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: 349 - 299

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

Member Since: Posts: Comments:
Humberto on the RGB Airmass:

Member Since: Posts: Comments:
Quoting 338. StormTrackerScott:
All the models seem to be pointing to a very active weather pattern across FL toward the end of September and going into October. Could be some historic rainfall in the offing for FL as the tropics look like they are about to get into rapid fire mode.



Are those the same models that you said were bringing flooding rains to Florida from 93L?
Member Since: Posts: Comments:
Quoting 318. Stormchaser2007:
THIS DISTURBANCE IS
FORECAST TO MOVE VERY SLOWLY ACROSS THE SOUTHERN GULF OF MEXICO
PRODUCING LOCALLY HEAVY RAINS OVER A LARGE PART OF EASTERN MEXICO
DURING THE NEXT SEVERAL DAYS. THESE RAINS COULD CAUSE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.


This kinda implies Nwrd movement, no? Not due W?
Member Since: Posts: Comments:
Got this off of Twitter so....

Warning sirens are going off around Boulder Creek. A report of a "wall of water" coming from Lefthand Canyon.

This is the dangerous part. They had a 15-20 foot wall come down the canyon this morning and now again.
Member Since: Posts: Comments:



Note the default from the er, "author"..

But people should still be concerned about global warming, Fitzpatrick says.
"The paper in no way diminishes the extensive body of observations that global warming is happening and that it is largely due to human activity," she added.
"Global surface temperature is still rising ... 2012 was in the top ten warmest years on record. The period 2001-2010 was the warmest on record since instrumental measurements began," she added.


Magine dat?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 337. will40:


they just took off


I know. :3
Member Since: Posts: Comments:
Quoting 335. MrMixon:
Image of rock slide in Boulder Canyon: That really is a very minor slide for Co. mtn. roads!
Member Since: Posts: Comments:
Quoting 337. will40:


they just took off
lol
Member Since: Posts: Comments:
At 17:39:00Z (last observation), the observation was 51 miles (82 km) to the ESE (122°) from New Orleans, LA, USA.
Member Since: Posts: Comments:
All the models seem to be pointing to a very active weather pattern across FL toward the end of September and going into October. Could be some historic rainfall in the offing for FL as the tropics look like they are about to get into rapid fire mode.

Member Since: Posts: Comments:
Quoting 332. Torito:
15mph wind max so far and they aren't even near the system xD


they just took off
Member Since: Posts: Comments:
93L and 90E on the Day/Night Visible:

Member Since: Posts: Comments:
Image of rock slide in Boulder Canyon:


Credit: Catherine Camp

Rain continues to pour here...

Member Since: Posts: Comments:
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU SEP 12 2013

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
HUMBERTO...LOCATED SEVERAL HUNDRED MILES NORTHWEST OF THE CAPE
VERDE ISLANDS...AND ON TROPICAL STORM GABRIELLE...LOCATED A
COUPLE OF HUNDRED MILES WEST-NORTHWEST OF BERMUDA.

SATELLITE AND SURFACE OBSERVATIONS INDICATE THAT A TROPICAL
DEPRESSION COULD BE FORMING IN THE SOUTH-CENTRAL BAY OF
CAMPECHE...AND IF THIS TREND CONTINUES...ADVISORIES WILL BE
INITIATED LATER TODAY OR TONIGHT. AN AIR FORCE PLANE IS SCHEDULED
TO INVESTIGATE THIS DISTURBANCE LATER TODAY. EVEN IF A TROPICAL
CYCLONE DOES NOT FORM TODAY...ENVIRONMENTAL CONDITIONS ARE FORECAST
TO REMAIN VERY FAVORABLE FOR DEVELOPMENT...AND THIS LOW HAS A HIGH
CHANCE...80 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS...AND A HIGH CHANCE...90 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS. THIS DISTURBANCE IS
FORECAST TO MOVE VERY SLOWLY ACROSS THE SOUTHERN GULF OF MEXICO
PRODUCING LOCALLY HEAVY RAINS OVER A LARGE PART OF EASTERN MEXICO
DURING THE NEXT SEVERAL DAYS. THESE RAINS COULD CAUSE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.

