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

Share this Blog
58
+

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

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: 1049 - 999

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 | 38Blog Index

1049. MrMixon
Quoting 1047. daddyjames:
Mr. Mixon,

Good news, only 2-3 inches forecast for the next 24 hours.

sarcasm flag on.




I'm really kicking myself for procrastinating on buying that canoe...
Member Since: March 26, 2006 Posts: 44 Comments: 1520
1048. MrMixon
Quoting 1029. GatorWX:
Still falling rather heavy. Good luck and stay safe!



Yes, rain has really picked up here at the house over the past hour. Fog is starting to settle in. I feel bad for anyone unfortunate enough to be out driving in the foothills tonight after dark.
Member Since: March 26, 2006 Posts: 44 Comments: 1520
Mr. Mixon,

Good news, only 2-3 inches forecast for the next 24 hours.

sarcasm flag on.
Member Since: June 25, 2011 Posts: 2 Comments: 3731
What MH09 said earlier pretty much sums up my feelings toward the people on here who constantly whine and complain.
Quoting 924. MiamiHurricanes09:
If you aren't going to contribute to the blog with constructive posts, feel free to leave and not come back.
Member Since: August 9, 2009 Posts: 10 Comments: 4905
Why Has It Been So Long Since a Major Hurricane Hit the US?

Excerpt:

Luck

Luck probably plays the biggest role in the lack of major hurricane hits, said Chris Landsea, the science and operations officer at the National Hurricane Center (NHC).
Member Since: Posts: Comments:
If...
In 5 days Humberto becomes a hurricane again and TD 10 eventually makes landfall at the same time as a hurricane.

Wouldn't be awesome for Mexico, but it's a possibility it could happen...
Member Since: July 19, 2011 Posts: 11 Comments: 2139
Quoting 1037. LAbonbon:


Listening to the Sheriff & Fire live feed, and cross-referencing locations w/ Google maps - evacuations, swift water rescues, and bridge & road damage/washouts are over a really large geographic area.

Honestly, listening to this is the most stressed I've been in quite a while. The rescuers just can't get to all the locations easily. The emergency responders are amazing, and the dispatchers are cool as cucumbers.

And more rain on the way...NWS is saying peak risk (flood stages) could be at 2200 hours

I'd be interested to know how many evacuations and swift water rescues they've done. They've been at it non-stop.


Local Live News Coverage
Member Since: Posts: Comments:
Quoting 1036. GeoffreyWPB:


Good question! In this case it means hello. :)
You say goodbye, and I say hello,hello hello, I don't know why you say goodbye I say hello...
Member Since: October 3, 2008 Posts: 0 Comments: 5822
1041. Patrap
Colorado Flooding Emergency (PHOTOS)
Member Since: Posts: Comments:
1040. Patrap
Northern Colorado Flood Live Updates
Member Since: Posts: Comments:
1039. barbamz
Quoting 1030. Stoopid1:


Tone of your post aside, I guess I should have said more. Looking at the way Humberto's structure is evolving and how he's still maintaining good convection, and the conditions it is going into, I was thinking that an annular storm could be a possibility. Small chance all things considered, I know.


What I've found interesting is, that Humberto yet didn't decide to make this shift to the northwest as forecast points already would suggest. Look at its floater. Maybe just a little delay though ...
Good night anyway!
Member Since: October 25, 2008 Posts: 52 Comments: 5699
never know I guess.....Hello then
Member Since: October 3, 2008 Posts: 0 Comments: 5822
Quoting 1011. MrMixon:
Boulder is full of crazy people outdoor enthusiasts.

A kayaker on Boulder Creek earlier this afternoon:



A "gymnast" over Boulder Creek:


------------------
Click images for originals. File both of these under "Do not attempt"


Listening to the Sheriff & Fire live feed, and cross-referencing locations w/ Google maps - evacuations, swift water rescues, and bridge & road damage/washouts are over a really large geographic area.

Honestly, listening to this is the most stressed I've been in quite a while. The rescuers just can't get to all the locations easily. The emergency responders are amazing, and the dispatchers are cool as cucumbers.

And more rain on the way...NWS is saying peak risk (flood stages) could be at 2200 hours

I'd be interested to know how many evacuations and swift water rescues they've done. They've been at it non-stop.
Member Since: June 26, 2013 Posts: 0 Comments: 1817
Quoting 1033. PalmBeachWeather:
Always wondered.....Does "Good Evening" mean Hello or Goodbye?


