March 13/14th Post Storm Undertaking (psu) Storm

[vinylfreak89]

I think some of the issues with snow maps are simply they are not as mature as other tools we use in modeling. Therefore, I don't think we should avoid them, but rather figure out ways to utilize them in their respective capacities... correcting for bias, etc, the same way we interpret models.

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[dallen7908]

Must say I'm disturbed by the weather service's decision to stick with the forecast for heavy snow even after the model's backed off.  With all of the other forecasts out there the decision by the NWS to stick with an old forecast and ignore new data adds confusion and encourages people to look elsewhere for information.  The proper approach is to back away slowly .. but back away.   Why set yourself up to fail? 

I enjoy the snow maps but the map of Kucseria values may be informative.  Glad the NC guy risked the ire of our forum's policemen and posted it.  

[Stradivarious]

Watching the news... the story is the National weather service knew or had a very good idea  ( being generous here) that the storm would produce less than forecast in the big cities (DC, Balt, Philly, and NY) by Monday afternoon..but didn't change their forecast because they didn't want to "confuse" the public...that is a problem I imo. I want to trust that the National Weather Service is leveling with me as to what severe weather is on tap...but if I have to alway wonder if they might not be telling me the truth as they know it...or overhyping on purpose...what is their credibility when a disaster is truly looming?

 

http://wtop.com/science/2017/03/weather-service-decided-last-minute-not-to-cut-snow-forecast/

 

 

[gymengineer]

5 minutes ago, Stradivarious said:

Watching the news... the story is the National weather service knew or had a very good idea  ( being generous here) that the storm would produce less than forecast in the big cities (DC, Balt, Philly, and NY) by Monday afternoon..but didn't change their forecast because they didn't want to "confuse" the public...that is a problem I imo. I want to trust that the National Weather Service is leveling with me as to what severe weather is on tap...but if I have to alway wonder if they might not be telling me the truth as they know it...or overhyping on purpose...what is their credibility when a disaster is truly looming?

 

http://wtop.com/science/2017/03/weather-service-decided-last-minute-not-to-cut-snow-forecast/

 

 

LWX *did* cut back and pushed the 6" line well northwest in their afternoon update. Taunton also put a note on their snow total graphic that confidence was lower for an encircled (coastal) portion because of possible mixing. 

[North Balti Zen]

Yeah, not sure why LWX is getting lumped in with whatever the issues were to the northeast of the beltways with a bust. I thought LWX was pretty responsive to the situation and did a good job with it. Not sure why people still don't get how razor thin it can be on the east coast trying to pin down conditions and snow totals when the line between snow and mix and rain is so hard to figure in any given nor'easter...

[gymengineer]

13 minutes ago, Stradivarious said:

Watching the news... the story is the National weather service knew or had a very good idea  ( being generous here) that the storm would produce less than forecast in the big cities (DC, Balt, Philly, and NY) by Monday afternoon..but didn't change their forecast because they didn't want to "confuse" the public...that is a problem I imo. I want to trust that the National Weather Service is leveling with me as to what severe weather is on tap...but if I have to alway wonder if they might not be telling me the truth as they know it...or overhyping on purpose...what is their credibility when a disaster is truly looming?

 

http://wtop.com/science/2017/03/weather-service-decided-last-minute-not-to-cut-snow-forecast/

 

 

And I started a thread below about this very article with the title "AP claims....." because I can't tell from the article if the local forecast offices agreed with the WPC forecaster's assessment. As in maybe the WPC were convinced of the warm incursion but Upton was still convinced of their own numbers. The WPC percent probability maps don't line up verbatim with the local offices sometimes.

[mappy]

2 hours ago, Bob Chill said:

I've decided I hate snow maps in the short range. A pure clean storm with no chance of mixing is the only time snow maps are accurate but even then using soundings, surface, and midlevel temp plots and thinking it through is an exercise that is far more intellectual and fun. When I started seriously tracking weather back in 06 there was no such thing as a snow map. They are a recent development. There is no standardized consistency in the algorithm each vendor uses. Kuchera is relatively new and I like those the best if I had to pick one. 

