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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recon google tracker
Member Since: July 3, 2005 Posts: 426 Comments: 128657
Quoting 295. Patrap:
www.tropicalatlantic.com/recon/URNT15/KNHC

They still on the Tarmac

17:17:00Z 30.400N 88.917W 1016.3 mb
(~ 30.01 inHg) 1 meters
(~ 3 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 30.4°C
(~ 86.7°F) 22.7°C
(~ 72.9°F) No Wind - - - -
17:17:30Z 30.400N 88.933W 1016.3 mb
(~ 30.01 inHg) 1 meters
(~ 3 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 30.0°C
(~ 86.0°F) 22.8°C
(~ 73.0°F) No Wind - - - -
17:18:00Z 30.400N 88.933W 1015.7 mb
(~ 29.99 inHg) 3 meters
(~ 10 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 30.6°C
(~ 87.1°F) 22.8°C
(~ 73.0°F) No Wind - - - -
17:18:30Z 30.400N 88.933W 1015.4 mb
(~ 29.98 inHg) 3 meters
(~ 10 feet) 1016.4 mb
(~ 30.01 inHg) - No Wind 31.0°C
(~ 87.8°F) 22.7°C
(~ 72.9°F) No Wind - - - -
17:19:00Z 30.400N 88.933W 1016.0 mb
(~ 30.00 inHg) 4 meters
(~ 13 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 31.7°C
(~ 89.1°F) 22.7°C
(~ 72.9°F) No Wind - - - -
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
HDOB Observations
Independent Calculations from Tropical Atlantic
At 17:09:30Z (first observation), the observation was 10 miles (15 km) to the E (84°) from Gulfport, MS, USA.
At 17:19:00Z (last observation), the observation was 9 miles (14 km) to the E (91°) from Gulfport, MS, USA.
Quoting 294. will40:


its still on runway


Ok, thanks guys.
Member Since: Posts: Comments:
Quoting 291. Torito:
can someone link me to the data website for recon (wind speed, Pressure, exc)?


Hey Torito - here is the link. http://tropicalatlantic.com/recon/

Right now they are still sitting...
Member Since: September 5, 2007 Posts: 0 Comments: 3488
www.tropicalatlantic.com/recon/URNT15/KNHC

They still on the Tarmac

17:17:00Z 30.400N 88.917W 1016.3 mb
(~ 30.01 inHg) 1 meters
(~ 3 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 30.4°C
(~ 86.7°F) 22.7°C
(~ 72.9°F) No Wind - - - -
17:17:30Z 30.400N 88.933W 1016.3 mb
(~ 30.01 inHg) 1 meters
(~ 3 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 30.0°C
(~ 86.0°F) 22.8°C
(~ 73.0°F) No Wind - - - -
17:18:00Z 30.400N 88.933W 1015.7 mb
(~ 29.99 inHg) 3 meters
(~ 10 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 30.6°C
(~ 87.1°F) 22.8°C
(~ 73.0°F) No Wind - - - -
17:18:30Z 30.400N 88.933W 1015.4 mb
(~ 29.98 inHg) 3 meters
(~ 10 feet) 1016.4 mb
(~ 30.01 inHg) - No Wind 31.0°C
(~ 87.8°F) 22.7°C
(~ 72.9°F) No Wind - - - -
17:19:00Z 30.400N 88.933W 1016.0 mb
(~ 30.00 inHg) 4 meters
(~ 13 feet) 1016.5 mb
(~ 30.02 inHg) - No Wind 31.7°C
(~ 89.1°F) 22.7°C
(~ 72.9°F) No Wind - - - -
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor
HDOB Observations
Independent Calculations from Tropical Atlantic
At 17:09:30Z (first observation), the observation was 10 miles (15 km) to the E (84°) from Gulfport, MS, USA.
At 17:19:00Z (last observation), the observation was 9 miles (14 km) to the E (91°) from Gulfport, MS, USA.
Member Since: July 3, 2005 Posts: 426 Comments: 128657
Link
Quoting 291. Torito:
can someone link me to the data website for recon (wind speed, Pressure, exc)?


its still on runway
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292. Tygor
Quoting 289. Naga5000:


Misleading, not 117 climate models 117 simulations made by the CIMP5 model suite. 1 model suite, 117 simulations. Fox can't even read the paper correctly. This actually has been known for a bit, there are some inherent problems with natural forcing attribution in the CIMP5 models. That's why you see papers like this crop up to better understand why this particular one did so poorly and to better tune the model.

