Late June 2012 storms

[Ellinwood]

What the hell... I had a well-written explanatory post in response to the "2012 DMV Derecho" comment that got deleted on the CWG voting page. No trolling, no snide or sarcasm... just honest truth behind why the DMV part wouldn't work and why June needed to be in the name. Some odd moderating over there...

[Ian]

here's my derecho fail piece

http://www.washingtonpost.com/blogs/capital-weather-gang/post/could-forecasters-have-done-better-with-the-june-29-derecho/2012/07/03/gJQAbgkwKW_blog.html

[Ian]

What the hell... I had a well-written explanatory post in response to the "2012 DMV Derecho" comment that got deleted on the CWG voting page. No trolling, no snide or sarcasm... just honest truth behind why the DMV part wouldn't work and why June needed to be in the name. Some odd moderating over there...

The commenting sys is messed up. Did you see it post?

[Kmlwx]

What the hell... I had a well-written explanatory post in response to the "2012 DMV Derecho" comment that got deleted on the CWG voting page. No trolling, no snide or sarcasm... just honest truth behind why the DMV part wouldn't work and why June needed to be in the name. Some odd moderating over there...

People only care about what happens in their area. If it kills 50 people in one state but then makes them so much as lose power for a day or two - they were clearly the only ones that got hit

The public is really stupid...actually - most people are pretty stupid.

[H2O]

We need some more votes for "June 2012 Derecho"

http://www.washingtonpost.com/blogs/capital-weather-gang/post/vote-for-best-washington-dc-derecho-storm-name/2012/07/03/gJQAPqmiKW_blog.html

DerechOMG storm

[Ellinwood]

The commenting sys is messed up. Did you see it post?

Indeed. Even refreshed it once and it was still there. Went back some 1/2 hour later and it was gone.

[Ian]

Indeed. Even refreshed it once and it was still there. Went back some 1/2 hour later and it was gone.

Troublemaker

Derechohnoes got to you

[Ellinwood]

Troublemaker

Derechohnoes got to you

I'll just have to spam CWG with ponies then...

Oh well. Mistake, malfunction or intentional, I won't make any more of a fuss about it.

[Ian]

I'll just have to spam CWG with ponies then...

Oh well. Mistake, malfunction or intentional, I won't make any more of a fuss about it.

i gotta wonder if we're really going to start calling it derechosaurus wrecks if it wins.

[Kmlwx]

If "Derechosaurus Wrecks" wins, I'm quitting.

You might have to quit.

The DC area idiots are out in full force. I don't understand the obsession with naming disasters. Would you name a terrorist attack a joke name? I mean people died...You wouldn't nickname a train bombing something like "Crazy Trainz Dayz"

[Kmlwx]

i gotta wonder if we're really going to start calling it derechosaurus wrecks if it wins.

Trust me...the masses will. CWG is to blame.

[BTRWx]

http://rapidrefresh.noaa.gov/hrrrconus/jsloop.cgi?dsKeys=hrrr:&runTime=2012070318&plotName=1ref_sfc&fcstInc=60&numFcsts=16&model=hrrr&ptitle=HRRR%20Model%20Fields%20-%20Experimental&maxFcstLen=15&fcstStrLen=-1&resizePlot=1&domain=full&wjet=1

[Riptide]

Looks like a 6/29/12 redux.

[Ian]

i see ellinwood's comment

[Chumpson]

After a few busy days and a chance to reflect on the recent events, I've decided to throw in my $0.02. I went back and read through the posts on this board, as well as the OH Valley/Lakes forum, leading up to the 6/29/12 derecho event. I also reviewed the CWG blog post this afternoon regarding predictability of this event.

My first thought is it's almost always pretty easy to throw out *something* in support of an historic severe weather event, because these things don't materialize out of nothing. Yes, there was an unusually unstable environment from the OH valley to the mid Atlantic on 6/29/12, S of a diffuse front and on the srn fringe of roughly 30 kt midlevel flow. To get an MCS is this sort of environment is not a shock to anyone that has dealt with severe storm forecasting for any significant length of time. However, to get something "historic" is another matter! The following is my take on a few aspects of the event, and responses to a few questions I've read in various places:

1. The mid Atlantic severe threat was *entirely* conditional. Big CAPE and an EML are much more common across the Plains, and like many Plains days without a clear focus for initiation, you need storms to move into that environment from somewhere else. Indeed, no storms formed (that I recall) away from the MCS itself.

