Dan McCarthy Chat Transcript: March 20, 2006

Dec 26, 2004
Booneville, KY
<ef> First Question: What do you consider a tornado outbreak in terms of tornadoes or by tornadoes in to relation land area for a tornado outbreak?

<DMcCarthy> ef- I pretty much agree with the Galway definition of at least 10 tornadoes within an area of maybe 1/4 or 1/2 the size of IA about 25,000 sq. mi.
<DMcCarthy> And they have to be actual tornadoes-not tornado reports.

<GeorgeT> <TonyLyza> Mr. McCarthy, where does the 3/12 outbreak rank in regards to recent outbreaks (i.e. 5/3/99, 5/4/03), and where does it rank for you in terms of March outbreaks?

<DMcCarthy> TonyLyza..I was ready for that question. Sice I was on vacation last week, I spent the day working on the outbreak.
<DMcCarthy> I figure we had 57 tornadoes on Sunday, which would be #2 to March 13, 1990 with 59 tornadoes including Hesston.
<DMcCarthy> The 3-day outbreak is also #2 to March 13-15, 1990 where there were 74 tornadoes. This March 11-13 is close to 70 tornadoes.
<DMcCarthy> In regards to fatalities-we now have 10 dead, compared to 5/3/99 when there was 40 killed. Outlooks-Watches-Warnings saved lives.

<GeorgeT> <mikeS> how will the new probabilities used in the convective outlooks affect the number of high and moderate days

<DMcCarthy> Depends on the forecaster. If a forecaster is conservative, there will be about the same. But, with the ability to go 60% probability, we will be able to really go for the bigger days.

<GeorgeT> <ScottOlson> Dan, is there any plans for any new products at SPC?

<DMcCarthy> I think for now, you are seeing the two newest products, the 4-8 Outlook and the Enhanced Thunder probabilities, and the watch probabilities. These three products will be implemented before we come into anything else new.

<GeorgeT> <TonyLyza> What kind of situation would you see that would prompt you to issue a 60% tornado area?

<DMcCarthy> Hmmm. Another 4/3/74 would do it. Smile
<DMcCarthy> Anytime you have 3000 J/kg, deep layer shear to 60 kt, 60 kt LLJ with 100 kt at 500 mb and 120+ at ULJ would raise my eyebrows.

<GeorgeT> <ScottOlson> Are you looking forward to the move to the National Weather Center? What benefit do you think this will have?

<DMcCarthy> I am looking forward to the NWC. 400-500 meteorologists in one place can be awesome...an observation deck on the 6th floor...and the OU Meteorology dept. within the building is a lot of atmospheric brain power.

<GeorgeT> <ef> Another question, I notice an increase in tornadoes the last few years, where you are seeing multiple tornado touchdowns in a single county, what actually constitute a tornado touchdown, i seen people county a new tornado with every touchdown, people counting multiple vorticies, people counting tornado, if the funnel is half down to the ground, if the storm does not recycle at all, what criteria is used for counting tornado touchdowns?

<DMcCarthy> With the big observation deck, I figure once we're all in, softball hail will hit Norman. Smile
<DMcCarthy> ef - good question. What people report as a touchdown is beyond our control. Multiple vortices occur within one tornado. Skipping of a tornado is considered one tornado unless the funnel lifts/breaks apart, the reforms completely as another funnel then touches down.
<DMcCarthy> The tough ones are the high based, lack of condensation cloud, yet debris is occurring on the ground. There must be an extension from cloud base to ground. Not just a swirl on the ground. That can be a dust devil.
<DMcCarthy> Here's a question: what is a gustnado? If it does not reach a cloud base, it is not a tornado. If it extends to a cloud base it IS a tornado. Period.

<GeorgeT> <TonyLyza> Why was 5/4/03 so much deadlier than 3/12/06, when the tornadoes hit the same areas and were nearly the same intensity? I know 11 of the ~38 deaths on 5/4/03 were in Jackson, TN, but other than that, what differences can you attribute to such differences?

<DMcCarthy> TonyLza- Good question. Both were on a Sunday. Maybe we all better prepared this time with an outlook 8 days out up to the event! We are not as active outside, yet as we are in May, but we expect tornadoes more in May. I think the pattern may have been better defined and consistent in the models this time.

<GeorgeT> <gpswx4cster> What is the status of the new dual polarization radar?

<DMcCarthy> I am really not sure on the dual polarization radar. I know both Pleasant Hill and St. Louis have upgraded their radars. That may be why.

<GeorgeT> <EricS> I noticed in the tornado stats for last year, May was much below normal, but many other months were near normal. Do you have any comment on that?

