December 16/17 Winter Event

[DDweatherman]

1 minute ago, psuhoffman said:

I don't know if I really view the GFS as a reversal of the trend.  It shifted the low track NW.  That is the trend...all our other problems come from the fact the low keeps trending west with every run.  Within that the GFS improved on some meso features that helped us out.  An earlier close of the mid level circulation and such a more tightly wound system.  And that worked for us wrt snowfall.  But that is a meso detail within the larger scale...and on the larger scale the trend was another shift west in the low track.  It is fine to celebrate the good things about this GFS run but we shouldn't overlook the bad.  If the trend in the track were to halt NOW and adjust east slightly we are still close enough (NW of 95) to salvage things if the details like early close of the mid levels and banding and fast WAA thump go our way.  So its good to see some of that on the GFS.  But we need the larger trend with the track of the system to stop or it wont make any difference.  If this tracks up west of the bay no one in here is going to be happy no matter how the meso nowcast details shake out.  

I agree with you on this. It does seem like the meso features help the thermals quite a bit on the GFS wrt evolution, and as I pointed out the ML's closing off. Agreed though that a track up the bay to NAK isn't going to get it done. The double barrel low structure we have seen on a number of models is still a bit puzzling to me, and I've dug into the mid level maps to see if that's warranted. I wonder realistically if that's driven by convection on some models since the UL features don't align with the base of the trough putting a low over the middle of the Chesapeake. I'm still liking a track from VA beach to east of SBY (hopefully on the coast of OC) north to Lewes before going more ENE. 

[baltosquid]

HREF ensemble shows Snow-Mix-Snow for Baltimore, Snow-Mix-Rain-Snow for DC. 2-4 inches for the former and maybe an inch for the latter through 00z Thursday. No back end snow totals shown yet but it looks like there will be a couple hours of it for Baltimore and not much for DC.

[psuhoffman]

6 minutes ago, DDweatherman said:

The GEM is the only 12z model that got worse for us so far thankfully. We're gonna need the Euro to hold up. 

I don't agree.  There are meso scale features to any run that might change the exact snow/ice output on some snowmap for a specific location.  But the trend killing us is the NW shift in the low track.  It's been relentless for 48 hours...it started as a very slow bleed that was hardly noticeable run to run but it where there...and its accelerated the last 3 runs.  The 12z guidance shifted west again...across EVERYTHING i saw.  Some of the runs had a better snow result for a specific spot due to a meso scale feature within the run...but across the board the track was a bad move.   And that is way more important because those meso details will change every run and be a nowcast thing...but if that track keeps adjusting west it won't matter.  Every shift west reduces the chances of all those meso features to help much.  I think we have reached the stage where a lot of people are grasping at straws and holding on tight to whatever little speck of data they can find to give hope.  I get it.  I really do.  But I just can't do the blinders bad analysis thing.  

[clskinsfan]

3 minutes ago, psuhoffman said:

I don't agree.  There are meso scale features to any run that might change the exact snow/ice output on some snowmap for a specific location.  But the trend killing us is the NW shift in the low track.  It's been relentless for 48 hours...it started as a very slow bleed that was hardly noticeable run to run but it where there...and its accelerated the last 3 runs.  The 12z guidance shifted west again...across EVERYTHING i saw.  Some of the runs had a better snow result for a specific spot due to a meso scale feature within the run...but across the board the track was a bad move.   And that is way more important because those meso details will change every run and be a nowcast thing...but if that track keeps adjusting west it won't matter.  Every shift west reduces the chances of all those meso features to help much.  I think we have reached the stage where a lot of people are grasping at straws and holding on tight to whatever little speck of data they can find to give hope.  I get it.  I really do.  But I just can't do the blinders bad analysis thing.  

psu what is causing the western shift of the track? Is it a more wound up system?

[WinterWxLuvr]

12 minutes ago, psuhoffman said:

I don't know if I really view the GFS as a reversal of the trend.  It shifted the low track NW.  That is the trend...all our other problems come from the fact the low keeps trending west with every run.  Within that the GFS improved on some meso features that helped us out.  An earlier close of the mid level circulation and such a more tightly wound system.  And that worked for us wrt snowfall.  But that is a meso detail within the larger scale...and on the larger scale the trend was another shift west in the low track.  It is fine to celebrate the good things about this GFS run but we shouldn't overlook the bad.  If the trend in the track were to halt NOW and adjust east slightly we are still close enough (NW of 95) to salvage things if the details like early close of the mid levels and banding and fast WAA thump go our way.  So its good to see some of that on the GFS.  But we need the larger trend with the track of the system to stop or it wont make any difference.  If this tracks up west of the bay no one in here is going to be happy no matter how the meso nowcast details shake out.  

