Flash Flood Warning 5, NWS Denver/Boulder, CO

Area Forecast Discussion
National Weather Service Denver/Boulder CO
500 PM MDT Wed Jul 1 2026

.KEY MESSAGES...

- Critical fire weather conditions will be present in South Park,
  the southern foothills, and the Palmer Divide today due to
  warm, dry and windy conditions.

- Elevated to critical fire weather conditions are expected
  Thursday and Friday especially along and south of I-70.

- There will be very limited coverage of showers and storms
  Wednesday and Thursday with the best chance over the far
  northeast corner of Colorado.

- Near normal temperatures with scattered showers and storms on
  July 4th.

&&

.DISCUSSION /Through Wednesday/...
Issued at 205 PM MDT Wed Jul 1 2026

A Denver Cyclone has set up to the south/southeast of Denver.
Surface convergence with the cyclone and along a weak boundary
extending to the east/northeast could be enough to trigger an
isolated storm. However, weak subsidence at mid levels and dry air
near the surface will put a damper on potential rain this
afternoon, leading to potential virga near the cyclone. Later
this evening and early overnight, surface convergence and weak
mid level QG lift could be enough for a storm or two to develop in
northern Weld, Morgan, or Logan county area. Any storm that can
overcome the surface cap and get going could tap into decent mid
level lapse rates and DCAPEs, leading to the possibility of
strong winds with any storms. There will also be potential for
hail with any storm that develops, but the main threat will likely
be strong winds. Winds gusts associated with a storm will most
likely range from around 40 to 50mph, but we could see a gust or
two approach 60mph.

Tomorrow, the surface low will remain over our eastern plains. Winds
to the north and east of the low will be lighter from the northwest,
whereas winds from the south and west will be a bit breezier.
Similar to today, an isolated storm or two could fire up where
surface convergence sets up with the low/dry line. Once again,
any storm that can develop will remain on the marginally severe
side, with winds as the main threat. Temperatures will rise a
couple of degrees for tomorrow afternoon, putting highs in the low
to mid 90s across the plains. Relative humidities will remain low
for much of the area leading to continued fire weather concerns
(more on this in the fire weather discussion below).

The thermal ridge will continue to expand and strengthen into
Friday, raising highs another degree or two for Friday afternoon.
The surface low looks to push more to the south and east for Friday,
leading to more widespread northerly winds. These winds will help
bring in higher dewpoints, increasing RHs above critical fire
weather thresholds for much of the plains. Most of the thunderstorm
activity is expected to stay off to our north and east, but we
can't rule out an isolated storm in our northeastern counties in
the afternoon.

The ridging breaks down slightly for Saturday as a shortwave moves
through the flow aloft. This shortwave could provide enough lift
for some scattered showers and thunderstorms in the afternoon and
evening. The highest chance for rain on the evening of July 4th
will be in our northeastern plains counties. Ridging will build
back over the area for Sunday into the middle of next week,
leading to above normal temperatures in the 90s.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 500 PM MDT Wed Jul 1 2026

Denver cyclone is centered just south of KAPA, and is slow to move
east so that could delay the expected wind shift to N-NW behind
the cyclone. On the northern periphery of the cyclone, enhanced
E winds gusting to around 24-28 kts are occurring, and will hold
til 02Z-03Z or as winds start shifting northerly. As mentioned,
that now appears to be a slower transition so we've delayed that
more northerly shift to around 01Z for KAPA (much uncertainty as
cyclone is very close here and could also have VRB winds), and to
about 03Z-04Z for KDEN. KBJC should see a little earlier and more
gradual shift 00Z-02Z. There is still a small (20% chance) that
virga develops over the airport for VRB gusty winds.

Winds should turn more NW-WSW overnight, and then become VRB again
by 15-16Z Thursday. Expect a more diurnal E wind to develop by 18Z
Thursday but winds should be lighter than today (8-14 kts).

Additionally, we still expect enough smoke from southern Colorado
fires to impact operations through the evening. Thus, IMC is
expected to prevail through 03Z due to limited slant range
visibility. We're also seeing signs of a more WSW flow tomorrow
which could potentially bring in even thicker smoke from
southwestern CO fires and some visibility restriction down to
5-6SM possible by late afternoon. Thus, we've gone with the 6SM FU
for now to address that expected thickening.