<DMcCarthy> May stunk! No, the jet stream really did a skip last May. In March and April, the southern stream was where it should be, then in mid-may it jumps to the northern Plains. We talk about this in the new Weatherwise.

<GeorgeT> <ScottOlson> On a day where a tornado outbreak or derecho is in progress, what is it like at SPC?

<DMcCarthy> Fun! I mean, BUSY! A good example was 5/3/99. I did the outlook that day that raised to High Risk. There were so many people talking, yet hearing and listening to every word. The shifts go by so fast that before you know, you've worked 8 hours and don't want to leave.

<GeorgeT> <ScottK> What about tornadic gustnadoes so to speak? Chasers and researchers have observed gustnadoes evolve into tornadoes with full contact from surface into cloud, and some research now indicates that some tornadoes form from gustnadoes and/or the consolidation of multiple smaller vortexes.

<DMcCarthy> That's valid. That's how we got the Plainfield, IL tornado.

<GeorgeT> <ef> I like to do research in severe weather climatology, where can I get data on severe weather watches and warnings going back to 1980

<DMcCarthy> Research on watches are hard. I can go back to maybe 1996, and warnings only go back to 1996. I don't know why, either. But, SPC has paper copies that go back to maybe 93? Then the rest of our watches maybe on microfilm.
<DMcCarthy> I too would like to improve our watch database. Good project for an intern who doesn't want to make any $$$.

<GeorgeT> <ChrisV> In my METR class this morning at OU, we discussed forecaster skill scores. Do the SPC meteorologists track their own skill scores? Additionally, I've seen this occur a few times in the past few years -- there will be a minor outbreak of severe storms (generally < 10 reports, a mixture of mainly hail and some tornado reports) without a WW, but possibly a MD discussing possible storms developing. MDs aren't generally seen by the majority of the public, does the SPC consider it a failure to warn the general public in this instance?

<DMcCarthy> True. SPC tries to forecast organized storm events. The isolated events are hard to anticipate, the hard to forecast their continuance. Not every report will occur in a watch. So, the forecasters may decide to cover it with a MD. All our products can be seen on our web page at www.spc.noaa.gov.
<DMcCarthy> Regarding skill score, we receive our scores once I get the verification data from D.C. We also compare reports with our outlooks and watches to see how we did?

<GeorgeT> <scottishrebel87> What would you suggest doing, or where would you suggest starting to further get into weather. A friend got me interested and I was wondering where to go from here.

<DMcCarthy> scottishrebel87-How old are you?

<scottishrebel87> currently i'm 16
<scottishrebel87> sophomore in highschool

<DMcCarthy> Okay. Many of us go 6 years to college. My son is 17 and interested in meteorology. So, I am encouraging Physics and at least Pre-Calculus for his senior year.
<DMcCarthy> Take the chemistry your junior year! then read as much about weather on the internet as you can.

<GeorgeT> <ScottK> this is a comment not a question:
<GeorgeT> <ScottK> EAX and LSX upgraded their radars recently to make them more 'modular" and upgradable in the future, it's the first major hardware upgrade since WSR-88D implementation and a major software upgrade; however, dual polarization is still in the future and I don't know when that will be implemented
<GeorgeT> <ScottK> I talked about it with the Science and Operations Officer at LSX last week

<DMcCarthy> Scott- thanks for that info. I do not have a date for dual=polarization.

<GeorgeT> <Guest57> for developers do you recommend they plot county outlines for watches or the watch polys? Which one do you prefer operationally?

<DMcCarthy> I'll have to say plot the counties for watches. That is the watch! Warnings come in polys for better detail.

<GeorgeT> <TonyLyza> Do you personally believe there is a link between the ENSO cycle and tornado activity? I would like to know your thoughts because I am trying to tell people in this area (where they don't realize that we live in a tornado-prone area) that they need to end their passive ways, and that argument may work for me. I live east of the MS, and I remember reading an article by Dr. Schafer about a possible correlation for this area.

<DMcCarthy> Dr. Schaefer and I agree that there is no correlation between ENSO and number of tornadoes. We do know that in an active El Nino, the southern stream is more active which could lead to more tornadoes from MS through FL. See 1992-93.

<GeorgeT> <ScottOlson> Do you have any thoughts on the changeover to the NAM WRF-NMM, or the special high resolution NMM-WRF run from last spring?

<DMcCarthy> I think this model is going to be terrific. I got to use it the 9th on an evening shift and thought it did really well. It is going to be an interesting time in model forecasting.

<GeorgeT> <ef> What do you think of having the severe hail criteria raised to 1.00 inch
<GeorgeT> <ef> and with the new EF scale, will it be possible at all to rank past tornadoes

<DMcCarthy> We'll leave past tornadoes alone in the tornado database. The EF Scale is enhanced because there are Damage Indicators and Degrees of Damage for each DI. The wind speeds were adjusted downward, yes, but there is consistency in those _estimates_. I would like to see the hail criteria raised to 1.00".

