3/25/2007 DISC:MN/IA/WI

[Mike Hollingshead]

I'm betting most places in se MN with mid-50 dews yesterday afternoon were very shallow by then, as they were scoured out from the top down. Not that no one doesn't already know that, but just saying what was there wasn't the "good" 55 sfc TDs. I'm not sure I even looked at the se MN obs that hard. I saw the 81/46 or whatever it was south of me and knew it was over.

 

[afischer]

To touch on what Beau, Rich, and Mike H. have mentioned with respect to the dry surge coming northeastward out of Iowa, I was able to dig up two TAMDAR (aircraft) soundings from Waterloo. They are remarkable in showing 850 dewpoints dropping from 9.5C at 1930Z (similar to the 18Z DVN RAOB) to just 4C by 2015Z... ouch. I assume this very rapid dry surge ultimately impacted points farther northeast per the METAR evolution.

 

[Simon Brewer]

I tend to agree with the folks "blaming" the moisture for the chase let down. It sure would have helped to have a sounding in central IA along about early afternoon. The DVN sounding revealed a rather deep moist layer at 18z, but it was tough to say how far west that profile extended. In retrospect, it obviously didn't extend far enough west as the moisture mixed pretty badly from the DSM area newd into WI - just ahead of the primary convective band.

We did get a few discrete storms with some supercell structure, and who knows how close we were to seeing more robust storms. A few degrees on the Tds through the boundary layer would substantially increase CAPE, and perhaps change the whole situation from a "bust" to a few solid supercells and perhaps a couple of tornadoes.

Forecasts are incorrect at times, and it's not always because the forecaster is a moron. We suspected the moisture was marginal, but SPC forecasts include the influence of other forecasters and previous outlooks. In this case, those influences didn't happen to help. Sometimes they do help. For those of you that thrive on criticizing public forecasts, do us all a favor and broadcast every detail of your erroneous forecasts. For those of you that have the guts to admit in public that you messed up, you have my utmost respect.

Rich T.

First: Good Job to the SPC and any other forecasters who kept their eyes on IA/MN/WI on Sunday and gave warning to the public and kept spotters on gaurd.

Second: No one really forecasts tornadoes, they forecast environments in which tornadoes form. I could care less if the SPC threw up a watch box and it resulted in no severe reports; only problem I would have is if severe reports came flooding in and no watch box was issued.

The Sunday forecaster/forecasters at the SPC did a great job in my opinion, because whatever doubts they had with the 'setup' in IA/MN/WI still resulted in a watch box.

"For those of you that have the guts to admit in public that you messed up, you have my utmost respect." Rich T.

Rich and I had a discussion in the fall regarding a quote similiar to the one above, because I had a problem with a few previous SPC forecasts; basically I had beef with the SPC for not issuing watches on a few occasions. Rich IMed me some reasons and that was that.
But some people need to realize the SPC and individual NWS offices are not forecasting for storm chasers; they are forecasting severe weather environments, which may produce severe weather for the public, so don't blame another person's forecast for your bust!

 

[Mike Hollingshead]

At least in this case I don't see one person who was blaming the spc for their bust. I see people disagreeing with the spc, many as it was happening and pretty much all of them weren't chasing(so no real blame to be bothered with). Nothing wrong with that.

 

[Rich Thompson]

At least in this case I don't see one person who was blaming the spc for their bust. I see people disagreeing with the spc, many as it was happening and pretty much all of them weren't chasing(so no real blame to be bothered with). Nothing wrong with that.

Mike,

I should have qualified my last statement as being more general and not particular to Monday's MDT risk. I agree with you - there's nothing wrong with making a forecast that's different than something from the SPC. We're not the end-all in severe weather forecasting, we simply provide our best (collective) guess at the same time each day.

Rich T.

 

[Rich Thompson]

What sort of "pressure" is there to "conform" to earlier outlook? For example if you sat down yesterday to write the 4pm DY1 and concluded that this no longer was worthy of a PWO, after a few days of broadcasting this to be a big event, is there a rule (written or unwritten) that would make you reluctant to downgreade the MDT for whatever reason?

We have this debate in the TV side frequently - where some feel that you shouldn't change the forecast much from the previous met's to remain consistant, but others say you always give out your best (since the public forgets within 5 minutes of hearing in the first place ;> ) I guess my experience seeing mets give a forecast they don't agree with but "flows" better with preceeding outlooks is more bad than not.

And telling whiners to show their own forecast is a lost cause... The reason they rely so heavily on SPC usually has to do with their lack of ability, and regardless of how it happens - if a busted forecast impacts somebody, the American Way is to complain about the forecaster ;>

- Rob

Rob,

We have the same internal debates about forecast consistency versus accuracy. If we're absolutely certain that the forecast needs to be changed, we'll upgrade or downgrade as necessary. However, the "penalty function" within the NWS seems to be quite asymmetric, with much more emphasis placed on POD compared to FAR. That approach creeps into the SPC outlooks because the burden of proof is on the person proposing the downgrade. All it takes is one aggressive forecaster in the outlook sequence to introduce an upgrade, but it takes many people in agreement to ensure that a downgrade will remain a downgrade and not result in the dreaded "yo-yo" forecasting. For example, the 20z outlook forecaster on Monday did want to downgrade to SLGT, but I was already on the conference call dealing with the potential watch. How will folks view the SPC products when they see a tornado watch at 1955z (agreed upon by several WFOs) followed 5 minutes later by an outlook downgrade? We decided to half-heartedly stay with the MDT so that we weren't seen as sending mixed signals. Was that the right approach? I don't really know...