Member Since: Posts: Comments:
Quoting 319. SLU:


Yes since late July the trades have slackened greatly and the SSTs have skyrocketed as a result. Most of the models got that totally wrong calling for overall cooling.


The models have been for the most part wacky this season.
Member Since: Posts: Comments:
15mph wind max so far and they aren't even near the system xD
Member Since: Posts: Comments:
Quoting 324. Stormchaser2007:
Closed low in the BOC

yep,I guess we have 10L.
Member Since: June 11, 2013 Posts: 18 Comments: 2211
Member Since: Posts: Comments:
Quoting 321. TimSoCal:
Days like today are a little bit heartbreaking for me. I work in insurance, and I keep having to tell people in CO that their homeowners insurance doesn't cover floods. It's sad, because I can hear the desperation in their voices, and I wish there was something else I could do.


Tim, I am in the same industry. It's one of the hardest things that you have to do. The National Flood Insurance Assoc. had a large campaign a few years back to remind inform people that most homeowners policies don't cover flood. Also, agent tell their clients this when purchasing homeowners. Fact is, unless the bank requires it people don't think they will ever need it.

It is a horrible situation to watch unfolding right now.
Member Since: Posts: Comments:
Published on Sep 12, 2013

Colorado Flash Flood AMAZING Video: Man Rescued from Overturned Car during Severe Flood Boulder Colorado (CNN) -- Emergency crews in Colorado braved racing flood waters early Friday, rescuing a man from a partially submerged car, live on television.
The scene unfolded in video from CNN affiliate KCNC after a night of torrential rain that left at least two people dead amid rock slides and flash flooding that collapsed homes, put dams at risk and forced hundreds of people to evacuate.
Firefighters on a yellow dinghy bobbing in the swift waters rescued the man from the overturned car about 12 miles southeast of Boulder.

The man, whose identity wasn't immediately known, walked out of the water with the aid of firefighters. He was taken away on a stretcher. His condition was not immediately known.
Deadly flooding in Colorado Massive rains swamp Colorado
Video from KNCN also showed two other vehicles, one dangling from the edge of a washed-out road, the other in the water beneath what appeared to be a telephone pole. The station said two people were rescued earlier and taken to a hospital.

In a separate incident, one person died after being trapped in a collapsed building, in Jamestown, Boulder County spokeswoman Gabbie Boerkircher said.
The circumstances of the other death weren't clear early Thursday, but the Colorado Springs Fire Department said on Twitter that the body had been recovered by a "heavy rescue team."

Member Since: Posts: Comments:
This is bound to get a few comment on TWU

Climate models wildly overestimated global warming, study finds



Link
Member Since: Posts: Comments:
Member Since: June 11, 2013 Posts: 18 Comments: 2211
Closed low in the BOC

Member Since: Posts: Comments:
Quoting 312. MrMixon:
Water is rising in Boulder Creek. Just heard scanner traffic report a large wall of water coming down Logan Mill.

10:56am


11:32am


Not to knock CO, but that is simply a rain-swollen gully in some other places.
Member Since: Posts: Comments:
Quoting 284. HuracandelCaribe:
Funny little sucker!!





If it can fire convection then we might have a Tropical Depression on our hands as the pressure is really dropping with ex 98L.
Member Since: Posts: Comments:
Days like today are a little bit heartbreaking for me. I work in insurance, and I keep having to tell people in CO that their homeowners insurance doesn't cover floods. It's sad, because I can hear the desperation in their voices, and I wish there was something else I could do.
Member Since: Posts: Comments:
Quoting 231. Tygor:


Bad choice in an area that has been known to get hurricanes. It reminds me of those in Florida and the Carolinas who are shocked when a hurricane hits...seems to be part of the risk.


I know-as soon as my policy expires, I'm going with someone else who will insure without a windstorm certificate-the roof is actually pretty new-not sure why they didn't get an engineer to inspect and get the certificate.
Member Since: Posts: Comments:
319. SLU
Quoting 48. CaribBoy:


Yes very impressive SSTs especially when compared with july's values..............

I HOPE!!!!!!!!


Yes since late July the trades have slackened greatly and the SSTs have skyrocketed as a result. Most of the models got that totally wrong calling for overall cooling.
Member Since: July 13, 2006 Posts: 12 Comments: 4733
SATELLITE AND SURFACE OBSERVATIONS INDICATE THAT A TROPICAL
DEPRESSION COULD BE FORMING IN THE SOUTH-CENTRAL BAY OF
CAMPECHE...AND IF THIS TREND CONTINUES...ADVISORIES WILL BE
INITIATED LATER TODAY OR TONIGHT. AN AIR FORCE PLANE IS SCHEDULED
TO INVESTIGATE THIS DISTURBANCE LATER TODAY. EVEN IF A TROPICAL
CYCLONE DOES NOT FORM TODAY...ENVIRONMENTAL CONDITIONS ARE FORECAST
TO REMAIN VERY FAVORABLE FOR DEVELOPMENT...AND THIS LOW HAS A HIGH
CHANCE...80 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS...AND A HIGH CHANCE...90 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS. THIS DISTURBANCE IS
FORECAST TO MOVE VERY SLOWLY ACROSS THE SOUTHERN GULF OF MEXICO
PRODUCING LOCALLY HEAVY RAINS OVER A LARGE PART OF EASTERN MEXICO
DURING THE NEXT SEVERAL DAYS. THESE RAINS COULD CAUSE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.
Member Since: Posts: Comments:
Quoting 315. WalkingInTheSun:
Invest 90E models on this site shows one possible course taking it from the Pacific...to the BOC/GOM...then back towards the Pacific again.
How radical that would be if it was to do that & stay a named storm, throughout!
I think so.
Member Since: June 11, 2013 Posts: 18 Comments: 2211
Quoting 312. MrMixon:
Water is rising in Boulder Creek. Just heard scanner traffic report a large wall of water coming down Logan Mill.

10:56am


11:32am

I keep seeing people stand right next to the water in that park and I just want to yell at them. During flash flooding often times debris will build up dams that can break suddenly and you'll see a very rapid rise in water downstream, it is terribly dangerous to stand next to flooded creeks.
Member Since: Posts: Comments:
Invest 90E models on this site shows one possible course taking it from the Pacific...to the BOC/GOM...then back towards the Pacific again.
How radical that would be if it was to do that & stay a named storm, throughout!
Member Since: Posts: Comments:
Member Since: June 11, 2013 Posts: 18 Comments: 2211
Quoting 274. CaneHunter031472:
Looking great and moving WNW. Heads up Mehhhiiicooo

Sure is doing a good job of getting sheared!
Member Since: Posts: Comments:
Water is rising in Boulder Creek. Just heard scanner traffic report a large wall of water coming down Logan Mill.

10:56am


11:32am
Member Since: Posts: Comments:
311. SLU
Quoting 33. CybrTeddy:


ECMWF is showing a very active pattern setting up, unlike what it showed for September.


Do you have a link for the EURO Oct forecast.
Member Since: July 13, 2006 Posts: 12 Comments: 4733
Quoting 302. Naga5000:


Yet here it is. :)


Sort of like going to NPR for weather. :-)
For REAL weather, tune in to....wunderground.com.
Member Since: Posts: Comments:
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 12th day of the month at 17:29Z
Date: September 12, 2013
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)
Mission Purpose: Investigate fifth suspect area (flight in the North Atlantic basin)

Mission Number: 1
Observation Number: 05

17:29:00Z 30.167N 89.050W 789.7 mb
(~ 23.32 inHg) 2,180 meters
(~ 7,152 feet) 1016.9 mb
(~ 30.03 inHg) - From 40° at 10 knots
(From the NE at ~ 11.5 mph) 13.3°C
(~ 55.9°F) 4.2°C
(~ 39.6°F) 11 knots
(~ 12.6 mph) - - - -
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 17:19:30Z (first observation), the observation was 9 miles (14 km) to the E (91°) from Gulfport, MS, USA.