Good question! In this case it means hello. :)
Member Since: Posts: Comments:
Quoting 1034. TropicalAnalystwx13:
New Jersey Governor Chris Christie is briefing everybody on the out-of-control fire going on in Seaside Heights, a place just devastated by Superstorm Sandy in October.

Link
That's so sad...Love the Gov
Member Since: October 3, 2008 Posts: 0 Comments: 5822
New Jersey Governor Chris Christie is briefing everybody on the out-of-control fire going on in Seaside Heights, a place just devastated by Superstorm Sandy in October.

Link
Member Since: July 6, 2010 Posts: 113 Comments: 31554
Quoting 1032. GeoffreyWPB:
Good evening all...

Always wondered.....Does "Good Evening" mean Hello or Goodbye?
Member Since: October 3, 2008 Posts: 0 Comments: 5822
Good evening all...

Member Since: Posts: Comments:
Quoting 1025. CaribBoy:
Man I'm tired with Mexico BOC BORING storms.

Do you do anything other than complain?

Member Since: July 6, 2010 Posts: 113 Comments: 31554
Quoting 1009. sar2401:

It might be even more interesting if you told us what storm this is and what your find particularly interesting about it.


Tone of your post aside, I guess I should have said more. Looking at the way Humberto's structure is evolving and how he's still maintaining good convection, and the conditions it is going into, I was thinking that an annular storm could be a possibility. Small chance all things considered, I know.
Member Since: Posts: Comments:
1029. GatorWX
Still falling rather heavy. Good luck and stay safe!

Member Since: Posts: Comments:
Quoting 1026. MrMixon:


What this kayaker did was illegal and unsafe. Still, it made for a neat photo...
It is neat, but that's just too dangerous. At least French Broad wasn't at the point you can't raft that day... it was almost to the limit that is allowed to raft at French Broad that day I raft.
Member Since: August 1, 2011 Posts: 28 Comments: 7912
Quoting 1026. MrMixon:


What this kayaker did was illegal and unsafe. Still, it made for a neat photo...
Standstill Mr
Member Since: October 3, 2008 Posts: 0 Comments: 5822
1026. MrMixon
Quoting 1024. Bluestorm5:


Even it's pretty stupid to kayak on... you don't know how unpredictable streams are when it is high as result of heavy rain. Guides at French Broad struggled with the river since water was high and we had a 10 feet drop (uncommon for the area I rafted at) which results me falling out of raft. Luckily, I didn't smash into any rocks and I had fun :)


What this kayaker did was illegal and unsafe. Still, it made for a neat photo...
Member Since: March 26, 2006 Posts: 44 Comments: 1520
Man I'm tired with Mexico BOC BORING storms.
Member Since: Posts: Comments:
Quoting 1011. MrMixon:
Boulder is full of crazy people outdoor enthusiasts.



A kayaker on Boulder Creek earlier this afternoon.


Even it's pretty stupid to kayak on... you don't know how unpredictable streams are when it is high as result of heavy rain. Guides at French Broad struggled with the river since water was high and we had a 10 feet drop (uncommon for the area I rafted at) which results me falling out of raft. Luckily, I didn't smash into any rocks and I had fun :)
Member Since: August 1, 2011 Posts: 28 Comments: 7912
1023. Patrap
Member Since: Posts: Comments:
Quoting 1012. all4hurricanes:
We got a lot of rain at Albany
apparently the lecture centers flooded
and one of my friends classes was canceled because the ceiling tiles got soaked and fell down.


NY?
Member Since: June 26, 2013 Posts: 0 Comments: 1817
1021. Patrap
Member Since: Posts: Comments:
1020. Patrap
Member Since: Posts: Comments:
TD10 still lack concentrated convection over the center should pull a look of moisture and humid from the EPAC and wrap it around its circulation across the hot dry landmass of Mexico creating plenty of instability. The biggest threat will definitely be the extreme rainfall expected regardless of it just making Hurricane statues or not.

Member Since: Posts: Comments:
Quoting 1003. SuperStorm093:
I honestly do not try to start trouble, I just say what I think will happen. And I was wrong about Gabby coming back to life.
LOL..........I love trouble..
Member Since: October 3, 2008 Posts: 0 Comments: 5822
1017. Patrap
Member Since: Posts: Comments:
Quoting 1010. Stormlover16:


Thanks guys, I'm in South Delaware. We're not supposed to get hit hard, but the sky is probably the darkest I've seen all year.