You have forgotten more weather than I’ll ever know but I have to say that I don’t agree with this.  It seems everyone just looks at the letters L and H but never at the isobars. At 36 the gfs has the lowest pressure over Norfolk. Same as previous run. At 42 the lowest pressures are well off shore where as at 6z they were right over Ocean City. Just my take.

[Eskimo Joe]

9 minutes ago, baltosquid said:

HREF ensemble shows Snow-Mix-Snow for Baltimore, Snow-Mix-Rain-Snow for DC. 2-4 inches for the former and maybe an inch for the latter through 00z Thursday. No back end snow totals shown yet but it looks like there will be a couple hours of it for Baltimore and not much for DC.

The 12z HREF ensemble is actually a touch colder than it's 00z counterpart. I do not know the blend of what goes into it. 

[WinterWxLuvr]

I don’t agree that it came more NW from 6z

[Ellinwood]

21 hours ago, Ellinwood said:

Updated my snow map... cut down on the total on the eastern gradient (mainly DC up I-95 and through southern and central NJ). Increased totals along the Appalachians.

No changes... gradient area near I-95 is boom or bust at this point. Leaning slightly toward bust near I-95, but this isn't worth micro-editing.

[baltosquid]

1 minute ago, Eskimo Joe said:

The 12z HREF ensemble is actually colder than it's 00z counterpart. I do not know the blend of what goes into it. 

HRRR, HRRR 6h, HRW ARW, HRW ARW 12h, HRW NMMB, HRW NMMB 12h, HRW NSSL, HRW NSSL 12h, NAM CONUS Nest, NAM CONUS Nest 12h

SPC HREF Ensemble Viewer - 500 mb wind/height, ens mean (noaa.gov)

They've got a surprisingly good interface imo. At least compared to some other .gov sites lol.

[Fozz]

Just now, Ellinwood said:

No changes... gradient area near I-95 is boom or bust at this point. Leaning slightly toward bust near I-95, but this isn't worth micro-editing.

Yeah I’m thinking @North Balti Zen should stay the course on his planned trip. 

[PhineasC]

After all these years, people still don’t recognize when psuhoffman goes into reverse psychology mode. LOL

[FXW176]

2 minutes ago, Ellinwood said:

No changes... gradient area near I-95 is boom or bust at this point. Leaning slightly toward bust near I-95, but this isn't worth micro-editing.

Thank you as always @Ellinwood. Your maps are seriously one of the very few I share with friends and fam. Apprec!

[WinterWxLuvr]

Also take a look at the precip maps at 42. Toggle between the 12z and 6z runs. You can see a pronounced counterclockwise turn. I think that’s significant if you’re hoping for a temp crash and a burst of snow on the backend

[aldie 22]

4 minutes ago, PhineasC said:

After all these years, people still don’t recognize when psuhoffman goes into reverse psychology mode. LOL

I swear I was about to write the same thing....."it's the debate coach in me" excuse is gonna come out next

[DDweatherman]

Just now, WinterWxLuvr said:

Also take a look at the precip maps at 42. Toggle between the 12z and 6z runs. You can see a pronounced counterclockwise turn. I think that’s significant if you’re hoping for a temp crash and a burst of snow on the backend

Although I am definitely rooting for that as part of the outcome, I'd favor a good slug/thump of WAA on the front end to lay a nice base of snow and get some good rates. That could also help keep the column cool if we do get the secondary snow from any wraparound. Keep watching those h7/h85 depictions...those closing off is part of our recipe to do well. 

[aldie 22]

2 minutes ago, WinterWxLuvr said:

Also take a look at the precip maps at 42. Toggle between the 12z and 6z runs. You can see a pronounced counterclockwise turn. I think that’s significant if you’re hoping for a temp crash and a burst of snow on the backend

his rebuttal to you is going to be 2 pages long and I swear i'm going to quote it 5 times

[Amped]

2 minutes ago, WinterWxLuvr said:

Also take a look at the precip maps at 42. Toggle between the 12z and 6z runs. You can see a pronounced counterclockwise turn. I think that’s significant if you’re hoping for a temp crash and a burst of snow on the backend

Last second trends always make an accurate forecast practically impossible. Now it's up to mets to gamble and extrapolate the  models even further NW cause the models are playing catch up and won't quite make it.

 

[baltosquid]

Here's what the HREF ensemble spits out through 12z Thursday.

[DDweatherman]

Just now, wxtrix said:

our upper air temps never go above freezing on that run so i don't think it's west.

