Flash Floods Kill 3 in Colorado; Dangerous 93L Developing in Gulf of Mexico

By: Dr. Jeff Masters , 3:06 PM GMT on September 12, 2013

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Devastating flash floods swept though numerous canyons along the Front Range of Colorado's Rocky Mountains Wednesday night and Thursday morning, washing out roads, collapsing houses, and killing at least two people. The floods were triggered by widespread torrential rains of 4 - 6" that fell in less than twelve hours, thanks to a flow of extremely moist air from the southeast that pushed up against the mountains. These sort of upslope rain events are so-named because as the air flows uphill, it expands and cools, forcing the moisture in it to fall as rain. Balloon soundings from Denver last night and this morning recorded the highest levels of September moisture on record for the station. The total precipitable water (PW), which is how much water would fall at the ground if the entire amount of water vapor through the depth of the atmosphere was condensed, was 1.33" at 12Z (8 am EDT) on September 12, and 1.31" at 00Z September 12. The previous September record was 1.23", set on September 10, 1980. Balloon soundings began in 1948. Wednesday night's rainfall was heaviest near Boulder, Colorado, where a flash flood watch continues through Thursday evening. Though rainfall amounts today are not expected to be as great as on Wednesday, the soils are saturated, and additional flash flooding will occur today as an upper-level low centered over the southern Great Basin continues to pull a moist southeasterly surface flow of air across Eastern Colorado. A map of Boulder flood zones and detailed history of previous floods in the area may be found here.


Figure 1. Flooding in Boulder, Colorado on Wednesday evening, September 11, 2013. Photo posted by brandish on Instagram @photogjake.


Figure 2. Radar-estimated rainfall for the Colorado's Front Range from the September 11 - 12 flash flood event. Rainfall amounts of 6 - 8" (dark rad colors) were indicated near Boulder (circle with a "+" symbol), and confirmed by rain gauge measurements.


Video 1. Flooding in Boulder, Colorado at 36th and Colorado Street on Wednesday night, September 11, 2013.

Dangerous 93L developing in the Gulf of Mexico
A low pressure system (Invest 93L) over the Southwestern Gulf of Mexico's Bay of Campeche is generating heavy rains over the Yucatan Peninsula and adjacent waters as it moves west-northwest at about 5 mph. Radar loops from Mexico show that 93L has a pronounced rotation and is developing low-level spiral bands, and there is a strong possibility that the Air Force hurricane hunter plane scheduled to investigate 93L Thursday afternoon will find that a tropical depression has formed. Satellite loops show only a modest area of heavy thunderstorms, but these are steadily growing in intensity and areal coverage. The atmosphere is unusually moist, ocean temperatures are a very warm 29 - 29.5°C (84 - 85°F), and wind shear is a moderate 10 - 15 knots. These favorable conditions for development are expected to continue through Monday, according to the latest SHIPS model forecast. The computer models predict a landfall location along the Mexican coast between Veracruz and a location a few hundred miles south of the Texas/Mexico border by early next week. The storm is expected to maintain a forward speed of about 5 mph during the coming five days, and this slow motion will potentially allow 93L enough time to intensify into a hurricane before landfall. The high levels of moisture and slow motion of 93L make it a very dangerous rainfall threat, and I expect rainfall amounts of 5 - 10 inches will affect portions of the Mexican coast between Veracruz and Brownsville, Texas over the next five days. An added danger is the presence of tropical disturbance 90E in the Eastern Pacific Ocean, on the other side of Mexico. If 93L intensifies sufficiently, it could draw in the moisture from 90E across Southern Mexico, resulting in torrential rains on both the Pacific and Atlantic sides of Southern Mexico. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave 2-day odds of development of 60% and 5-day odds of 80%.


Figure 3. Latest satellite image of Tropical Depression Ten.

Humberto peaks in intensity
Hurricane Humberto is headed northwards over the far Eastern Atlantic, and has likely peaked in strength, with 85 mph winds. Humberto is listed in NHC's preliminary Best-Track data repository as having achieved hurricane strength at 8 am EDT on September 11, which would tie it with Hurricane Gustav of 2002 for latest appearance of the season's first hurricane since 1941. Satellite loops show that Humberto is well-organized hurricane with a distinct eye, but the storm has moved over waters cooler than 26°C, and wind shear has risen to 20 knots, which will likely cause weakening over the next few days. Humberto is not expected to be a threat to any land areas.

Gabrielle heads towards Canada
Tropical Storm Gabrielle is headed northwards to Canada after bringing 40 mph winds and just over an inch of rain to Bermuda on Tuesday night. Satellite loops show that wind shear has ripped up Gabrielle, leaving the storm with almost no heavy thunderstorms, and exposing the low level circulation to view. Wind shear is expected to rise to an extremely high 45 - 70 knots on Friday as Gabrielle encounters a trough of low pressure, which will likely destroy the storm. Gabrielle's remnants will likely bring heavy rain to the Canadian Maritime Provinces on Friday and Saturday.