Dark skies? I absolutely love storms like that!
Member Since: Posts: Comments:
Pressures are falling all across the Caribbean Sea.
Member Since: Posts: Comments:
1014. beell
Quoting 999. daddyjames:
It looks as if one thing that will prevent 10L from significantly strengthening is sheer.






24hours


72 hours


Sometimes, indicated or modeled shear in a system with an abundance of deep convection is strong outflow out the top as the column warms-and can be a a bit misleading. Sometimes not, lol.
Member Since: Posts: Comments:
Quoting 1001. TropicalAnalystwx13:

Anticyclonic aloft as seen in those images promotes lower shear. It won't be an issue.


SHEAR (KT) 17 15 14 14 18 18 15 6 5 7 4 6 3
SHEAR ADJ (KT) 0 0 0 1 2 -3 -1 -5 0 -2 0 -3 -1
Member Since: July 8, 2005 Posts: 259 Comments: 23627
We got a lot of rain at Albany
apparently the lecture centers flooded
and one of my friends classes was canceled because the ceiling tiles got soaked and fell down.
Member Since: Posts: Comments:
1011. MrMixon
Boulder is full of crazy people outdoor enthusiasts.

A kayaker on Boulder Creek earlier this afternoon:



A "gymnast" over Boulder Creek:


------------------
Click images for originals. File both of these under "Do not attempt"
Member Since: March 26, 2006 Posts: 44 Comments: 1520
Quoting 1007. 62901IL:

Stay safe,
Quoting 1008. SuperStorm093:
Got DRILLED here is south central PA, huge winds and LOTS of rain. Stay safe.


Thanks guys, I'm in South Delaware. We're not supposed to get hit hard, but the sky is probably the darkest I've seen all year.
Member Since: Posts: Comments:
1009. sar2401
Quoting Stoopid1:
Interesting.


It might be even more interesting if you told us what storm this is and what your find particularly interesting about it.
Member Since: Posts: Comments:
Quoting 1005. Stormlover16:
Whoever was getting hit by strong storms an hour ago- well, that's me now. Lot of thunder and really dark skies.
Got DRILLED here is south central PA, huge winds and LOTS of rain. Stay safe.
Member Since: Posts: Comments:
1007. 62901IL
Quoting 1005. Stormlover16:
Whoever was getting hit by strong storms an hour ago- well, that's me now. Lot of thunder and really dark skies.

Stay safe,
Member Since: Posts: Comments:
Quoting 1003. SuperStorm093:
I honestly do not try to start trouble, I just say what I think will happen. And I was wrong about Gabby coming back to life.


The truth is, we are all wrong often here. We learn from our errors here. That is what meteorology is about.
Member Since: Posts: Comments:
Whoever was getting hit by strong storms an hour ago- well, that's me now. Lot of thunder and really dark skies.
Member Since: Posts: Comments:
1004. sar2401
Quoting TheGreatHodag:


that's what concerns me as well. Also, Joe Bastardi is expecting a Cat 2/3 from td 10 a little north of Tampico bringing devastating rains to Monterrey. Though, of course, this is Joe Bastardi.

I imagine Big Joe is using Alex as his analogue, since that's one that produced severe flooding in Monterrey. Other than the fact Alex was already a TS before it made landfall in Belize, and then came back into the BOC in a moisture rich, low shear, environment, with an anticyclone forming right over it, TD10 and Alex are almost a perfect match. :-) If the center (assuming it has one) gets to about 22N, 88W, then I'll start to worry about it becoming a hurricane. Otherwise, I have no reason to think it will behave any different than the four systems that preceded it this year.
Member Since: Posts: Comments:
Quoting 1000. FunnelVortex:


Okay, just stay out of trouble.
I honestly do not try to start trouble, I just say what I think will happen. And I was wrong about Gabby coming back to life.
Member Since: Posts: Comments:
Interesting.

Member Since: Posts: Comments:
Quoting 999. daddyjames:
It looks as if one thing that will prevent 10L from significantly strengthening is sheer.






24hours


72 hours

Anticyclonic aloft as seen in those images promotes lower shear. It won't be an issue.
Member Since: July 6, 2010 Posts: 113 Comments: 31554
Quoting 996. SuperStorm093:
Back from the ban yes.


Okay, just stay out of trouble.
Member Since: Posts: Comments:
It looks as if one thing that will prevent 10L from significantly strengthening is sheer.






24hours


72 hours
Member Since: June 25, 2011 Posts: 2 Comments: 3731

Viewing: 1049 - 999

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 | 38Blog 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.