December 16-17, 2020 Winter Storm

[Birds~69]

 

7 minutes ago, Ralph Wiggum said:

I take full responsibility. I saw once the thread was started in the Mid Atl forum it began to unravel for them. I should have known better.  The second I started one for us things began to unravel here. Not sure if they started one in the other PA forum. 

Public hanging? Perhaps a PPV event...

[Moderately Unstable]

Mkay gotta correct the record here. Kuchera totals are used because they calculate how TEMPERATURE affects RATIOS. Sometimes, that results in greater than 1:10, but NOT always. Here, the Kuchera ratios have been *consistently* less than the 1:10 ratios. Therefore, Kuchera ratios are NOT giving falsely high amounts. If anything, the 1:10 maps do that. Let's check out how:

 

Ratio= 12 + 2(271.16K-T_max), when Tmax is >271.16K. Note, 273.15K=0C; 1 degree increment C=1 degree increment K. 

Ratio = 12 + (271.16K-T_max), when Tmax is <271.16K. 

Cool. So, the max temp in the column here is between 1 and 1.5 degrees C. 273.15+1=274.15, 273.15+1.5=274.65. Let's plug that in. 12+2(271.16-274.15)=12 MINUS 2*3...12-6....SIX. 1:6. Kuchera ratios are not the problem. 

 

GFS Kuchera ratio for hour 42, 12z run, attached, for PHL.

 

Please note, I am not "defending the models" here, or trying to claim the city will see more snow. I'm mainly saying, there's a lot of claims of Kuchera being pointless. It isn't. It takes 1:10, which is the forecast equivalent of using the 540 line as your rain snow line, and makes it more scientifically precise by calibrating it to the situation. Right or wrong, the Kuchera method itself is not the problem. 

[Hurricane Agnes]

1 hour ago, MA-EOC said:

This may not be a totally bad thing if this thing heads off somewhere else.

I have been involved with emergency management at the county, state and federal levels for almost 30 years. Our agency is now directly involved with a logistical mission that easily rivals D-Day (less the ships) that include 10’s of thousands of trucks loads/last mile deliveries, over a thousand aircrews on hundreds of aircraft, regular army, reserve units and national guard units along with state and county assets all orchestrated 24/7 to delivering vaccines to the MidAtlantic NE region front line workers and first responders most at risk. The delays this storm will cause will be monumental. If this thing ends up dry slotting here and dumping somewhere else it may actually save lives locally. Having to re-task guard units, local assets and reroute aircraft and trucks will take a week or more to recover from. Truth is, these storms cause serious injury and deaths to older or more health challenged citizens, neighbors and family members during a “normal year”, this year especially with CO-19 the challenges have multiplied exponentially. Maybe we should hope for a nice warm rainy winter this year.

We receive our briefings from NWS and two private services. The private services have been spot-on, early-on during the majority of heavy weather events and even with their tropical discussions (I am not permitted to divulge specifics, but both services were bearish on the actually snow accumulations in Metro Philly since Sunday). I learn much more here. Although they will answer specific questions, they have neither the time nor inclination to teach even fundamental meteorology. Some of the folks here are amazing - insights, discussions, explanations are incredibly helpful to me when I’m involved with one of our briefs. Keep up the awesome work, you guys should get paid for this. Stay Safe / Stay Healthy!

Definitely appreciate what you guys are doing and then trying to do it in winter during an active weather period (am watching Philly's weekly coronavirus briefing right now).

ETA - I just segued to Gov. Wolf who is doing a weather briefing with PEMA...

[RedSky]

12 minutes ago, Moderately Unstable said:

Mkay gotta correct the record here. Kuchera totals are used because they calculate how TEMPERATURE affects RATIOS. Sometimes, that results in greater than 1:10, but NOT always. Here, the Kuchera ratios have been *consistently* less than the 1:10 ratios. Therefore, Kuchera ratios are NOT giving falsely high amounts. If anything, the 1:10 maps do that. Let's check out how:

 

Ratio= 12 + 2(271.16K-T_max), when Tmax is >271.16K. Note, 273.15K=0C; 1 degree increment C=1 degree increment K. 

Ratio = 12 + (271.16K-T_max), when Tmax is <271.16K. 

Cool. So, the max temp in the column here is between 1 and 1.5 degrees C. 273.15+1=274.15, 273.15+1.5=274.65. Let's plug that in. 12+2(271.16-274.15)=12 MINUS 2*3...12-6....SIX. 1:6. Kuchera ratios are not the problem. 

 

GFS Kuchera ratio for hour 42, 12z run, attached, for PHL.

 

Please note, I am not "defending the models" here, or trying to claim the city will see more snow. I'm mainly saying, there's a lot of claims of Kuchera being pointless. It isn't. It takes 1:10, which is the forecast equivalent of using the 540 line as your rain snow line, and makes it more scientifically precise by calibrating it to the situation. Right or wrong, the Kuchera method itself is not the problem. 

Paul's kuchera map is a fail for the ECM as it is going with strict 10:1 ratio over SEPA euro liquid output is 1.0-1.2" I don't know what happened but it miscalculated.

 

[Rockem_sockem_connection]

The Kuchera would show double the regular model and that's the images that were being plastered everywhere simply because they showed more snow. I understand how it's supposed to work but people can't just favor whatever shows the most snow because that's what they want. Wish casting isn't a thing.

[Itstrainingtime]

31 minutes ago, Ralph Wiggum said:

I take full responsibility. I saw once the thread was started in the Mid Atl forum it began to unravel for them. I should have known better.  The second I started one for us things began to unravel here. Not sure if they started one in the other PA forum. 

No, we didn't start a thread specific to this storm. We did back in January 2016 and that worked out pretty well.  This storm seems likely to be a true divider in our sub with areas near UNV looking at perhaps 20" while southern parts of York and Lancaster might see 1/4 of that. 

[Moderately Unstable]

Well, yeah, I *do* agree that if a model is showing a 1:10 ratio for SEPA for this storm, regardless of which one, that's not credible. Sometimes, Kuchera does go ham --when the conditions aren't so marginal--and can indeed overdo things substantially. Here though, I honestly think the "main story" is, the models are, collectively, shifting the storm North. They're doing that due to the Canadian HP traveling more E than previously forecast, so the expected strong block in place that would preclude a negative NAO from shoving a low into the coast, is not progged as being as influential, so the tucked in solutions end up working more. I don't think the Kuchera ratios were wrong relative to the dynamics the models in question forecasted earlier on. They weren't 1:10. The maps I have with 1:10, and in this thread, show 18-20+" in Philly consistently. Kuchera is more in the 10-15 range. Both seem high now, but Kuchera was lower. The thing I am disputing is that "kuchera inflates the totals". At best, it isn't deflating them enough. Euro may have incorrectly parameterized the column temp, sure. Again, not an issue with the method itself though, and the theory behind it. 

 

Final point (unrelated to Kuchera): the storm isn't here yet, and won't peak until tomorrow night for this forum's area. The trends are bad, the fat lady has left her dressing room, but she is not yet at the microphone. In other words, trends are bad. They will keep oscillating, one way or another. 

[Birds~69]

Little early for the MA forum to start nowcasting but hey if it works...it works.

36F

[LVblizzard]

Here’s my guess for accumulations:

Philly: 3-6”

Trenton: 4-8”

Lancaster: 8-14”

Doylestown: 6-10”

Harrisburg: 12-18”

Allentown: 8-14”

[The Iceman]

Mt Holly update. Big time cut in places.

 

 

[hazwoper]

18Z NAM has ticked south

[Birds~69]

2 minutes ago, LVblizzard said:

Here’s my guess for accumulations:

Philly: 3-6”

Trenton: 4-8”

Lancaster: 8-14”

Doylestown: 6-10”

Harrisburg: 12-18”

Allentown: 8-14”

Solid and fair. Non weenie...

[LVblizzard]

1 minute ago, The Iceman said:

Mt Holly update. Big time cut in places.

