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Late June 2012 storms

Ian

By Ian,
in Mid Atlantic

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Kmlwx

Kmlwx

Posted
Posted

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.

Ah, I see what you're saying. I would definitely support that if the kinks were worked out and tested.

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Bob Chill

Bob Chill

Posted
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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.

I thought that was the point you were trying to make but it's good that you drilled it down with your response.

We see potential high impact winter events played well with a few of our local media folks. IMO- Doug Hill always did a good job explaining that the ingredients are there but it's too early to tell with confidence. He did a good job alerting people days in advance without alarming them.

It was clear more than a day in advance that some of the necessary ingredients were there for something significant to happen on Friday but there was really no way to say for sure until all the ingredients were in play. That couldnt be resolved until quite close to game time.

I have no idea if it's possible to convey the "if everyrhing comes together just right then it could get ugly even though the odds of it happening are small" type of message. It would be helpful at least from a public awareness standpoint if the call for increased attention could be blended into forecasts. At least when the potential exists to impact a large geographic area. These events aren't that common so the additional message delivered by the official forecasting offices wouldn't be necessary that often.

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snowfan

snowfan

Posted
Posted

Article from the Baltimore Sun about motorists saying the Bay Bridge should have been closed Friday night before the storm hit

http://www.baltimore...0,5489010.story

"We cannot simply close a major interstate and travel artery on the basis of a forecast projection alone, otherwise the Bay Bridge and other bridges would be closed quite often," Melhem said. "We are always prepared to act immediately in the event of an unusual weather occurrence like the derecho on Friday that took Maryland and neighboring states by surprise."

1) This is why you view obs to see what's coming your way. It was quite clear for some time on Friday evening that the derecho was going to be powerful as it approached the area. They could have held traffic at about 11pm....even if only for 20 minutes during the strongest of winds. At that time of night, the inconvenience on motorists would have been minimal.

2) No, it should not have caught anyone by surprise.....anyone, of course, that is required to keep track of the weather.

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HM

HM

Posted
Posted

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.

Thanks for taking the time to share the day's events with us.

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:

You said it yourself; It was a common environment supportive of an MCS and the probabilities day 2 into early day 1 did not even reflect that. No one was expecting you to forecast a historic event that early, but at least some potential for "regular" severe would have been nice.

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.

Well yeah, that's how the EML works. I don't mean to be telling the expert that but of course there were no other storms. The beauty of the EML is holding off anything until sufficient forcing arrives initiating convection. You issued an MD in the morning as the developing elevated MCS was propagating eastward and you were predicting it to become increasingly surfaced-based, as anyone would, given the parameters downstream. At that point, I think probabilities were becoming increasingly elevated for anyone downstream that sufficient forcing could break the cap. Suggesting that the Mid Atlantic's threat was "entirely conditional" is basically pointless.

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.

Once again, this really isn't a point for the situation at hand. There was nothing usual about the extent of the heat and EML, as you noted in your post. It is hard to find a reason why the MCS would not intensify again after any orographic issues, especially since by that time the system was well organized, there was synoptic support too.

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).

Given that the agreeable issue at hand is that the forecasts earlier in the day might have been costly for human life and injury by not appropriately conveying the potential, the biggest concern is the 13z and 1630z outlooks (and I'm being generous by stopping at 13z). You essentially held the SLT risk just west of DCA in both updates, indicating low probabilities across the Mid Atlantic. This simply was not sufficient.

There have been numerous instances where moderate and high risks were issued before the event was underway. Granted, they can be and sometimes are clearer than this setup but it seems like the decisions being made were way too cautious throughout the day in a construct designed around probability. If you truly believe 5-15% wind probabilities (from east to west) across the Mid Atlantic were the right decisions based on what you knew at the time (13-1630z) then I don't know what to say. What are some ways in the future we can improve earlier forecasts then?

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.

From an operational end of things, that is good information and we (meteorologists and hobbyists) can appreciate that unfortunate timing. However, this means nothing to the public east of the Appalachians who got a morning forecast that said "Most Sunny and Hot with a 20% chance for a late day thunderstorm." And that is the central issue at hand.

Let's just cut to the chase. You're not happy about the forecasts right? They likely did take a toll in some way, correct? Everything during and just before the derecho in terms of watches and the WFO warnings were adequate and appropriate. The biggest issue was the forecast leading up to the watches and warnings. The PDS issue, while a concern, is tertiary.

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.

What type of environment east of the mountains would have pushed you more into issuing a PDS and/or raising probabilities in the convective outlook at 13-1630z?