<GeorgeT> <allisonhouse> does the NHC and the SPC work together during huricane season? If so..to what extent?

<DMcCarthy> We have the hurricane hotline (phone) next to the Lead Forecaster desk. We coordinate with TPC/NHC before landfall for the issuance of tornado watches and for tornado probabilities in the public products issued by NHC.

<GeorgeT> Dan, has there ever been a time since Apr 3, 1974 when you were preparing a forecast, seeing a very impressive event shaping up and thinking (at least to yourself), "ohhhhhhh boy, here we go again"? Nov 10, 2002 and May 30, 2004 were two events that looked very, very big in the hours leading up to iniation.
<GeorgeT> have there been any other days that looked like potential "Super Outbreaks"?

<DMcCarthy> George-YES! May 3rd, April 26th, June 2 in Indiana, May 4, 2003...
<DMcCarthy> April 3, 1974, I was 18. Guess what pushed me into the business, not of weather, but tornadoes!

<GeorgeT> <allisonhouse> if HQ could grant one wish to the SPC what would you want?

<DMcCarthy> allisonhouse...well we have the new building...it would be great to issue watches (alone), this is just a personal opinion.........More upper air obs in space and time, or let's make profilers operational!
<DMcCarthy> I probably made alot of NWS folks mad just then....

<GeorgeT> <ef> At one time, I remember hearing talk about the WSO's issuing watches and SPC would take the role as providing guidance to WSO's will that ever happen?

<DMcCarthy> No. The SPC and WFOs closely coordinate with the initial issuance of the watch. Then, the watch is solely the WFO's. They clear the counties in the watch, then we adjust the WOU's.

<GeorgeT> <ScottK> What do you think of upgrading the severe criteria for both hail and wind? To what magnitudes? What about differentiation for different regions, formally or informally?
<GeorgeT> <ScottK> There was a formula computed to cleanly connect the F-scale and EF-scale to maintain the tornado database:
<GeorgeT> <ScottK> y = 0.6246x + 36.393; R² = 0.9118
<GeorgeT> <ScottK> where x is 3-second gust speeds adjusted from original F-scale fastest 1/4 mile speeds, and y is the derived EF scale 3 second gust speeds.

<DMcCarthy> Whoh! I think just upgrading hail. Wind is fine except tree damage should not be severe. The whole tree must be down, to me, to have 60 mph wind.
<DMcCarthy> Yes, and the plot of Ef-Scale closely correlates to the F-Scale.

<GeorgeT> <allisonhouse> do you ever get sick of off-work friends asking you what the weather will be tomorrow? Smile
<DMcCarthy> A little. But, I have a great comeback, "I'm in marketing, not production."

<GeorgeT> <ChrisV> This is a question forwarded from my meteorology professor, regarding skill scores: What skill score is received and what is the reference forecast?

<DMcCarthy> Oh my! Skill scores. I would have to refer that question to the programmer. I just want my POD better than 70%, my False alarm below 30%. and all reports near or around my outlook or watch.
<DMcCarthy> The numbers baffle me. They are like batting averages.. I know that sounds simplistic, but one of the Lead forecasters would be best to answer those questions.

<GeorgeT> <TonyLyza> Since 1950 (in the history of the official NWS database), in your opinion, which tornado was the strongest/most powerful? I know Dr. Fujita mentioned Plainfield, Jordan IA, and Xenia OH as some of his strongest. What are yours?

<DMcCarthy> Recently, I added Fujita's log(Area) to my personal database. He then classified micro- meso-Giamt tornadoes. The two biggest that stood out was Monticello, In on April 3, 1974 and Niles, OH May 30, 1985.

<GeorgeT> <KimTwister> do u stormchase ????

<DMcCarthy> Yes, I do chase when I get the chance. I have a close friend who is in the insurance business and loves the weather and my sons. We haven't been out since May 4, 2003. So, we are due!

<GeorgeT> <ef> Do you find working with wind climatology frustrating, when you have reports of wires down, a tree branch down, estimated winds of 60 mph you often see, and very few actual wind measurements
<DMcCarthy> Yes. Especially if it's all .75 hail and I don't have a watch issued....Smile

<GeorgeT> ok, that looks like all the questions I have in waiting at this time, so being you have a meeting coming up within about 20 minutes, we can end here if you wish?

<DMcCarthy> Thanks. I appreciate the chance to talk to everyone. I hope we can do it again soon. Good luck chasing this year!

<gw7> thanks for taking time out of your busy schedule to be our guest, Dan.[/b]