 

 

I’ll permanently delete my account if Doylestown hits 16”

[Birds~69]

1 minute ago, LVblizzard said:

I’ll permanently delete my account if Doylestown hits 16”

10-12" max I would think?

This has to be a bitch of a forecast for Mets...

[hazwoper]

still ends up in same position 9Z on Thursday off AC, but a tad colder

[Newman]

18z NAM says NW folk don't jump off the cliff yet. Came back SE. One or two more bumps like that at 0z and 6z and Philly is in good shape. A big thing to look for is how quick the low escapes east. It'll drag the warm layer/dry slot with it and you'll limit any time before the CCB pulls through.

12z:

 

18z:

 

Great improvement. And I know people will bash Kuchera, but it will excel in cases like this. It won't count sleet as snow. See the 12z map and how low the totals are in SE PA? That's because the Kuchera map takes into account sleet. Much less at 18z. 

[The Iceman]

Just now, Newman said:

18z NAM says NW folk don't jump off the cliff yet. Came back SE. One or two more bumps like that at 0z and 6z and Philly is in good shape. A big thing to look for is how quick the low escapes east. It'll drag the warm layer/dry slot with it and you'll limit any time before the CCB pulls through.

12z:

 

18z:

 

Great improvement. And I know people will bash Kuchera, but it will excel in cases like this. It won't count sleet as snow. See the 12z map and how low the totals are in SE PA? That's because the Kuchera map takes into account sleet. Much less at 18z. 

Much better WAA thump before the changeover to sleet even down to 95. Great improvement!

[Animal]

16 minutes ago, The Iceman said:

Mt Holly update. Big time cut in places.

 

 

Reasonable forecast.. 6-8 my area in the southern snow belt. 

[hazwoper]

17 minutes ago, LVblizzard said:

I’ll permanently delete my account if Doylestown hits 16”

click on the figure.  It is updated to 10" in Doylestown

[LVblizzard]

5 minutes ago, hazwoper said:

click on the figure.  It is updated to 10" in Doylestown

Ah good catch. That’s definitely more reasonable.

[ChescoWx]

18z NAM much more in line now with GFS Euro.....makes more sense

[Moderately Unstable]

18z nam is definitely an improvement for my area. 500 mb heights down substantially, better CCB positioning.

[MPotter_WX]

41 minutes ago, The Iceman said:

Mt Holly update. Big time cut in places.

 

 

Honestly, this should have been the forecast this AM...

[Birds~69]

1 minute ago, MPotter_WX said:

Honestly, this should have been the forecast this AM...

True.

They went haywired nuts early for some reason....  

[ChescoWx]

Just want to be sure everyone on here knows sleet counts as snow.....it just accumulates slower. When measuring tomorrow you should measure the snowfall when it changes to sleet/IP and then measure the sleet accumulation in inches. If it goes back to snow clean the board and start over. You then add the 3 together to get the total snow total. No doubt most know this but want to be sure

[Newman]

3 minutes ago, ChescoWx said:

Just want to be sure everyone on here knows sleet counts as snow.....it just accumulates slower. When measuring tomorrow you should measure the snowfall when it changes to sleet/IP and then measure the sleet accumulation in inches. If it goes back to snow clean the board and start over. You then add the 3 together to get the total snow total. No doubt most know this but want to be sure

I have work Thursday morning, but I guess I'll be pulling an all-nighter anyway to get the most accurate measurements 

[Animal]

3k nam ween map

[Furrawn]

Honestly, even six inches will feel like a monumental windfall to me after the past 652 days. 

[Birds~69]

Glenn's 4pm snow map. Honestly I don't what we may be bitching about? Compared to last year this is gold...

[Animal]

1 minute ago, Birds~69 said:

Glenn's 4pm snow map. Honestly I don't what we may be bitching about? Compared to last year this is gold...

 

solid storm..just proves how hard it is to get the big ticket snow events, especially at phl airport. Need to have a reality check with what your seasonal snow averages are by location.