Flash Flood Warning 22, NWS Denver/Boulder, CO

003 
WGUS75 KBOU 142224
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
424 PM MDT Fri Aug 14 2026

COC005-031-059-150030-
/O.CON.KBOU.FF.W.0022.000000T0000Z-260815T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Arapahoe CO-Denver CO-Jefferson CO-
424 PM MDT Fri Aug 14 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM MDT THIS
EVENING FOR EAST CENTRAL JEFFERSON, FAR NORTHWESTERN ARAPAHOE, AND
CENTRAL AND SOUTHWESTERN DENVER COUNTIES...

At 424 PM MDT, Doppler radar and automated rain gauges indicated
thunderstorms producing heavy rain had weakened across the warned
area. Between 1 and 1.5 inches of rain have fallen. Additional
rainfall amounts up to 0.3 inches are possible in the warned area.
Flash flooding and street flooding is ongoing or expected to begin
shortly.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar and automated gauges.

IMPACT...Flash flooding of small creeks and streams, gulches, roads,
         and poor drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Denver, Lakewood, northeastern Littleton, Englewood, Greenwood
  Village, Sheridan, Morrison, Cherry Hills Village, Columbine and
  Ken Caryl.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Excessive runoff from this storm will cause flash flooding of small
creeks and streams, highways, streets, underpasses, drainage areas
and other low lying spots.

&&

LAT...LON 3959 10505 3958 10513 3968 10518 3979 10495
      3968 10484 3960 10499
PARTITION...408005

FLASH FLOOD...RADAR AND GAUGE INDICATED

$$

20

756 
WGUS75 KBOU 142309
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
509 PM MDT Fri Aug 14 2026

COC005-031-059-142319-
/O.CAN.KBOU.FF.W.0022.000000T0000Z-260815T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Arapahoe CO-Denver CO-Jefferson CO-
509 PM MDT Fri Aug 14 2026

...FLASH FLOOD WARNING IS CANCELLED FOR JEFFERSON, WESTERN ARAPAHOE
AND DENVER COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining closures.

A Flood Watch remains in effect until 1000 PM MDT for portions of
central, east central, and northeast Colorado.

&&

LAT...LON 3959 10505 3958 10513 3968 10518 3979 10495
      3968 10484 3960 10499
PARTITION...408005

$$

09

Area Forecast Discussion
National Weather Service Denver/Boulder CO
111 PM MDT Fri Aug 14 2026

.KEY MESSAGES...

- Flash flooding and a few severe storms will be the main threats
  through this evening, as another round of storms moves east-
  northeast across the forecast area.

- Monsoon moisture lasts through the weekend, bringing scattered
  showers and thunderstorms each day with locally heavy rain and a
  severe weather threat.

- Warming and drying trend still set to begin Monday.

- Another active day possible middle of next week.

&&

.DISCUSSION /Through Friday/...
Issued at 111 PM MDT Fri Aug 14 2026

Our main concern late this afternoon and evening will be another
round of strong thunderstorms, capable of producing flash flooding
and severe weather. Nearly full sunshine over the plains has
allowed the airmass to destabilize through early this afternoon.
Low level moisture was rather impressive with dewpoints holding in
the lower to mid 60s east of the I-25 Corridor. That's pushing
MLCAPE values into the 1000-2000 J/kg range per latest SPC
analysis. While bulk shear is marginal (only around 25 kts) for
organized severe storms, we have sufficient instability to drive
large hail and damaging wet microbursts from stronger storms.
While there was some drying noted in the 700-600 mb layer on the
most recent ACARS soundings, we still expect efficient rain
producers given low level moisture and updraft intensity, and
enough to warrant a Flood Watch for flash flooding in areas that
saw recent heavy rains - see HYDROLOGY section below for more
details.

Like most convective episodes, there will probably be some weaker
convection that lingers behind the initial stronger storms that
push east across the plains. Otherwise look for gradual clearing
overnight, but patchy fog/stratus development once again with a
very moist boundary layer.

On Saturday, deep layer shear increases as flow aloft strengthens
from the west-southwest. At the same time, we'll still have a fair
amount of low/mid level moisture present, which means growing
instability and another round of afternoon and evening storms.
Some of these may be severe again due to increased shear but
a little decrease in instability as some slight drying is still
forecast.

Sunday is shaping up to be another active weather day, and
potentially even higher than Saturday as persistent low level
easterly flow and moisture advection occurs over the plains. A
failure mode would be too much moisture/low level cloudiness over
the plains, but at the same time that could mean even greater
instability and more favorable shear profiles if we get enough
heating to break the cap.