My favorite pre-storm discussions are when Wes, Matt, Ian and I look at the fine details of all the different layers. Breaking down the atmosphere at the different levels and envisioning what sort of ground truth to expect is the art of this hobby. Snow maps are a shortcut, often misleading, and require no skill to understand. 

With that being said, individual ensemble member snow maps at range are pretty useful for setting confidence at longer leads. You get a fast glance at how much support there is for frozen precip in general within the ensemble means. There is value there. 

I agree completely that ensemble member snow maps should totally be used. You can easily see the highs, lows and middle of the model output without being distracted by the OMG MY AREA IS GETTING A FOOT BASED ON THIS ONE ALGORITHM map that many sites put out now. 

2 hours ago, MN Transplant said:

Another point on the HRRR though, it really went off-the-rails at one point with the QPF amounts.  I think it is having some trouble with too much precipitation in banded features.

I didn't pay enough attention towards the end of day Monday. By that point I was tired and just wanted the storm to play out as it was going to and not torture myself looking at HRRR every hour. With that said, I don't recall what it had for the eastern shore, but KSBY broke a daily rainfall record yesterday with 2.92" precipitation. I know that none of the major models were putting out that kind of precip for that area. So the HRRR may not have been too far off, if it had that kind of values on the eastern shore. 

1 hour ago, cae said:

I get what you're saying, but some of that has more to do with the models than the maps.  A lot of models missed the warm layer until the last couple of days (and even then some of the globals struggled with it).  It's frustrating, but overall I still think the models are pretty impressive.  There's clearly still room for improvement when it comes to getting precipitation type right, which is understandable considering that a small error in temperature can have a big effect on what falls out of the sky.  If the models ever do get good enough to be able to nail p-type well in advance, I wonder if I'll miss these days.  In a way it's more interesting when we know there's a reasonably good chance of a last-minute surprise.

Regarding maps, another innovation that I've seen more use of is the "snow depth" maps.  I'm not sure what algorithm pivotalweather uses for theirs and I'm not sure how accurate they are, but I like the idea.  Snow depth gives a more complete picture of what to expect out of a storm.  I think yesterday was a good example.  It was snowing here at different rates through much of the day, and I'm pretty sure some of it accumulated, as areas that had been trampled sleet in the morning had a layer of snow on them by the evening.  But snow depth in my yard was roughly steady or even decreasing throughout the day, as the new accumulations were offset by melting/compacting of what was already on the ground.

Yes, the models missed the warm layer, mainly because the models had the low further east. It nudging just a tad west is what pushed the 850 warm nose into our area (I mean, well into our area, who thought the Carroll County folks would even see sleet??). No model was going to nail that down until the very last second and by then, nothing you can do. This also goes into the whole NWS blew the forecast thing. While yes, the forecast IMBY was a horrible bust, I can't blame LWX for it. The potential for 12+ was there, even just hours leading to precip starting. I have no idea if they ended up dropping totals throughout the night, as I decided sleep was more important than staying up to see what happened, but I didn't expect to flip to sleet at 2-3am and stay there for 8+ hours. I can imagine LWX didn't expect it either, given they stayed the course. The weather is humbling and I wish more amateurs would understand that instead of throwing the weather people under the bus. 

I'm okay with snow depth too, but without knowing what goes into it to decide how fall snow melts or doesn't melt, I'm still iffy on it. The maps are great to look at it, and in a crystal clear 10:1 situation, where mixing won't be an issue, dry slot, etc. Sure, use them. But how often are systems that perfect?? 

[Stradivarious]

i understand it was a difficult forecast to make. My problem is with the weather service not informing the public of their best information to enable the public to make good decisions. To hype a situation to goad the public to take precautions they might not otherwise take. To assume we are easily confused. Can you say "cry wolf"?