At 17:29:00Z (last observation), the observation was 16 miles (26 km) to the S (174°) from Gulfport, MS, USA.
Member Since: Posts: Comments:
Quoting 304. will40:
recon in the air now


yea I see, where are the cool graphics at on this website? :P
Member Since: Posts: Comments:
307. xcool
New Network Weather Coverage Planned


Link
Member Since: Posts: Comments:
Quoting 301. GetReal:


Stick another 2013 fork in 93L; it's probably done for! :)
Get real, this will be one of 2013
best
Member Since: Posts: Comments:

000
ABNT20 KNHC 121730
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT THU SEP 12 2013

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
HUMBERTO...LOCATED SEVERAL HUNDRED MILES NORTHWEST OF THE CAPE
VERDE ISLANDS...AND ON TROPICAL STORM GABRIELLE...LOCATED A
COUPLE OF HUNDRED MILES WEST-NORTHWEST OF BERMUDA.

SATELLITE AND SURFACE OBSERVATIONS INDICATE THAT A TROPICAL
DEPRESSION COULD BE FORMING IN THE SOUTH-CENTRAL BAY OF
CAMPECHE...AND IF THIS TREND CONTINUES...ADVISORIES WILL BE
INITIATED LATER TODAY OR TONIGHT. AN AIR FORCE PLANE IS SCHEDULED
TO INVESTIGATE THIS DISTURBANCE LATER TODAY. EVEN IF A TROPICAL
CYCLONE DOES NOT FORM TODAY...ENVIRONMENTAL CONDITIONS ARE FORECAST
TO REMAIN VERY FAVORABLE FOR DEVELOPMENT...AND THIS LOW HAS A HIGH
CHANCE...80 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS...AND A HIGH CHANCE...90 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 5 DAYS. THIS DISTURBANCE IS
FORECAST TO MOVE VERY SLOWLY ACROSS THE SOUTHERN GULF OF MEXICO
PRODUCING LOCALLY HEAVY RAINS OVER A LARGE PART OF EASTERN MEXICO
DURING THE NEXT SEVERAL DAYS. THESE RAINS COULD CAUSE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.

THE SHOWER ACTIVITY ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE
CENTERED ABOUT 450 MILES EAST OF THE LEEWARD ISLANDS REMAINS
LIMITED. ALTHOUGH SURFACE PRESSURES ARE STILL FALLING IN THE
AREA...ENVIRONMENTAL CONDITIONS ARE NOT FAVORABLE FOR DEVELOPMENT.
THIS DISTURBANCE HAS A LOW CHANCE...10 PERCENT...OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ALTHOUGH UPPER-LEVEL
WINDS COULD BECOME A LITTLE MORE FAVORABLE IN SEVERAL DAYS...THIS
SYSTEM STILL HAS A LOW CHANCE...20 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 5 DAYS AS IT MOVES TOWARD THE
WEST-NORTHWEST.

&&

FIVE-DAY FORMATION PROBABILITIES ARE EXPERIMENTAL IN 2013. COMMENTS
ON THE EXPERIMENTAL FORECASTS CAN BE PROVIDED AT...

WWW.NWS.NOAA.GOV/SURVEY/NWS-SURVEY.PHP?CODE=ETWO

$$
FORECASTER AVILA
Member Since: June 11, 2013 Posts: 18 Comments: 2211
recon in the air now
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting 292. Tygor:


I can't believe people turn to Fox News for weather/climatology information.


Yet here it is. :)
Member Since: Posts: Comments:
Quoting 282. HurricaneCamille:
cloud tops are warming bigtime on 93L right now.

wonder what going on


Stick another 2013 fork in 93L; it's probably done for! :)
Member Since: Posts: Comments:
Humberto to become a Major Hurricane almost in the same spot as Michael.

Member Since: Posts: Comments:
Member Since: June 11, 2013 Posts: 18 Comments: 2211

Viewing: 349 - 299

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.