2. It's unusual for an MCS to survive passage across the Appalachians, though this was the rare thermodynamic environment where storms wouldn't necessarily die.

3. The day 1 outlook was expanded to very near DC at 13z, and probabilities were raised across IN/OH. There was some internal talk of a MDT at 1630z, but we held off until 20z when we were much more certain the MCS would be a pretty big wind producer. Yes, the MDT stayed W of the mountains, but the SLGT (by 20z) was extended to the Atlantic coast. I fully realize that the verifying event looks like a HIGH risk in terms of coverage, but keep in mind that it was barely starting when the upgrade was introduced, and it wasn't overly clear that we needed to upgrade to MDT all the way to the Atlantic by then (when the MCS was just getting organized across IN).

4. Nobody seemed to pay any attention to the OH SVR watch, even though I mentioned "bow echo", "widespread damaging winds /some significant", and pretty much nailed the path of the system. The wind probabilities were maxed out for a "regular" SVR watch. Keep in mind that the 91 mph gust at FWA was measured exactly 5 minutes before I sent the watch, and that was just about the strongest gust from the entire event. The watch process takes longer than 5 minutes to complete, so the decision to go "PDS" would have to come before any such evidence existed.

5. The first watch to reach DC was issued when the storms were still in OH, and that watch also included maxed wind probabilities for a non-PDS SVR watch. Yeah, you can ask "why not PDS since you knew it was going?" Well, you folks know as well as anyone that the Appalachians would have some impact on the storms, and it's awfully tough to make the PDS call well before the storms even reach the mountains! Just because I admit that 6/29 had an environment that would support the storms not fizzling when crossing the mountains, that doesn't mean that it's automatically going to be maintained as a high-end threat. I essentially faced the same kind of problem with the OH watch - I had to make the PDS call with a few 60 mph wind measurements, in a regime where predictability is far less than something like a major tornado outbreak.

I'm sure some of you will see this as whining or CYA, and that's fine. My point is this isn't an easy job, and you always have 100% POD and 0% FAR *after* the event! I'm flattered that some people expect something close to perfection out of SPC for every major event, but that's simply not possible given our current state of physical understanding, observations, and communications.

[Ian]

Awesome post, thank you.

I was very hesitant to write anything but the idea seemed too interesting to skip. I wholly agree that there is almost always *potential* for more than avg if you look hard enough. I was in no way implying that a historic event should be forecast with accuracy from even much further than it was. I love SPC.. I am usually an SPC apologist and will almost always defer.

I think yes usually the Apps would have a strong impact on storms in a negative way. However, given the longevity of the system I think it was somewhat obvious that when it ran back into supercharged air it might pep up a bit again or at the very least hold its own.

The post is not CYA at all. Looking back is easier than looking forward.

I'm actually more interested in the communications angle, and I've been surprised that a fairly small percentage actually care much about getting an earlier lead that there is a supportive pattern (over X days with X areas of possible range).

[The Dude]

After a few busy days and a chance to reflect on the recent events, I've decided to throw in my $0.02. I went back and read through the posts on this board, as well as the OH Valley/Lakes forum, leading up to the 6/29/12 derecho event. I also reviewed the CWG blog post this afternoon regarding predictability of this event.

My first thought is it's almost always pretty easy to throw out *something* in support of an historic severe weather event, because these things don't materialize out of nothing. Yes, there was an unusually unstable environment from the OH valley to the mid Atlantic on 6/29/12, S of a diffuse front and on the srn fringe of roughly 30 kt midlevel flow. To get an MCS is this sort of environment is not a shock to anyone that has dealt with severe storm forecasting for any significant length of time. However, to get something "historic" is another matter! The following is my take on a few aspects of the event, and responses to a few questions I've read in various places:

1. The mid Atlantic severe threat was *entirely* conditional. Big CAPE and an EML are much more common across the Plains, and like many Plains days without a clear focus for initiation, you need storms to move into that environment from somewhere else. Indeed, no storms formed (that I recall) away from the MCS itself.

