Mile-wide tornado smashes Windsor, Colorado; plus, hurricane season commentary

By: Dr. Jeff Masters , 1:23 PM GMT on May 23, 2008

Share this Blog
2
+

A mile-wide tornado swept through Colorado between 11am and noon yesterday, ripping the roofs off buildings, tossing cars into the air, and killing at least one person in Weld County, northeast of Denver. Hail up to 2.75" in diameter accompanied the storm, which took an unusual north-northwesterly track , parallel to the Rocky Mountains north of Denver. Hardest hit was the town of Windsor, between Fort Collins and Greely, where damage appeared to be at least EF3. A local TV station took some impressive live video of the tornado, and a wunderground web cam video in Windsor, Colorado (Figure 1) caught the funnel as it passed east of the camera.


Figure 1.Webcam view looking east at 11:45am MDT in Windsor, Colorado as the tornado passed by. Note the golf ball-sized hail covering the ground. Image credit: windsorweather.com.

The Weather Underground's tornado expert, Rob Carver, had this explanation of yesterday's tornadoes:

Two low pressure systems over the Western U.S. were the cause of the severe weather outbreak of May 22. A strong upper-level low over the Great Basin formed a surface low in the lee of the Rockies, and brought a strong southerly mid-level jet over the Plains of Colorado and Kansas. As the surface low formed, it brought warm moist air northwards, forming a warm front. This warm air moved westward, rising with the terrain, causing thunderstorms to form. Once these storms formed, the juxtaposition of easterly flow at the surface with southerly flow aloft (i.e., wind shear) produced significant spin in the horizontal direction, which was tilted by the storms to vertical spin, which triggered the formation of tornadic thunderstorms. This movement of the warm front up the slope of the Rockies to help trigger tornadic thunderstorms is a rare occurrence.



Figure 2. Radar reflectivity image (top) of the Windsor, Colorado tornado at 11:45am MDT May 22, 2008. Note the classic hook-shaped echo associated with the tornado. 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. For those interested, we've saved an animation of the reflectivity and Doppler velocity.

Severe weather forecast
Severe weather is expected today over Kansas, Nebraska, and surrounding states. NOAA's Storm Prediction Center has placed portions of this area 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, which SPC later upgraded to "High Risk" once the tornadoes started pounding Colorado. More severe weather is expected Saturday and Sunday over the Midwest as the upper-level low pressure system responsible moves slowly eastward. The Weather Underground Severe Weather page and Tornado page and WebCam 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, who was in Kansas yesterday, and has posted many spectacular photos of yesterday's storms. According to Mike's blog:

Today Cloud 9 Tours saw 4 tornadoes and ONE developing almost overhead. We experienced winds over 100mph from the circulation of the meso that passed overhead as a cone tornado developed. Stay Tuned....


Possible development in the Eastern Pacific late next week
The past four days, the ECMWF model has been predicting the formation of a tropical storm in the the Eastern Pacific, just off the coast of Guatemala, around May 29. The GFS model has also been predicting something might develop, but in the Western Caribbean near Mexico's Yucatan Peninsula. The GFS has been rather inconsistent with its handling of this potential storm, and I am inclined to discount its forecast--especially since last night's long range runs of the NOGAPS, Canadian, and UKMET models all show development in the Eastern Pacific, not the Caribbean. All five models predict a northward shift in the jet stream and substantial relaxation in wind shear over the Eastern Pacific and Western Caribbean next week. It is common to see May tropical storms in the Eastern Pacific, and it would not be a surprise to see something develop there. I'd put the odds of something popping up in the Western Caribbean or Gulf of Mexico at less than 10%, though.

NOAA's seasonal hurricane forecast
NOAA issued its annual seasonal hurricane forecast yesterday, which I discussed in detail in yesterday's blog entry. Yesterday's forecast came out with a little more uncertainty attached to it than previous forecasts, which is a good thing. The media attention and fanfare that accompanies these forecasts is rather excessive, given the low skill they have. In fact, we don't even know if the NOAA forecasts have ANY mathematical skill, because they've never released a verification study of their forecasts. I doubt that the skill is very high--as Eric Berger of the Houston Chronicle pointed out in a blog yesterday, NOAA has blown its forecast of Accumulated Cyclone Energy (ACE) each of the last six years. NOAA held its usual press conference to announce the forecast; this year, it was held at the home of the NOAA Hurricane Hunter aircraft, MacDill AFB in Tampa. The NOAA dignitaries present said all the right things, preaching the need for preparedness regardless of the forecast for the upcoming hurricane season. Still, I wonder if NOAA might be hurting themselves by making such a public spectacle over the release of a forecast that no one knows the accuracy of, and has performed poorly by some measures in recent years. I do like the fact they are issuing public hurricane forecasts, as I expect their accuracy and value will improve in coming years, but they're definitely not worth the attention they're getting at present.

