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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Quoting 1745. ILwthrfan:
Is there any way that the Mountains of Mexico could contribute dry air to Ingrids circulation? As the circulation grows stronger and more expansive I would imagine wind pulling in from the west would be compressing and drying as moves downslope of the mountains, maybe keeping Ingrid in check somewhat? Something to keep an eye on as it is very close land as it is.


Too much moisture in region right now for that to occur. If anything, moisture from the Pacific will amplify things.
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Quoting 1739. daddyjames:


I don't think so, it looks as if the trough/front to the north is not going to penetrate as far south and west into Texas as originally forecast. The ridge will build back in and start pushing this towards Mexico, around Tampico.


Open your eyes man, the thing is down there intensifying I type this.
Member Since: September 6, 2012 Posts: 0 Comments: 299
1747. JNTenne
Vera Cruz MX webcam
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Quoting 1676. help4u:
Enjoy the weather it is the only weather you got!Forgot to tell you he nailed Gabby too.

Maybe that suggests he could stick with hurricanes where he has the experience and appropriate knowledge to be successful.
Quoting 1665. ILwthrfan:
People should always see viewpoints of all sides, not just one. The more viewpoints the more accurate you can deduct accurate information.

No, that is not necessarily accurate.
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Is there any way that the Mountains of Mexico could contribute dry air to Ingrids circulation? As the circulation grows stronger and more expansive I would imagine wind pulling in from the west would be compressing and drying as moves downslope of the mountains, maybe keeping Ingrid in check somewhat? Something to keep an eye on as it is very close land as it is.
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Just looked at the surf cam in Port Aransas-higher than normal tides-pretty sure my boss is surfing this a.m.
Member Since: July 15, 2005 Posts: 25 Comments: 333
Quoting 1729. GTstormChaserCaleb:
The interesting thing will be to see what implications a quieter period in the Atlantic has on the US during the winter time. If indeed we return to the 70s-80s the south had some really brutal winters and they were at least 2 legitimate instances where snow accumulated in Central and South FL. 1977 and 1989.


Accumulate in SoFL? Only on cars, not on the ground. Unfortunately, I remember that event - only because of the age implications. :)
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1742. GatorWX
This makes me think it may not go north.



Needs disconnection from 90E.
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Quoting 1736. ihave27windows:


I was making a point. Maybe it wasn't clear...my point, that is. Regardless, I am old enough to know there are three sides to every story. =)
The male side, the female side, and what actually really happened. I learned this from someone older than me. With age comes wisdom.
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MIMIC showing a westward movement and intensification...

Link
Member Since: September 5, 2007 Posts: 0 Comments: 3480
Quoting 1706. CybrTeddy:


I think it's premature to make that conclusion, this thing is going to still have many days to sit around the BoC. I think it'll make a run for hurricane status, models seem to think so too.


I don't think so, it looks as if the trough/front to the north is not going to penetrate as far south and west into Texas as originally forecast. The ridge will build back in and start pushing this towards Mexico, around Tampico.
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1738. GatorWX
Second, refs can't treat every push like it's a late hit. Enjoy rushing the prolate spheroid piece of leather.

In the nude!

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Quoting 1731. Doss2k:
In early August I told my friend that we would have two storms head towards the US this year. Gabrielle would hit the east coast and Jerry would hit along the gulf. Canada counts as the east coast right? ;)
To some it depends on a matter of perspective, geographically speaking it is part of the East Coast, well Northeast Coast to be exact. :P
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Quoting 1720. schistkicker:


Confirmation bias does no one any favors.


I was making a point. Maybe it wasn't clear...my point, that is. Regardless, I am old enough to know there are three sides to every story. =)
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Radar also shows just how close this storm is to land as well. I am not quite sold on the northern side of the track. This could easily go south of Veracruz, Mexico IMO

Radar, ALvarado, MEXICO.
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Quoting 1712. GTstormChaserCaleb:
Too soon to claim that Natalie, give it 2-3 more years then we will know for sure if we are entering a quieter phase. Wonder if we will get an El-Nino next year, as my first thoughts before this season began was that we were going to get one this season.
Definitely too early. I'm not in any way claiming that 2013 will equal 2010's prodigious output, but the former is at the moment very closely tracking the latter:

2013
Member Since: November 8, 2009 Posts: 4 Comments: 13276
Ingrid will definitely be an interesting one. It would be very cool to see this intensify rapidly from a meteorological enthusiast's perspective. However, that could be devastating in this location. We will just wait and see, it seems.
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Quoting 1654. PensacolaDoug:




Analysis in 140 characters or less?
It's twitter. Get a grip!
Quoting 1652. Patrap:
A alarmist?

I think your kinda tossing around words that you dont understand.

Dr. Masters is a realist when it comes to Data, any data he use's on anything is well presented, and you wont find him en meshed in Politics that's fer sure.

Your statement is not only factually incorrect, it says a lot about why your here Dawlin'



It's obvious to me those that haven't followed closely the climatic events and peer-reviewed publications of the last dozen or so years. If they had, they'd know that Dr. Masters is not an alarmist. He mentions worst case scenarios, but there is a lot more depth to the pessimistic possibilities of the next 50 to 100 years. More than likely, your average AGW contrarian or denier has not spent a lot of time researching the worst-case scenarios, and why the odds of those scenarios are increasing each year we don't act.
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1731. Doss2k
In early August I told my friend that we would have two storms head towards the US this year. Gabrielle would hit the east coast and Jerry would hit along the gulf. Canada counts as the east coast right? ;)
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1730. JNTenne
"Here's lookin' at you kid"
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Quoting 1718. SouthernIllinois:

You're right. We'll know definitely then. I am going out on a limb and saying this is it though. 1995-2012 RIP Active Atlantic Season.
The interesting thing will be to see what implications a quieter period in the Atlantic has on the US during the winter time. If indeed we return to the 70s-80s the south had some really brutal winters and they were at least 2 legitimate instances where snow accumulated in Central and South FL. 1977 and 1989.
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1727. GatorWX
Quoting 1706. CybrTeddy:


I think it's premature to make that conclusion, this thing is going to still have many days to sit around the BoC. I think it'll make a run for hurricane status, models seem to think so too.


It's shallow in the BOC, 10/Ingrid is carrying a lot of rain. Remember Debbie? I'm just saying. If it was sitting south of Cuba, it'd be in a much better position. I most certainly am not ruling it out however.
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1725. Patrap
Furst TB has to work on Winning with a lead and :28 secs left and the other Team has 0 Time Outs.

; )

Member Since: July 3, 2005 Posts: 414 Comments: 125613
Quoting 1707. GTstormChaserCaleb:
Going to probably need to watch the GOM, East Coast of FL. or Western Caribbean for any signs of development next week.



Heck GT - I'm watchin' this week :) Anything below my feet makes me nervous
Member Since: September 5, 2007 Posts: 0 Comments: 3480
Quoting 1702. CybrTeddy:
Recon finding a much tighter pressure drop/rise than yesterday, 1000mb before going back up to around 1005mb. Meaning the LLC is better established and better organized. Intensification should begin in earnest today.


It almost appears that it's backing somewhat to the east on satellite this morning, although that is the upper levels of the storm, so at the lower levels it could be still stationary or moving west. Maybe a tilted circulation? The ULL that was dropping south to its northwest yesterday seems to be backing to the west now. I would think shear should drop some compared to yesterday. This could help ventilate his north side in addition to the already good ventilation to east that was already in place. That disturbance in the Pacific is also helping that ULL fuel the Southwesterly shear that we have been seeing the last few days as well, although not as strong is still present.


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is the area 15N 73W the precursor of the 'J' storm. strong mid level circulation.
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Quoting 1642. ihave27windows:


I do not find left leaning news organizations to be credible. I watch Fox News, and I don't give a rat's behind what you think. Ugh! You are a snob, and you are officially disliked, and IGNORED.


Confirmation bias does no one any favors.
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1719. hydrus
Quoting 1709. SouthernIllinois:

No doubt this system will flirt with 75 MPH. I could see it easily happen.
Plenty of warm water, and the geography there is conducive rapid intensification..Shear. not so much.
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1717. GatorWX
Quoting 1703. SouthernIllinois:

That think is getting sheared to pieces. Yeah, Saints have this one no problemo. Brees ze Going 2-0.


Waaa waaa waaaaaaaaaaa

Good little saints and dirty ragged pirates, c'mon!

It's Freeman's year! Tellin' ya! :P

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1716. Patrap
A new entry is imminent.




Controls and ZOOM active

10L Short Floater - Visible Imagery Loop
Member Since: July 3, 2005 Posts: 414 Comments: 125613
Quoting 1701. RyanSperrey:
Couple of days ago, it looked like the curse of the i storm was going to continue...

In terms of intensity, no way at all is this reach Hurricane strength that I can see, so in that regard the curse is broken.

BUT BUT BUT!

The rains from Ingrid are going to be catastrophic in Mexico, we're talking 2+ feet of rain in a rather large sloth of land because of this her, which is absolutely horrible after the same exact area has already been hit by 3 other tropical systems this year.

The iCurse may be broken for the USA, but for the Atlantic as a whole...it's still alive.


Its not just where its going to hit. The combination of all the interactions looks as if a good portion of the entire nation are going to be impacted significantly.



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Quoting 1690. Patrap:



You missed the Friday uber Liberal Skype confernce call.

Still a strong "Brees" forecasted for Tampa Sunday.

JB jus tweeted it.


Well TB has a AOI slated for a Cat-5-Martin forecasted so we shall see :)
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Quoting 1696. SouthernIllinois:

1995-2012 active period of Atlantic storms. RIP.
Too soon to claim that Natalie, give it 2-3 more years then we will know for sure if we are entering a quieter phase. Wonder if we will get an El-Nino next year, as my first thoughts before this season began was that we were going to get one this season.
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Interesting tidbit - 2007's Tropical Storm Ingrid also formed on the 12th of September, and was named on the 13th.
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1710. hydrus
This is the 240 hour GFS, it is to far out to consider, but this would make for a stormy pattern.
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19.667N 95.233W 959.4 mb
(~ 28.33 inHg) 376 meters
(~ 1,234 feet) 1001.7 mb
(~ 29.58 inHg) - From 84� at 45 knots
(From the E at ~ 51.7 mph) 21.5�C*
(~ 70.7�F*) 21.4�C*
(~ 70.5�F*) 45 knots
(~ 51.7 mph)

we will have a tropical storm now
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Going to probably need to watch the GOM, East Coast of FL. or Western Caribbean for any signs of development next week.

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Quoting 1701. RyanSperrey:
Couple of days ago, it looked like the curse of the i storm was going to continue...

In terms of intensity, no way at all is this reach Hurricane strength that I can see, so in that regard the curse is broken.

BUT BUT BUT!

The rains from Ingrid are going to be catastrophic in Mexico, we're talking 2+ feet of rain in a rather large sloth of land because of this her, which is absolutely horrible after the same exact area has already been hit by 3 other tropical systems this year.

The iCurse may be broken for the USA, but for the Atlantic as a whole...it's still alive.


I think it's premature to make that conclusion, this thing is going to still have many days to sit around the BoC. I think it'll make a run for hurricane status, models seem to think so too.
Member Since: July 8, 2005 Posts: 259 Comments: 23012
welcome aboard Ingrid. The blog will start to explode.
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Recon finding a much tighter pressure drop/rise than yesterday, 1000mb before going back up to around 1005mb. Meaning the LLC is better established and better organized. Intensification should begin in earnest today.
Member Since: July 8, 2005 Posts: 259 Comments: 23012
Couple of days ago, it looked like the curse of the i storm was going to continue...

In terms of intensity, no way at all is this reach Hurricane strength that I can see, so in that regard the curse is broken.

BUT BUT BUT!

The rains from Ingrid are going to be catastrophic in Mexico, we're talking 2+ feet of rain in a rather large sloth of land because of this her, which is absolutely horrible after the same exact area has already been hit by 3 other tropical systems this year.

The iCurse may be broken for the USA, but for the Atlantic as a whole...it's still alive.
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Hello Ingrid...
Member Since: September 5, 2007 Posts: 0 Comments: 3480

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About JeffMasters

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