&&

.FIRE WEATHER...
Issued at 205 PM MDT Wed Jul 1 2026

A Red Flag Warning will remain in effect for South Park, the
Southern Foothills, and the Palmer Divide through 8PM this
evening. As of early this afternoon, winds are gusting around 20
to 25mph with RHs in the single digits to low teens. Winds will
strengthen slightly as we go into the late afternoon and evening,
with gusts up to 30mph. Winds will weaken in these areas around
8PM. Tomorrow, conditions will remain similar for the South Park
area, so we've put out another RFW for zone 214 tomorrow. Winds
will be slightly weaker for the Southern Foothills and Palmer
Divide, so we've left them out of the Red Flag Warning for
Thursday at this time. RHs will remain below critical thresholds
for much of our forecast area for Friday, but winds will be
borderline again, with gusts around 20 to 25mph in the higher
terrain and in our southern counties. Moisture increases some for
Saturday, bringing RHs above 15% for much of the plains for
Saturday afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM MDT this evening for COZ214-216-241.

Red Flag Warning from noon to 8 PM MDT Thursday for COZ214.

&&

DISCUSSION...AP
AVIATION...20
FIRE WEATHER...AP

Special Weather Statement
National Weather Service Denver CO
1015 PM MDT Wed Jul 1 2026

COZ035-038-039-020500-
Larimer County Below 6000 Feet/Northwest Weld County CO-Boulder
And Jefferson Counties Below 6000 Feet/West Broomfield County CO-
Larimer and Boulder Counties Between 6000 and 9000 Feet CO-
1015 PM MDT Wed Jul 1 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN LARIMER AND
NORTHEASTERN BOULDER COUNTIES UNTIL 11 PM MDT...

At 1015 PM MDT, Doppler radar was tracking a strong thunderstorm near
Pinewood Springs, or 27 miles southwest of Fort Collins, moving
northeast at 25 mph.

HAZARD...Wind gusts up to 40 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...
  Berthoud, Lyons, Carter Lake, Cedar Cove, Pinewood Springs and
  Campion.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

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

&&

LAT...LON 4015 10534 4023 10545 4049 10522 4035 10500
      4035 10506 4032 10506
TIME...MOT...LOC 0415Z 221DEG 19KT 4022 10533

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

MAI

Special Weather Statement
National Weather Service Denver CO
1101 PM MDT Wed Jul 1 2026

COZ038-020545-
Larimer County Below 6000 Feet/Northwest Weld County CO-
1101 PM MDT Wed Jul 1 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN WELD COUNTY UNTIL
1145 PM MDT...

At 1101 PM MDT, Doppler radar was tracking a strong thunderstorm over
Pierce, or 14 miles north of Greeley, moving northeast at 25 mph.

HAZARD...Wind gusts up to 40 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...
  Ault, Pierce, Nunn and Purcell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4058 10479 4061 10485 4088 10471 4076 10439
      4058 10467
TIME...MOT...LOC 0501Z 214DEG 20KT 4062 10473

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

MAI

Special Weather Statement
National Weather Service Denver CO
1145 PM MDT Wed Jul 1 2026

COZ038-042-043-020630-
Northeast Weld County CO-Central and South Weld County CO-Larimer
County Below 6000 Feet/Northwest Weld County CO-
1145 PM MDT Wed Jul 1 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN WELD COUNTY UNTIL
1230 AM MDT...

At 1145 PM MDT, Doppler radar was tracking strong thunderstorms 6
miles north of Milliken, or 5 miles west of Greeley, moving north at
15 mph.

HAZARD...Wind gusts up to 40 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. Hail may accumulate on roadways causing hazardous
         travel.

Locations impacted include...
  Greeley, Windsor, Eaton, Severance, Ault, Pierce, Grover, Purcell,
  Galeton and Lucerne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4058 10482 4097 10453 4093 10405 4034 10480
      4042 10493
TIME...MOT...LOC 0544Z 201DEG 12KT 4041 10484

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

MAI