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: 849 - 799

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

Quoting 786. zicoille:
They are so lucky in Colorado: 6 inches of rain, WOW!
RAIN, That's what we want in the northern leewards islands. And to be egoist, that's what we want in St Barth's!
So long time without good and heavy rain!
I don't understand why, again, 98L is gone....in the south!
They don't need in Martinique !
WE NEED RAIN HERE !


How is flash flooding that is causing deaths lucky?
Member Since: Posts: Comments:
Quoting 826. Ameister12:

Keep in mind, upwelling could be a problem if it stalls for too long.


It's not really expected to stall for that long.

Highly unlikely upswelling will be a major issue with this in the future.
Member Since: September 6, 2012 Posts: 0 Comments: 299
Quoting 841. Ameister12:
If we see another forecast cone posted, Taz is gonna have a conniption fit! :P
The Ice Cream Cone of Uncertainty:



3 Cones to represent the 3 storms we have out there.

Member Since: Posts: Comments:
Quoting 839. CybrTeddy:
10L will probably show us just how hard it is to predict intensity is my guess.
Upwelling may be a problem at the rate is moving,and it will probably be a re-Nate I just can see them very similar.
Member Since: Posts: Comments:
TD 10 can be a hard TD when it be comes in getting names out of it in past years when it comes too TD 10 they all ways go poof after getting forming
Member Since: Posts: Comments:
Quoting 827. GTstormChaserCaleb:
Well I'd say it's about time, looking more like a hurricane season out there now.

Yes it is GT...But the "about time " is not my liking
Member Since: October 3, 2008 Posts: 0 Comments: 5750
Quoting 810. TropicalAnalystwx13:
Only expected to reach 50 knot before landfall.



So are there 2 LLC's?
Member Since: Posts: Comments:
Quoting 828. washingtonian115:
Well server thunderstorm outside.But after last year these are like kittens being compared to lions.

More BOC trash?.Getting sick of these storms.Don't care for it.See ya's.


Door's right there. You'll note though this storm will have 96 hours over water, unlike the meager 12 or so Barry and Fernand had. Plenty of time for intensification.
Member Since: Posts: Comments:
If we see another forecast cone posted, Taz is gonna have a conniption fit! :P
Member Since: Posts: Comments:
Well, if this pans out - we'll also be seeing floods of biblical proportions throughout a significant portion of Mexico. On both coasts.

A distinct possibility given the current setup.

Remember, the GFS max is 24 inches.

Edit: Wind won't be important with this one, it'll be rain. Reminds me of Mitch in Honduras.


Member Since: June 25, 2011 Posts: 2 Comments: 3731
10L will probably show us just how hard it is to predict intensity is my guess.
Member Since: Posts: Comments:
Quoting 828. washingtonian115:
Well server thunderstorm outside.But after last year these are like kittens being compared to lions.

More BOC trash?.Getting sick of these storms.Don't care for it.See ya's.
Another fiasco.
Member Since: Posts: Comments:
Not sure I agree with either of these points, but ok LOL.

THE LOW PRESSURE AREA IN THE
SOUTHERN BAY OF CAMPECHE HAS DEVELOPED A WELL-DEFINED CENTER OF
CIRCULATION AND ENOUGH ORGANIZED CONVECTION TO BE CLASSIFIED AS A
TROPICAL DEPRESSION.
Member Since: Posts: Comments:
TD10 or s in the BOC

Member Since: Posts: Comments:
Quoting 829. RGVtropicalWx13:

Friday u mean lol today is Thursday. :P
Yes, lol I was thinking today was Wednesday. I think it's time for a nap.
Member Since: Posts: Comments:
TROPICAL DEPRESSION TEN DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL102013
400 PM CDT THU SEP 12 2013

SATELLITE DATA...SURFACE OBSERVATIONS AND DATA FROM AN AIR FORCE
RECONNAISSANCE PLANE INDICATE THAT THE LOW PRESSURE AREA IN THE
SOUTHERN BAY OF CAMPECHE HAS DEVELOPED A WELL-DEFINED CENTER OF
CIRCULATION AND ENOUGH ORGANIZED CONVECTION TO BE CLASSIFIED AS A
TROPICAL DEPRESSION. IT APPEARS THAT THE ENVIRONMENT IS FAVORABLE
FOR ADDITIONAL DEVELOPMENT AND THE DEPRESSION COULD BECOME A
TROPICAL STORM TONIGHT OR FRIDAY. SOME ADDITIONAL STRENGTHENING IS
POSSIBLE AFTER THAT TIME.

