Impact Briefing from Derecho Event from NWS

[phlwx]

http://www.erh.noaa.gov/er/phi/briefing/packages/current_briefing.pdf

[Parsley]

Interesting read.....

Like the briefing said, watches and warnings were issued well in advance of strike time. I think the timing of the event 10pm-1am (in our area) resulted in some, if not many people just not getting those watches/warnings (some people already sleeping, others out enjoying Friday night festivities). Add to the fact that this appears to be a once in 5-10 year severe storm event and the NWS did all they can do.

Going forward, can there be a strong thunderstorm warning VS. severe/extreme thunderstorm warning?? Sure. But besides us weather weenies, I fear most of the general public won't give two sh#ts about the wording of any warnings.

[cast4]

Interesting read.....

Like the briefing said, watches and warnings were issued well in advance of strike time. I think the timing of the event 10pm-1am (in our area) resulted in some, if not many people just not getting those watches/warnings (some people already sleeping, others out enjoying Friday night festivities). Add to the fact that this appears to be a once in 5-10 year severe storm event and the NWS did all they can do.

Going forward, can there be a strong thunderstorm warning VS. severe/extreme thunderstorm warning?? Sure. But besides us weather weenies, I fear most of the general public won't give two sh#ts about the wording of any warnings.

Yeah, it would probably confuse the general public even more considering most people have problems even recognizing the difference between a watch and warning.

[NickD2011]

People ignore severe thunderstorm warnings since they happen so frequently and are issued for an entire county. Some people think "severe thunderstorm warning...oh it's just going to rain". In the midwest, they ignore tornado warnings. In fact, some people go outside to look for the tornado when a tornado warning is issued, since they won't believe it until they see the tornado.

[RobbTC]

Reading the last couple pages where they discuss newer warnings I was surprised they didn't go with the wording PDS since they already have PDS Tornado Warnings they could also have PDS Thunderstorm Warnings for consistency.

[MGorse]

People ignore severe thunderstorm warnings since they happen so frequently and are issued for an entire county. Some people think "severe thunderstorm warning...oh it's just going to rain". In the midwest, they ignore tornado warnings. In fact, some people go outside to look for the tornado when a tornado warning is issued, since they won't believe it until they see the tornado.

Severe weather warnings are not county based, they are storm based (polygons). This was changed in 2007.

[MGorse]

http://www.erh.noaa....nt_briefing.pdf

Do you have any comments on this? If I recall correctly, you posted at one point about the low POPs that were in the forecast still even late Friday evening.

[SouthernNJ]

This is the final update of the AFD before everything likely went into Severe Weather mode.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE MOUNT HOLLY NJ

918 PM EDT FRI JUN 29 2012

NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...

CIRRUS SPILLING OUT FROM A ROBUST MCS HAD MOVED OVER MOST OF THE

AREA THIS EVENING, WHILE CONVECTION FROM IT WAS MOVING THROUGH THE

EASTERN PANHANDLE OF WEST VIRGINIA. NOW THAT THE EVENING HAS WORN

ON, IT BECOMES DIFFICULT TO FORECAST THE COMPLEX TO FALL APART ALL

THAT MUCH BEFORE IT REACHES OUR SOUTHERN ZONES. CAPES AND LI ARE

DROPPING RATHER SLOWLY AND LOWER LEVEL THETA E ADVECTION IS

MAINTAINED BY THE MODELS. WE HAVE GONE WITH SLIGHT CHANCE POPS

FROM NORTHERN DELAWARE INTO SOUTHEASTERN NEW JERSEY AND GRADUATED TO

HIGH CHANCE POPS BY THE TIME WE REACH SOUTHERN DELAWARE AND OUR

SOUTHERN PORTION OF THE MARYLAND EASTERN SHORE. OTHERWISE, A WARM,

MUGGY NIGHT IS IN STORE.

KLINE/DELISI

[Thunder Road]

People ignore severe thunderstorm warnings since they happen so frequently and are issued for an entire county. Some people think "severe thunderstorm warning...oh it's just going to rain". In the midwest, they ignore tornado warnings. In fact, some people go outside to look for the tornado when a tornado warning is issued, since they won't believe it until they see the tornado.

