February 19-20 Major Winter Storm Threat

[GaWx]

13 minutes ago, NorthHillsWx said:

Absolutely epic model fail north of NC. To the point there aren’t terribly many examples of similar fails in that timeframe with a predicted major storm. WPC is usually conservative and even they honked the horn early based on the amazing model consensus we had. But weather is gonna weather, it’s why we’re here. If the 96 hour EURO was right everytime this wouldn’t be as fun. Eventually we’ll get one that tends positively for the forum. With all the negativity, central and eastern NC are still looking at a significant snow. It could die later but for now this is far from dead 

Indeed, the fact that the best models can and do miss so badly even just a few days out makes this far more interesting than it would otherwise be due to higher uncertainty. Can you imagine how boring forecast discussions would be if the models were perfect?

[neatlburbwthrguy]

is this the type of set-up that high elevations in north Georgia like around Suches could see a couple inches of snow?

[NorthHillsWx]

11 minutes ago, GaWx said:

Yeah, it hasn’t had as big jumps as the Euro op run to run on this.

I’m not sure I agree with this. It’s has had several jumps of 300+ miles and actually corrected to the Euro at one point. It did start east and overall has stayed east and colder but it has been pretty jumpy in last 24 hours. 

[WXNewton]

Since the 12z runs about to start, are going positive trends start now or does the bleeding keep happening?

[Brick Tamland]

HRRR at 48.

[NorthHillsWx]

We’re in the range where you cannot discredit the NAM completely. Other short range guidance can start to be used more critically 

[tarheelwx]

5 minutes ago, NorthHillsWx said:

I’m not sure I agree with this. It’s has had several jumps of 300+ miles and actually corrected to the Euro at one point. It did start east and overall has stayed east and colder but it has been pretty jumpy in last 24 hours. 

In the last 48 hours for the triad, it has given 0.2” qpf  the first 4 of those runs and 0.10” the last four runs.  Not saying it will be right, but that’s about as consistent as it gets.  
TW

[olafminesaw]

5 minutes ago, NorthHillsWx said:

I’m not sure I agree with this. It’s has had several jumps of 300+ miles and actually corrected to the Euro at one point. It did start east and overall has stayed east and colder but it has been pretty jumpy in last 24 hours. 

It has been very good for the most part at identifying the late phase/QPF distribution. This is the last four days of model runs. It lost it there for a bit, but no other model came close to getting it right up until yesterday 

[StantonParkHoya]

3 minutes ago, NorthHillsWx said:

We’re in the range where you cannot discredit the NAM completely. Other short range guidance can start to be used more critically 

NAM had 5 inches for RDU at 6z

[BooneWX]

4 minutes ago, Brick Tamland said:

HRRR at 48.

Paltry. The transfer to the coast is going to really do a number on CNC as well imo. Someone forecasted to get 2-4” is going to get dry slotted.

[GaWx]

From JB: Opportunity to learn:

Perfect 500 mb forecast, but the surface not responding likely due to lack of focused warm advection The warm advection term is just as important as upper divergence in cyclogenesis and I thought there would be more resistance. AI looks like it will be right.

That 9-day call on 500 mb was as good as I can do.

In retrospect the development of heavy precip on the gulf coast shuts down any inflow north into the arctic boundary. and the precip weakens in the cold air. Once that convective feedback takes off, there is no chance for the kind of warm advection needed for the more northern route. I obviously thought this was not going to happen to this extent. But that kind of vv there means that is where this wants to form. As it moves along the snow shield to the north weakens instead of the other way. Once the focus gets to the coast its too late and only light snows from the upper low come across.

[franklin NCwx]

12 minutes ago, neatlburbwthrguy said:

is this the type of set-up that high elevations in north Georgia like around Suches could see a couple inches of snow?

Yes. Depending on how much moisture they receive.  Should be cold enough 

[NorthHillsWx]

1 minute ago, GaWx said:

From JB: We learn…

Perfect 500 mb forecast, but the surface not responding likely due to lack of focused warm advection The warm advection term is just as important as upper divergence in cyclogenesis and I thought there would be more resistance. AI looks like it will be right.

