer than NAM suggests

• Warm nose (if it arrives) is:

  • Later

  • Weaker

  • South/west of DC

• Snow extends well south of the fall line initially

• Any mix issues become:

  • Late-stage

  • South-focused

  • Elevation-dependent

NAM is probably correct that warm air exists aloft eventually
FV3 is probably correct on timing and impact

---

How forecasters would weight this right now

At Hour 40–60:

• Reject the NAM snowfall cliff

• Flag the NAM warm nose as a risk, not an outcome

• Lean FV3 for:

  • Snow extent

  • Cold-air durability

  • Early & mid-storm evolution

If future NAM runs:

• Delay the warm nose

• Soften the cutoff

• Trend colder

That’s convergence toward FV3, not the other way around.

---

Bottom line (plain language)

• The NAM is likely too warm, too fast, and too sharp

• The FV3/NWS solution is meteorologically cleaner

• At this range, widespread snow is the higher-probability outcome

• Mixing concerns are real but premature

This is exactly the kind of setup where:

NAM scares you early
FV3 ends up closer on the big picture

If you want, next we can:

• Walk through what would need to change for the NAM solution to win

• Identify the specific upstream feature that decides this

• Compare this setup to Jan 2016 / Jan 2018 / Jan 2000-style cases

Just tell me where you want to go next.

 

 

 

So ChatGPT is a weenie? Who would have guessed lol.

[stormtracker]

2 minutes ago, NorthArlington101 said:

Crashouts? Who, me? 

We've all had them. It's a rite of passage here.

[Maestrobjwa]

Just now, stormtracker said:

We've all had them. It's a rite of passage here.

And to tell ya the truth, even as we learn to control them on here, it would not surprise me if even the most measured posters on here still have them silently from time to time--it's a part of our syndrome, lol

[TSSN+]

So how many accidents are we predicting on the roads Monday? Cause people will be idiots and try and drive on the ice rink roads. 

[NorthArlington101]

3 minutes ago, Terpeast said:

Low end map from LWX

I'd probably add 1" to this and call it my forecast map atp for the most part. Ignoring far western zones and mountains.

[konksw]

1 minute ago, NorthArlington101 said:

I'd probably add 1" to this and call it my forecast map atp for the most part. Ignoring far western zones and mountains.

Because of the NAM??

[NorthArlington101]

3 minutes ago, konksw said:

Because of the NAM??

Partially to preserve my own sanity and grind expectations low, but yeah, kinda because of the NAM. Also matches the EURO as far as snow goes, really, perhaps a tad more conservative. I guess the sleet would probably make my map wrong but I'll never really count that as snow even if you are supposed to

[RevWarReenactor]

5 minutes ago, NorthArlington101 said:

I'd probably add 1" to this and call it my forecast map atp for the most part. Ignoring far western zones and mountains.

NWS has been over forecasting for this area for quite sometime. I can count at least 5 storms in the last 10 years where they where saying 3-6 or even 4-8 and I got a dusting on the grass.

Furthermore, the mixing ALWAYS happens way quicker than forecasted. 

[caviman2201]

I know its unavoidable and unfair, but shit like this is exactly why the public makes "weathermen" the butt of so many jokes and thinks they over-hype the weather. These models really do seem to have gotten worse than they used to be. The public is out there right now being told to expect a foot of snow based on the NWS forecast... and the doubters and mockers are laughing saying that isn't going to happen and they're crazy... and sadly I now expect them to be right when we wake up Sunday morning

[caviman2201]

10 minutes ago, NorthArlington101 said:

I'd probably add 1" to this and call it my forecast map atp for the most part. Ignoring far western zones and mountains.

Honestly thats bold at this juncture... my wife just asked and I said unless this trend stops today I don't know if we get any freaking snow. There's enough time left that if this trend doesn't stop we will be down to a dusting + a sleet bomb in the cities

I'm not new to this but I was not expecting the trend to just keep going and going and going until it took everything. Usually we get our hopes dashed relatively mercifully quickly... this is like being flayed alive