Some do, but in general I'd say there's a higher appreciation for weather warnings out there than there is here.

[Thunder Road]

Reading the last couple pages where they discuss newer warnings I was surprised they didn't go with the wording PDS since they already have PDS Tornado Warnings they could also have PDS Thunderstorm Warnings for consistency.

Watches can be PDS, not warnings. (And if I understand things correctly, a PDS watch can only be issued when there is a High Risk out from SPC.)

You can get Tornado and Flash Flood Emergencies, however. I don't think I've ever seen a Severe Thunderstorm Emergency, however.

[phlwx]

Do you have any comments on this? If I recall correctly, you posted at one point about the low POPs that were in the forecast still even late Friday evening.

tee hee...I do!

Original post on Friday night about the low POPs

From a "watch and warning" standpoint, you guys did as you should have. There's no disputing of it...the watch was positioned right and the warnings had "sufficient notice" so your verification scores will turn out well.

zone product (because that's what I can find to back up my point) for coastal atlantic for Friday night:

NJZ025-300800-

COASTAL ATLANTIC-

INCLUDING THE CITIES OF...ATLANTIC CITY

630 PM EDT FRI JUN 29 2012

TONIGHT

MOSTLY CLEAR. LOWS IN THE LOWER 70S. SOUTHWEST WINDS

10 TO 15 MPH...BECOMING NORTHWEST 5 TO 10 MPH AFTER MIDNIGHT

NJZ025-300815-

COASTAL ATLANTIC-

INCLUDING THE CITIES OF...ATLANTIC CITY

721 PM EDT FRI JUN 29 2012

TONIGHT

MOSTLY CLEAR. LOWS IN THE LOWER 70S. SOUTHWEST WINDS

10 TO 15 MPH...BECOMING NORTHWEST 5 TO 10 MPH AFTER MIDNIGHT.

NJZ025-301615-

COASTAL ATLANTIC-

INCLUDING THE CITIES OF...ATLANTIC CITY

904 PM EDT FRI JUN 29 2012

REST OF TONIGHT...PARTLY CLOUDY LATE THIS EVENING

THEN

BECOMING MOSTLY CLOUDY. LOWS IN THE LOWER 70S. WEST WINDS 5 TO

10 MPH...BECOMING NORTHWEST.

NJZ025-300800-

COASTAL ATLANTIC-

INCLUDING THE CITIES OF...ATLANTIC CITY

930 PM EDT FRI JUN 29 2012

TONIGHT...PARTLY CLOUDY THIS EVENING

THEN BECOMING MOSTLY

CLOUDY. LOWS IN THE LOWER 70S. SOUTHWEST WINDS 5 TO 10 MPH...

BECOMING NORTHWEST AFTER MIDNIGHT.

NJZ025-300815-

COASTAL ATLANTIC-

INCLUDING THE CITIES OF...ATLANTIC CITY

1014 PM EDT FRI JUN 29 2012

...SEVERE THUNDERSTORM WATCH 439 IN EFFECT UNTIL 2 AM EDT

SATURDAY...

OVERNIGHT...PARTLY CLOUDY LATE THIS EVENING

THEN MOSTLY CLOUDY

WITH A SLIGHT CHANCE OF THUNDERSTORMS. SOME THUNDERSTORMS MAY BE

SEVERE WITH DAMAGING WINDS AND FREQUENT LIGHTNING. LOWS IN THE

LOWER 70S. WEST WINDS 5 TO 10 MPH. CHANCE OF PRECIPITATION

20 PERCENT.

The AFD was posted earlier in the thread and mentioned but the forecasts didn't reflect any confidence that the storms were in fact going to hit. A "slight chance" of storms to the public means odds lean strongly against storms. The wording was there for damaging winds but a 20 POP was far, far too low given how those storms were holding their own, how temperatures/moisture/dynamics were setting up.

That said, the forecasts late in the afternoon/early in the evening...not just NWS' but everyone else's...were less-than-stellar...and the AFD's didn't really do quite enough justice (decaying MCS mentioned as late as 7:30 PM's AFD) to play up the threat. To be fair, it is tough to forecast derecho/MCS behavior and whether or not they indeed survive after dark or if they fall apart but it was becoming pretty clear as the evening rolled on that this meant business.