 

this clearly has nothing to do with a disagreement between the WPO and local national weather offices

 

https://www.google.com/amp/www.dailymail.co.uk/news/article-4314124/amp/Weather-Service-decided-minute-not-cut-snow-forecast.html

 

[hosj III]

I don't think the harm is in snow maps per se, but perhaps in sharing them to the public. Most enthusiasts and I would hope all meteorologist know the limitations of snow maps, but the public does not. We know for instance that weatherbell maps will almost laughably overestimate totals on the r/s line, and that stormvista maps will tend to underestimate them.

The move towards communicating specific model outputs to the public and especially sharing snow maps might have the intention of educating the public about the process of forecasting, but I think it falls flat because they don't have the right context to understand and interpret weather models. People tend to latch on to the highest model outputs and things such as "CWG said the GFS shows 18" can easily be lost in translation as "CWG said 18"!

The information about weather models should be out there for people looking to dig deeper but I think there should be a wide degree of separation between that and the actual forecast.

Also, Maue and Bastardi need to change the darn algothorithm on their snow maps. I don't imagine it would be that difficult and a great proportion of the weenie maps that float around are from weatherbell.

[SomeguyfromTakomaPark]

6 minutes ago, hosj III said:

I don't think the harm is in snow maps per se, but perhaps in sharing them to the public. Most enthusiasts and I would hope all meteorologist know the limitations of snow maps, but the public does not. We know for instance that weatherbell maps will almost laughably overestimate totals on the r/s line, and that stormvista maps will tend to underestimate them.

The move towards communicating specific model outputs to the public and especially sharing snow maps might have the intention of educating the public about the process of forecasting, but I think it falls flat because they don't have the right context to understand and interpret weather models. People tend to latch on to the highest model outputs and things such as "CWG said the GFS shows 18" can easily be lost in translation as "CWG said 18"!

The information about weather models should be out there for people looking to dig deeper but I think there should be a wide degree of separation between that and the actual forecast.

Also, Maue and Bastardi need to change the darn algothorithm on their snow maps. I don't imagine it would be that difficult and a great proportion of the weenie maps that float around are from weatherbell.

Yeah I agree with this.  People share the snow model maps on facebook and the public thinks they are snow forecast maps, like the ones NBC/ABC/Capitol Weather Gang make.  People don't know the difference between a model snow map and a forecast map. 

[BTRWx]

A random thought to add is if we use snow-maps we should compare them more often with as many different sites as possible for each model run especially when the rain/snow line comes anywhere close to our cwa.

Excellent points being made by everyone!

[Stradivarious]

This is becoming big news on Fox... Shepard Smith "the weather service lied to us".

 

just sayin it's a big problem

[EastCoast NPZ]

Therein lies the problem when entities come to think that they know what's best for you.  The best play is to always level with the public and then let them decide what to do with that information.

[SomeguyfromTakomaPark]

I'm not sure I've seen it mentioned here yet, but the U.K. did a good job with this storm IMO.  That weird 18z map someone posted showed a track that screwed all the major cities.   

[das]

Model depictions of precip, especially the East/West gradient, were very good, even with the slight westward shift of the track. 

[high risk]

On 3/15/2017 at 3:33 PM, Stradivarious said:

i understand it was a difficult forecast to make. My problem is with the weather service not informing the public of their best information to enable the public to make good decisions. To hype a situation to goad the public to take precautions they might not otherwise take. To assume we are easily confused. Can you say "cry wolf"?

 

         This isn't a fair assessment of what happened.   Your description makes it sounds like they always thought that, say, 6-12" was likely, but they were afraid that people might not take proper precautions, so they upped the forecast to 18-24" to scare the crap out of everyone.