Jeff Masters

After the Rain (mtnwoman67)
Lots of rain in Colorado for weeks. Last evening's setting sun gave us a great show east of us.
After the Rain

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Guess who's back? .... LOLLink
Member Since: Posts: Comments:
Quoting 1394. RufusBaker:


why would the blog interfere with his health??


My guess is that after his heart attack, his doctors and nurses would very much appreciate it if he took it easy for some time, and not get caught up in the blog's dramatic life. Rest is one of the best ways to recovery.

Edit: Kori! Don't even hint at the others like that. You gonna make people worry too much.
Member Since: Posts: Comments:
Grothar left, but it's not for the reasons most people believe. His health was not the sole factor.

Out of respect for what he said about not divulging it to anyone, I won't.

But yeah... it's not.
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1396. BtnTx
Quoting 1392. FWBRuss:
Grothar was online a few days ago. Said he wasn't mad at anyone, but because of serious health issues, he was dropping off. He will be missed! I've lurked for years and think all will miss the "BlobCons"
I very much agree!
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1395. bappit
Quoting 1370. Astrometeor:
How come SPC doesn't issue hydrologic discussions more often?

Today's Reports:

Scott Lincoln would be the one to answer that, but I'll guess the SPC does not have the expertise.
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Quoting 1390. Astrometeor:


He's left the blog for an indeterminate amount of time to recover his health.


why would the blog interfere with his health??
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1393. MrMixon
Current Boulder Creek flows far exceed our spring snowmelt peak this year...

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1392. FWBRuss
Quoting 1384. BtnTx:
is he ok? or just blog upset?
Grothar was online a few days ago. Said he wasn't mad at anyone, but because of serious health issues, he was dropping off. He will be missed! I've lurked for years and think all will miss the "BlobCons"
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1391. BtnTx
Quoting 1390. Astrometeor:


He's left the blog for an indeterminate amount of time to recover his health.
Thanks: wishing the best for Gro!
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Quoting 1384. BtnTx:
is he ok? or just blog upset?


He's left the blog for an indeterminate amount of time to recover his health.
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Quoting 1387. TropicalAnalystwx13:

Maybe if you researched instead of making blatantly false accusations you'd realize that The Weather Channel covered this event nearly nonstop from 9am to 11pm EDT. Coverage starts again at 1am EDT.


Probably because Big Brother is watching us :p
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Quoting 1383. WxGeekVA:


Two men enjoy a (legal) joint while watching floods near Boulder, Colorado.

(Hope I don't get banned for this, if it is removed I understand)


I live in WA state, it's only legal until the FED has an issue. Recently the Justice dept stated they won't pursue, but that can change on a whim.
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Quoting 1379. Barkeep1967:
TWC is not really covering the Colorado floods because it hurts their Global Warming agenda. If the Drought ends in Colorado it kills one more of their hot topics

Maybe if you researched instead of making blatantly false accusations you'd realize that The Weather Channel covered this event nearly nonstop from 9am to 11pm EDT. Coverage starts again at 1am EDT.
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Quoting 1383. WxGeekVA:


Two men enjoy a (legal) joint while watching floods near Boulder, Colorado.

(Hope I don't get banned for this, if it is removed I understand)


Lol as long as you're not advocating it. That is so cliche though.
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CONUS WINDS

It will zoom in, too, if you click on an area.
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1384. BtnTx
Quoting 1381. BtnTx:
What happened with Grothar?
is he ok? or just blog upset?
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Two men enjoy a (legal) joint while watching floods near Boulder, Colorado.

(Hope I don't get banned for this, if it is removed I understand)
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Quoting 1377. wxgeek723:


-____-

You formal.


Oops. :D
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1381. BtnTx
Quoting 1354. KoritheMan:


The **** did hit the fan the other day, but that seemed to be more related to why Grothar left than altercations about the tropics.

I would say you more than slightly exaggerated it.
What happened with Grothar?
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1380. FWBRuss
Quoting 1376. moonlightcowboy:


Link
Thanks!
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TWC is not really covering the Colorado floods because it hurts their Global Warming agenda. If the Drought ends in Colorado it kills one more of their hot topics
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Member Since: Posts: Comments:
Quoting 1362. KoritheMan:


I do?


-____-

You formal.
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Quoting 1373. FWBRuss:
MLC, Do you have the link for the moving map for steering currents, I believe its a five day loop?


Link
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1375. MrMixon
Boulder Creek is going for river status...