The toughest outlooks to downgrade are HIGH risks given everything that's been set in motion, while downgrading a SLGT is not too big of a deal. We also end up talking to many WFOs during the MDT and HIGH risk days, so they also have an influence. I'm convinced that forecast consistency versus accuracy is one of the bigger challenges I face each day. It's easier to talk about downgrades when you don't have to answer to anyone but yourself

Rich T.

p.s. I haven't heard a peep about the MDT risk from anyone outside of this thread.

Rich T.

 

[Jesse Risley]

I think the SPC and the NWS did a good job given the forecasting tools available and also taking into consideration what was known (atmospherically speaking) at that time.

Let's not forget the simplicity of a rather complex situation - we're dealing with nature here, and computer models and forecast soundings still can't paint at wholistic picture of every atmospheric condition on a minute-by-minute basis.

Like all members of the public sector, I guess you're damned if you do and damned if you don't in the eyes of some.

 

[Brandon Sullivan]

As someone said earlier, I think it would be better to have a watch with no weather, than have nothing and get hammered.. There is a lot of time between soundings, assuming no special sounding is done.. And areas in between WFO's are somtimes left in the dust. I think they did a good job. Lots of thought and discipline would have to go into making a forecast that you know tons of people look at! Kudos Guys!

 

[Jim Bishop]

I don't care if I offend anyone, it's freakin March and you're wondering why there aren't any tornadoes up in Wisconsin and Minnesota, while on the same day there was a tornado in Texas which should have give you a very good clue as to why you're not seeing any tornadoes in Wisconsin. I know, I was there for March 12th as well but that is THE exception. You're probably looking at this Wednasday as well thinking South Dakota looks pretty good too but you would probably have to be a few hundred miles south to get the good stuff. Keep focused guys and practice patience, I know it sucks, we're not there yet but we're close.

It's posts like this that make me want to scream. Are you KIDDING me with this post? You think the time of year actually matters when it comes down to a dynamic system with deep moisture?? Give me a break. Do you have any idea how many tornado outbreaks have occurred outside of your May/June timeframe outside of the southern plains? Here's a few to study:

November 12, 2005 Iowa
November 10, 2002 Ohio/Tennessee
September 16, 2006 South Dakota

Those are just a few events off the top of my head where tornadoes have occurred outside of the usual May/June tornado season north of the Southern Plains. There are tons more that I cannot think of right now, but try doing a little research before making yourself look like a complete moron.

According to your logic, I guess on November 12, 2005 people in Gilbert Iowa should have been wondering why an F2 tornado hit their house...because it was November and they were too far north for that type of weather!? I don't think so.

I once had someone say to me in March "wait 'till May". No, chase when there's a setup conducive for tornadoes. When the conditions come together, it doesn't matter what month it is or where you are. Sometimes setups don't pan out...it happens.

Wednesday or Thursday there might be tornadoes in South Dakota because the conditions conducive for tornadoes may be present. This is independent of the time of year AND the location. Think before you speak.

 

[rdale]

TAMDAR soundings are a MAJOR help for convective forecasting, especially in that part of the country through the Great Lakes. Much more useful than ACARS.

 

[Robert Dewey]

Do you have any idea how many tornado outbreaks have occurred outside of your May/June timeframe outside of the southern plains? Here's a few to study...

I went to the Tornado History Project and mapped out several states for March. There are plenty of cases where strong tornadoes have occured in MN, IA, WI, etc.. The most surprising one was MI, which features several strong tornadoes, and a few violent ones.

Think before you speak.

Good advice.

 

[Jeremy Lemanski]

The most surprising one was MI, which features several strong tornadoes, and a few violent ones.

I think, correct me if i'm wrong, that most of Michigan's F4 and F5 tornadoes have occured in march and april.

I don't understand your way of thinking Sean. Your trying to show the point that it takes a ton of things to come together to get a big outbreak in the early or late season, correct?
Well, the same can be said for late spring into summer. Cap problems, poor, or complete lack of, dynamics, Death ridges, etc. all can cause days upon days of "calm" during the best time of the year. Why wait for the "prime time" when it could in fact be as bad or worse then the current. The WI/MN setup HAD THE CHANCE to be a big outbreak, people chased, and the storms failed to live up to the hype so to speak. Why is this any different then a threat in the same area in late may that busts?

 

[Dan Robinson]

Your trying to show the point that it takes a ton of things to come together to get a big outbreak in the early or late season, correct? Well, the same can be said for late spring into summer.

I think the main point is that all of those factors are climatologically more likely to come together in May and June. In March and April, one or more of those ingredients are more likely to be missing than in May and June (particularly moisture/instability). In other words, expect the early setups to be lacking more so than their mid-to-late spring counterparts.

Again, you can't let climatology completely blind you to the rare times that a good setup DOES happen in early spring. None of us are saying "don't ever chase in March". But looking at the stats, year after year, you are more likely to bust (and burn hard-earned chase funds) on a March chase than a May chase.

Yes, not every May and June is going to deliver. But how quickly do years like 2002 and 2006 cloud our perspective. Remember 2003, 2005, 2004, and so on. May and June have always been 'better for the money' for a chaser taking a long-distance trip to chase.

I guess the main point is not that we should/shouldn't chase too early, but when it is early, not to have our expectations as high.

 

[Joel Wright]

Well I guess hindsight is 20/20. We are all ultimately responsible for our own forecasts, so blaming a bust on anyone but ourselves would be asinine really.

We weren't too happy with busting, but who is? As others have said, some good things did come out of it for us. Got a great chance to check out some new toys.

I don't know about anyone else, but I got my first tan of 2007 on Sunday standing outside for almost three hours lol. So I guess that's a plus.