Jeff Masters

Tornado1 (kd7tda)
One of several tornados. This one was near Grainfield, KS
Tornado1
Tornado Damage 3 (jlg)
Damage from today's Tornado in Windsor, Colorado
Tornado Damage 3
()
Mean Looking Meso with Cone Tornado (MikeTheiss)
Photo os a wallcloud with a developing tornado passing just to the north of our location on May 22nd, 2008. Photo copyright Mike Theiss
Mean Looking Meso with Cone Tornado

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 507 - 457

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48Blog Index

507. weathersp
6:42 PM EDT on May 23, 2008
The Atlantic Wave looks like it was riding the Durnal Max phase... it really looks striped of convection now.

Link
Member Since: Posts: Comments:
505. mississippiwx23
10:42 PM GMT on May 23, 2008
Can someone show me a storm that developed that far south and moved north? I cant recall any, but there might be.
Member Since: Posts: Comments:
504. mississippiwx23
10:37 PM GMT on May 23, 2008
Ok jp and drak...maybe I am off on that. I just remember that 108 hours thing yesterday.
Member Since: Posts: Comments:
502. Drakoen
10:37 PM GMT on May 23, 2008
499. mississippiwx23 10:37 PM GMT on May 23, 2008
Drak,

Its not doing what? Both of my statements or just one?


both.
Member Since: October 28, 2006 Posts: 57 Comments: 30823
501. pearlandaggie
10:36 PM GMT on May 23, 2008
cchs, i wouldn't put so much stock in the Mud Wrestling Federation's ability to predict long-range storms!

LOL
Member Since: Posts: Comments:
500. TerraNova
6:34 PM EDT on May 23, 2008
I havn't seen the ECMWF do this so far. I don't think a low could survive the trek across mexico. Does the ECMWF factor in elevation?

What matters is that both the GFS, NAM, and now the ECMWF are showing that conditions will become favorable for tropical cyclone development in the near future, whether or not the individualy predicted cylone occurs.

Member Since: Posts: Comments:
499. mississippiwx23
10:33 PM GMT on May 23, 2008
Drak,

Its not doing what? Both of my statements or just one?
Member Since: Posts: Comments:
498. pearlandaggie
10:35 PM GMT on May 23, 2008
so, PDFs don't appear as pictures...

Member Since: Posts: Comments:
497. cchsweatherman
6:31 PM EDT on May 23, 2008
488. JFV 6:30 PM EDT on May 23, 2008
Good Friday evening all!!! Hey weatherman, are you still expecting tropical development in the Carribean Sea next week my cyber buddy?


Based upon the latest model outputs from the ECMWF (showing a strong Eastern Pacific storm moving across Mexico and into the Bay of Campeche), the NAM (showing early tropical development in 84 hours in the Southwest Caribbean), and the GFS (continuing to show a tropical system developing in the Southwest Caribbean now in about four to five days), I have higher confidence in Western Caribbean development for next week, but my confidence remains at around 25-30%. Need some more models to start jumping onboard for my confidence to grow into the moderate range.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
495. mississippiwx23
10:32 PM GMT on May 23, 2008
I would want to be chasing in North Colorado or SE WY right now, it seems there are weak tornadoes touching down everywhere. Would make for a fun day. Kansas looks a bit too clustered with large hail as well at this time.
Member Since: Posts: Comments:
494. StormJunkie
10:32 PM GMT on May 23, 2008
484.

18z GFS shows a very similar storm starting at the 120hr time frame.

Ok, see y'all later
Member Since: August 17, 2005 Posts: 26 Comments: 16874
493. Drakoen
10:32 PM GMT on May 23, 2008
490. mississippiwx23 10:31 PM GMT on May 23, 2008
The GFS is jumping so much with the storm and never getting past 108 hours, which tells me it doesnt really know what is going on down there. And a low developing right over Panama?!? That isn't going to happen.


