Flash Flood Warning 2, NWS Denver/Boulder, CO

150 
WGUS75 KBOU 012149
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
349 PM MDT Mon Jun 1 2026

COC001-005-031-012159-
/O.CAN.KBOU.FF.W.0002.000000T0000Z-260601T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Adams CO-Arapahoe CO-Denver CO-
349 PM MDT Mon Jun 1 2026

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

The heavy rain has ended. Minor urban and small stream flooding is
expected to continue through 5 PM.

&&

LAT...LON 3980 10485 3981 10485 3983 10473 3982 10475
      3982 10473 3973 10470 3971 10483
PARTITION...408005

$$

Schlatter

Area Forecast Discussion
National Weather Service Denver/Boulder CO
205 PM MDT Mon Jun 1 2026

.KEY MESSAGES...

- A chance for strong and severe thunderstorms this afternoon
  along the I-25 Corridor, with large hail, gusty winds, and a
  brief tornado possible.

- Severe storms will be possible again Tuesday afternoon, with
  locally heavy rain possible.

- Thunderstorm chances will continue on Wednesday with lower
  threat for severe storms, however, locally heavy rain will be
  possible.

- Trending warmer and drier by the end of the week.

&&

.DISCUSSION /Through Monday/...
Issued at 158 PM MDT Mon Jun 1 2026

The synoptic pattern shows a broad upper-level low is in place over
the Pacific Northwest, with a 80kt, southwest to northeast situated
upper-level jet residing across the Central Rockies on this Monday
morning. This is bringing southwesterly flow aloft across Colorado,
with fairly robust low-level moisture (50F dewpoints) advecting into
eastern Colorado via southeasterly upslope.

Latest East Meso-2 Day Cloud Phase shows cumulus clouds along the
Front Range Mountains are starting to show vertical growth early
this afternoon. These storms are expected to become more robust
within the next hour or two with potential for severe storms to
develop along the I-25 Corridor between the 1-2PM time frame, where
the SPC has the majority of our lower elevations in a Slight Risk
(2/5 threat level). Latest ACARS sounding shows MLCAPE values around
1000 J/kg, with only a few degrees of surface heating needed to
overcome a 700 mb inversion. Upslope flow to near 700 mb is also
visible on KFTG VAD Wind Profiler, with surface dewpoints ranging
from the upper-40s to mid-50s across the foothills and plains.
Expecting storms to initially be discrete in nature with large hail
(2-3") being the main threat, before progressing eastward where the
environment will be more conducive to a more linear storm mode, with
strong winds becoming the primary threat. While tornadoes are not
expected to be the main threat today, a brief tornado cannot be
ruled out where any low-level circulations can hold together. The
severe threat is expected to diminish from west to east, moving out
of metro Denver by 6PM and 8PM-9PM for the eastern plains. Hi-res
guidance has continued to show shower and non-severe thunderstorms
becoming reestablished behind the exiting severe threat, mainly
along the South Platte River Valley, by 11PM-12AM continuing to
around sunrise.

For Tuesday, flow aloft will transition to a more zonal pattern with
surface dewpoints expected to remain fairly robust once again.
MLCAPE values are not expected to be as strong as today, but values
between 500 to 1200 J/kg will be in place by the afternoon, with
conditions favorable for another day of severe storm potential
across the eastern plains. MUCAPE increasing to greater than 1500
J/kg mixed with steep mid-level lapse rates will support the
development of baseline severe hail size potential, with shear
weaker than today looking to keep the threat of anything larger than
2" limited and gusty outflows the most likely severe threat.
Expecting storms to initiate between 1PM to 3PM and coverage to be
far less than today, with the SPC having areas generally east of I-
25 in a Marginal risk (1/5 threat level).

Afternoon thunderstorms will be possible once again Wednesday, with
an isolated threat of some becoming severe, mainly for the eastern
plains. Temperatures are forecast to gradually increase through the
week, reaching for the 90s by Thursday as 700 mb flow warms by about
10C. Warmer and drier conditions are expected from Thursday onward,
with increasing elevated fire weather conditions expected as the
warmer and drier weather persists into the weekend, though with
greenup well underway and multiple chances for precip through
mid-week, any developing fire weather concerns will likely remain
limited and localized.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1158 AM MDT Mon Jun 1 2026

East to southeast winds have increased moisture across the area
and brought stratocumulus clouds at 3,500 to 5,000 feet. These
clouds will burn off soon as the airmass warms.  This increase in
moisture will fuel thunderstorm development this afternoon
beginning around 19Z. Main time frame for a thunderstorm at DEN
will be 20Z to 23Z. Hail (possibly large), heavy rain, and wind
gusts to 50 knots will be possible under the stronger storms.
Models agree there should only be one round of thunderstorms this
afternoon, so by 22-00Z, expect storms to be east of DEN. 

Low clouds will develop after midnight between 08Z and 10Z and
then linger most of Tuesday morning. Ceilings are expected to be
in the 1000 to 3000 foot range, with a slight chance (20%) of
ceilings under 1,000 feet.  A Denver cyclone is expected to help
form the low clouds. Then mid morning winds become southeast. This
will end the threat of lower ceilings (~1000 feet) and slowly
erode the remaining low clouds. Another round of afternoon
thunderstorms is expected, beginning around 21Z. There's a chance
the airmass is capped, with the best chance for this occurring
north of Denver.  