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.

No one expects perfection here and obviously hindsight is 20/20 (sorry about the lame idiom). Like Ian, I am a huge SPC apologist and usually find myself defending you guys 95% of the time. However, in this case, I fail to see your logic on 6/29 and again here in this post. The funny thing about major, historic events is that they are the most anomalous, despite their low frequency, and as such should be detected more easily than a usual summertime convective episode. Instead, we are hearing the exact opposite: that because this event was so rare, it was hard to forecast. Missing a high-impact severe weather event in a higher population area until the event is practically underway (watch to warning time period) is a major failure. This simply will not do next time.

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dan11295

dan11295

Posted
Posted

Interesting I still haven't any estimates of the damage caused by this event. Given the widespread nature of the event and the high population areas it affected It wouldn't surprise me if this was one of the most damaging severe thunderstorm events that did not involve a tornado, with the possible exception of a couple DFW hail events.

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The Dude

The Dude

Posted
Posted

Our founding Fathers wrote th decloration of independednce with no AC and no Iphones in 100 degree heat. Because back then, they weren't a bunch of ******* like us.

My neighbor and I were discussing this last week. I pointed out that their life expectancy was much shorter. His reply: "Yeah, but without AC, it sure seemed a lot longer." Touche.

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arlwx

arlwx

Posted
Posted

Just checking in from Arlington County.

House power was off for about 24 hours after the storm, and it took another day to get the phones back working.

I knew we could be in trouble when it was bright and sunny at 7 pm at Congressional and clouding up at 8 pm back in Arlington.

But Topper on the Congressional clubhouse roof was focusing much more on the record heat (and on the golf tournament) through at least the start of the 6 pm broadcast.

It was hard to see even by 8 pm that something could be coming, as the TV radars really didn't look that far west.

But by 9 pm the storm line was moving along.

When it came through, there was a big thud and I ran down to the basement for the rest of the night (should have done that earlier).

We got "lucky" in that the 8"-10" tree that got snapped off about 10 feet up got tossed into the neighbor's back yard (with some of it denting the chain link fenceline between us). Only a few branches from other trees were broken off.

My neighbor on the other side had a tree about the same diameter or a bit more come down on his driveway.

Quite a few trees were uprooted or semi-uprooted (imagine a 1' or so diameter tree half out of the ground and tearing up a driveway, propped up against other trees.

We could have had it so much worse. I even made it out to the tournament on Sunday.

If this had been an unofficial hurricane, I would have voted for "Hurricane Woods", as he came to town and so did the derecho.

But it's not one, and no doubt someone will stick an unofficial name on this storm.

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Ian

Ian

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this is funny

Reader Meter: Cleaning up from the derecho storm

Kudos also go to the Capital Weather Gang, Jason Samenow and his crew, plus a thanks to storm-chasers Kevin Ambrose and Ian Livingston, who were out photographing the onset of the storm, only to get caught in it themselves by surprise, sustaining damage to their equipment and nearly to themselves. (Ambrose’s harrowing account of getting caught in the storm with Livingston is well worth your time.)

http://www.washingtonpost.com/blogs/omblog/post/reader-meter-cleaning-up-from-the-derecho-storm/2012/07/13/gJQA7JwjiW_blog.html#pagebreak

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PhineasC

PhineasC

Posted
Posted

this is funny

Reader Meter: Cleaning up from the derecho storm

Kudos also go to the Capital Weather Gang, Jason Samenow and his crew, plus a thanks to storm-chasers Kevin Ambrose and Ian Livingston, who were out photographing the onset of the storm, only to get caught in it themselves by surprise, sustaining damage to their equipment and nearly to themselves. (Ambrose’s harrowing account of getting caught in the storm with Livingston is well worth your time.)

http://www.washingto....html#pagebreak

LOL

High drama right there.

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CranberryWX

CranberryWX

Posted
Posted

Article in todays paper about the Charleston NWS office losing communication with the outside world during the storm.

http://dailymail.com/News/201207250143

...For a while, the Charleston office was an island of information in an ocean of silence.

Backup generators automatically kicked in but without phones or the Internet, weather information couldn't be shared with the world.

Meteorologist Simone Lewis said the office went to its emergency backup plan: By the time she left at midnight on June 29, all of the weather products normally produced by Charleston had been shifted to the Weather Service's office in Pittsburgh.

Lewis said Pittsburgh employees kept in touch using the Charleston employees' cellphones to call and text so they could learn what was on the Charleston office's radar screen...

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