2. It's unusual for an MCS to survive passage across the Appalachians, though this was the rare thermodynamic environment where storms wouldn't necessarily die.

3. The day 1 outlook was expanded to very near DC at 13z, and probabilities were raised across IN/OH. There was some internal talk of a MDT at 1630z, but we held off until 20z when we were much more certain the MCS would be a pretty big wind producer. Yes, the MDT stayed W of the mountains, but the SLGT (by 20z) was extended to the Atlantic coast. I fully realize that the verifying event looks like a HIGH risk in terms of coverage, but keep in mind that it was barely starting when the upgrade was introduced, and it wasn't overly clear that we needed to upgrade to MDT all the way to the Atlantic by then (when the MCS was just getting organized across IN).

4. Nobody seemed to pay any attention to the OH SVR watch, even though I mentioned "bow echo", "widespread damaging winds /some significant", and pretty much nailed the path of the system. The wind probabilities were maxed out for a "regular" SVR watch. Keep in mind that the 91 mph gust at FWA was measured exactly 5 minutes before I sent the watch, and that was just about the strongest gust from the entire event. The watch process takes longer than 5 minutes to complete, so the decision to go "PDS" would have to come before any such evidence existed.

5. The first watch to reach DC was issued when the storms were still in OH, and that watch also included maxed wind probabilities for a non-PDS SVR watch. Yeah, you can ask "why not PDS since you knew it was going?" Well, you folks know as well as anyone that the Appalachians would have some impact on the storms, and it's awfully tough to make the PDS call well before the storms even reach the mountains! Just because I admit that 6/29 had an environment that would support the storms not fizzling when crossing the mountains, that doesn't mean that it's automatically going to be maintained as a high-end threat. I essentially faced the same kind of problem with the OH watch - I had to make the PDS call with a few 60 mph wind measurements, in a regime where predictability is far less than something like a major tornado outbreak.

I'm sure some of you will see this as whining or CYA, and that's fine. My point is this isn't an easy job, and you always have 100% POD and 0% FAR *after* the event! I'm flattered that some people expect something close to perfection out of SPC for every major event, but that's simply not possible given our current state of physical understanding, observations, and communications.

Great post. Thanks for adding your unique perspective. Yours is a thankless job.

[RodneyS]

My point is this isn't an easy job, and you always have 100% POD and 0% FAR *after* the event!

An excellent point, but one suggestion: It would be helpful if SPC would attach a "Potential Worst Case Impact" analysis to its probability analysis. For example: "The probability of this storm system surviving passage across the Appalachians is low. However, it it does, the impact on the Mid-Atlantic could be severe and possibly even catastrophic."

[Kevin Druff]

Every frequent visitor and contributor to these boards should read that for an education on the thought process. Thanks for chiming in.

[Chumpson]

An excellent point, but one suggestion: It would be helpful if SPC would attach a "Potential Worst Case Impact" analysis to its probability analysis. For example: "The probability of this storm system surviving passage across the Appalachians is low. However, it it does, the impact on the Mid-Atlantic could be severe and possibly even catastrophic."

You're essentially asking for "conditional" severe storm probabilities. We *could* do that, but it would either be in addition to the "unconditional" probabilities we already produce, or you would have to combine the thunderstorm probabilities and the "conditional" severe probabilities to get the "unconditional" severe storm risk. The toughest forecast problems are cases when the conditional risk is high and the chance for storms appears low (like 29 June across the Mid Atlantic), or cases where the chance for storms is high and the conditional risk for severe storms is low (like many Gulf coast winter events). There's also the concern about workload - the convective outlooks (for the whole CONUS) are put together by two people (one for the thunderstorm probabilities, one for the severe probabilities) in a time window of 2-3 hours. Adding more graphics (and related decision points) would just make the task even harder. I'm not saying it's impossible, but the demands on forecaster time have been steadily increasing. Meanwhile, the number of people and the amount of time available to complete these tasks has not increased.

[Kmlwx]

An excellent point, but one suggestion: It would be helpful if SPC would attach a "Potential Worst Case Impact" analysis to its probability analysis. For example: "The probability of this storm system surviving passage across the Appalachians is low. However, it it does, the impact on the Mid-Atlantic could be severe and possibly even catastrophic."

