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: 2157 - 2107

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

2157. Michfan
8:16 PM CDT on May 25, 2008
Also noticing on the 18z GFS that its predicting that same anticyclone to setup 10 days out above the low pressure system.
Member Since: Posts: Comments:
2156. Chicklit
1:14 AM GMT on May 26, 2008
Is an earthquake a weather event?
The magnitude of the Chinese earthquakes this week is mind boggling.

From a MSN Article:
"...More than 15 million homes were destroyed in the disaster, and the Chinese government has appealed for tents to help shelter survivors.

Across town, about 10 families were living in makeshift shelters of picnic table umbrellas and nylon tarps draped over simple wood frames, pitched in a muddy lot that used to be a food market. Chickens pecked at watermelon rinds, while the survivors used plastic basins to wash and piles of scrap wood for cooking fires.

"The local government officials have done a good job for themselves. They're living up there," said a camp resident who pointed to a neat row of tents up a hill.

"They didn't do such a good job here where the regular folks have to live," said the man, who would only give his surname, Wang.

Member Since: Posts: Comments:
2155. Baybuddy
1:16 AM GMT on May 26, 2008
The only Hebert I have EVER believed in was Bobby Hebert! Back to lurking and chanting the serinity prayer.
Member Since: Posts: Comments:
2154. Stormchaser2007
9:15 PM EDT on May 25, 2008
Hades whats the next name that will be used if this thing develops??
Member Since: Posts: Comments:
2153. Stormchaser2007
9:14 PM EDT on May 25, 2008
Hey haha!! Little muggy here but im doing good....
Member Since: Posts: Comments:
2152. HadesGodWyvern (Mod)
1:12 AM GMT on May 26, 2008
Tropical Disturbance Summary (0030z 26May)
==============================================

An area of convection 91W located near 8.8N 141.5E or 215 NM east southeast of Yap. Recent animated satellite imagery and a 2145z SSMI Microwave Image shows preliminary signs of weak convective banding beginning to wrap towards a broad and weak low to mid level circulation center. A recent westerly wind shift in Koror suggest that the mid-level circulation associated with the easterly wave has begun to build down to the surface. Nearby Maritime Observations to the west northwest of Koror confirms westerly winds as well, which will initiate cyclonic turning at the surface. Upper level analysis indicates a favorable environment for continued development with low vertical wind shear and good diffluence.

Sea surface temperatures and ocean heat content will also facilitate further development. Maximum sustained winds near the center is 15-20 knots with a minimum sea level pressure of 1006 mb. Due to an overall favorable environment with the exception of the low level structure, the potential for this disturbance to form into a significant tropical cyclone within the next 24 hours is UPGRADED TO FAIR.
Member Since: Posts: Comments:
2151. StormJunkie
1:11 AM GMT on May 26, 2008
2141 :~))

2145...
So now the government is using computers to generate a storm that will hit Pensacola next week ~)
Member Since: Posts: Comments:
2150. hahaguy
9:12 PM EDT on May 25, 2008
i'm pretty good how bout you chaser.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
2149. Michfan
8:11 PM CDT on May 25, 2008
The most interesting thing about the models is seeing if they are actually right in the long run. I think most of us like to see if they do in fact predict cyclogenesis fairly well.
Member Since: Posts: Comments:
2148. JLPR
9:11 PM AST on Mayo 25, 2008
ahh lol Weather456
I have been 10years hurricane free I am afraid something ends that time of peace =(

But I guess that comes with living on an island in the ocean =P
Member Since: Posts: Comments:
2147. Stormchaser2007
9:11 PM EDT on May 25, 2008
Jeez dont all answer at once......
Member Since: Posts: Comments:
2146. kmanislander
1:11 AM GMT on May 26, 2008
Hi MLC

If the Caribbean can go from bone dry with major subsidence to tropical storm in 6 days that would be a first !
Member Since: Posts: Comments:
2145. kmanislander
1:09 AM GMT on May 26, 2008
Hi there haha

Just throwing in my 2 cents worth

I think that too much reliance is being placed on computer generated storms.