THE DEPRESSION IS CURRENTLY EMBEDDED WITHIN LIGHT STEERING CURRENTS
AND LITTLE MOTION IS ANTICIPATED DURING THE NEXT DAY OR TWO. AFTER
THAT TIME...A SMALL MID-LEVEL RIDGE IS FORECAST TO DEVELOP OVER THE
SOUTHERN UNITED STATES AND WILL PROVIDE SOME WEST-NORTHWESTERLY
STEERING TO THE CYCLONE. NEVERTHELESS...THE CYCLONE IS EXPECTED TO
MEANDER OVER THE EXTREME SOUTHWESTERN GULF OF MEXICO FOR THE NEXT 2
TO 3 DAYS. THIS IS CONSISTENT WITH MOST OF THE GLOBAL MODELS AND
THE HWRF.

GIVEN THE SLOW MOTION AND THE PROXIMITY TO THE COAST OF MEXICO...A
TROPICAL STORM WARNING HAS BEEN ISSUED BY THE GOVERNMENT OF MEXICO
FOR A PORTION OF THE COAST. THE MAIN HAZARD FROM THIS CYCLONE...IN
COMBINATION WITH ANOTHER DISTURBANCE IN THE EASTERN PACIFIC...WILL
BE LIFE-THREATENING FLOODING OVER EASTERN MEXICO FOR THE NEXT FEW
DAYS.
Member Since: Posts: Comments:
Quoting 827. GTstormChaserCaleb:
Well I'd say it's about time, looking more like a hurricane season out there now.



You can say that again!
Member Since: Posts: Comments:
Note the use of the word "Dangerous" when Dr. Masters talks about 93L. I remember him using this word to describe the wave that became Irene and him noting that he only uses the word "Dangerous" for important systems. Could be one to watch very closely.
Member Since: Posts: Comments:
TROPICAL DEPRESSION TEN DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL102013
400 PM CDT THU SEP 12 2013

SATELLITE DATA...SURFACE OBSERVATIONS AND DATA FROM AN AIR FORCE
RECONNAISSANCE PLANE INDICATE THAT THE LOW PRESSURE AREA IN THE
SOUTHERN BAY OF CAMPECHE HAS DEVELOPED A WELL-DEFINED CENTER OF
CIRCULATION AND ENOUGH ORGANIZED CONVECTION TO BE CLASSIFIED AS A
TROPICAL DEPRESSION. IT APPEARS THAT THE ENVIRONMENT IS FAVORABLE
FOR ADDITIONAL DEVELOPMENT AND THE DEPRESSION COULD BECOME A
TROPICAL STORM TONIGHT OR FRIDAY. SOME ADDITIONAL STRENGTHENING IS
POSSIBLE AFTER THAT TIME.

THE DEPRESSION IS CURRENTLY EMBEDDED WITHIN LIGHT STEERING CURRENTS
AND LITTLE MOTION IS ANTICIPATED DURING THE NEXT DAY OR TWO. AFTER
THAT TIME...A SMALL MID-LEVEL RIDGE IS FORECAST TO DEVELOP OVER THE
SOUTHERN UNITED STATES AND WILL PROVIDE SOME WEST-NORTHWESTERLY
STEERING TO THE CYCLONE. NEVERTHELESS...THE CYCLONE IS EXPECTED TO
MEANDER OVER THE EXTREME SOUTHWESTERN GULF OF MEXICO FOR THE NEXT 2
TO 3 DAYS. THIS IS CONSISTENT WITH MOST OF THE GLOBAL MODELS AND
THE HWRF.

GIVEN THE SLOW MOTION AND THE PROXIMITY TO THE COAST OF MEXICO...A
TROPICAL STORM WARNING HAS BEEN ISSUED BY THE GOVERNMENT OF MEXICO
FOR A PORTION OF THE COAST. THE MAIN HAZARD FROM THIS CYCLONE...IN
COMBINATION WITH ANOTHER DISTURBANCE IN THE EASTERN PACIFIC...WILL
BE LIFE-THREATENING FLOODING OVER EASTERN MEXICO FOR THE NEXT FEW
DAYS.