NEAR TERM /UNTIL 6 AM SATURDAY MORNING/

VERY WARM AND MAINLY CLEAR CONDITIONS WILL CONTINUE FOR OUR AREA

THROUGH THE REMAINDER OF THE DAY AND INTO THE EVENING, WITH AN AREA

OF HIGH PRESSURE CENTERED OVER THE SOUTHERN STATES. FOR OVERNIGHT

LOW TEMPERATURES, WE GENERALLY USED A BLEND OF MOS GUIDANCE AND

CONTINUITY, WITH LOWS PRIMARILY IN THE 70S FROM THE LOWER DELAWARE

VALLEY SOUTH INTO THE DELMARVA. OF NOTE, BOTH THE GFS AND NAM BRING

WHAT LOOKS TO BE ANOTHER DECAYING MCS TOWARD SOUTHERN PORTIONS OF

OUR FORECAST AREA. THAT MCS WAS MOVING INTO WESTERN PA AND NORTH

CENTRAL WV THIS EVENING WITH SOME SCATTERED ACTIVITY AS FAR EAST

AS AOO. THERE CONTINUES TO SEEM TO BE SUFFICIENT INSTABILITY IN

PLACE AS THIS ACTIVITY APPROACHES, AND WE HAVE MAINTAINED POPS

MAINLY THROUGH THE DELMARVA.

From a "severe thunderstorm warning" perspective, you did well...I just don't think many of us locally forecasted this well at all earlier in the day and didn't adjust the forecasts accordingly until it was nowcast time. I don't remember anyone locally (TV, private forecasters) really talking about this being a threat for South Jersey or even Northern Delaware late Friday PM as everyone thought the MCS/derecho was going to pass down towards DC and then graze the Delmarva.

What I do think would be beneficial is getting a better understanding of derecho/MCS behavior so we can improve the short range (6-18 hour) forecast to get a better handle on how these behave/track/sustain themselves.

Generally, you guys do really, really well in forecasting...but this was one event that I think many forecasters missed on locally...

[MGorse]

tee hee...I do!

Original post on Friday night about the low POPs

From a "watch and warning" standpoint, you guys did as you should have. There's no disputing of it...the watch was positioned right and the warnings had "sufficient notice" so your verification scores will turn out well.

I think you covered it all. Thanks for getting back to me.

[phlwx]

I think you covered it all. Thanks for getting back to me.

I'll add this -- my hope is that the NWS doesn't look at the severe warning verification score as the golden goose to chase. Since the warnings occurred at night, most folks probably went to bed thinking little more than a round of thunder may come through (if that) and some probably didn't even know there was a watch out either.

Nighttime events suck because of the higher "caught off guard" factor...people going to sleep thinking nothing's (or very little) is going to hit and then they wake up to a tree down on their car...or worse.

I'll stop now.

[Boch23]

Yeah, it would probably confuse the general public even more considering most people have problems even recognizing the difference between a watch and warning.

This. Everytime I tell my family that we are in a watch, my mom in particular, starts freaking out because she thinks its the warning. It's a great idea to have different levels of warning but as the breifing suggests, educating the public will be needed to some degree no matter what system you come up with.

[Rainshadow]

I'll add this -- my hope is that the NWS doesn't look at the severe warning verification score as the golden goose to chase. Since the warnings occurred at night, most folks probably went to bed thinking little more than a round of thunder may come through (if that) and some probably didn't even know there was a watch out either.

Nighttime events suck because of the higher "caught off guard" factor...people going to sleep thinking nothing's (or very little) is going to hit and then they wake up to a tree down on their car...or worse.

I'll stop now.

The biggest problem is currently there is no differentiation (or too hidden in the body of the warning) between the severe thunderstorm warning that knocks down four large tree limbs and the one that knocks out power to 3/4ths of a county. Mesoscale modeling has improved with the mcs(s), the problem is there is still a lack of run to run continuity especially when your churning that HRRR out every hour. But, they are not there yet and when the mcc does not make the right hand turn toward the more unstable air, you get a 20% pop with a 67% outage number. Lost in all of this the more consistent modeling of mcs(s) across the heart of the PHI CWA on Saturday evening never materialized.

I will respectfully disagree with you about the overnight timing, I believe the potential number of deaths and injuries would have been higher if this occurred at 5 pm on a getaway Friday afternoon with everyone driving around all over the place. Too many people ignore severe thunderstorm warnings which brings us back to sentence number one.

[Rainshadow]

Also, we don't throw our hands up and say what can we do, too much conflicting information, this will be dissected with a fine tooth comb and we will learn from it. Gotta go golf with dryslotted, later.

[Eskimo Joe]

I like the idea of the a two tiered severe thunderstorm warning. Perhaps the extreme thunderstorm wording could be used for winds <80mph +. But, this higher tiered warning should be included with the Blizzard, Tornado and Flash Flood warnings on IPAWS. That will undoubtedly help to spread the word to those outside or away from conventional media (ie: radio, tv) or traveling out of their area on a vacation. Thoughts?

[phlwx]

I like the idea of the a two tiered severe thunderstorm warning. Perhaps the extreme thunderstorm wording could be used for winds <80mph +. But, this higher tiered warning should be included with the Blizzard, Tornado and Flash Flood warnings on IPAWS. That will undoubtedly help to spread the word to those outside or away from conventional media (ie: radio, tv) or traveling out of their area on a vacation. Thoughts?

NWS in the Twin Cities at one time used "very severe thunderstorm" warnings if the wind speeds were >75 mph. Was used only for storms that impacted the immediate Twin Cities metro. This probably would work just fine since it has been played around with before.

[Parsley]

Getting back to the timing aspect.....yes, loss of life and amount of damage likely would have been worse (across S. Jersey) if the storms moved through between 3-7 pm on Friday because more people would have been out on the roads. But in terms of "warning" the public I think the timing of the event got the word out to less people than it would have had the derecho been approaching early Friday afternoon. You would have had more people online, watching television and in contact with each other and the word on watches and warnings would have gotten out better.

Nothing the NWS can do about making sure people received word of watches or warnings, not everyone has storm radios by their bedside or alerts from their Iphones. I guess if the NWS ever implemented a strong thunderstorm warning vs. severe thunderstorm warning.....an alert (siren like tornado warnings) could go out in communities to warn the public. That may catch more people's attention at 11pm at night hearing a siren go off. That type of warning should only occur in EXTREME severe (non-tornadic) storms like derechos.

[chubbs]

Also, we don't throw our hands up and say what can we do, too much conflicting information, this will be dissected with a fine tooth comb and we will learn from it. Gotta go golf with dryslotted, later.

Shoot low - expect a report if there are any spectacular shots. Back on topic - an extra category for top end events is a good idea

[phlwx]

Getting back to the timing aspect.....yes, loss of life and amount of damage likely would have been worse (across S. Jersey) if the storms moved through between 3-7 pm on Friday because more people would have been out on the roads. But in terms of "warning" the public I think the timing of the event got the word out to less people than it would have had the derecho been approaching early Friday afternoon. You would have had more people online, watching television and in contact with each other and the word on watches and warnings would have gotten out better.

That's the point I'm trying to make. If it were a run-of-the-mill weekday (not a Friday, but a regular weekday) at 3-7 pm it's a rush hour bi*tch and there's a good deal of impact getting home but some folks hunker down in the office and wait for the storm to pass before trying to head home. That said, more people would know about it if it were coming through at 3 PM than did with this particular storm.

There might have been more loss of life had the storm come through at 5 PM on a Friday instead of Midnight (we're lucky only three died in NJ from this) but I don't think the damage would have been significantly different...whether or not they ignore the warnings is another story but I think more folks would have been aware...and I think a # would have probably held off on going to the Shore until after the storm had passed...of course, getting down there would have been a whole different story.

Tony, had Friday's event fizzled we would probably have gotten something from that dead MCS on Saturday that merely was a deck of clouds and a couple of drying sprinkles as it moved through. We've been down that road before with severe around here where one day overperforms at the expense of another (or vice versa).

[Sunny and Warm]

I like the idea of the a two tiered severe thunderstorm warning. Perhaps the extreme thunderstorm wording could be used for winds <80mph +. But, this higher tiered warning should be included with the Blizzard, Tornado and Flash Flood warnings on IPAWS. That will undoubtedly help to spread the word to those outside or away from conventional media (ie: radio, tv) or traveling out of their area on a vacation. Thoughts?

my concern is scope creep of a new warning. Over time, criteria for an event can change or be bent for non-weather reasons. For example, a snow advisory or WSW may be issued for marginal events from a standards POV because the event falls during a holiday or because many people may be out on the highway. It may be prudent to raise the level of awareness for an event that may impact the public more than usual, but I'm not sure bastardizing your criteria standards is the right way to go. Same for the Irene hurricane warnings last year. The warnings along Jersey were kept so as to keep the public in a high state of awareness. That's all well and good, but eventually, the public becomes jaded to warnings that do not materialize. My concern is that the definition of an "extreme" warning will change over time so that it fits more and more events. It should fit a standard deviation from normal model for either rain, hail, wind, lightning, heat, cold, or snow. If it's 3 or 4SD's or greater or some such standard, it is extreme and warned accordingly. I'd like to remove the subjectivity that I've seen creep into warning criteria, or so it seems to me.

My post is not a cut on the NWS or its employees.

[Parsley]

That's the point I'm trying to make. If it were a run-of-the-mill weekday (not a Friday, but a regular weekday) at 3-7 pm it's a rush hour bi*tch and there's a good deal of impact getting home but some folks hunker down in the office and wait for the storm to pass before trying to head home. That said, more people would know about it if it were coming through at 3 PM than did with this particular storm.

There might have been more loss of life had the storm come through at 5 PM on a Friday instead of Midnight (we're lucky only three died in NJ from this) but I don't think the damage would have been significantly different...whether or not they ignore the warnings is another story but I think more folks would have been aware...and I think a # would have probably held off on going to the Shore until after the storm had passed...of course, getting down there would have been a whole different story.

Yup. That's the way I see it. I think back to Friday night and being one of maybe 10 people in this subforum watching those storm barrel toward S. Jersey and then thinking about my neighborhood and how most people were already asleep (including my wife and child). The thought of that derecho rolling through with so many people off guard was a scary thought. It's just a matter of timing and alot of people being caught off guard as a result (similar thing happened in the 98' derecho in western NY). Remember, us weather weenies are in the minority of keeping track of the weather 24/7. Most people spend a few minutes max. online/watching TV ingesting their expected weather for the day ahead.

[Lady Di]

Speaking as a lay person who is just interested in weather, my opinion would be to leave the severe warning as it is and include anything extreme in the text or at the end as seems they maybe doing in the central US. If a tornado is confirmed on the ground then put it in the warning. Confirmed wind speeds with the location of a storm and where it is indicated to go I believe is very helpful to the public.

You poor guys just can't win either way. I agree about these overnight warnings that go out. Most folks don't get them unless they have a weather radio by the bed, their cell phone going off, or a siren.

I totally missed this event btw. I must have turned in early.

[Boch23]

Yup. That's the way I see it. I think back to Friday night and being one of maybe 10 people in this subforum watching those storm barrel toward S. Jersey and then thinking about my neighborhood and how most people were already asleep (including my wife and child). The thought of that derecho rolling through with so many people off guard was a scary thought. It's just a matter of timing and alot of people being caught off guard as a result (similar thing happened in the 98' derecho in western NY). Remember, us weather weenies are in the minority of keeping track of the weather 24/7. Most people spend a few minutes max. online/watching TV ingesting their expected weather for the day ahead.

As soon as my friend said she saw lighting I was scrambling around my freinds apartment for her laptop. I didn't expect that but then again like you said when us weenies see something its almost a reaction for us to assume something has changed and need to check whats going on. This is one of the few reasons I want to get a smart phone. The rest of the normies wouldn't give it a second thought and just assume it would be a passing storm. With smart phones today people have the ability to know whats going on a whim but when it comes to weather its not utilized.

As others have said improvements can be made but I'm not sure it will be achieved unless you have cooperation from all parties involved (public media NWS etc.). I know if changes do occur in the warning systems I'll be jaming them down my friends and familys throat. Just my meaningless .02 cents.