That 9-day call on 500 mb was as good as I can do.

In retrospect the development of heavy precip on the gulf coast shuts down any inflow north into the arctic boundary. and the precip weakens in the cold air. Once that convective feedback takes off, there is no chance for the kind of warm advection needed for the more northern route. I obviously thought this was not going to happen to this extent. But that kind of vv there means that is where this wants to form. As it moves along the snow shield to the north weakens instead of the other way. Once the focus gets to the coast its too late and only light snows from the upper low come across.

Was wondering when he’d cave. Actually shocked it was this early when he dug in yesterday lol

[NorthHillsWx]

7 minutes ago, olafminesaw said:

It has been very good for the most part at identifying the late phase/QPF distribution. This is the last four days of model runs. It lost it there for a bit, but no other model came close to getting it right up until yesterday 

That’s a very good GIF. I guess I haven’t been following the AI much but my take was when it jumped to more of a tucked look north of hatteras in alignment with EURO at the time. It truly hasn’t been gung ho with inland precip at any point though to y’all’s point. I’ll rescind my comments as that’s as consistent as any model for this storm. I guess a blind squirrel found a nut

[GaWx]

 Don’t forget that there’s another system waiting in the wings once we’re done following this one. There’s always a next time. Maybe that will be more impactful than this one. One never knows, especially since it is still out 6-7 days, a relative eternity!

[StantonParkHoya]

Just now, GaWx said:

 Don’t forget that there’s another system waiting in the wings once we’re done following this one. There’s always a next time. Maybe that will be more impactful than this one. One never knows and it is still out 5-7 days.

March starts next week. Ain’t always a “next time” maybe a next winter

[GaWx]

10 minutes ago, StantonParkHoya said:

March starts next week. Ain’t always a “next time” maybe a next winter

It will still be only Feb 23-24 for the next one and with cold air still nearby.

[wncsnow]

Nam is slower than other guidance... but its also paltry

[olafminesaw]

The lower resolution NAM tends to do an abysmal job at precip distribution, I would wait for the hires version to come into range

[wncsnow]

Just now, olafminesaw said:

The lower resolution NAM tends to do an abysmal job at precip distribution, I would wait for the hires version to come into range

Its paltry too

[Brick Tamland]

[NorthHillsWx]

NAM gets its act together 

[wncsnow]

Hi Res Nam

[olafminesaw]

4 minutes ago, wncsnow said:

Its paltry too

Looks okay to me. It is indicating light precip with heavy radar returns, so obviously indicating dry air cutting into totals. I think if those kind of radar returns develop, the column would saturate

[olafminesaw]

I am beginning to wonder if the mantra that the warm nose always wins will actually be a benefit, to those of us north and west especially. Could help develop heavier precip returns as I believe the hires NAM might be starting to pick up on

[NorthHillsWx]

3 minutes ago, olafminesaw said:

Looks okay to me. It is indicating light precip with heavy radar returns, so obviously indicating dry air cutting into totals. I think if those kind of radar returns develop, the column would saturate

Its much better precip wise than its last couple runs and goes sub 1000 mb just east of hatteras. Historically that’s a great spot for NC. Only problem and this is something we (RDU) knew but thermals suck and it’s almost all sleet in Raleigh. Better run I-85 NE

[HKY_WX]

I think this one is going to come down to how quickly that trailing PJ energy phases into the trough. At this point I would rather see it trend stronger even if it results in a changeover as i'm more concerned now with it trending to a quick nuisance event for everyone. The  -AO/Blocking in Canada has really played havoc with the models, but it's necessary in the end if we want a storm.

[GaWx]

12Z NAM: look how much further W is the low compared to other models. But it is the latter hours of the NAM…so take with a humongous grain:

[wncsnow]

If only the hi Res NAM is on to something..

[olafminesaw]

Notice the banding from the Triad N & W. Precip distribution is always less uniform and more unpredictable than we tend to expect