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

By: Dr. Jeff Masters , 2:08 PM GMT on May 26, 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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809. MississippiWx
11:34 PM GMT on May 26, 2008
806. nrtiwlnvragn 11:34 PM GMT on May 26, 2008 Hide this comment.
Conditions at San Andres Isla (Island off the east coast of Nicaragua 12.35N 81.43W)as of 7PM

Wind from the E (080 degrees) at 6 MPH (5 KT)
Visibility greater than 7 mile(s)
Sky conditions mostly cloudy
Temperature 77 F (25 C)
Dew Point 73 F (23 C)
Relative Humidity 88%
Pressure (altimeter) 29.76 in. Hg (1007 hPa)

Pressure dropped from 1010 at 1PM today

Remember, it's normal for pressures to drop in the afternoons. A 3mb pressure change in a day is common.
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807. StormJunkie
11:32 PM GMT on May 26, 2008
See ya kman

lol press, soon enough!
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806. nrtiwlnvragn
7:33 PM EDT on May 26, 2008
Conditions at San Andres Isla (Island off the east coast of Nicaragua 12.35N 81.43W)as of 7PM

Wind from the E (080 degrees) at 6 MPH (5 KT)
Visibility greater than 7 mile(s)
Sky conditions mostly cloudy
Temperature 77 F (25 C)
Dew Point 73 F (23 C)
Relative Humidity 88%
Pressure (altimeter) 29.76 in. Hg (1007 hPa)

Pressure dropped from 1010 at 1PM today
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805. Weather456
7:26 PM AST on May 26, 2008
Yep circulation north of Panama

Member Since: July 24, 2005 Posts: 407 Comments: 19076
804. kmanislander
11:32 PM GMT on May 26, 2008
Out for now but will BBL
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803. Drakoen
11:29 PM GMT on May 26, 2008
The NOGAPS remains relatively consistent in the 18z run.
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802. kmanislander
11:31 PM GMT on May 26, 2008
Wind shear tendency has been falling in the extreme Southern Caribbean but on the rise to the North of there.
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800. extreme236
11:29 PM GMT on May 26, 2008
Wind shear is already dropping in part of the SW Caribbean.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
799. MississippiWx
11:26 PM GMT on May 26, 2008
760. weatherblog 6:04 PM CDT on May 26, 2008
731. MississippiWx 10:50 PM GMT on May 26, 2008
In my opinion, this system won't be much of anything until it separates itself from land a bit more. Remember, it's impossible for a tropical system to develop over land! :-)

Not disagreeing with you, but I think we all remember Tropical Storm Erin from last year:


The NHC says that Erin wasn't tropical over land... see the NHC report


Indeed it wasn't tropical, but Erin was neat to look at. If I remember correctly Erin was a slow mover and it took a few days before it took on the signature in Oklahoma. Therefore, it would have been impossible for the low pressure to be of tropical nature. However, that doesn't mean Erin's remnant low wasn't a strong one.
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798. HurricaneGeek
7:27 PM EDT on May 26, 2008
The windshear seems a little high, doesn't it? I would guess its predicted to drop. Just a question form an observation of mine, thanks
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797. KEEPEROFTHEGATE (Mod)
7:24 PM EDT on May 26, 2008
jm
you are lost but we can help you find the way
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796. presslord
7:22 PM EDT on May 26, 2008
sj...Have thee Charleston weather hysterics begun to predict this will cross Fla and come up and devastate us yet?
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794. AWeatherLover
11:23 PM GMT on May 26, 2008
785. Weatherblog, can you post a link to that? Thanks!
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793. HadesGodWyvern (Mod)
11:24 PM GMT on May 26, 2008


92W near the Philippines and "JMA Tropical Depression" near Yap
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792. kmanislander
11:22 PM GMT on May 26, 2008
Panama City, which is to the East of Bocas del Toro has a South wind @ 8 mph. Bocas has a N wind at the same time further West.

Certainly suggests a surface low N of Panama.
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791. KEEPEROFTHEGATE (Mod)
7:23 PM EDT on May 26, 2008
good right on time
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790. extreme236
11:24 PM GMT on May 26, 2008
The convection in the Caribbean isnt very impressive but it looks less linear for sure.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
789. juniormeteorologist
11:09 PM GMT on May 26, 2008
hey guys, CaneAddict stole my website..who does that kind of storm to a 14 year old boy? well i got my site back and turned him in to the Technicians at my website...
788. KEEPEROFTHEGATE (Mod)
7:19 PM EDT on May 26, 2008
that qs will be gone soon anyway

better be careful might have to resign
lol
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787. HurricaneGeek
7:22 PM EDT on May 26, 2008
weatherblog, you got it.
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786. Drakoen
11:21 PM GMT on May 26, 2008
Most of the convection right now in the EPAC is looking like one big linear mess.
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785. weatherblog
11:19 PM GMT on May 26, 2008
*782

It looks like there's a more defined circulation with the disturbance in the SWCAR than with the one in the EPAC.
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784. aspectre
11:10 PM GMT on May 26, 2008
690. extreme236 "GFS shows a system off Africa in about 132 hrs or so lol"
691. weatherblog "CMC showing developin storm off of Africa."
As I posted back at 626:
SeaSurfaceTemperatures in most of the NorthAtlantic tropical cyclone MainDevelopmentRegion are pretty close to seasonal average.
However last I saw, SSTs in the far eastern portion of the MDR -- plus in the area east of CapeVerde while south of the MDR -- are 1&1/2 to 2 degrees above normal.