News is reporting a new pulse of water is going down Boulder Creek now. Please, if you are out in Boulder get away from Boulder Creek.
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1374. flsky
9:07 p.m. MDT The White House has announced that President Barack Obama approved federal disaster assistance for hard-hit Boulder, El Paso and Larimer counties, authorizing the Federal Emergency Management Agency to coordinate the relief effort.
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1373. FWBRuss
Quoting 1369. moonlightcowboy:
Updated charts show even weaker steering.


MLC, Do you have the link for the moving map for steering currents, I believe its a five day loop?
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Could TD 10 end up pulling off a Bret 1999?
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Quoting 1369. moonlightcowboy:
Updated charts show even weaker steering.




It's not going to move much as long as it's being tugged by the ridge over the western United States and the developing disturbance near the Gulf of Tehuantepec.
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How come SPC doesn't issue hydrologic discussions more often?

Today's Reports:
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Updated charts show even weaker steering.


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Quoting 1366. lobdelse81:
Does anyone remember Hurricane Bret of 1999? That system originated in the BOC similar to TD 10. It managed to become a monster hurricane before hitting South Texas as a strong cat3. I believe it ended up hitting Kennedy County, the least vulnerable location any major hurricane could have ever chosen in the US. Only cattle live there.


We've got flying cows, everyone!
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Member Since: Posts: Comments:
Does anyone remember Hurricane Bret of 1999? That system originated in the BOC similar to TD 10. It managed to become a monster hurricane before hitting South Texas as a strong cat3. I believe it ended up hitting Kennedy County, the least vulnerable location any major hurricane could have ever chosen in the US. Only cattle live there.
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1364. flsky
Quoting 1317. wxgeek723:
Lol you'd think the floods in Colorado would be enough for TWC to break programming but alas, no.


VERY odd - I thought that, too. Any word about how things are going in Denver (I was born there)?
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Quoting 1360. Tazmanian:
TWC Is showing nothing but old re runs of nothing at lest its late at night so am going too turn them off now and head too bed


Have a good sleep, Taz and GetReal. :) I'm getting ready to head that way to bed too. Get some rest, the tropics may be coming alive.
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Quoting 1357. wxgeek723:


You usually exaggerate when describing an exaggeration.


I do?
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TWC Is showing nothing but old re runs of nothing at lest its late at night so am going too turn them off now and head too bed
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1359. GetReal
Quoting 1348. sunlinepr:
Once more we have a ULL interacting (S tip of Tx) that is shearing the NW quadrant of TD10.... thats what is affecting it....





That ULL is definitely having a negative effect on 10L ATT. With that, this is a good night to all!
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Quoting 1355. HurricaneCamille:


That ULL is weaksauce.

Wouldn't expect that pathetic little thing to be around much longer


Its going to be absorbed but meanwhile will do its fight....
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Quoting 1354. KoritheMan:


The **** did hit the fan the other day, but that seemed to be more related to why Grothar left than altercations about the tropics.

I would say you more than slightly exaggerated it.


You usually exaggerate when describing an exaggeration.
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Quoting 1308. Tazmanian:



nop TD 10 will be a CA event...
Quoting 1317. wxgeek723:
Lol you'd think the floods in Colorado would be enough for TWC to break programming but alas, no.


Are they showing reruns of Desperate Housewifes?
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Quoting 1348. sunlinepr:
Once more we have a ULL interacting (S tip of Tx) that is shearing the NW quadrant of TD10.... thats what is affecting it....





That ULL is weaksauce.

Wouldn't expect that pathetic little thing to be around much longer
Member Since: September 6, 2012 Posts: 0 Comments: 304
Quoting 1349. wxgeek723:


Well yeah it's standard to see but I feel like it's been more vehement than usual, quite a flair for the dramatic.


The **** did hit the fan the other day, but that seemed to be more related to why Grothar left than altercations about the tropics.

I would say you more than slightly exaggerated it.
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Quoting 1346. MrMixon:
The list of closed roads in Boulder County is kind of hilariously long...

Boulder Office of Emergency Management

I've spared you all the full list, but here's the beginning. Check the link above or my blog for the full list.

• Boulder Canyon Drive between Boulder and Nederland
• US 36 from McCaslin Boulevard to Flatiron Crossing
• CO 93 (South Foothills Highway) from Greenbriar Boulevard to Eldorado Springs Drive
• Sunset Street from Boston Avenue to Donovan Drive
• Hover Street from Rogers Road to 3rd Avenue
• Ute Highway from 75th Street to McCall Drive
• Hygiene Road from North 75th Street to Crane Hollow Road
• North 75th Street from St. Vrain to Hygiene
• Airport Road from St. Vrain to 9th Avenue
• US 287 from Ken Pratt to Boston Avenue
• 39th Street from Ogallala to Plateau Road
• CO Road 7 from Middle Fork to Plateau Road
• North 95th Street from Valmont Road to Lookout Road
• South 120th Street from Commerce Street to South Boulder Road
• Horizon Avenue from Majestic Drive to Panorama Point
• South 120th Street at Dillon Road
• Spring Valley Road
• Westbound US 36 at McCaslin Boulevard
• Eastbound US 36 at Table Mesa Drive
• SH 157 from US 36 to Pearl Parkway
• US 36 North 95th from Lookout Road to Valmont
• SH 93 from 64th Parkway to SH 128
• Lee Hill Road at Olde Stage Road
• Four Mile Canyon from Boulder Canyon to Poorman
• Bow Mtn Rd from Wagon Wheel Gap to Pine Brook Rd
• 95th from Lookout Road to Valmont Road
• 75th from Jay Road to Valmont Road
• Broadway from Quince to Lee Hill Road