FORECAST POSITIONS AND MAX WINDS

INIT 12/2100Z 19.7N 93.6W 30 KT 35 MPH
12H 13/0600Z 19.7N 94.7W 30 KT 35 MPH
24H 13/1800Z 19.5N 95.2W 35 KT 40 MPH
36H 14/0600Z 19.3N 95.3W 40 KT 45 MPH
48H 14/1800Z 19.3N 95.0W 45 KT 50 MPH
72H 15/1800Z 20.7N 95.9W 45 KT 50 MPH
96H 16/1800Z 22.0N 97.5W 50 KT 60 MPH
120H 17/1800Z 23.5N 100.0W 25 KT 30 MPH...INLAND

$$
FORECASTER AVILA/BRENNAN
Member Since: Posts: Comments:
Quoting 800. barbamz:

Humberto. Saved image.

Humberto defeated the entrainment of some dry air. Should make the turn to the west now.


Behind him new SAL is emerging:
Bye bye.To Fishland with love.
Member Since: Posts: Comments:
Quoting 821. GTstormChaserCaleb:
Look at that stall on 4PM Thursday. Not out of the question we get a hurricane out of this.

Friday u mean lol today is Thursday. :P
Member Since: Posts: Comments:
Well server thunderstorm outside.But after last year these are like kittens being compared to lions.

More BOC trash?.Getting sick of these storms.Don't care for it.See ya's.
Member Since: Posts: Comments:
Well I'd say it's about time, looking more like a hurricane season out there now.

Member Since: Posts: Comments:
Quoting 821. GTstormChaserCaleb:
Look at that stall on 4PM Thursday. Not out of the question we get a hurricane out of this.

Keep in mind, upwelling could be a problem if it stalls for too long.
Member Since: Posts: Comments:
Quoting 818. MrMixon:


Thanks! I know of the site, but hadn't noticed the Storify link. Some absolutely crazy photos in there...








I don't think that window will hold back too much more water.
Member Since: Posts: Comments:
Quoting 817. MiamiHurricanes09:
Well, Avila did write it. ;)

It's virtually just a reflection of the SHIPS/LGEM. Seeing how quickly Fernand intensified in similar conditions, I'm confident 10L will make a run for hurricane status.
It might but I am not sure,her slow movement may bring her to upwell water like Nate.Like I say a Nate is the most possible solution imo.
Member Since: Posts: Comments:
BULLETIN
TROPICAL DEPRESSION TEN ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL102013
400 PM CDT THU SEP 12 2013

...TROPICAL DEPRESSION FORMS IN THE SOUTHERN GULF OF MEXICO...
...EXTREME RAINFALL EXPECTED OVER PORTIONS OF EASTERN MEXICO...


SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...19.7N 93.6W
ABOUT 175 MI...280 KM ENE OF VERACRUZ MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...W OR 270 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES
Member Since: Posts: Comments:
Quoting 810. TropicalAnalystwx13:
Only expected to reach 50 knot before landfall.


Conservative forecast.
Member Since: April 29, 2009 Posts: 75 Comments: 13292
Quoting 809. Ameister12:
The cone of DOOM!
Look at that stall on 4PM Thursday. Not out of the question we get a hurricane out of this.
Member Since: Posts: Comments:
when you do live weather reports please indicate your position on earth too many characters to keep up
Member Since: September 11, 2010 Posts: 0 Comments: 4017
Large cone but very low confidence.

Member Since: Posts: Comments:
Quoting 16. LAbonbon:
Excellent blog. You likely have been to this site:

Boulder Flood Info

From there, if you follow the Storify Link there are quite a few amazing photos and videos of the flooding.


Thanks! I know of the site, but hadn't noticed the Storify link. Some absolutely crazy photos in there...






Member Since: March 26, 2006 Posts: 44 Comments: 1520
Quoting 810. TropicalAnalystwx13:
Only expected to reach 50 knot before landfall.
Well, Avila did write it. ;)

It's virtually just a reflection of the SHIPS/LGEM. Seeing how quickly Fernand intensified in similar conditions, I'm confident 10L will make a run for hurricane status.
Member Since: Posts: Comments:
816. HadesGodWyvern (Mod)


it kind of clutters there at about 95W.. goes stationary for about a day?
Member Since: Posts: Comments:
TROPICAL STORM GABRIELLE ADVISORY NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072013
500 PM AST THU SEP 12 2013
Member Since: March 12, 2013 Posts: 7 Comments: 11044
Quoting 802. Doppler22:
I have never seen storm clouds like the ones outside my window right now...


Take a picture, please.
Member Since: October 25, 2008 Posts: 43 Comments: 5020
Quoting 803. GTstormChaserCaleb:
TD 10, TS Gabrielle, and Hurricane Humberto, right on time as we are pretty much at statistical peak.
LETS NOT FORGET EX INVEST 98l to
Member Since: March 12, 2013 Posts: 7 Comments: 11044
Member Since: Posts: Comments:
THE GOVERNMENT OF MEXICO HAS ISSUED A TROPICAL STORM WARNING FOR THE
GULF COAST OF MEXICO FROM COATZACOALCOS TO BARRA DE NAUTLA.

TROPICAL DEPRESSION CENTER LOCATED NEAR 19.7N 93.6W AT 12/2100Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT 6 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1003 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.
Member Since: Posts: Comments:
Only expected to reach 50 knot before landfall.
Member Since: July 6, 2010 Posts: 108 Comments: 30251
The cone of DOOM!
Member Since: Posts: Comments:
TD 10. 3 storms at once after struggling to even get one storm per week in August :) lol

If this thing goes too slow, will upwelling occur?
If it goes fast enough, Hurricane Ingrid aint out of the question...
Member Since: Posts: Comments:
10L expected to intensify up to 50kts before landfall.

OUTLOOK VALID 16/1800Z 22.0N 97.5W
MAX WIND 50 KT...GUSTS 60 KT.
Member Since: Posts: Comments:
Well we got 10L. It's circulation should tighten up as it slowly makes its way through the BoC.

Member Since: Posts: Comments:
Quoting 802. Doppler22:
I have never seen storm clouds like the ones outside my window right now...


Same here. :P
Member Since: Posts: Comments:

TROPICAL STORM GABRIELLE ADVISORY NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072013
500 PM AST THU SEP 12 2013

...GABRIELLE EXPECTED TO WEAKEN ON FRIDAY...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...34.4N 67.9W
ABOUT 230 MI...370 KM NW OF BERMUDA
ABOUT 490 MI...790 KM SSE OF NANTUCKET MASSACHUSETTS
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...N OR 350 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL STORM GABRIELLE
WAS LOCATED NEAR LATITUDE 34.4 NORTH...LONGITUDE 67.9 WEST.
GABRIELLE IS MOVING TOWARD THE NORTH NEAR 8 MPH...13 KM/H. A TURN TO
THE NORTH-NORTHEAST WITH INCREASING FORWARD SPEED IS EXPECTED ON
FRIDAY.

MAXIMUM SUSTAINED REMAIN NEAR 40 MPH...65 KM/H...WITH HIGHER
GUSTS. GABRIELLE IS FORECAST TO WEAKEN ON FRIDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 90 MILES...150 KM
TO THE NORTHEAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 PM AST.

Member Since: March 12, 2013 Posts: 7 Comments: 11044
TD 10, TS Gabrielle, and Hurricane Humberto, right on time as we are pretty much at statistical peak.
Member Since: Posts: Comments:
I have never seen storm clouds like the ones outside my window right now...
Member Since: February 13, 2012 Posts: 10 Comments: 3263
And she is here it looks like,might be Ingrid by tonight.
Member Since: Posts: Comments:

Humberto. Saved image.

Humberto defeated the entrainment of some dry air. Should make the turn to the west now.


Behind him new SAL is emerging:
Member Since: October 25, 2008 Posts: 43 Comments: 5020
Guess the second vorticy doesn't matter. 10L it is. ;P
Member Since: Posts: Comments:

Viewing: 849 - 799

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 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.