Anybody have any idea how that's going to affect the 2008 hurricane season?
Any comparable seasons [ie with comparably high SSTs in the east]?
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783. kmanislander
11:18 PM GMT on May 26, 2008
Keeper

25 installed and 11 to go !.

Will be done by the weekend
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782. HurricaneGeek
7:16 PM EDT on May 26, 2008
good evening you too, SJ =)
Alrighty, thanks for the answer

There was a mention before from post 767.. here is a visual;
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781. extreme236
11:17 PM GMT on May 26, 2008
I would also think it looks like a TS...but looks can be deceiving I guess. The JTWC should classify it soon however.
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780. MississippiWx
11:15 PM GMT on May 26, 2008
LOL, weatherblog...

I do remember that. Erin was definitely very amazing.
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779. kmanislander
11:16 PM GMT on May 26, 2008
SJ

Yeah I know. Mention the QS pass and a "blank" is almost guaranteed LOL
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778. KEEPEROFTHEGATE (Mod)
7:14 PM EDT on May 26, 2008
kman your windows done
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777. kmanislander
11:09 PM GMT on May 26, 2008
surfmom

If you read my posts you will see that I look for obs and then try to draw a few conclusions or probabilities without hype. I do not pay too much attention to models unless there is a consensus 48 hrs out with multiple model runs.

It is entirely conceivable that the wind will swing again near Panama but having watched the Caribbean for many years there are certain areas that produce tell tale signs as precursors.

A W or N wind at Bocas del Toro is one. Another is a W wind at Bluefields Nicaragua ( for weather N of there ).

These are but two that John Hope would look for and he was one of the best that ever worked the Tropical desk anywhere.
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776. AWeatherLover
11:12 PM GMT on May 26, 2008
Presslord you have mail!
Wow Exreme236, I hadn't looked recently, I didn't realize 91W became so developed.
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775. StormJunkie
11:14 PM GMT on May 26, 2008
Evening HG

Don't think it is completely random, but not sure there is a way to figure it out either.
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774. weatherblog
11:12 PM GMT on May 26, 2008
Wow, extreme26, how can that only be an invest? Looks like at least a moderate tropical storm. lol
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773. KEEPEROFTHEGATE (Mod)
7:12 PM EDT on May 26, 2008
one will become prime which one remains to be seen
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772. HurricaneGeek
7:12 PM EDT on May 26, 2008
Hi everyone! Is there a pattern that the QuikScat follows as far as the blank spots go, so we would know when it will catch the spot that we are looking for and when it won't, or is it totally random? Thanks
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771. extreme236
11:12 PM GMT on May 26, 2008
91W

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770. StormJunkie
11:10 PM GMT on May 26, 2008
768.

You just blew it for us kman !~)

Can almost promise that area falls in the blank spot with the descending pass!

lol
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769. surfmom
11:07 PM GMT on May 26, 2008
Out for the night guys, got a predawn start tomorrow. have a good time this evening!

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768. kmanislander
11:07 PM GMT on May 26, 2008
SJ

But we will have the quikscat pass for this evening which will tell us whether there is anything down at the surface that is measurable at this time.

I am inclined to believe that the vorticity has worked its way down but is weak.
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767. extreme236
11:04 PM GMT on May 26, 2008
The vorticity is less broad in the Caribbean than in the EPAC...the TPC maps also now show the low in the Caribbean.
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766. Weather456
7:05 PM AST on May 26, 2008
758. Drakoen 7:03 PM AST on May 26, 2008
Thats true...it appears to be two areas of vort max...in the EPAC and SW Cariibean with the EPAC one more define.
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765. surfmom
11:04 PM GMT on May 26, 2008
kman - yeah I saw that post and thought "hummmmm - is he wishing this???, but it's the kman - wait & watch" ...could be showtime in a few
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764. StormJunkie
11:05 PM GMT on May 26, 2008
Interesting kman & Drak, good calls. Ashame we won't have visible for much longer.
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762. MississippiWx
11:03 PM GMT on May 26, 2008
Drak-

I see what you're saying. In fact, there is a slight turn on satellite imagery just north of Panama.
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761. HadesGodWyvern (Mod)
11:03 PM GMT on May 26, 2008
you're welcome surfmom
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760. weatherblog
11:04 PM GMT on May 26, 2008
731. MississippiWx 10:50 PM GMT on May 26, 2008
In my opinion, this system won't be much of anything until it separates itself from land a bit more.
Remember, it's impossible for a tropical system to develop over land! :-)

Not disagreeing with you, but I think we all remember Tropical Storm Erin from last year:

Member Since: July 10, 2006 Posts: 27 Comments: 1623
759. Drakoen
11:03 PM GMT on May 26, 2008

Member Since: October 28, 2006 Posts: 57 Comments: 29938

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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.