That's because all roads in and out of the city of Boulder have been closed. It's inaccessible by an automobile.
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Quoting 1346. MrMixon:
The list of closed roads in Boulder County is kind of hilariously long...

Boulder Office of Emergency Management

I've spared you all the full list, but here's the beginning. Check the link above or my blog for the full list.

• Boulder Canyon Drive between Boulder and Nederland
• US 36 from McCaslin Boulevard to Flatiron Crossing
• CO 93 (South Foothills Highway) from Greenbriar Boulevard to Eldorado Springs Drive
• Sunset Street from Boston Avenue to Donovan Drive
• Hover Street from Rogers Road to 3rd Avenue
• Ute Highway from 75th Street to McCall Drive
• Hygiene Road from North 75th Street to Crane Hollow Road
• North 75th Street from St. Vrain to Hygiene
• Airport Road from St. Vrain to 9th Avenue
• US 287 from Ken Pratt to Boston Avenue
• 39th Street from Ogallala to Plateau Road
• CO Road 7 from Middle Fork to Plateau Road
• North 95th Street from Valmont Road to Lookout Road
• South 120th Street from Commerce Street to South Boulder Road
• Horizon Avenue from Majestic Drive to Panorama Point
• South 120th Street at Dillon Road
• Spring Valley Road
• Westbound US 36 at McCaslin Boulevard
• Eastbound US 36 at Table Mesa Drive
• SH 157 from US 36 to Pearl Parkway
• US 36 North 95th from Lookout Road to Valmont
• SH 93 from 64th Parkway to SH 128
• Lee Hill Road at Olde Stage Road
• Four Mile Canyon from Boulder Canyon to Poorman
• Bow Mtn Rd from Wagon Wheel Gap to Pine Brook Rd
• 95th from Lookout Road to Valmont Road
• 75th from Jay Road to Valmont Road
• Broadway from Quince to Lee Hill Road


I think this is the point where you should issue a travel ban.
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1351. FWBRuss
DaddyJames,

Check post 1320, that was for you. You posted a link a few days ago, and I lost it. TIA!
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Quoting 1346. MrMixon:
The list of closed roads in Boulder County is kind of hilariously long...

Boulder Office of Emergency Management

I've spared you all the full list, but here's the beginning. Check the link above or my blog for the full list.

• Boulder Canyon Drive between Boulder and Nederland
• US 36 from McCaslin Boulevard to Flatiron Crossing
• CO 93 (South Foothills Highway) from Greenbriar Boulevard to Eldorado Springs Drive
• Sunset Street from Boston Avenue to Donovan Drive
• Hover Street from Rogers Road to 3rd Avenue
• Ute Highway from 75th Street to McCall Drive
• Hygiene Road from North 75th Street to Crane Hollow Road
• North 75th Street from St. Vrain to Hygiene
• Airport Road from St. Vrain to 9th Avenue
• US 287 from Ken Pratt to Boston Avenue
• 39th Street from Ogallala to Plateau Road
• CO Road 7 from Middle Fork to Plateau Road
• North 95th Street from Valmont Road to Lookout Road
• South 120th Street from Commerce Street to South Boulder Road
• Horizon Avenue from Majestic Drive to Panorama Point
• South 120th Street at Dillon Road
• Spring Valley Road
• Westbound US 36 at McCaslin Boulevard
• Eastbound US 36 at Table Mesa Drive
• SH 157 from US 36 to Pearl Parkway
• US 36 North 95th from Lookout Road to Valmont
• SH 93 from 64th Parkway to SH 128
• Lee Hill Road at Olde Stage Road
• Four Mile Canyon from Boulder Canyon to Poorman
• Bow Mtn Rd from Wagon Wheel Gap to Pine Brook Rd
• 95th from Lookout Road to Valmont Road
• 75th from Jay Road to Valmont Road
• Broadway from Quince to Lee Hill Road


o.o
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Quoting 1344. KoritheMan:


That's the nature of this blog, lol.

I'm contributing to that until I get my hurricane, so I apologize in advance for that. Maybe. :P


Well yeah it's standard to see but I feel like it's been more vehement than usual, quite a flair for the dramatic.
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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.

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