No its not doing that.
Member Since: October 28, 2006 Posts: 57 Comments: 30823
492. kingy
10:13 PM GMT on May 23, 2008
Interesting how the tropical wave has shown some impressive early appearance. Current climatic conditions would suggest this wave may struggle to survive long term. But still... we can take this as a warning sign that this season may prove to be one that surprises us. Storm frequency and prevalence through the recent years has shown us that there are weather trends to be concerned about. The continued urbanisation around the gulf and florida coasts only increases our risk. I shouldn't complain too much... as my company made a fortune in the 90's with the building boom. But in hindsight (admittedly), and having sold the company now, I worry about some of the developments that are at risk against surge and cat3 wind damage. Here i refer to low lying islands that are covered with million dollar bungalows - go on google earth and look at some of the developments that have sprung up all over the place, florida, GOM, you name it. Do i have a sense of guilt regarding this - well, yes I do actually but struggle to do much about it. What I am surprised about is that we keep populating the coastal areas, and the pace of development in that last 10 years has exceeded the previous 50 years. I retired early and this gave me the privelige to look back and think about these matters. I feel that the time is coming when we will need to pay greater heed to our town planning rules when we consider where we are building. There is more to life than money and a condo on the beach front - Believe me.
Member Since: Posts: Comments:
491. IKE
5:31 PM CDT on May 23, 2008
There it is again at 156 hours on the GFS...6+ days away...

Link
Member Since: Posts: Comments:
490. mississippiwx23
10:30 PM GMT on May 23, 2008
The GFS is jumping so much with the storm and never getting past 108 hours, which tells me it doesnt really know what is going on down there. And a low developing right over Panama?!? That isn't going to happen.

Basically, I don't see anything in the Atlantic side for the next two weeks.
Member Since: Posts: Comments:
489. pearlandaggie
10:28 PM GMT on May 23, 2008
484. something like this? God, I hope not!

:)

Member Since: Posts: Comments:
487. weatherboyfsu
10:29 PM GMT on May 23, 2008
Good evening,

The state of Kansas is getting bombarded...........Hugh tornadoes........WOW!!!!!
Member Since: Posts: Comments:
486. IKE
5:29 PM CDT on May 23, 2008
484. mississippiwx23 5:28 PM CDT on May 23, 2008
Anyone else notice that the latest European model develops a storm in the Pacific and then brings it over Mexico into the Gulf? Long range models are always fun!


I noticed that too.
Member Since: Posts: Comments:
485. HurricaneGeek
6:29 PM EDT on May 23, 2008
Thanks W456
Member Since: Posts: Comments:
484. mississippiwx23
10:27 PM GMT on May 23, 2008
Anyone else notice that the latest European model develops a storm in the Pacific and then brings it over Mexico into the Gulf? Long range models are always fun!
Member Since: Posts: Comments:
483. smmcdavid
5:26 PM CDT on May 23, 2008
So, how many aggies... lol. J/K!
Member Since: Posts: Comments:
482. StormJunkie
10:24 PM GMT on May 23, 2008
479 & 476
A+

The Bay is what would cause you your problem smmc. Typically surges will not travel 25 miles inland with out a low lying area, bay, or river.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
481. Weather456
6:24 PM AST on May 23, 2008
463. HurricaneGeek 6:18 PM AST on May 23, 2008
"All the tropical wave needs in order to warrant a possible invest tag is some convection"

And there would have to be convection for a period of time, no?


about 24 hrs and up....taking into consideration diurnal variations. That is even as convection wanes during the diurnal min....as long as the convection remains evident it counts as peristence.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
480. pearlandaggie
10:26 PM GMT on May 23, 2008
DOH!

(_8(|)
Member Since: Posts: Comments:
479. pearlandaggie
10:25 PM GMT on May 23, 2008
seeing if a pdf will show up as a picture...

Member Since: Posts: Comments:
478. smmcdavid
5:24 PM CDT on May 23, 2008
Thanks guys... I've had kind of a rough day and just don't know how to phrase things right now. Sorry.
Member Since: Posts: Comments:
477. cchsweatherman
6:22 PM EDT on May 23, 2008
Just based on some apporximate calculations, it would likely take a strong Category 3 or a Category 4 hurricane to affect your area with storm surge.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
476. Patrap
5:23 PM CDT on May 23, 2008
League City Emergency Management With Hurricane Evac Zones Link

League City proper Website Link
Member Since: July 3, 2005 Posts: 428 Comments: 129796
475. pearlandaggie
10:21 PM GMT on May 23, 2008
smmc...check the link i posted. it contains what you need to know about surge.
Member Since: Posts: Comments:
474. smmcdavid
5:23 PM CDT on May 23, 2008
Way to be terrifying Pat... which is okay.
Member Since: Posts: Comments:
473. StormJunkie
10:21 PM GMT on May 23, 2008
smmc, you are going to have to look at some land surveys as well as surge models. My initial reaction would be no for a Cat 2, but again you would have to look at several details to be sure. The other problem is that there is always a potential for a storm to start strengthening 24-36hrs before landfall leaving you with a Cat 3 or 4 surge.