          There was a time (Sunday) when the WFOs in Upton and Mt Holly thought that 18-24" was the most likely outcome for their CWAs.    By Monday, it was fairly clear that lower amounts were more likely.      The risk was that if they canceled the blizzard warning, people would treat the event as much less of a threat and not take the precautions that one should still take in a winter storm.     There was also still enough uncertainty, especially for the Upton CWA, that 18-24" was still a possibility even if it was no longer the most likely outcome.     It would be an even bigger disaster to lower amounts and then have to quickly raise them again.

           Don't get me wrong - I'm not convinced that the approach they took was correct.   I'm just saying that they were in a no-win situation.     Ultimately, conveying uncertainty in any forecast remains a massive challenge.

 

     

[Bob Chill]

I think the criticism is silly. It's not like they expected no storm and called for a phantom big storm. There was a time when it looked fairly likely that a very large stripe of heavily populated real estate was going to receive significant snow accumulations. And only at very short leads did it become more likely that it would be a smaller storm for population centers close to the coast.  

It was still a significant storm with hazardous travel conditions for a large area containing heavily traveled interstates. What measurable harm was caused by not lowering snow amounts? How many resources were wasted? 

There is more harm forecasting lower amounts and ending up getting a crippling snow storm. People were prepared for a high impact winter event and even though the snow amounts verified much lower than forecast closer to the coast, it still was a very bad night for unnecessary travel. 

Personally, I think a big deal is being made about it for the sake of it and not because the forecast had a large negative impact on a lot of people. The biggest "victims" were snow weenies who didn't get their historic blizzard. Lol

[EastCoast NPZ]

8 hours ago, Bob Chill said:

I think the criticism is silly. It's not like they expected no storm and called for a phantom big storm. There was a time when it looked fairly likely that a very large stripe of heavily populated real estate was going to receive significant snow accumulations. And only at very short leads did it become more likely that it would be a smaller storm for population centers close to the coast.  

It was still a significant storm with hazardous travel conditions for a large area containing heavily traveled interstates. What measurable harm was caused by not lowering snow amounts? How many resources were wasted? 

There is more harm forecasting lower amounts and ending up getting a crippling snow storm. People were prepared for a high impact winter event and even though the snow amounts verified much lower than forecast closer to the coast, it still was a very bad night for unnecessary travel. 

Personally, I think a big deal is being made about it for the sake of it and not because the forecast had a large negative impact on a lot of people. The biggest "victims" were snow weenies who didn't get their historic blizzard. Lol

Snow weenies lives matter.

[North Balti Zen]

The one takeaway that I would have if I were the NWS is maybe not go to "Blizzard Warnings" before the storm has started. I would think a Winter Storm Warning package with wording that it may be raised to Blizzard Warnings language would give them some wiggle room. I know I raised my eyebrows at the widespread blizzard warnings posted before the storm began. I would imagine that by itself raised people's expectations.

[Amped]

Some day I'd like to understand why about 50 percent of major east coast snowstorms are horrible busts for the southern 1/3  of the warned area.  

It's only a big deal when it's happens over I95 nobody talks about last year's Blizzard bust in  NC and SW VA.

[snowfan]

I'm on board w bob....the criticsm is silly. CWG is now on day 3 of trying to make this a big deal. Jason should just move on at this point. Storm is a memory at this point for most in our area.

[Bob Chill]

17 minutes ago, snowfan said:

I'm on board w bob....the criticsm is silly. CWG is now on day 3 of trying to make this a big deal. Jason should just move on at this point. Storm is a memory at this point for most in our area.

Seems that CWG is trying to make it some sort of political thing or something since NWS is an agency. Maybe it is a big deal but I fail to see why. I'm not big on politics. After living here for nearly 40 years you tend to start ignoring politics. At least I do anyways. There are much better things to do with my time. 

[EastCoast NPZ]

44 minutes ago, Amped said:

Some day I'd like to understand why about 50 percent of major east coast snowstorms are horrible busts for the southern 1/3  of the warned area.  