Member Since: Posts: Comments:
2144. Michfan
8:05 PM CDT on May 25, 2008
Looks like the GFS is aiming for the Panhandle of Florida. I still see that it has a 1034 mb high forecast that far out but with a trough weakening its western side as the low pressure moves north through the gulf. Can't wait to see the 00Z run says. Looks like the season is going to start at the very least with a bang. They have us model watching already.
Member Since: Posts: Comments:
2143. moonlightcowboy
8:08 PM CDT on May 25, 2008
K'man, hey! Makes plenty of sense to me, lots of dry air hangin' round those parts.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2142. Stormchaser2007
9:09 PM EDT on May 25, 2008
Hello all, hows everyone tonight!!
Member Since: Posts: Comments:
2141. pottery
9:07 PM AST on May 25, 2008
All Americans should feel justifiably proud, of that incredible piece of precision engineering.
Amazing performance by all concerned.
Congratulations..........
Member Since: Posts: Comments:
2140. hahaguy
9:08 PM EDT on May 25, 2008
hey kmanislander how are you doing tonight.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
2139. kmanislander
12:59 AM GMT on May 26, 2008
I have been watching the discussions on the blog about the various models forecasting a NW Caribbean system at the end of this week.

Climatology has shown year after year that if tropical systems do develop in either the early or late part of the season they tend to do so in the Southern Caribbean. In addition, such development tends to be very slow, often taking 4 to 5 days to produce a closed low.

Given the extremely dry conditions seen so far and still prevailing in the Caribbean I would be surprised if the models verify with a tropical cyclone in 5 to 7 days. Looking at the basin now there is not even a rain shower around.

To go from this to a well organised system by the end of this week is, in my opinion, more than a stretch
Member Since: Posts: Comments:
2138. Weather456
9:02 PM AST on May 25, 2008
MLC I will try to find it and post it


2136. JLPR 9:00 PM AST on May 25, 2008
Hey Weather456 considering the fact that 08 may have an active cape Verde season and with the amount and the organization of the tropical waves in May do you think the islands are in for a bad season?


I am afraid to answer lol, but in my forecast and other forecasts put out by Caribbean mets...it appears the Caribbean is at a higher risk especially the northern part. But that does not mean anything....Every year we get affected by hurricanes, that is one thing I can guarantee.
Member Since: Posts: Comments:
2137. moonlightcowboy
7:59 PM CDT on May 25, 2008
- haha, I've heard several talk about the HBox before, but I've not gotten a great deal out of it's theory. Baha could probably give some good info on that!
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2136. JLPR
8:58 PM AST on Mayo 25, 2008
Hey Weather456 considering the fact that 08 may have an active cape Verde season and with the amount and the organization of the tropical waves in May do you think the islands are in for a bad season?
Member Since: Posts: Comments:
2135. moonlightcowboy
7:58 PM CDT on May 25, 2008
456, do you still have that graphic close? If not, no big deal. Thanks.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2134. JLPR
8:53 PM AST on Mayo 25, 2008
I hope this season gets 30 storms with 28 being fish storms =)
if not then can I have only 12 storms =)
Member Since: Posts: Comments:
2133. moonlightcowboy
7:52 PM CDT on May 25, 2008
Ok, then we can expect less and weaker TUTTS; again, trouble. hhhhhmmmm!
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2132. Weather456
8:48 PM AST on May 25, 2008
2130. moonlightcowboy 8:48 PM AST on May 25, 2008
2128. 456, ok, expand, plz, on that comment. TIA


Remember when I posted the graphic ealrier in the yr.