[Grothar]

The answer to the extreme severe thunderstorm weather warning is to leave out the word thunderstorm. Here are some ideas that mean business and will grab the attention of the residents and businesses in the affected area:

1. Electrical Grid Warning - meaning that a severe disruption to the entire electrical grid system is anticipated or expected to last more than two hours because of some type of weather phenomena - high winds, severe icing, or heavy snow. Believe me, when you inform the resident or business that his or her power may fail for two or more hours, they will take action to prepare, especially if they have experienced one already like in the Halloweenie storm. PMJ in Lower Providence Township should work hand in hand with MT Holly to issue this type of warning. This would put PPL, PECO, Met ED etc on stand by and put municipalities on notice for damage assessment and or damage removal/repair work. Many times municipalities are not adequately prepared as well as the residents in this situation.

2. Classifying derechos as tornado warnings instead as severe thunderstorms. Whats the difference- one must take immediate cover, property damge is equal or worse than a EF1 tornado and sirens should sound if a derecho is expected especially if the municipality has existing tornado sirens. Adding the word extreme is not strong enough IMHO and only serves to confuse the uneducated public and again forces the public to take a cry wolf attitude toward the severe thunderstorm weather warning system.

3. Asking volunteer fire companies to provide a different sounding sirens on their siren pole for tornado warnings. I could never understand why this is not possible and many residents and businesses of these unprotected communities would donate dollars to their local fire company to provide this service which could be inked by the county EMS or the MT Holly when issuing warnings

[phlwx]

re: electrical grid warnings...peco, et al have private meteorologists...they usually aren't relying on the NWS (although they may look at their information and data...PECO, PPL, Met Ed to my knowledge either use an in house met or they contract out. Their private meteorologist(s) should be the ones keeping tabs on that stuff and giving the proper "heads up" on any potential issues.

there's no need to confuse the public and issue tornado warnings for straight line winds...they can't figure out the difference between the two as it is...they'll think every episode of straight line winds from a run of the mill severe storm is a tornado. Tornadoes can do a lot worse in a localized area than EF-1...that may only mute the impact of tornado warnings down the line.

I do think that sirens should go if a warning is either PDS, extreme, very severe in addition to tornado.

[Parsley]

re: electrical grid warnings...peco, et al have private meteorologists...they usually aren't relying on the NWS (although they may look at their information and data...PECO, PPL, Met Ed to my knowledge either use an in house met or they contract out.

there's no need to confuse the public and issue tornado warnings for straight line winds...they can't figure out the difference between the two as it is...they'll think every episode of straight line winds from a run of the mill severe storm is a tornado. Tornadoes can do a lot worse in a localized area than EF-1...that may only mute the impact of tornado warnings down the line.

I do think that sirens should go if a warning is either PDS, extreme, very severe in addition to tornado.

As "old-school" as sirens are, I think they can be effective. The monthly Limerick Power Plant test gets my attention every time. Severe thunderstorm warnings could very well be given a siren alert for communities and it would help in my opinion. I wonder what the average number of severe thunderstorm & tornado warnings combined are in a given year around here.

My guess for Montgomery County, PA.....10-15? It's not like a siren would be overkill.... they wouldn't be going off 50x a year since this isn't the Midwest.

[Boch23]

IF you started using sirens for Severe thunderstorms you would run into the same problems of people ignoring it. Also, when you live in a town where if the wind is blowing a certain direction you can't even hear the sirens go off, i don' think sirens are the answer. Gaurentee 80% of the people would still think the siren was for the FD even if you had different tones for weather/fires etc.

[Maximum lawman]

I think you covered it all. Thanks for getting back to me.

On the grid thing, I've been following MCS around the Great Lakes pretty closely this summer. It does not seem to matter what WFO I look at, when you see an MCS on the radar there are warnings for the countyies immediately proximateto the storm but the next county over a 40% POP. This afternoon as the line went through Dubois, for example, theres a short term forecast that discusses the incoming storm (well in advance) but the point and click says 40% POP. I'm wondering if that it because of the mechanics of changing the grids or that any MCS is a low confidence forecast. Just curious.