December Medium/Long Range Discussion

[Weather Will]

7 minutes ago, mappy said:

terrible. people really need to look at temps before posting them. 

I did.  I posted them as well.

[aldie 22]

8 minutes ago, mappy said:

Those maps are lol. 850/925 are both above freezing for many of us, myself included. 

Not here

[whiteout]

With all the focus on the Midweek event next week, how is the long range pattern looking? Are we still building into a good pattern for mid-late December?


.

[LeesburgWx]

As long as Leesburg gets Nam’d, please post any and all snow maps for Ji

[WxUSAF]

1 minute ago, high risk said:

        In these events with very marginal temperatures, the Tropical Tidbits accumulated positive snow depth change are the best maps to examine.    They show what the model believes can actually accumulate on the ground.

I've always found those to be low, even in marginal situations, but they're going to be closer than those 10:1 wxbell maps!

Everyone has to keep normal Mid-Atlantic marginal event rules in mind here.  Elevation STRONGLY favored.  Rural N/W areas favored.  White rain likely for a time, even in places where accumulation happens.  That it might touch 60F Sunday doesn't matter much.  

[Weather Will]

Just now, Weather Will said:

I did.  I posted them as well.

It is going to be near 60 over the weekend, so not expecting 4 inches on the ground Monday, not even an inch.  But a dusting would put people in the holiday spirit and we need that in 2020.

[Eskimo Joe]

Just now, WxUSAF said:

I've always found those to be low, even in marginal situations, but they're going to be closer than those 10:1 wxbell maps!

Everyone has to keep normal Mid-Atlantic marginal event rules in mind here.  Elevation STRONGLY favored.  Rural N/W areas favored.  White rain likely for a time, even in places where accumulation happens.  That it might touch 60F Sunday doesn't matter much.  

Counterpoint...if we somehow don't get to 60 or even the mid 50s then it works out even better.

[aldie 22]

6 minutes ago, leesburg 04 said:

Not here

That said I have zero expectations for Monday I'm all in on the midweek storm. I do like gravy though

[Weather Will]

3 minutes ago, WxUSAF said:

I've always found those to be low, even in marginal situations, but they're going to be closer than those 10:1 wxbell maps!

Everyone has to keep normal Mid-Atlantic marginal event rules in mind here.  Elevation STRONGLY favored.  Rural N/W areas favored.  White rain likely for a time, even in places where accumulation happens.  That it might touch 60F Sunday doesn't matter much.  

I agree completely.  Brunswick is NW rural.  I don’t see snow depth option for NAM on WB.  But I can post with other models if it gives a more accurate depiction if it is available.

[high risk]

3 minutes ago, WxUSAF said:

I've always found those to be low, even in marginal situations, but they're going to be closer than those 10:1 wxbell maps!

Everyone has to keep normal Mid-Atlantic marginal event rules in mind here.  Elevation STRONGLY favored.  Rural N/W areas favored.  White rain likely for a time, even in places where accumulation happens.  That it might touch 60F Sunday doesn't matter much.  

          They do run tend to a bit low (especially when the ground is relatively "warm", but they're so much better than 10:1 maps in any event in marginal thermodynamic environment.

          I honestly don't blame WB or TT.    The problem is that NCEP doesn't generate true snow accumulation output for any models except RAP and HRRR, so it's up to the user to assign and apply an SLR.       This is going to be addressed going forward.

  

  

[mappy]

11 minutes ago, WxUSAF said:

I'm pretty sure WxBell assumes 850mb temp below 0C = snow

In this very marginal situation, that's going to give a really bad impression.  

Happens every year though. People see snow maps and take them as gospel. 

9 minutes ago, Weather Will said:

I did.  I posted them as well.

you post every map there is available. 

9 minutes ago, leesburg 04 said:

Not here

you're at 0. congrats!

[WxUSAF]

5 minutes ago, high risk said:

        

          I honestly don't blame WB or TT.    The problem is that NCEP doesn't generate true snow accumulation output for any models except RAP and HRRR, so it's up to the user to assign and apply an SLR.       This is going to be addressed going forward.

  

  

Good to hear!  Are they going to output what SLR they're calculating as well as the accumulation?  That way we weenies will just adjust upward

[usedtobe]

4 minutes ago, high risk said:

          They do run tend to a bit low (especially when the ground is relatively "warm", but they're so much better than 10:1 maps in any event in marginal thermodynamic environment.