It's only a big deal when it's happens over I95 nobody talks about last year's Blizzard bust in  NC and SW VA.

I think that's just the nature of the beast.  East coast storms are usually terribly complex scenarios, often with lows transferring from one to the next, where the coastal low actually forms, how quickly it can deepen and form the CCB that usually provides the meat of the storms has great impact on the ground.  That usually means a pretty narrow stretch of the heaviest snows, so slight storm track differences have a huge net effect on snowfall totals and intensities.... not to even mention precip type.  It's amazing the forecasts are even as good as they are.

I'm not sure the busts are that much more horrible in the south. The last couple years alone have featured some big busts for NYC.  The southern areas due to their climo are always more at risk.  They have more temp issues and they are closer to the coastal low initialization, so the storm usually doesn't have as much time to mature for them.  If the low location is not south enough, or if it doesn't deepen in time, they are screwed.

Just give me CAD and a nice juicy low pressing into the OH valley.

[gymengineer]

11 hours ago, high risk said:

 

         This isn't a fair assessment of what happened.   Your description makes it sounds like they always thought that, say, 6-12" was likely, but they were afraid that people might not take proper precautions, so they upped the forecast to 18-24" to scare the crap out of everyone.

          There was a time (Sunday) when the WFOs in Upton and Mt Holly thought that 18-24" was the most likely outcome for their CWAs.    By Monday, it was fairly clear that lower amounts were more likely.      The risk was that if they canceled the blizzard warning, people would treat the event as much less of a threat and not take the precautions that one should still take in a winter storm.     There was also still enough uncertainty, especially for the Upton CWA, that 18-24" was still a possibility even if it was no longer the most likely outcome.     It would be an even bigger disaster to lower amounts and then have to quickly raise them again.

           Don't get me wrong - I'm not convinced that the approach they took was correct.   I'm just saying that they were in a no-win situation.     Ultimately, conveying uncertainty in any forecast remains a massive challenge.

 

     

This whole issue in the media would not have started if Greg Carbin (WPC) hadn't gone on record in an interview and said what he said. Sure, the reaction has been over the top, but this simply would have been viewed as a busted forecast and nothing more until the article came out.

[psuhoffman]

1 hour ago, Amped said:

Some day I'd like to understand why about 50 percent of major east coast snowstorms are horrible busts for the southern 1/3  of the warned area.  

It's only a big deal when it's happens over I95 nobody talks about last year's Blizzard bust in  NC and SW VA.

Because most of the time with an amplifying system along the east coast the adjustment at gametime is north. It's less then it once was. I don't think we still want to see a storm over the Carolinas 3 days out like we did 15 years ago. Now perhaps being in the northern portion of the depicted snow zone north of the bullseye is the ideal spot to be 2-3 days out. 

Yes there are exceptions and no rule works 100%. But those exceptions like feb 5 2010 usually involve extreme blocking and locked in confluence. Most of the time absent that the models tend to place the location of these systems just slightly southeast of reality, and they underdo the extend of mid level warming and they struggle with the extent of the northern expands of the qpf. Those 3 combined cause the famed north trend late. 

I said when we were still 4-5 days out we wanted enough south adjustment to be far enough into the snow to survive the late north adjustment. That never happened. If anything I violated my own advice when I wanted to believe we would do ok despite the writing being on the wall if I was objective the last 24 hours leading in. 

[psuhoffman]

There has been some really good points in here. Sometimes I think we over analyze the weather just being the weather. Could we have used the 50/50 to hold longer sure.  Maybe as I "feared" early on when I said that even when models were east our bigger threat given the pattern was west, that the timing was just off. Sunday's vort was 24 hours too soon and Tuesday's was 12 hours late for our perfect window for snow. Too much suppression then not enough. 

The track wasn't off by that much.  You all covered that well.