Isn't that pretty much like saying - could be anything from garden variety storms to an all out devastating derecho? I mean - kind of like saying chance of 1-25 inches of snow.

[wxmeddler]

1. The mid Atlantic severe threat was *entirely* conditional. Big CAPE and an EML are much more common across the Plains, and like many Plains days without a clear focus for initiation, you need storms to move into that environment from somewhere else. Indeed, no storms formed (that I recall) away from the MCS itself.

This actually brings up a great point which is how many factors were against this happening. Climo is one, in that these only roll around the Mid-Atl every half-decade or so and the fact that it actually survived the App mtns. Other factors include that there was a tiny bit of a cap with a relatively moist EML above it. The LCL was above 850mb and the mean wind speed through 500mb was only ~25kt, so that there wasn't UL winds being transferred to the surface, it was pretty much all downdraft/cold pool generation.

It's easy for the public and the media to say "oh look there's 5000 CAPE, and that translates into to storm energy, how could of they missed this? It's a really big number!" but what the public does not understand (and will likely never understand) is how many factors are needed to be analyzed in order to make a forecast. Of course this leads back to the holy grail question of how do we tell the public whats happening/happened with lots of detail, while being accurate, while being simple about it so that they can comprehend. It's a very tough task, Props to all of you at SPC who do this every day..

PS. Don't be a stranger around here Chumpson, we understand and support your daily challenge.

[Ellinwood]

Thanks for all of your input in this discussion, Chumpson. It's good to gt all sides of the argument out there for us to digest and understand. There may not be 100% agreement with how well the SPC handled the forecast, but after hearing the full justification I can definitely share and understand your perspective behind what happened that day.

PS. Don't be a stranger around here Chumpson, we understand and support your daily challenge.

This x1000000000! It's great to get Chumpson's unqiue perspective, especially with events like this. A valuable source of insight and information that everyone can and will benefit from. Even if it's just post-event posts, I think everyone here would agree that you're welcome any time, Chumpson.

[RodneyS]

You're essentially asking for "conditional" severe storm probabilities. We *could* do that, but it would either be in addition to the "unconditional" probabilities we already produce, or you would have to combine the thunderstorm probabilities and the "conditional" severe probabilities to get the "unconditional" severe storm risk. The toughest forecast problems are cases when the conditional risk is high and the chance for storms appears low (like 29 June across the Mid Atlantic), or cases where the chance for storms is high and the conditional risk for severe storms is low (like many Gulf coast winter events). There's also the concern about workload - the convective outlooks (for the whole CONUS) are put together by two people (one for the thunderstorm probabilities, one for the severe probabilities) in a time window of 2-3 hours. Adding more graphics (and related decision points) would just make the task even harder. I'm not saying it's impossible, but the demands on forecaster time have been steadily increasing. Meanwhile, the number of people and the amount of time available to complete these tasks has not increased.

Again, excellent points, and it's likely that in our current economic environment that pleading your case to Congress for more resources to do conditional severe storm probabilities would fall on deaf ears. Still, I think even some seat-of-the-pants worst case analysis from experts like you would be helpful, particularly from a public relations perspective. I don't think many people care if you totally miss a minor storm event, but being even somewhat late on a big one gets folks riled up, similar to winter storm forecasters being late on a 10-12 inch snowstorm. Having said that, I have the utmost respect for what you do, and you can take comfort in the fact that some of your forecasts have likely saved lives.

[Kmlwx]

Again, excellent points, and it's likely that in our current economic environment that pleading your case to Congress for more resources to do conditional severe storm probabilities would fall on deaf ears. Still, I think even some seat-of-the-pants worst case analysis from experts like you would be helpful, particularly from a public relations perspective. I don't think many people care if you totally miss a minor storm event, but being even somewhat late on a big one gets folks riled up, similar to winter storm forecasters being late on a 10-12 inch snowstorm. Having said that, I have the utmost respect for what you do, and you can take comfort in the fact that some of your forecasts have likely saved lives.

Unfortunately, the general public likes to jump on conditional things. I feel like if you used a protocol like that, lay people would automatically assume that the forecaster was thinking about pulling the trigger on something huge. I know it sounds ridiculous but I've seen people act like that first hand. You tell somebody that there's a "chance" that something much larger will happen and they assume it's going to (winter storm example is good). I think most well balanced people know that there is a range of possibilities. If it could be worked out - then I could see it being a good product.