Also,

2007 - Positive NAO ridge, potent TUTT
2004 - Negative NAO, weak TUTT
Member Since: Posts: Comments:
2131. hahaguy
8:50 PM EDT on May 25, 2008
does anyone actually believe the theory about the Hebert boxes?
Member Since: August 12, 2007 Posts: 2 Comments: 2838
2130. moonlightcowboy
7:45 PM CDT on May 25, 2008
2128. 456, ok, expand, plz, on that comment. TIA
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2128. Weather456
8:39 PM AST on May 25, 2008
Speaking of the TUTT....remember the TUTT is maintained by subsidence in the subtropical ridges. If those ridges are forecasted to be weaker than normal, then that is an idicator of the strength and nature of the TUTT. An example would be to look at two years on different ends of the spectrum:

2007 and 2004
Member Since: Posts: Comments:
2127. Weather456
8:33 PM AST on May 25, 2008
090. aspectre 7:02 PM CDT on May 25, 2008
....Welcome to the North Pole of Mars."


I am a big fan of mars....I want them to confirm frozen water and find some sort of present or signs of past life. It would be awesome of that rover could melt a sample of the ice.
Member Since: Posts: Comments:
2126. moonlightcowboy
7:35 PM CDT on May 25, 2008
I know if "ifs and butts" were candy and nuts, we'd all have a merry Christmas; BUT, that last wave with the closed low would have probably developed absent the TUTT - prolly a fish storm, but could have real easily been our first invest, first storm. Granted a right turn would have found cooler waters though. Still, very interesting so early in the season (May), lol!
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2125. keywestdingding
12:35 AM GMT on May 26, 2008


i wonder if they will ever fix the sst's on here. most of the GOMex is already at 80.
Member Since: Posts: Comments:
2124. hahaguy
8:34 PM EDT on May 25, 2008
Does anyone believe the hebert box box? truthfully i dont.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
2123. FLWeatherFreak91
8:32 PM EDT on May 25, 2008
This season will have all different types of storms like many of them do but I can almost totally assure you it will be known as mainly a bad CV season. 456 is correct about the overly high organization of these early waves. In years past i can't recall talking about an atlantic wave until mid or late july
Member Since: Posts: Comments:
2122. moonlightcowboy
7:29 PM CDT on May 25, 2008
2120. Thought so, thanks. 1 + 1 = T R O U B L E, ugh!
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2121. Drakoen
12:27 AM GMT on May 26, 2008
I think in July we could see a CV storm or 2 form easily especially judging from the anomalously high precip values that area forecast by the CFS and ECMWF..
Member Since: October 28, 2006 Posts: 57 Comments: 30615
2120. Weather456
8:20 PM AST on May 25, 2008
2114. moonlightcowboy 8:18 PM AST on May 25, 2008
456, sure seems CV is shooting pretty hard, fairly early - like a sling shot pulling back ready to fire all that potential energy. Does this seem normal to you, timeliness and frequency, now, at which they're rolling off? Or is it just me noticing them more?


The frequency is matched with 2005 and to some extent 2004. We have a little more than 2004. But thats not really what suprises me, its the organization of these waves in May. They are not normal. I have spotted several waves this month that had the organization of June, July and August waves. The only difference between these waves and the ones found during those months is the latitude. What is also extraordinary is that one of these waves aquired a close circulation. If another waves attempt that even late next month or July at 10-15N with more moisture, less shear....1 plus 1 equals 2.
Member Since: Posts: Comments:
2119. surfmom
12:22 AM GMT on May 26, 2008
have a good evening all, thanks for those phoenix links, and keep an eye on what's cooking in the BOC ---I like seeing those channel swell waves visit my beach from there.
Member Since: Posts: Comments:
2118. Patrap
7:21 PM CDT on May 25, 2008
Join Barometer Bob for The 2008 Hurricane Preparedness Week will be held May 25th through May 31st.


Bob will be hosting "Hurricane Hollow's Hurricane Awareness Week" Internet Broadcasts each evening beginning at 8PM/ET on WRBN.Net with your host Barometer Bob Brookens and special guests.


Scheduled Guests

Sunday May 25 - Lew Fincher, from HurricaneConsulting.Net. You have seen him on the History Channel special about "Isaac's Storm" the 1900 Galveston Hurricane.
Monday May 26 - Jamie Rhome, Hurricane Specialist at the National Hurricane Center.
Tuesday May 27 - Bob Breck, Chief Meteorologist from WVUE-TV - Fox 8 in New Orleans, LA.
Wednesday May 28 - Laura Algeo, FEMA Region IV, National Flood Insurance Program.
Thursday May 29 - Eric Blake, Hurricane Specialist at the National Hurricane Center. We will also have Butch Loper "AKA sandcrab", Emergency Operations/Civil Defense Director for Jackson County, MS.
Friday May 30 - Leslie Chapman-Henderson, Director of FLASH.Org.
Saturday May 31 - Michelle Jantz Manager, Program Management and Support Preparedness and Health and Safety Services from the American Red Cross.

Hurricane Hollow's Eye on the Storm June 1st Broadcast

I will have special guests, callers and you can join us in Storm Chat!
My guests include:
Spokeperson from 511 the Traffic Information Portal.
Gary Padgett, from the Tropical Cyclone Summeries.
And more! Stay tuned for more information on the 8 nights of broadcasts from www.WRBN.Net!


Come join in chat for a full week of Hurricane Prepardness.

Show Link Link

StormChat Link
Member Since: July 3, 2005 Posts: 426 Comments: 129093
2117. Weather456
8:14 PM AST on May 25, 2008
2093. moonlightcowboy 8:03 PM AST on May 25, 2008
2078. Gotcha 456, but weeks ago we came to consensus in here that most dust rides at the mid-levels. The cATL shows really nothing in the upper levels and only a spot in the mids. Water vapor looks plentiful and Navy's TPW product pretty much reflects that, too.


Ur correct, and I just check TRMM measurements...near-above normal moisture out there.
Member Since: Posts: Comments:
2116. surfmom
12:15 AM GMT on May 26, 2008
older son graduates as a commercial diver/diver EMT & underwaterwelding --graduates this Friday...looks like a job in the gomex or Malta. If it's the gulf - should be interesting.

younger son dreams of doing some kind of engineering for the space program - this kind of an event really stokes the fires in a kid.

So I'll have one working the heavens, the other under the sea.
Member Since: Posts: Comments:
2115. Drakoen
12:17 AM GMT on May 26, 2008
Yea W456, I was just looking at the EUMETSAT animations on that.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
2114. moonlightcowboy
7:16 PM CDT on May 25, 2008
456, sure seems CV is shooting pretty hard, fairly early - like a sling shot pulling back ready to fire all that potential energy. Does this seem normal to you, timeliness and frequency, now, at which they're rolling off? Or is it just me noticing them more?
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2113. Drakoen
12:14 AM GMT on May 26, 2008
Member Since: October 28, 2006 Posts: 57 Comments: 30615
2112. StormJunkie
12:15 AM GMT on May 26, 2008
Dude said pucker factor....lmao :c)
Member Since: Posts: Comments:
2110. moonlightcowboy
7:13 PM CDT on May 25, 2008
2103. Yeah, SJ, listening! What a happy crew...still hearing lots of laughter. UofA now takes on the mission - .25 degree tilt? That's like perfect! WTG, NASA!

Yeah, those pictures should be awesome!!!
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2109. Weather456
7:55 PM AST on May 25, 2008
A possible tropical wave across West Africa



This is no doubt an african easterly wave across Central Africa



Member Since: Posts: Comments:
2108. surfmom
12:12 AM GMT on May 26, 2008
a rare moment Nash! ...hee hee
Member Since: Posts: Comments:
2107. StormJunkie
12:11 AM GMT on May 26, 2008
Ditto nash, can not wait until we get to put a foot down over there. Can only hope I get to live long enough to see it.
Member Since: Posts: Comments:

Viewing: 2157 - 2107

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.