I just don't get it....PDS

[Elinor McLennon]

Ok, what went wrong with the PDS in OK area? I know there were a few tornaoes but to hear the weather service, the weather channel and the local media, imminent Armageddon was on the way.
I don't know alot about forecasting and this may be the dumbest question/observation ever, but here it goes:
My thermometer at home read 74-75 all day. It was cloudy, and extremely windy all day. I tried to walk my small dog and she was getting blown off the walking path several times So, did the cloud cover and brutal "ground" level winds change the dynamics in the environment?
Last, I know we have beat this to death but I heard alot of people scoff this evening about "forecasters" over reacting and if they say we have a mod/high risk in Oklahoma that we won't get anything. I am afraid that people are so apathetic to the media "crying wolf" that there will be alot of injuries/deaths some day if we get bad storms.
I am renaming PDS to Pretty Dang Stupid after today. I'll cheer up by tomorrow.

 

[Joey Ketcham]

I don't think it's really crying wolf, after all there were tornadoes today.

Keep in mind that PDS watches are issued when atmospheric conditions can support long-lived, violent tornadoes. That doesn't necessarily mean it will happen, it's just wording enhancement to let people know that should tornadoes occur they can become long-lived and violent.

You have to remember that this is still a realitively new science and part of the on-going research is trying to understand why these atmostpheric conditions exist, but yet you don't get those deadly tornadoes that you would expect.

Just my .02 cents.

 

[Greg McLaughlin]

I believe this setup was an EPIC FAIL because we didn't have a good EML (capping inversion) in place. Too much convection fired early in the day and ruined the instability by the time the dryline mixed east. The only tornadoes formed along the outflow boundary where horizontal vorticity was maximized and could be ingested into an updraft despite the less than idea instability.

 

[Chris Allington]

I believe this setup was an EPIC FAIL because we didn't have a good EML (capping inversion) in place. Too much convection fired early in the day and ruined the instability by the time the dryline mixed east. The only tornadoes formed along the outflow boundary where horizontal vorticity was maximized and could be ingested into an updraft despite the less than idea instability.

Greg hit the nail on the head with this one... there was not capping and way to much linear forcing along the frontal boundary. As soon as storms started to go it all when into linear modes in a hurry.

EDIT: Weren't there even people talking about how the NAM forcasted junk convection to be ongoing in much of the warm sector all day? I think that was brought up in the forecast thread if I'm not mistaken.

 

[Elinor McLennon]

Yes, i believe it was mentioned about the NAM forecast.

Just seems to me that I can't think of a day with all the cloud cover and "hurricane" force winds from sun up to sun down turning into a major day. Seems like it's always hot, muggy and still.
The early morning junk confused me this morning....just didn't seem to add up for a major event this afternoon.
Sorry if I seem cranky.....just disappointed is all.....happy nobody was injured, disappointed from a chaser perspective.
Thanks for the replies and thanks for not hammering me about my forecasting inexperience.

 

[CZandbergen]

I am with Greg on this one. i was planning to chase till I saw the runs late last night. I figured there would be a couple good storms, but the aforementioned junk and a general model disagreement (and a probable 14 hour round trip drive) made me decide to sit this one out. It looked like a dynamic situation and it ended up being one from my seat back here in Tulsa. Good news is my forecast was good as a tornado was on the ground within about 20 miles of my target. I for one will catch the next one.

As far as the PDS goes, I have no comment. That is a pay grade far higher than mine....

 

[Joey Ketcham]

On the record, I do believe that today was a huge bust.

 

[Jason Foster]

To me....as a chaser....I don't pay much attention to the level of Risk beyond Moderate. The same holds true for PDS watches. While I do show excitement as soon as they are issued, in retrospect they do tend to be more disappointing for the kind of chasing I like. High Risks and PDS watches may have more to do with the SPC's public and government agency planning responsibilities than conditions for us chasers. I'm think it's been discussed in other threads, but I wanted to post here anyway.

 

[Jeff Snyder]

On the record, I do believe that today was a huge bust.

Earlier today, it certainly looked to me like there was an enhanced risk of strong tornadoes across the High Risk area. Very strong 0-1km SRH, moderate instability, 40-45 kt deep-layer shear, etc, all supported significant supercells.

That said, by 00-01 UTC, we knew that storm mode wasn't working out well, the line of semi-discrete storms in NW and NC OK was burfing cold outflow, and there was an expanding shield of weak convection SW of OKC. The supercells that had been moving northeastward out of TX and into the area SW of Lawton were dissipating (presumbly, there was a lot of seeding occcurring from the upstream storms). Surface obs in southwestern OK largely had Tds that dropped into the 60-61 with relatively cool temps. There was (and is) a small zone of undisturbed warm sector in the extreme SE TX PH east of the dryline (and west of the cold pool / outflow driven by the southwestern OK convection), and in far southcentral OK and northcentral TX was (and is) also undisturbed. However, Tds nearer I35 dropped a bit to the 59-60 F range. With these considerations, I found it very interesting that the SWODY1 maintained the high risk for 30% hatched tornadoes. The 30% prob implies a high coverage of tornadic supercells, which seemed quite doubtful given surface obs and radar. I do NOT criticize official forecasts often since tornadoes and severe convection are often very difficult to forecast. Heck, I'm wrong more often than not anyway, and these guys are pros. I fully supported the earlier outlooks, but I wonder how much continuity played in maintaining the high for the evening SWODY1. I do like how OUN NWSFO handled it in their evening HWO, mentioning only a "risk" (unspecified in terms of slight/moderate/high) and not mentioning any tornado risk overnight.

 

[Steve Miller TX]

http://en.wikipedia.org/wiki/List_of_SPC_High_Risk_days

 

[Derek Weston]

On the record, I do believe that today was a huge bust.

While I don't think it lived up to a high-risk billing in the way most people think of high risk... I don't know that it'd be considered a huge bust either.

There are, from what I understand, some still outstanding storm reports from the western OK area. (more tornadoes than the 1 report listed on the SPC) I say this because I know that many people judge such a risk on the tornado reports it generates.

Of course . . . the risk isn't to be judged by the actual result as much as its reasoning before hand. . . but if you don't participate in forecasting with a valuation of risk attached to your prediction... it's easier to sit back and criticize after the fact.

I have not been watching SPC forecasts or severe weather forecasting in general very long. However. . . I have noticed that there seems to be a fine line between major outbreak and "messy-junk" much of the time with these sort of dynamic setups that could potentially produce a "high" end severe outbreak. ("these sort" being a certain subclass, I suppose, of dynamic events -- I'll list a few examples)

Storm mode being the trickiest aspect to nail due to the nature of the forcing and directional shear we have to work with. (and that's probably simplifying things a bit)

Today ended up being messy and rather linear -- I believe it was another dynamic setup, June 5 of last year, that ended up somewhat similar. I think it was June 5 of 07 that also disappointed chasers -- a bust from the tornado perspective for these two.

Of course, we had another major outbreak a few weeks back that resulted in many tornadoes with fairly unidirectional shear and lots of forcing from a cold front in the Southeast, if I remember correctly. That day, to me, looked as though it could've been pretty messy. But it wasn't.

I think the super-outbreak in 74 featured a mixed convective mode due to the nature of the shear profiles and forcing mechanisms in place. (and there are more examples of this sort of dynamic situation resulting in a big outbreak)

Long story short: seems to me that it is hard to pick out some of the exact variables that will turn a possibly messy mostly linear 'outbreak' into a monster tornado producer.... beforehand.

Or, perhaps... the variables are properly identified and weighed... but the valuation (to the extent that it ends up in a high risk forecast) isn't exactly right on... or at least what you think it should be.

Some folks have pointed out in this thread some of the variables they thought might be problematic for this setup -- how confident were they that these variables would indeed prove to be problematic? And given your level of confidence... how do you then weigh the chances for a significant severe weather outbreak? Basically... how much confidence do you need to go high risk? What should result in high risk -- how much confidence ought a forecaster have in their forecast?

These are tricky questions to me, and I'm not exactly sure where I stand... honestly.

I want to say that certain types (some of them touched upon above) of high risk days are more inclined to bust than others. May 29 08, for example, looked a big tornado day to me -- I had high confidence. I didn't feel the same way about June 05 08... however... should it turn out... we've got an amazing environment for tornadic supercells and we could be looking at an enormous outbreak.

I guess the big question for me is... how much ought 'high risk' be about potential?

 

[STurner]

I myself was wondering about PDS tornado watches and high risk days. It seems that quite a bit of moderate risk cases with 15% hatched areas for strong tornadoes has performed just as well as high risk days. There has also been a few slight risk days that have overperformed. I am no expert but do you think that a high risk day for severe weather is needed since they are only issued about three times a year. For instance the Greensburg and Parkersburg EF5 tornadoes came out of moderate risk days. Also the two EF4 tornadoes this year came out of moderate risk areas. I know the Murfreesboro tornado happened on a high risk day but came out of the moderate risk area. Even last year during the Super Tuesday Outbreak I think two of the five EF4 tornadoes came out of the moderate risk area. Other moderate risk days were March 1, 1997 and November 23-24, 2001 which had 3 F4 tornadoes from both events. Now I feel PDS watches are needed especially for an enviroment where there will be multiple strong/violent tornadoes but IMO there seems to be no difference between a high-end moderate risk or a high risk of severe weather. So it makes me wonder if there is even a need for high risks.

 

[Brian Kruse]

Hi Mike. Just wanted to let everyone know that we were 3 1/2 inches away from the "death zone" sunday. Saturday night we were within centimeters. The whole weekend seemed particularly dangerous.

 

[Steve Miller]

That's funny, I posed a similar question last night in the NOW thread regarding the 01z SPC update and it got erased. I thought maybe asking why this particular update was still a HIGH risk was against the rules of a WEATHER-related forum. I'm happy to see other people agree with the concern.
I have no opinion about the specific PDS watches issued yesterday other than to say 190 was somewhat justified but 192, I would have thought would be dropped, replaced or whatever the proper government wording for "downgrade" would be.

 

[Elinor McLennon]

Steve Miller's post showing the SPC high risk stats was interesting. It made me re-think my bad attitude towards SPC statements. The dang media hype is ridiculous...we're all gonna get hit by long-lived deadly tornadoes. But re-issuing watch til 3am puzzled me, especially when they were saying the threat was diminishing. Downgrade should have been done and if the media continues to stay on live basically non stop for 2 days and nothing happens then people will have a worse attitude that they already do about these watches.
I've had several calls today from people saying "i told you nothing was going to happen, it never does....they always get excited for no reason".

Hope everyone has a good day.