  Something I think hurt is also that hasn't been talked about as much was the lack of a well synced up system between the surface and upper levels. The h5 low was way behind and initially associated with the northern stream vort that went to our west. The storm was kind of a disjointed mess between the levels. That prevented a good compact Ccb development. It meant most of the precip until well north of us was waa driven. 

We could have survived a slp track like this and still done ok if the storm was better phased and then the heights crashing in the back side and better defined Ccb would have helped flip us back. But without that there was nothing to fight the mid level warming once it took over. 

In the end the places that got a crap ton of snow where places far enough north to survive the warm layer intrusion and get dumped by the waa moisture feed up the coast.  

The weird hybrid nature didn't work out for us. Had the southern vort been ahead like bob pointed out it might have. But once it dug in behind we needed a more consolidated system for that to work. I'm just disappointed it didn't work out better for all of us. 

[isohume]

On 3/15/2017 at 3:33 PM, Stradivarious said:

i understand it was a difficult forecast to make. My problem is with the weather service not informing the public of their best information to enable the public to make good decisions. To hype a situation to goad the public to take precautions they might not otherwise take. To assume we are easily confused. Can you say "cry wolf"?

 

this clearly has nothing to do with a disagreement between the WPO and local national weather offices

 

https://www.google.com/amp/www.dailymail.co.uk/news/article-4314124/amp/Weather-Service-decided-minute-not-cut-snow-forecast.html

 

So if the NWS would have said 8" in stead of 12" at the last hr in an uncertain fcst, how would that have benefited the civic actions already in play? They did actually lower their numbers on the evening shift to 8", which accounted for no change in the the em response already decided on hours earlier. The thing they should have done, IMO, is relay their uncertainty better, which is hard to do and not necessarily heard.  The NWS needs a way to quantify uncertainty where it is understood by the general public. This will be an arduous task to say the least and will take years.       

[BTRWx]

6 minutes ago, isohume said:

So if the NWS would have said 8" in stead of 12" at the last hr in an uncertain fcst, how would that have benefited the civic actions already in play? They did actually lower their numbers on the evening shift to 8", which accounted for no change in the the em response already decided on hours earlier. The thing they should have done, IMO, is relay their uncertainty better, which is hard to do and not necessarily heard.  The NWS needs a way to quantify uncertainty where it is understood by the general public. This will be an arduous task to say the least and will take years.       

I wish I could +1 some of these without clogging the thread.

[isohume]

2 minutes ago, BTRWx said:

I wish I could +1 some of these without clogging the thread.

Ideally the uncertainty should fall out of the spread, but it can't. We're actually working on a way to normalize the uncertainty, given the base and the spread. This would then highlight areas on a map in shades of grey indicating low-high uncertainty. Doubt our customers will like it tho as they always want our deterministic "best guess".   

[Amped]

I created an album for this storm with TT images.   Sorry if this clogs up your computer.

 

The GFSs 850mb low was too far east and too small over the Carolinas.

The NAMs 850mb low extended further west but northwest instead of southwest like what verified.

In other words, the NAMs forecast likely worked out better out of luck here, liked we suspected.  Take every storm too far northwest and eventually you'll get one right!

The Euro likely did better than the GFS at 850mb heights given that it's 500mb troff over the Carolina's looks more like what verified.

The coastal low was less compact and further west than modeled.

The northern stream dug further south than modeled.

There were lower 700mb, 500mb, and 850mb heights over the coastal plane between the disturbances than any model showed, the Euro was the closest.  In laymens terms,  a low tried to form aloft over the coastal plain CAD wedge and it pulled the coastal and the northern stream together quicker.   I saw HM's post about frotogenesis band orientation on twitter.  It maybe related to the lowering pressures aloft if it extended into the Carolinas.

Euros 850 0c line was way too far south 24hrs out, despite having the surface right.

Here is the link to the Album.

http://imgur.com/a/HYsB6