As pat says, Run from water, hide from wind.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
472. Patrap
5:22 PM CDT on May 23, 2008
Surge can travel Miles inland.
Cyclone Nargis surge in Myanmar wasnt the Largest,but a 12-14 ft surge is devastating for any Delta region.The Population density and Lowness of the dwellings there were the killers.

With no way up and away from Surge,one has to find refuge as it comes.



Many in Waveland Miss,and other points during Katrina Clung for their very Lives till it was over.





Member Since: July 3, 2005 Posts: 428 Comments: 129796
471. cchsweatherman
6:21 PM EDT on May 23, 2008
469. smmcdavid 6:21 PM EDT on May 23, 2008
Okay, let's try this... we live in League City, Texas (about 25 miles north, inland of Galveston) and about 2 miles from Galvelston Bay. Um, let's say a cat 2 landfall just south of the island.

Will it get me? LOL


I'm checking Google Earth for the topography and location and will get back with you in a minute on that.

Member Since: April 14, 2007 Posts: 8 Comments: 5169
470. pearlandaggie
10:20 PM GMT on May 23, 2008
Link

FM1462 is a good 20 miles inland, yet the surge studies indicate that a Cat4-5 hurricane would flood to nearly FM1462.
Member Since: Posts: Comments:
469. smmcdavid
5:19 PM CDT on May 23, 2008
Okay, let's try this... we live in League City, Texas (about 25 miles north, inland of Galveston) and about 2 miles from Galvelston Bay. Um, let's say a cat 2 landfall just south of the island.

Will it get me? LOL
Member Since: Posts: Comments:
468. cchsweatherman
6:19 PM EDT on May 23, 2008
The 18UTC GFS now develops the parent low for the potential Western Caribbean storm by 108 hours right around Panama.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
467. KEEPEROFTHEGATE (Mod)
6:17 PM EDT on May 23, 2008
30 miles if hilly 100 m if flat i figure in worst case senarios
Member Since: Posts: Comments:
466. StormJunkie
10:16 PM GMT on May 23, 2008
Evening smmc :~) Good to see you.

Not sure, but I think it is dependent upon land elevation and slope.

A perfect example of this is where it traveled in so far in the Irrwaddy delta, where such a large portion of the land mass is less the 5 meters above sea level.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
465. pearlandaggie
10:18 PM GMT on May 23, 2008
pat, that was a great, heart-warming picture for Memorial weekend. Thanks for that, man!
Member Since: Posts: Comments:
464. cchsweatherman
6:16 PM EDT on May 23, 2008
460. smmcdavid 6:16 PM EDT on May 23, 2008
How far inland can storm surge travel?


It depends upon three factors.
1) Location
2) Storm Landfalling Angle
3) Storm Strength

Member Since: April 14, 2007 Posts: 8 Comments: 5169
463. HurricaneGeek
6:16 PM EDT on May 23, 2008
"All the tropical wave needs in order to warrant a possible invest tag is some convection"

And there would have to be convection for a period of time, no?


Member Since: Posts: Comments:
462. pearlandaggie
10:17 PM GMT on May 23, 2008
460. In certain areas, depending on the strength of the storm, the surge can travel inland 20 miles or more.
Member Since: Posts: Comments:
461. KEEPEROFTHEGATE (Mod)
6:15 PM EDT on May 23, 2008
the four winds got to fire right over the centre cchs its got to fine its trigger
Member Since: Posts: Comments:
460. smmcdavid
5:12 PM CDT on May 23, 2008
How far inland can storm surge travel?
Member Since: Posts: Comments:
459. cchsweatherman
6:13 PM EDT on May 23, 2008
All the tropical wave needs in order to warrant a possible invest tag is some convection. It could acquire some convection overnight as diurnal maximum will occur then. Will certainly be interesting to watch.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
458. StormJunkie
10:11 PM GMT on May 23, 2008
It was a dry humor joke cchs, just kind of lead in to the co-ed part! No offense meant to anyone.

That said, if they are building them like that I will not be getting involved in that co-ed wrestling!


Nice pearland, I think we have the winner!
Member Since: August 17, 2005 Posts: 26 Comments: 16874
457. Weather456
6:01 PM AST on May 23, 2008
Lastest image of the tropical wave out there:

Member Since: July 24, 2005 Posts: 407 Comments: 19076

Viewing: 507 - 457

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48Blog Index

Top of Page

About

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

Local Weather

Overcast
28 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron