Killer tornadoes rip Iowa, and Minnesota; tropical depression possible late this week

By: Dr. Jeff Masters , 02:08 PM GMT die 26o May, anno 2008

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The 2008 Memorial Day Weekend tornado outbreak will continue to hammer the U.S. today, even as residents from Iowa and Minnesota clean up from the devastating tornadoes that killed eight people Sunday afternoon. A mile-wide tornado plowed through Parkersburg, Iowa between 5pm and 6pm CDT yesterday, killing five people in that city, and two in nearby New Hartford. It was the deadliest tornado in Iowa in more than 40 years. The tornado passed just north of the airport in Waterloo, Iowa, which recorded sustained winds of 64mph, gusting to 94 mph at 5:37pm CDT. Damage appeared to be at least EF-4 in photos I saw, and possibly EF-5 (over 200 mph). In Minnesota, another powerful twister killed at least one person and injured 9 in the Minneapolis suburb of Hugo.


Figure 1. Satellite image of the supercell thunderstorms that spawned the Parkerburg, Iowa and Hugo, Minnesota tornadoes on May 25, 2008.

The slow-moving low pressure system responsible for all the mayhem began in Colorado on Thursday, when the Storm Prediction Center (SPC) recorded 48 reports of tornadoes, including the EF-3 mile-wide twister that killed one person in Windsor, Colorado. On Friday, an additional 63 tornado reports occurred, mostly in Kansas. The tornado that hit Quinter, Kansas on Friday was the eighth violent EF-4 tornado of the year. Also on Friday, two people were killed in Cairo, Kansas when a tornado smashed a car trying to flee the storm. If you want to see why one should not try to escape a tornado in a car, take a look at what the tornado did to the car. Saturday was relatively quiet, with only 13 tornado reports, but Sunday's tally of 43 brought the 4-day total from the 2008 Memorial Day weekend outbreak to a remarkable 157 tornado reports. Some of these tornado reports are undoubtedly of the same tornado, so the actual number of tornadoes for the 4-day outbreak may be less than 150. BBC has some awesome aerial footage of the weekend tornadoes.



Figure 2. Radar reflectivity image (top) of the May 25, 2008 Parkersburg, Iowa tornado. The position of Parkersburg is marked by a circle with a cross in the middle. Bottom: Doppler velocity image of the tornado, showing a small core of red and blue colors right next to each other, denoting strong winds towards and away from the radar, the classic signature of a tornado vortex.



Figure 3. Radar reflectivity image (top) of the May 25, 2008 Hugo, Minnesota tornado. The position of Hugo is marked by a circle with a cross in the middle. Bottom: Doppler velocity image of the tornado, showing a small core of red and blue colors right next to each other, denoting strong winds towards and away from the radar, the classic signature of a tornado vortex. We've also saved a 12-frame radar animation of the Hugo cell, thanks to wunderground member Todd S.

Tallying up the numbers
The death toll from Sunday pushes this year's tornado deaths to 111, the most since 1998, when 130 were recorded. Assuming that the Parkersburg, Iowa tornado was an EF-4 or EF-5, there have been nine violent EF-4 or EF-5 tornadoes this year. This is the most since 1999, when 13 such twisters were recorded. The total number of tornadoes this year is approaching 1100, and we may challenge the all time record for tornadoes in a year of 1817, set in 2004. Could this be a sign of climate change? No, I don't think so, and I'll explain why in a blog later this week.

Severe weather forecast
Severe weather will pound the U.S. again this Memorial Day, with the main action expected to stretch more than halfway across the country--from Texas to New York. NOAA's Storm Prediction Center has placed much of Kansas, Oklahoma, and the Texas Panhandle under its "Moderate Risk" category for severe weather, one step below its highest level of concern, "High Risk". Yesterday was also a "Moderate Risk" day in Iowa and Minnesota. The Weather Underground Severe Weather page and Tornado page are good places to go to follow the severe weather. Also, tune in to the chase accounts and awesome storm photos from Wunderblogger Mike Theiss. After today, it appears the severe weather outbreak will finally diminish, with only a slight risk of severe weather expected Tuesday, and no severe weather expected Wednesday.

Possible development in the Western Caribbean or Eastern Pacific late this week
For the past 3-6 days, our most reliable global computer weather forecast models have been predicting the development of a low pressure system near or over Central America by Friday of this week. Given the persistence in the models in developing this low, we need to be alert to the possibility of a tropical depression forming in either the Western Caribbean or Eastern Pacific, on either side of Costa Rica and Nicaragua. It is uncertain which ocean basin such a storm might form in, and whether or not there will be a tropical wave around to help kick off development. It may be that the low pressure region will stay anchored over land south of the Yucatan Peninsula, preventing any development. This is the solution preferred by the ECMWF model in its last few runs. However, the GFS, NOGAPS, and Canadian models all predict a tropical depression might form in the Western Caribbean near Mexico's Yucatan Peninsula. In contrast, the UKMET shows development in the Eastern Pacific, on the Pacific side of Central America. Climatologically, May tropical storms are much more common in the Eastern Pacific than the Western Caribbean, so we should not discount the UKMET solution, even though it is an outlier. All five models predict that the Central American low pressure area will move northward towards the Gulf of Mexico, and wind shear may fall enough to allow a tropical depression to form should the low's center emerge over water. I'll be posting daily updates on the situation this week.

Jeff Masters

Wedge Tornado (MikeTheiss)
A large and violent wedge tornado near Quinter, Kansas. Photo Copyright Mike Theiss
Wedge Tornado
Wallcloud near Lacrosse, Kansas (MikeTheiss)
Photo of a wallcloud crossing road near lacrosse, Kansas on May 25, 2008. Photo copyight Mike Theiss
Wallcloud near Lacrosse, Kansas
Storm Damage (CAPEdcrusader)
These are pictures taken of the storm that went through Forest Lake / Hugo, MN. The tornado passed 3 miles south of us, but we got a pretty vicious shot of hail for about 15 minutes straight. The pictures of bldg damage are west of the worst tornado damage, probably where the funnel cloud was just about to reach the ground.
Storm Damage

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1459. groundswell
05:20 PM GMT die 27o May, anno 2008
BROAD AND DISORGANIZED LOW PRES NEAR OR OVER
CENTRAL AMERICA WILL MOVE SLOWLY NW FRI AND SAT INCREASING WINDS
AND SEAS OVER THE WESTERN WATERS.

From NWS...but have winds topping out at 25 knots, so maybe just a squally system. I don't see shear disappearing, in fact it looks like a shortwave dropping in from the north.
Member Since: August 28, 2006 Posts: 0 Comments: 381
1458. Cavin Rawlins
05:12 PM GMT die 27o May, anno 2008
1438. cchsweatherman 12:58 PM AST on May 27, 2008

While QuikSCAT and ASCAT are rather useless right now....surface obsevervations indicate a circulation is being felt at the surface based on wind shifts...Its weak but its there. However, these observations are not detecting the full extent of the circulation. Products from CIMSS and satellite imagery show its larger than perceived here.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
1457. AWeatherLover
05:11 PM GMT die 27o May, anno 2008
What is Ascat? I'm familiar with quikscat imagery... Are they similar? Thanks, still trying to learn as much as I can.
Member Since: November 2, 2007 Posts: 0 Comments: 431
1455. zoomiami
05:10 PM GMT die 27o May, anno 2008
Thanks JP, you know how it is when you start thinking about something and just can't find it!

I think there were a lot of similarities between that situation and this one. What does stick out it the fact that it didn't do what everyone thought it would.

Hi Gamma - how have you been?
Member Since: August 13, 2007 Posts: 10 Comments: 4158
1454. cchsweatherman
05:09 PM GMT die 27o May, anno 2008
NEW BLOG!!!
Member Since: April 14, 2007 Posts: 8 Comments: 5169
1452. kmanislander
05:08 PM GMT die 27o May, anno 2008
Out for lunch

Will check back later
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1451. Michfan
05:08 PM GMT die 27o May, anno 2008
Now now JP :P
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1450. cchsweatherman
05:06 PM GMT die 27o May, anno 2008
Patrap, notice the time tags at the bottom of the image. That data was from 0:07 UTC, meaning about 15 hours ago.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
1447. Patrap
05:03 PM GMT die 27o May, anno 2008
Zoomed and enlarged Link
Member Since: July 3, 2005 Posts: 427 Comments: 129439
1446. kmanislander
05:03 PM GMT die 27o May, anno 2008
CCHS

Trying to determine whether a surface low exists just by the satellite prersentation is very difficult as a mid level low can give much the same visual appearance, particularly when we have, at best, a very weak low.

I would want to see surface obs confirm a low N of Panama before accepting the presence of one just by the sat images we now have. In fact, even the 850 mb vorticity is very weak suggesting no surface low at this time
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1445. pottery
05:02 PM GMT die 27o May, anno 2008
OK Kman.
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1444. Patrap
05:02 PM GMT die 27o May, anno 2008
quikSCAT Passes,ascending, and descending, Link
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1443. seflagamma
05:02 PM GMT die 27o May, anno 2008
1420. zoomiami 12:50 PM AST on May 27, 2008
Does anyone remember the system last year that had the circulation on one side of so fla and it had reformed to the other side by the next morning? I went through the archive yesterday, but couldn't seem to locate it.

Thanks



I remember that system but don't remember what month it was in either. it split in two!
Member Since: August 29, 2005 Posts: 301 Comments: 40945
1442. DocBen
05:02 PM GMT die 27o May, anno 2008
Maybe we have TWO Invests? One each in the Carib and the EPAC? Can that big mess split that way?
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1441. Michfan
05:02 PM GMT die 27o May, anno 2008
1435. MocDasters 11:57 AM CDT on May 27, 2008 Hide this comment.
For those that say put up or shut up may I suggest you enter your tropical synopsis here.


Don't fall for it!
Member Since: September 7, 2007 Posts: 0 Comments: 1747
1440. pottery
05:01 PM GMT die 27o May, anno 2008
456, comment on this yall........

Interesting feature for sure. Being sheared from south westerlies, that are bringing in moisture from Pacific and over Columbia. The shear is the key in my opinion here, and is serving to raise moisture levels, around the feature.
The 2 trop. waves east of it will also add moisture when they get there.

The shear will need to slack off considerably, to see any organisation of this feature.
IMHO.
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1439. weathers4me
04:59 PM GMT die 27o May, anno 2008
Link
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1438. cchsweatherman
04:58 PM GMT die 27o May, anno 2008
Many people have stated that there is no surface low associated with that disturbance in the SW Caribbean, but satellite imagery say otherwise. It looks like a fairly well-established, well-defined surface low 456. Too bad ASCAT missed the area and QuikSCAT is having problems or else we would have a far better idea on what may be brewing in the Southwest Caribbean.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
1437. kmanislander
04:58 PM GMT die 27o May, anno 2008
Hi Pottery

The Atl is too hostile this time of year to be of much interest other than to see how the progression of waves is looking as a possible downstream signal for the activity level of the CV season.

My focus until mid July is the Caribbean South of 15 degrees
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1436. StormHype
04:57 PM GMT die 27o May, anno 2008
12z GFS brings what looks like a good amount of moisture towards S.E. florida.Maybe a weak TS on this run.

Yeah, the more sure thing, if any, from the recent GFS runs is that FL seabreeze storms finally start to kick off by the weekend. This dry air made for a very comfortable holdiay weeekend, but it's hard on the lawn!


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1433. cdo
04:56 PM GMT die 27o May, anno 2008
I predict the first tropical storm will form early July, maybe a TD in June though.
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1432. cajunkid
04:55 PM GMT die 27o May, anno 2008
Link
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1431. weatherboykris
04:55 PM GMT die 27o May, anno 2008
Hey guys. As someone else said, doesn't look like much has changed. Just wait and see. Getcha popcorn ready.
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1430. nash28
04:55 PM GMT die 27o May, anno 2008
What it needs is a ULH to park over it.
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1429. Michfan
04:54 PM GMT die 27o May, anno 2008
Pretty much Nash. We need to invent the Masters Box.

Dates of Dr Master's Vacation = Highest probability for cyclone development.

Noname if a low does in fact form it has alot to contend with before it can. Dry air and wind shear are currently its way.
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1428. nash28
04:54 PM GMT die 27o May, anno 2008
If I am not mistaken, Barry was a Baroclinic system.
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1427. moonlightcowboy
04:54 PM GMT die 27o May, anno 2008
1423. That'd be perfect - depression or weak TS. Dump some needed rainfall.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
1426. tillou
04:53 PM GMT die 27o May, anno 2008
Anyone noticed the huge ULL Low in the central-eastern ATL? Not to mention the smaller one centered around Bermuda?

O well for a Bermuda high, huh?
Member Since: August 19, 2007 Posts: 0 Comments: 198
1425. StormHype
04:50 PM GMT die 27o May, anno 2008
My point is that last year we saw a few examples of systems that had no logical business forming that DID form.


Wasn't Barry a Sub-TS? I don't remember. But that would explain it.
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1424. nash28
04:50 PM GMT die 27o May, anno 2008
Hey, the surest way to get development is for Dr. Masters to go on vacation:-)

Happens every time he does that.
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1423. hurricane23
04:50 PM GMT die 27o May, anno 2008
12z GFS brings what looks like a good amount of moisture towards S.E. florida.Maybe a weak TS on this run.
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1422. moonlightcowboy
04:50 PM GMT die 27o May, anno 2008
LOL, Pottery, I'm thinking the same thing!
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1421. Cavin Rawlins
04:50 PM GMT die 27o May, anno 2008
Comment on this yall

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1420. zoomiami
04:50 PM GMT die 27o May, anno 2008
Does anyone remember the system last year that had the circulation on one side of so fla and it had reformed to the other side by the next morning? I went through the archive yesterday, but couldn't seem to locate it.

Thanks
Member Since: August 13, 2007 Posts: 10 Comments: 4158
1419. nash28
04:48 PM GMT die 27o May, anno 2008
Because of this, I come to expect the unexpected.
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1418. nash28
04:48 PM GMT die 27o May, anno 2008
Let's not forget what Barry had to deal with last year. First off, it traversed through shear ranging from 40-50kts. Wonder why it was a very dry TS? Because dry air was dominant over the GOMEX at that time. The reason Barry formed and maintained was due to the ULH that moved in tandem with the system protecting it from the destructive shear.

My point is that last year we saw a few examples of systems that had no logical business forming that DID form.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
1417. ajcamsmom2
04:47 PM GMT die 27o May, anno 2008
1414. StormHype 11:44 AM CDT on May 27, 2008
1413. kmanislander 11:42 AM CDT on May 27, 2008
Thanks
Member Since: March 15, 2008 Posts: 4 Comments: 2492
1416. pottery
04:46 PM GMT die 27o May, anno 2008
Hi there Kman.
Some interesting features in the Trop. Atl as well.
I am wondering if the Atl might not produce a disturbance, before anywhere else in the next week or so.
The race is on.........
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1415. groundswell
04:45 PM GMT die 27o May, anno 2008
Looks like a hostile environment to me-high shear & dry air to the north of the sw caribbean.
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1414. StormHype
04:44 PM GMT die 27o May, anno 2008
Did we have all this to look at this early last season? I thought we started watching things a bit later...


At this time last year, some posters here were already comparing the pre-Barry blob to hurricane Wilma of 2005.

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1413. kmanislander
04:42 PM GMT die 27o May, anno 2008
good day everyone.

Not much has changed overnight by the looks of things. Visible loops suggest two areas of low pressure, one near 8N 88W and the other near 12N 81W.

The area in the EPAC seems to be the strongest of the two at this time and that view is supported by the 850mb vorticity for the region. No doubt high shear in the Caribbean is holding back development just to the N of Panama and the West and NW winds that were evident at Bocas del Toro yesterday afternoon are no longer present.

Very slow development in the S Caribbean is the norm for this time of year and one would look for sustained and deep convection over several days before any appreciable development is likely to occur.

The EPAC is, however, typically more active now than the Caribbean and the odds are that the area near 88W will probably win out over the S Caribbean IF anything does develop
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1412. hurricane23
04:39 PM GMT die 27o May, anno 2008
AWeatherLover the NOGAPS model is run four times daily 00Z, 06Z, 12Z, 18Z.
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1411. IKE
04:39 PM GMT die 27o May, anno 2008
1408. tornadofan 11:37 AM CDT on May 27, 2008
The GFS, on the 12Z run, keeps it down around the Yucatan through 168 hours....

It does the Hokey Pokie and shakes it all about...


It does a twist and shout with it. lol.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1410. ajcamsmom2
04:38 PM GMT die 27o May, anno 2008
Did we have all this to look at this early last season? I thought we started watching things a bit later...
Member Since: March 15, 2008 Posts: 4 Comments: 2492

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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