We're still on course for drier weather Monday and Tuesday as the
ridge axis retrogrades slightly. That allows for a drier west-
northwest flow aloft and warm advection. High temperatures will
likely (>70% chance) return to 90F+ by Tuesday.

Wednesday should feature higher chances of storms again (30-50%
chance), as another front is scheduled to bring slight cooling
but moistening late Tuesday into Wednesday. We don't see much
change in the overall pattern through the end of next week, which
at this point favors fairly normal Colorado weather with near
normal temperatures and isolated to scattered afternoon and
evening storms each day.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1108 AM MDT Fri Aug 14 2026

Similar setup to yesterday. Sct tstms will develop between 20Z and
21Z and then move across the area thru 00Z or 01Z. Naturally if a
stronger storm were to hit one of the TAF sites visibility will
drop to 1 mile with brief MVFR ceilings. By 01z will see
decreasing activity, however, still can't rule out widely sct
showers/weaker tstms thru 05z so will keep Prob30 in TAFS.

As far as winds, expect light easterly winds outside of gusty
erratic winds from tsmts which may see bring gusts from 40 to 50
mph. For late this evening, winds will become light and variable
by 05z before going light drainage by 08z.

At this time, not expecting any low clouds or fog late tonight
thru mid morning on Sat.

&&

.HYDROLOGY...
Issued at 111 PM MDT Fri Aug 14 2026

While there was some mid level drying noted in the 700-600 mb
layer, instability is growing and precipitable water (PW) content
remains near 150% of normal. Warm cloud depths are expected to
average around 4,000-5,000 feet, just a tad less than yesterday.
Mean storm motion is expected to be a little higher as well,
closer to 15-20 kts as mean cloud layer flow has strengthen
slightly. Storms will still be efficient rainers today given the
above mentioned favorable parameters, but likely just a notch down
from yesterday. That still means we could see storms producing a
quick 1-2" in 30-45 minutes, and local totals pushing 3" where
storm mergers occur (per Local Probability Matched Means). Flash
flood guidance has dropped rather considerably in areas that saw
heavy rain yesterday, and enough to warrant another Flood Watch
for flash flooding in those locations.

For Saturday and Sunday, strong storms are expected again although
PW values are expected to nudge slightly lower (~125% of normal).
Locally heavy rains can still expected due to intensity of storms,
along with local flooding impacts mainly from training storms
since storm motions will be faster (20-25 kts).

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 10 PM MDT this evening for COZ036-041-042-
044>049.

&&

DISCUSSION...20
AVIATION...RPK
HYDROLOGY...20

Special Weather Statement
National Weather Service Denver CO
147 PM MDT Fri Aug 14 2026

COZ041-142030-
Elbert/Central and East Douglas Counties Above 6000 Feet CO-
147 PM MDT Fri Aug 14 2026

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL ELBERT AND EAST
CENTRAL DOUGLAS COUNTIES UNTIL 230 PM MDT...

At 147 PM MDT, Doppler radar was tracking a strong thunderstorm 4
miles south of Franktown, or 30 miles southeast of Denver, moving
northeast at 15 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Eastern Castle Rock, Elizabeth, Franktown, Ponderosa Park, The
  Pinery and Castlewood Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

&&

LAT...LON 3923 10472 3932 10485 3949 10473 3935 10449
TIME...MOT...LOC 1947Z 225DEG 13KT 3933 10473

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

63

Special Weather Statement
National Weather Service Denver CO
151 PM MDT Fri Aug 14 2026

COZ045-142015-
Central and East Adams and Arapahoe Counties CO-
151 PM MDT Fri Aug 14 2026

...A STRONG THUNDERSTORM WILL IMPACT ARAPAHOE AND EASTERN ADAMS
COUNTIES UNTIL 215 PM MDT...

At 151 PM MDT, Doppler radar was tracking a strong thunderstorm near
Strasburg, or 35 miles east of Denver, moving northeast at 10 mph.

HAZARD...Wind gusts up to 50 mph and half inch size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Bennett, Byers and Strasburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Heavy rain is occurring with this storm and may lead to flooding. Do
not drive your vehicle through flooded roadways.

&&

LAT...LON 3958 10425 3975 10448 3995 10429 3977 10395
TIME...MOT...LOC 1951Z 219DEG 10KT 3972 10429

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

63

Special Weather Statement
National Weather Service Denver CO
216 PM MDT Fri Aug 14 2026

COZ045-142045-
Central and East Adams and Arapahoe Counties CO-
216 PM MDT Fri Aug 14 2026

...A STRONG THUNDERSTORM WILL IMPACT ARAPAHOE AND CENTRAL ADAMS
COUNTIES UNTIL 245 PM MDT...