          I honestly don't blame WB or TT.    The problem is that NCEP doesn't generate true snow accumulation output for any models except RAP and HRRR, so it's up to the user to assign and apply an SLR.       This is going to be addressed going forward.

  

  

Geoff, How does the Parallel GFS do compared to the current version.  I noticed the 00Z parallel from last night had much lower pressure over the Great Lakes than the 00Z operational so it forecast all rain across the area.  It was quite a bit farther west with the secondary.  Despite the overly rosey Eruo ensemble snow probabilities, the lows were all over the place,  lots of spread. 

[high risk]

2 minutes ago, WxUSAF said:

Good to hear!  Are they going to output what SLR they're calculating as well as the accumulation?  That way we weenies will just adjust upward

         Honestly, those details haven't been sorted out yet.    It's not an output in the RAP/HRRR (which have actual snow accumulation as an output), although their SLR methodology is documented.       The plan is to carry over the RAP/HRRR products into the RRFS (replacing all of the regional models in 2023) and build it into the 2024 GFS/GEFS upgrade.

[WinterWxLuvr]

8 minutes ago, mappy said:

you post every map there is available. 

Literally laughed out loud in class with students looking at me like I’m crazy

[mappy]

1 minute ago, WinterWxLuvr said:

Literally laughed out loud in class with students looking at me like I’m crazy

oops! don't get me wrong, some are useful. but its expected that WeatherWill will post maps.  

[FPizz]

6 minutes ago, usedtobe said:

Geoff, How does the Parallel GFS do compared to the current version.  I noticed the 00Z parallel from last night had much lower pressure over the Great Lakes than the 00Z operational so it forecast all rain across the area.  It was quite a bit farther west with the secondary.  Despite the overly rosey Eruo ensemble snow probabilities, the lows were all over the place,  lots of spread. 

Last I saw a few days ago, it performs worse than the Euro, current GFS, Ukie and CMC.  

[high risk]

9 minutes ago, usedtobe said:

Geoff, How does the Parallel GFS do compared to the current version.  I noticed the 00Z parallel from last night had much lower pressure over the Great Lakes than the 00Z operational so it forecast all rain across the area.  It was quite a bit farther west with the secondary.  Despite the overly rosey Eruo ensemble snow probabilities, the lows were all over the place,  lots of spread. 

           The parallel GFS had statistically significant synoptic range improvement over the ops GFS in the medium range over the full course of the retrospective runs.     But that certainly doesn't preclude it doing worse on any single event.     I wish we were able to run it more than once per day right now.....

[Weather Will]

12z Icon is a miserable cold rain for everyone on Monday.  Rejoice, no snow map for anyone!

[mappy]

2 minutes ago, Weather Will said:

12z Icon is a miserable cold rain for everyone on Monday.  Rejoice, no snow map for anyone!

oh man, we lost the Icon? pack it up friends. 

[Snowchaser]

ICON coming in shitting for the Wednesday event. No big snow 

[LP08]

ICON for Wednesday looks like some light snow to frozen precip.  Nothing extraordinary for anyone even up the coast.

[Snowchaser]

This could be an ice storm in the making for the peeps in Virginia. 

[WinterWxLuvr]

I think the ICON is terrible but that’s just my opinion.

[BristowWx]

1 minute ago, Snowchaser said:

This could be an ice storm in the making for the peeps in Virginia. 

DT talked about that too.  Ice can be fun.

[Eskimo Joe]

What is the ICON, is it an American model that's operational or something still under DEV?

[usedtobe]

13 minutes ago, high risk said:

           The parallel GFS had statistically significant synoptic range improvement over the ops GFS in the medium range over the full course of the retrospective runs.     But that certainly doesn't preclude it doing worse on any single event.     I wish we were able to run it more than once per day right now.....

That's what I thought I remembered from yesterday's Sterling winter weather workshop.

[Scraff]

16 minutes ago, mappy said:

oh man, we lost the Icon? pack it up friends. 

I’m waiting for the CRAS and Panasonic model to tell me NO before I cliff dive. 

[mappy]

5 minutes ago, Scraff said:

I’m waiting for the CRAS and Panasonic model to tell me NO before I cliff dive. 

good call to wait for the best models to show their hands

[LP08]

Through 93, better confluence pressing down over the NE on the 12z GFS.