When the GFS is inaccurate, do hurricanes stop existing?


I can't believe people turn to Fox News for weather/climatology information.
Member Since: Posts: Comments:
can someone link me to the data website for recon (wind speed, Pressure, exc)?
Member Since: Posts: Comments:
Member Since: July 3, 2005 Posts: 426 Comments: 128657
Quoting 241. SouthernIllinois:
Climate models wildly overestimated global warming, study finds

Can you rely on the weather forecast? Maybe not, at least when it comes to global warming predictions over short time periods.

That%u2019s the upshot of a new study in the journal Nature Climate Change that compared 117 climate predictions made in the 1990's to the actual amount of warming. Out of 117 predictions, the study%u2019s author told FoxNews.com, three were roughly accurate and 114 overestimated the amount of warming. On average, the predictions forecasted two times more global warming than actually occurred.

Some scientists say the study shows that climate modelers need to go back to the drawing board.

Read More



Misleading, not 117 climate models 117 simulations made by the CIMP5 model suite. 1 model suite, 117 simulations. Fox can't even read the paper correctly. This actually has been known for a bit, there are some inherent problems with natural forcing attribution in the CIMP5 models. That's why you see papers like this crop up to better understand why this particular one did so poorly and to better tune the model.

When the GFS is inaccurate, do hurricanes stop existing?
Member Since: Posts: Comments:
Quoting 276. Tazmanian:



you don't speak for the blog and am not a troll



dos any one no how too ues the ignore tools on here I guss not other wise they would have ignore me by now some of you need too learn too open your eyes and ues the tools on here that's if you don't don't want too see me and my commets this put me on ignore and whats stop the bickering. about it

Yes, actually, had you ignored but decided to give you a 2nd chance. sometimes you have relevant inputs but back to silent mode for you.
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here come invest 93L!!
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Quoting 284. HuracandelCaribe:
Funny little sucker!!





Please go to the islands so Cariboy gets what he wants.
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Funny little sucker!!



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cloud tops are warming bigtime on 93L right now.

wonder what going on
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Quoting 233. Tazmanian:



they wont send a recon that far out they olny go out too 55W


Eastern Recon boundry was changed this year to 52.5W

Up to four 6-hourly fixes per day when a storm is within 500 nm
of landfall and west of 52.5ºW in the Atlantic.

National Hurricane Operations Plan Section 5.5.1.3.1.

Seems they are on their second plane attempting to go to 93L.
First Plane
URNT15 KNHC 121533
AF301 01FFA INVEST HDOB 03 20130912
Link

Second Plane
URNT15 KNHC 121659
AF302 01FFA INVEST HDOB 02 20130912
Link
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The ignore feature doesn't work with quotes unfortunately. -.-
Member Since: Posts: Comments:
am gone for the rest of the day I think I have de rail the blog a little too march this AM




I will be back next week


will be in lurk mode
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Quoting 275. HuracandelCaribe:
Ex-98L pressure still falling.


Cariboy is happy right now...
Member Since: Posts: Comments:
Ugh, more bad news.

Link

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Quoting 268. Torito:


I don't see the word recon in there anywhere. besides, I said this:
That's right off the NHC site, and it says it is possible. Don't assume that it is out of the question dude. Besides, they aren't using recon, it is global hawk.

Now leave me and the rest of the blog alone, no one likes trolls bothering everyone. Geez......



you don't speak for the blog and am not a troll



dos any one no how too ues the ignore tools on here I guss not other wise they would have ignore me by now some of you need too learn too open your eyes and ues the tools on here that's if you don't don't want too see me and my commets this put me on ignore and whats stop the bickering. about it
Member Since: Posts: Comments:
Ex-98L pressure still falling.
Member Since: Posts: Comments:
Looking great and moving WNW. Heads up Mehhhiiicooo
Member Since: Posts: Comments:
invest 93L LOOK like a tropical storm right now.
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Quoting 256. Tazmanian:



I no I look beautiful thanks for saying that




reproted
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LOL...

re: 148. georgevandenberghe 11:08 AM CDT on September 12, 2013
Quoting georgevandenberghe:

Quoting 97. SouthernIllinois:
Of course crapping out. Should have known better than to ever think this had a chance to make it into Cypress in the first place. :(

*** END QUOTES***

Just a reminder that Cumulonimbus_missingus is one of
the most frustratingly common cloud formations of summer.


