Saturday, May 31, 2008

Flooding in Ames, IA

With all the focus on severe weather, rain was the main damaging phenomena last night. 4 inches in some locations in 1 day. Couple that with probably as much snow as they have seen since 2001, meant soil moisture and probably the whole water table was higher than normal. Add a few rain events, and BAM ... floods. My favorite is the community pool construction site ... in a known flood plain ... which has consistently flooded for at least the last 3 wet seasons ... totally underwater.

With all the new construction, including the new Walmart which accounted for some kind of flood, we are at increasing infrastructure risk from what can be aptly described as regular, even somewhat regular events.

Here in the Tri-cities in Winter we saw a 5 inch snowfall ... last one was in 2001 I think. Pretty incredible for this neck of the woods, not to mention the 300 days of sun promise I heard before moving here. It has rained so many days (granted not much falls) since we moved in.

We shall see what the damage in Ames does on Monday ... but gear up for Tuesday when the next batch of rain is ready to go through.

Wednesday, May 28, 2008

Why ask why?

So the question of the day appeared to be: Why have so many tornado's occurred this year. As is typical with the hype, the "answers" given were not surprising. Early season, "rare" tornado outbreaks upped the numbers. The La Nina event was also cited as playing a role in the location of the jet stream.

Severe storms require instability and vertical wind shear AND they need to be co-located if only for a few hours usually in the late afternoon. The other ingredient in this concoction is the cap, or lid. This lid serves a dual purpose: it prevents the release of this instability so naturally the instability increases as the water vapor mixing ratio and surface temperature increases AND it helps determine downdraft characteristics. This latter part is not so well understood. I will blog on that some other time.

Tornado outbreaks occur in dynamically active patterns associated with a large scale or perhaps shorter trough (low pressure). With troughs come developing fronts and the clash of air masses OR simply different air masses. Since 2005 the moisture and dynamics have not been often colocated and when the dynamics appear to be present the moisture is missing in action. This has made chasing storms rather difficult, and thus observing tornado's difficult. More than a few storm chasers, myself included, have felt disenfranchised by the atmosphere. Until this year. The moisture is plentiful. The dynamics appear in spurts regularly.

I also must say that tornado season appears to be rather consistent about being inconsistent. Some years April seems more active than May or May more active June, but I doubt there is a trend there.

The death toll this year is not surprisingly high. Rather we should remark how low the death toll has been in recent memory. Tornado's are powerful and no matter the warning lead time, someone somewhere will be surprised. We are fortunate that the country is not one giant piece of habitated concrete otherwise tornado's would almost always kill someone. The real test of our science is to sample many tornado's with radar, get good surface wind speed and acceleration measurements, and correlate that data to observed damage.

The problem with damage however is that not every house is built well, or new, or has the same code. Damage in this case is relative. This is why Tim Marshall and many others led the charge for a new tornado rating scale. It was disappointing to not hear anyone speak about housing construction when the new scale went into effect, the news widely reported that wind speeds were lower because we knew more. True. We do know more ... about how crappy some homes were built (find any number of articles on Hurricane Andrew), how old others were, and how powerful some tornado can be. But we still need to know more so mitigation of damage leads to saving lives too.

Which leads back to why have so many tornado's occurred this year. There are more people to observe them, even in rural areas. There are more storm chasers. We are more well informed about storm potential. More people are paying attention, especially small town EM's. I was amazed that Parkersberg had just recently installed another siren. After the destruction in IA in November 2005 near Ames, IA and I think the F3's in 2004 or 2003 in IA, every small town should find the money or being given federal help to get a siren. Maybe the sirens will work, maybe they wont. Who cares. If 1 life was saved, it was worth it.

Tuesday, May 27, 2008

split supercell

The Iowa Environmental Mesonet via Daryl Herzman (and Ray Arritt) has been doing phenomenal work in data collection for Iowa. one of these ventures has been to cooperate with the local (and not so local) TV stations to acquire web cam movies, 1 minute schoolnet data, 1 minute awos data, and a whole host of other data (GIS included). Anyhow, Daryl has control of the cameras and has some great time lapse of all kinds of convection, gravity waves or bores (wait for that publication!), tornado's, and now a stunning movie of a splitting supercell.

Its one thin to watch the base of a supercell and slowly realize the precip. shield has seperated, but its another to be behind the storm and watch the overshooting updraft for a spell, and then notice that another updraft forms to the side. Then the two updrafts split apart and two storms emerge. Truly amazing. If anything needs to be shown in current meteorology classes (beginning met included) its the collection of web cam lapses that Daryl has amassed.

Tornado's in Iowa

Parkersburg, IA is gone. No doubt the damage was on the scale of devastating or EF4-EF5. I heard ten minutes was the lead time. Sometimes lead time is the difference between saved and lost lives. Sometimes there is simply nothing you can hope for besides a strong storm shelter underground.

The pictures reminded of Spencer, SD 1998 and others commented it was like Greensburg, KS 2007. Either way, I hope the folks in Parkersburg can get some help to rebuild safer just like Greensburg. Go green with a few cubic feet of storm shelter concrete.

Incredible the number of tornado's reported this year, especially given the relative lack of May-June tornado's in the last few years. No doubt the early season tornado's really ramp up the totals, but when this last wave is added to the count, the totals will continue to be impressive.

Wish I could be out there watching some of these supercells, but the IEM webcams are keeping me on the perpetual (not-so) virtual chase. Nice way to save on fuel, but it lacks the adrenaline, the thrill of forecasting and chasing down a supercell with a tornado warning.


NASA landed the Phoenix probe. Awe inspiring. The news coverage is always disheartening, as the most horendous news takes center stage. A bunch of scientists and engineers land the craft *perfectly* with what appears to be all instruments working, pictures flowing, and science ready. Awesome. Talk about a field project ... this is no way on par with the recent Met field projects though VORTEX2 folks should take notes since the recent tornado's attracted so much attention.

Can't wait for more pictures from Mars, cant wait for the science either. Tell me all about H20 on the red planet!