&&

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

&&

DISCUSSION...9
AVIATION...12

Special Weather Statement
National Weather Service Denver CO
822 AM MDT Mon Jun 1 2026

COZ042-044-048-011500-
Logan County CO-Morgan County CO-Northeast Weld County CO-
822 AM MDT Mon Jun 1 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN MORGAN...WEST CENTRAL
LOGAN AND EASTERN WELD COUNTIES UNTIL 9 AM MDT...

At 822 AM MDT, Doppler radar was tracking a strong thunderstorm 4
miles south of Stoneham, or 22 miles north of Fort Morgan, moving
northeast at 30 mph.

HAZARD...Wind gusts up to 40 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...
  Pawnee Pass, Willard, Stoneham and Logan Corners.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4052 10371 4059 10379 4083 10345 4063 10324
      4045 10363
TIME...MOT...LOC 1422Z 230DEG 28KT 4055 10365

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

09

Special Weather Statement
National Weather Service Denver CO
858 AM MDT Mon Jun 1 2026

COZ048-011545-
Logan County CO-
858 AM MDT Mon Jun 1 2026

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL LOGAN COUNTY UNTIL
945 AM MDT...

At 858 AM MDT, Doppler radar was tracking a strong thunderstorm near
Logan Corners, or 8 miles west of Sterling, moving northeast at 15
mph.

HAZARD...Wind gusts up to 40 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...
  Northwestern Sterling, North Sterling Reservoir and Logan Corners.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4058 10334 4069 10348 4084 10330 4070 10306
TIME...MOT...LOC 1458Z 225DEG 13KT 4066 10335

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

09

Preliminary Local Storm Report
National Weather Service Denver CO
115 PM MDT Mon Jun 1 2026

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

0105 PM     Hail             1 E Edgewater           39.75N 105.04W
06/01/2026  M1.00 Inch       Denver             CO   Trained Spotter

0106 PM     Hail             Denver                  39.74N 104.99W
06/01/2026  M0.75 Inch       Denver             CO   Public

            Report from mPING: Dime (0.75 in.).

0107 PM     Hail             Denver                  39.74N 104.99W
06/01/2026  M1.00 Inch       Denver             CO   NWS Employee

0110 PM     Hail             1 NW Denver             39.75N 105.00W
06/01/2026  E1.75 Inch       Denver             CO   Public

0110 PM     Hail             2 W Denver              39.74N 105.02W
06/01/2026  M1.00 Inch       Denver             CO   Trained Spotter

0111 PM     Hail             1 SE Denver             39.73N 104.98W
06/01/2026  E1.00 Inch       Denver             CO   Public

            Report from mPING: Quarter (1.00 in.).

0114 PM     Hail             1 SE Denver             39.73N 104.97W
06/01/2026  M1.50 Inch       Denver             CO   Trained Spotter

&&

Preliminary Local Storm Report...Summary
National Weather Service Denver CO
149 PM MDT Mon Jun 1 2026

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

0135 PM     Funnel Cloud     1 W Kassler             39.49N 105.11W
06/01/2026                   Jefferson          CO   Public

0134 PM     Funnel Cloud     1 S Chatfield Reservoir 39.54N 105.06W
06/01/2026                   Douglas            CO   Public

0133 PM     Hail             2 NW Denver             39.76N 105.02W
06/01/2026  M1.00 Inch       Denver             CO   Public

            Report from mPING: Quarter (1.00 in.).

0131 PM     Hail             2 SE Chatfield Reservoi 39.54N 105.03W
06/01/2026  E1.50 Inch       Douglas            CO   Public

0130 PM     Hail             4 E Denver              39.75N 104.91W
06/01/2026  M0.88 Inch       Denver             CO   Trained Spotter

0128 PM     Hail             2 E Denver              39.74N 104.95W
06/01/2026  E1.25 Inch       Denver             CO   Trained Spotter

            Report from mPING: Half Dollar (1.25 in.).

0123 PM     Hail             3 E Denver              39.74N 104.92W
06/01/2026  M1.00 Inch       Denver             CO   Public

            Report from mPING: Quarter (1.00 in.).

0122 PM     Hail             4 E Denver              39.75N 104.92W
06/01/2026  M1.75 Inch       Denver             CO   Trained Spotter

0119 PM     Hail             3 E Denver              39.74N 104.92W
06/01/2026  M1.00 Inch       Denver             CO   Public

            Report from mPING: Quarter (1.00 in.).

0115 PM     Hail             1 SE Denver             39.73N 104.98W
06/01/2026  M1.00 Inch       Denver             CO   Public

            Most hail was smaller.

0114 PM     Hail             1 SE Denver             39.73N 104.97W
06/01/2026  M1.50 Inch       Denver             CO   Trained Spotter

0111 PM     Hail             1 SE Denver             39.73N 104.98W
06/01/2026  E1.00 Inch       Denver             CO   Public

            Report from mPING: Quarter (1.00 in.).

0110 PM     Hail             2 W Denver              39.74N 105.02W
06/01/2026  M1.00 Inch       Denver             CO   Trained Spotter

0110 PM     Hail             1 NW Denver             39.75N 105.00W
06/01/2026  E1.75 Inch       Denver             CO   Public

0107 PM     Hail             Denver                  39.74N 104.99W
06/01/2026  M1.00 Inch       Denver             CO   NWS Employee

0105 PM     Hail             1 E Edgewater           39.75N 105.04W
06/01/2026  M1.00 Inch       Denver             CO   Trained Spotter

&&