Agreed trixie. I think in reality the surface reflection isn't indicative of where the true LP center is. Mesoscale differences aside, a more wound up system that does cause the mid levels to close off/stack for us might also be what is giving the double barrel look where we're seeing a low over the bay instead of over OC/right off the coast. 

[baltosquid]

And the weenie version of the same map...

I'm gonna pay attention to Frederick's totals to see if the HREF is picking up on the jackpot. No grades will be given but it will be fun to check.

[WinterWxLuvr]

3 minutes ago, baltosquid said:

And the weenie version of the same map...

I'm gonna pay attention to Frederick's totals to see if the HREF is picking up on the jackpot. No grades will be given but it will be fun to check.

I’m going with this one lol

[catoctin wx]

4 minutes ago, baltosquid said:

And the weenie version of the same map...

I'm gonna pay attention to Frederick's totals to see if the HREF is picking up on the jackpot. No grades will be given but it will be fun to check.

That jackpot appears to be right through Emmitsburg.  Well positioned for the win on this weenie map @North Balti Zen

[BTRWx's Thanks Giving]

5 minutes ago, baltosquid said:

And the weenie version of the same map...

I'm gonna pay attention to Frederick's totals to see if the HREF is picking up on the jackpot. No grades will be given but it will be fun to check.

What do you mean by weenie version? How are they different?

[North Balti Zen]

@catoctin wxWin. Snow, BBQ and my labrador retriever.  I would like this to work out.

[psuhoffman]

22 minutes ago, clskinsfan said:

psu what is causing the western shift of the track? Is it a more wound up system?

Death by a thousand paper cuts.  The high has trended SLIGHTLY NE of where it was days ago.  The confluence in the NE weakened some.  The 50/50 moves out slightly faster...and the storm slowed down 6-12 hours...increasing the spacing between the two and allowing for more ridging in front of it.  I was always bothered by how far west the upper level trough was going neutral and starting to lift, we needed all those other things to offset and they went the wrong way.  Some problems that I think the globals had a hard time seeing at range...that are now coming into focus (NAM saw it from jump) was the without a closed off mid and upper level circulation (ERS talked about this) there is nothing to stop the easterly flow north of the low from blasting way NW.  Add in all the warm water and that is shifting the boundary west...and the low track right with it.  I don't think there is any one thing to point to that did this...it was a lot of things that all went the wrong way...and that was partly why this was a slow bleed and not a sudden shift.  No one factor suddenly got a LOT worse...they all just degraded along the margins a little.  IMO what hurt us most was just a little too much spacing between the 50/50 combined with the trough digging in a little too far west then lifting instead of amplifying along the east coast.  The other factors like warm water and less confluence and shallow cold could have overcome that if they had all trended perfectly...but the warts in the overall synoptic setup required a lot else to go perfect...for a time it seemed like they all would.  

[catoctin wx]

1 minute ago, BTRWx's Thanks Giving said:

What do you mean by weenie version? How are they different?

Ensemble max vs. ensemble mean

[dailylurker]

Woohoo! Got an advisory! Yay flood watch lmao. I won't be laughing at the NAM anymore. 

[clskinsfan]

UKIE at the mouth of the bay at 36. But 540 line well west.

 

[DDweatherman]

Just now, psuhoffman said:

Death by a thousand paper cuts.  The high has trended SLIGHTLY NE of where it was days ago.  The confluence in the NE weakened some.  The 50/50 moves out slightly faster...and the storm slowed down 6-12 hours...increasing the spacing between the two and allowing for more ridging in front of it.  I was always bothered by how far west the upper level trough was going neutral and starting to lift, we needed all those other things to offset and they went the wrong way.  Some problems that I think the globals had a hard time seeing at range...that are now coming into focus (NAM saw it from jump) was the without a closed off mid and upper level circulation (ERS talked about this) there is nothing to stop the easterly flow north of the low from blasting way NW.  Add in all the warm water and that is shifting the boundary west...and the low track right with it.  I don't think there is any one thing to point to that did this...it was a lot of things that all went the wrong way...and that was partly why this was a slow bleed and not a sudden shift.  No one factor suddenly got a LOT worse...they all just degraded along the margins a little.  IMO what hurt us most was just a little too much spacing between the 50/50 combined with the trough digging in a little too far west then lifting instead of amplifying along the east coast.  The other factors like warm water and less confluence and shallow cold could have overcome that if they had all trended perfectly...but the warts in the overall synoptic setup required a lot else to go perfect...for a time it seemed like they all would.  

So, what do we look for now for some last minute respite? 

[BTRWx's Thanks Giving]

Just now, catoctin wx said:

Ensemble max vs. ensemble mean

Do ensemble max charts even belong here?