[Ian]

This actually brings up a great point which is how many factors were against this happening. Climo is one, in that these only roll around the Mid-Atl every half-decade or so and the fact that it actually survived the App mtns. Other factors include that there was a tiny bit of a cap with a relatively moist EML above it. The LCL was above 850mb and the mean wind speed through 500mb was only ~25kt, so that there wasn't UL winds being transferred to the surface, it was pretty much all downdraft/cold pool generation.

It's easy for the public and the media to say "oh look there's 5000 CAPE, and that translates into to storm energy, how could of they missed this? It's a really big number!" but what the public does not understand (and will likely never understand) is how many factors are needed to be analyzed in order to make a forecast. Of course this leads back to the holy grail question of how do we tell the public whats happening/happened with lots of detail, while being accurate, while being simple about it so that they can comprehend. It's a very tough task, Props to all of you at SPC who do this every day..

PS. Don't be a stranger around here Chumpson, we understand and support your daily challenge.

I was fairly unsure which day would fire up but it sure seemed like everything was coming together during that window. How often do we get a true Plains EML in here? Sure it might end up killing the threat entirely but how many big East Coast events have EML? Could it be considered a signal? I don't know the answers to all these questions.

[Avdave]

Thought this was pretty cool, power outages

june 29 2012

june 30 2012

http://earthobservat...ew.php?id=78445

[wxmeddler]

I was fairly unsure which day would fire up but it sure seemed like everything was coming together during that window. How often do we get a true Plains EML in here? Sure it might end up killing the threat entirely but how many big East Coast events have EML? Could it be considered a signal? I don't know the answers to all these questions.

The EML is a rarity in the mid-atlantic, in fact I don't even bother looking for it around here. After looking back in the RAOBS from SPC, I tracked the EML all the way back to 0z on the 28th out in Montana (t-36hrs), which makes total sense (high dry and hot!). Of course it wasn't a true plains EML by the time it got here, it had moistened up considerably on the trip over but it still likely provided a tiny bit of a cap to keep the pre-mechinical lift fodder to a minimum. Going to have to dig back in the records and see if any other big wind events have a transitioned EML.

How a EML Forms: (Left, High Terrain/Hot - Right,Transitions east/low level flow creates inversion compared to EML)

[nw baltimore wx]

The EML is a rarity in the mid-atlantic, in fact I don't even bother looking for it around here. After looking back in the RAOBS from SPC, I tracked the EML all the way back to 0z on the 28th out in Montana (t-36hrs), which makes total sense (high dry and hot!). Of course it wasn't a true plains EML by the time it got here, it had moistened up considerably on the trip over but it still likely provided a tiny bit of a cap to keep the pre-mechinical lift fodder to a minimum. Going to have to dig back in the records and see if any other big wind events have a transitioned EML.

Not sure if it helps but the following is a quote from http://bangladeshtornadoes.org/EML/emlpage.html

        These EMLs originated from the high plains and Rockies.

        Albany( Aug 28, 1973)  F4 killer tornado in Columbia county, NY and Berkshire county, MA

        Washington Dulles (Aug 28, 1973)

        Washington Dulles (July 10, 1989) Tornado family moved SSE from Montgomery county, NY to New Haven,

                                               CT to eastern Long Island. Near baseball sized hail(2.5") fell on eastern Long Island

                                               Another tornado family moved SE across northern New Jersey.

        Hatteras (Mar 28, 1984)  At least 2 tornadic supercells, one of which produced many tornadoes over a 5 hour period.

                                               57 people killed

 

[RodneyS]

Unfortunately, the general public likes to jump on conditional things. I feel like if you used a protocol like that, lay people would automatically assume that the forecaster was thinking about pulling the trigger on something huge. I know it sounds ridiculous but I've seen people act like that first hand. You tell somebody that there's a "chance" that something much larger will happen and they assume it's going to (winter storm example is good). I think most well balanced people know that there is a range of possibilities. If it could be worked out - then I could see it being a good product.

I understand what you're saying, but my point is that there is a big difference between a low probability minor impact event and a low probability major impact event. So, I think the wording of forecasts should reflect that difference, as opposed to simply stating that the probability of the event is low.