At 216 PM MDT, Doppler radar was tracking a strong thunderstorm over
Strasburg, or 34 miles east of Denver, moving northeast at 10 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Bennett, Byers and Strasburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Heavy rain is occurring with this storm and may lead to flooding. Do
not drive your vehicle through flooded roadways.

&&

LAT...LON 3963 10429 3976 10446 3998 10425 3977 10399
TIME...MOT...LOC 2016Z 219DEG 10KT 3974 10430

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

63

Special Weather Statement
National Weather Service Denver CO
259 PM MDT Fri Aug 14 2026

COZ039-040-142130-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield
County CO-North Douglas County Below 6000 Feet/Denver/West Adams
and Arapahoe Counties/East Broomfield County CO-
259 PM MDT Fri Aug 14 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN DENVER...WESTERN
ARAPAHOE...EAST CENTRAL JEFFERSON AND NORTHERN DOUGLAS COUNTIES UNTIL
330 PM MDT...

At 259 PM MDT, Doppler radar was tracking a strong thunderstorm over
Englewood, or 7 miles south of Denver, moving north at 5 mph.

HAZARD...Wind gusts up to 50 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Denver, western Aurora, eastern Lakewood, Centennial, northeastern
  Highlands Ranch, Littleton, Englewood, Greenwood Village, Lone
  Tree, Sheridan, Buckley SFB, Cherry Hills Village, Edgewater,
  Mountain View, Cherry Creek Reservoir, Columbine and Ken Caryl.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Heavy rain is occurring with this storm and may lead to flooding. Do
not drive your vehicle through flooded roadways.

&&

LAT...LON 3963 10511 3978 10506 3970 10475 3953 10489
      3954 10489 3953 10490 3953 10491 3960 10512
TIME...MOT...LOC 2059Z 198DEG 5KT 3962 10498

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

63

Special Weather Statement
National Weather Service Denver CO
314 PM MDT Fri Aug 14 2026

COZ041-045-046-142200-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County CO-Elbert/Central and East Douglas Counties Above
6000 Feet CO-Central and East Adams and Arapahoe Counties CO-
314 PM MDT Fri Aug 14 2026

...A LINE OF STRONG THUNDERSTORMS WILL IMPACT ARAPAHOE AND
NORTHWESTERN ELBERT COUNTIES UNTIL 4 PM MDT...

At 314 PM MDT, Doppler radar was tracking a line of strong
thunderstorms extending from 5 miles southwest of Byers to over
Elbert, or extending from 36 miles east of Denver to 42 miles
southeast of Denver, moving east at 10 mph.

HAZARD...Wind gusts up to 50 mph and half inch size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Elbert, Elizabeth, Kiowa, Ponderosa Park and Fondis.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Heavy rain is occurring with these storms and may lead to flooding.
Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3921 10466 3940 10464 3968 10441 3957 10422
      3941 10434 3921 10439
TIME...MOT...LOC 2114Z 271DEG 7KT 3965 10429 3939 10450 3920 10455

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

63

Special Weather Statement
National Weather Service Denver CO
330 PM MDT Fri Aug 14 2026

COZ040-043-142200-
Central and South Weld County CO-North Douglas County Below
6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield
County CO-
330 PM MDT Fri Aug 14 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN DENVER...SOUTH
CENTRAL WELD AND NORTHWESTERN ADAMS COUNTIES UNTIL 4 PM MDT...

At 330 PM MDT, Doppler radar was tracking a strong thunderstorm near
Lochbuie, or 20 miles northeast of Denver, moving northeast at 5 mph.

HAZARD...Landspouts, wind gusts up to 50 mph, and penny size hail.

SOURCE...Radar indicated.

IMPACT...Minor damage to outdoor objects is possible. Gusty winds
         could knock down tree limbs and blow around unsecured
         objects.

Locations impacted include...
  Northeastern Commerce City, Brighton, Denver International Airport,
  D.I.A Terminal and Concourses, Lochbuie, Hudson and Barr Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Heavy rain is occurring with this storm and may lead to flooding. Do
not drive your vehicle through flooded roadways.

&&

LAT...LON 4000 10481 4013 10471 4000 10445 4000 10450
      3994 10450 3982 10468 3993 10487
TIME...MOT...LOC 2130Z 219DEG 6KT 3995 10471

LANDSPOUT...POSSIBLE
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

63