Flash Flood Warning 36, NWS Denver/Boulder, CO

305 
WGUS75 KBOU 222254
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
454 PM MDT Sat Aug 22 2026

COC035-222304-
/O.EXP.KBOU.FF.W.0036.000000T0000Z-260822T2300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Douglas CO-
454 PM MDT Sat Aug 22 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 5 PM MDT THIS AFTERNOON FOR
EAST CENTRAL DOUGLAS COUNTY...

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

&&

LAT...LON 3936 10481 3932 10484 3930 10482 3930 10473
      3934 10469 3938 10471 3938 10476 3937 10479

$$

Hiris

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1250 PM MDT Sat Aug 22 2026

- Highest coverage of showers and storms expected today, along
  with a few severe storms and locally heavy rainfall this
  afternoon and evening.

- Scattered afternoon and evening showers and storms through
  Thursday. A risk of a couple severe storms each day.

- Temperatures settling back closer to (but still above) normal
  for Tuesday and Wednesday.

- Gradual drying end of next week, with a trend to more summer
  heat through next weekend.

&&

.DISCUSSION /Through Saturday/...
Issued at 1249 PM MDT Sat Aug 22 2026

Satellite and radar shows pretty healthy convection developing
across the Front Range Mountains and Foothills, while the airmass
is still somewhat stable (per ACARS and SPC analysis) but
increasingly moist over the plains. The increased moisture on the
plains is being reinforced by a couple westerly moving surges,
and dewpoints have held in the upper 50s and lower 60s east and
north of Denver. The latest surge coming back through Elbert
County will likely boost values over the Palmer Divide this
afternoon, especially as we develop a surface cyclone in vicinity
of Douglas or western Elbert County. That will aid moisture
convergence and potential for convective initiation there, along
with a risk of a landspout. Otherwise, stronger storms today will
be capable of hail and strong winds, along with locally heavy
rainfall as precipitable water (PW) values climb to 150-170% of
normal and low level moisture remains abundant over the plains. As
per typical, we still think the highest threat of strongest
storms would be along/east of the convergence zone associated with
the developing cyclone and points northward along/just east of
I-25 - essentially covering all of the plains. A couple severe
storms are likely due to MLCAPE increasing to 1200-2000 J/kg. Bulk
shear is weak and less than 25-30 kts, however, so majority of
the severe storms would tend to be pulse (brief). Storm motion
will be rather slow at 15 mph or less given lack of flow aloft,
which will lead to at least some minor flooding threats in a few
spots. Overall progression will eventually be to the east across
the plains into late evening, with potential for a generally
weaker subsequent batch or two of storms behind the initial
stronger ones that would have access to more instability.

We still expect some gradual clearing overnight, but patchy
stratus/fog possible across the plains given the very moist
airmass.

On Sunday, there is some drying noted as flow aloft turns a bit
more westerly. However, we're not convinced we'll erode all the
low level moisture across the plains. Even in the mountains we'll
still see enough to spark scattered thunderstorms, and then those
storms will likely intensify as they move onto the plains as they
encounter a richer, more unstable airmass. Bulk shear profiles are
still marginal, but a couple severe storms will be possible given
sufficient MLCAPE of 1000-1800 J/kg. Similar weather conditions
will likely persist into Monday with little change in the overall
pattern, moisture, and instability profiles. Temperatures will be
rather warm yet, with highs in the 90-95 degree range over the
I-25 Corridor and plains.

There is better agreement of a weak backdoor cool front or two for
Tuesday and Wednesday, offering up a few degrees of cooling and
potentially more active weather over the Front Range and plains.

Thursday and Friday are shaping up to be transition days into a
drier and warmer environment with progressively less storm
coverage, especially by Friday.

Ensembles are consistent showing a return of summer heat for next
weekend, with highs pushing into the mid 90s (30% chance of upper
90s) for the I-25 Corridor and plains as a stronger zonal flow
aloft develops. That would also lead to increasing fire danger as
we begin our journey toward autumn breezes. Unfortunately,
temperatures will feel more like mid summer and humidities will
drop in the drier westerly flow.

&&

.AVIATION /18Z TAFS through 18Z Sunday/...
Issued at 1131 AM MDT Sat Aug 22 2026

A boundary currently to the east of DEN and APA will continue to
move westward towards each of those terminals. It now appears
likely the boundary will get close enough to both of those
terminals to bring stronger easterly winds than previously
forecast. East winds could gust to around 20 knots. There is a
slight chance (20%), however, that a DCVZ develops just to the
east of DEN and APA that keeps winds more out of the northeast
with lighter speeds.

Storms are expected to develop this afternoon with the earliest
possible storms at 19Z at BJC and 20Z at DEN and APA. The most
likely time for storms to impact all terminals is between 22-02Z.
Strong outflow winds are likely with gusts 40-45 knots. It is even
possible (20%) that severe gusts above 50 knots occur at DEN or
APA. Besides winds, there is a chance (40%) that visibility will
be reduced to 2-4 miles and ceilings drop to 4,000-6,000 feet if a
storm were to move directly overhead.

In the evening, southerly winds are likely to develop at DEN and
APA with a small chance rain showers move overhead with little
impact. Drainage winds are expected for much of the night at all
terminals.

Normal wind patterns are expected throughout the day on Sunday.
There will be less low level moisture in place and coverage of
showers and storms will be lower as a result. However, an outflow
boundary or two is still expected to impact the terminals late
tomorrow afternoon and early evening.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

DISCUSSION...20
AVIATION...Danielson

Preliminary Local Storm Report
National Weather Service Denver CO
1214 PM MDT Sat Aug 22 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0941 PM     Tstm Wnd Gst     11 WNW Westplains       40.92N 103.70W
08/21/2026  M71 MPH          Weld               CO   AWOS

            Outflow winds from nearby thunderstorm.

0857 PM     Tstm Wnd Gst     11 WNW Peetz            40.99N 103.31W
08/21/2026  M62 MPH          Logan              CO   Public

            Personal weather station.

0847 PM     Tstm Wnd Gst     5 WNW Peetz             40.99N 103.19W
08/21/2026  M60 MPH          Logan              CO   Mesonet

            Personal weather station.

0847 PM     Tstm Wnd Gst     4 WNW Peetz             40.98N 103.20W
08/21/2026  M60 MPH          Logan              CO   Public

            Personal weather station.

&&

Special Weather Statement
National Weather Service Denver CO
142 PM MDT Sat Aug 22 2026

COZ040-041-222030-
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County CO-Elbert/Central and
East Douglas Counties Above 6000 Feet CO-
142 PM MDT Sat Aug 22 2026

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

At 142 PM MDT, Doppler radar was tracking a strong thunderstorm near
Franktown, or 28 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...
  Castle Rock, Parker, Elizabeth, The Pinery, Franktown, Ponderosa
  Park, southeastern Castle Pines and Castlewood Canyon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Prepare for sudden gusty winds. Secure loose objects and move to a
safe shelter inside a building or vehicle.

&&

LAT...LON 3953 10485 3958 10483 3958 10475 3940 10445
      3926 10474 3934 10489
TIME...MOT...LOC 1942Z 225DEG 13KT 3936 10474

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

Hiris