That's a rare phenomena here in my part of SE LA where we enjoy / suffer the (over)abundance of cumulonimbus prolificus daily... ;)

Glad to report as of last couple days it's gone MIA here... but in an unwelcome manifestation, they're all converging over Colorado...
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BORED... will check out the weather later.
Member Since: October 6, 2007 Posts: 0 Comments: 6229
hmm look like 93L slow down some
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Quoting 249. Tazmanian:



nop

Quoting 236. Torito:


That's right off the NHC site, and it says it is possible. Don't assume that it is out of the question dude



that's what you said above


I don't see the word recon in there anywhere. besides, I said this:
That's right off the NHC site, and it says it is possible. Don't assume that it is out of the question dude. Besides, they aren't using recon, it is global hawk.

Now leave me and the rest of the blog alone, no one likes trolls bothering everyone. Geez......
Member Since: Posts: Comments:
267. MahFL
Quoting 233. Tazmanian:



they wont send a recon that far out they olny go out too 55W


They would send Global Hawk as it has much longer range, it can fly for 28 hours non stop.
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Quoting 261. SFLWeatherman:
12Z GFS look at S FL wow!


While I'm still in the middle of the desert.
Member Since: October 6, 2007 Posts: 0 Comments: 6229
265. 7544
Quoting 253. SFLWeatherman:
12Z GFS look at that!



hmm looks like a fl strom there on the 25th?
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Quoting 262. hurricanehanna:

watching it, it almost appears they are turning back again


i think it is like Sky said they turn responses on before takeoff
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Looks like a wetter end of the month for south Florida as a low is forecast to move N or NE from the BOC.

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Quoting 250. will40:
looking at it im still not sure HH have lifted off yet

watching it, it almost appears they are turning back again
Member Since: September 5, 2007 Posts: 0 Comments: 3488
12Z GFS look at S FL wow!
Member Since: May 23, 2012 Posts: 0 Comments: 4681
Quoting 255. HurricaneCamille:


Looks like its intensifying at a pretty steady rate to me.

Looks like a 40 MPH TS


The "I" storm is usually a quick developer and/or a hurricane.
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A C-130 can fly from middle- Tenn. to the Azores but absolutely no ability to site-see in a storm. That's just to give you a picture of what a C-130 can do for length of flight.
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RECON still on Tarmac as per message 2

(~ 71.2F*) No Wind - - - -
16:58:30Z 30.417N 88.917W 1016.4 mb*
(~ 30.01 inHg*) - - - No Wind -* 21.8C*
(~ 71.2F*) No Wind - - - -
16:59:00Z 30.417N 88.917W 1016.4 mb*
(~ 30.01 inHg*) - - - No Wind -* 21.8C*
(~ 71.2F*) No Wind - - - -
Time Coordinates
Member Since: July 3, 2005 Posts: 426 Comments: 128657
12z GFS consistent on making Humberto a major hurricane as it goes OTS, 00z ECMWF showed the same.
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Quoting 251. redwagon:


She's beautiful!



I no I look beautiful thanks for saying that


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Quoting 205. Torito:
93L intensifying really slowly. When recon gets here, I would expect the NHC to declare it a td or a weak TS.



Looks like its intensifying at a pretty steady rate to me.

Looks like a 40 MPH TS
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Models calling for a re-intensification of Humberto.

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12Z GFS look at that!

Member Since: May 23, 2012 Posts: 0 Comments: 4681
Quoting 250. will40:
looking at it im still not sure HH have lifted off yet
there off.
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Quoting 201. FunnelVortex:
HWRF calling for slow-moving Ingrid.



She's beautiful!
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looking at it im still not sure HH have lifted off yet
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Quoting 246. Torito:


I didn't say recon in the first place?...



nop

Quoting 236. Torito:


That's right off the NHC site, and it says it is possible. Don't assume that it is out of the question dude



that's what you said above
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.