937
FXUS65 KBOU 292118
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
318 PM MDT Sun Jun 29 2025

.KEY MESSAGES...

- Strong to severe storms expected across the I-25 corridor and
  eastern plains today with large hail and damaging wind gusts
  possible.

- Monday will be cool with storms focused over the southern
  foothills and South Park.

- Scattered thunderstorms and normal temperatures are expected for
  the Fourth of July.

&&

.DISCUSSION /Through Sunday/...
Issued at 229 PM MDT Sun Jun 29 2025

Water vapor satellite shows a weak shortwave trough over Wyoming
with weak westerly flow aloft over Colorado. This flow and trough
are providing just enough lift and shear to allow for severe
convection in our area. The main reason for the strong to severe
storms in our area is due to moderate to strong instability with
surface CAPE values over 2,000 j/kg across the entire I-25
corridor and eastern plains with some areas above 3,000 j/kg
across the far eastern plains. This will support strong updrafts
and with just enough shear, a few storms may produce large hail
greater than an inch. It appears the may threat will end up being
severe wind gusts as strong storms will eventually merge into an
MCS once they get east of a line from Greeley to DIA. Wind gusts
up to 70 mph will be possible especially near Fort Morgan, Akron,
and Sterling.

The assumption is that the storms this afternoon and evening will
"work over" the environment such that strong storms are not
expected overnight tonight. Some slight chance PoPs were kept in
the forecast for the eastern plains since some high resolution
model data shows a few showers and storms. Having said that, the
QPF was largely taken out of the forecast for tonight.

On Monday, it appears there will be just enough low level
moisture to form stratus clouds in the morning hours across a good
portion of the I-25 corridor and eastern plains. With a strong cap
above the low level cool and moist air, it will take a very long
time for the boundary layer to mix out. Therefore, highs will
likely stay in the upper 70s across the I-25 corridor and plains.
Furthermore, it will likely be too stable anywhere from downtown
Denver and to the north and east for any showers and storms to
form so PoPs and QPF were lowered or taken out. Where it will
storm is over the southern foothills and Park County as the best
upslope flow and instability will be located there. Some of these
storms may produce heavy rainfall.

The center of a ridge aloft will be over Colorado on Tuesday and
Wednesday. Highs will warm up each day and there is good consensus
in the ensemble data that highs will reach the mid 90s across the
plains on Wednesday. SPC added an area of marginal risk for severe
weather across the far northeast corner of Colorado on Tuesday as
60+ degree dew points will create moderate instability.

Tropical moisture will be brought up to Colorado on Thursday and
Friday due to southerly flow. A trough will be roughly over
Arizona on Thursday and over eastern Colorado on Friday. The exact
timing of this trough will be very important to determine whether
Thursday will see widespread storms of if Friday will have
widespread storms. At this moment, models seem split roughly
50/50 so please stayed tuned to future forecast updates to get a
better idea of weather for the holiday.

&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1235 PM MDT Sun Jun 29 2025

Showers and storms are already forming over the higher terrain
today but they will initially struggle to move onto the plains due
to a strong inversion. By the mid afternoon, strong storms will
push across the Denver metro with hail and strong wind gusts
possible. All terminals will likely be impacted and gusts could
reach 50 knots. Once the storms pass through, winds will become
easterly for the evening.

Overnight tonight, there will be light drainage flow. By 08-11Z, a
push of northerly winds are expected to bring in a stratus deck
with ceilings around 1,000-2,000 feet. There is a 30% chance that
only a scattered layer develops instead of a broken layer. This
broken stratus layer will likely dissipate between 16-18Z tomorrow
morning.

Given the cool temperatures and stable conditions tomorrow, DEN
and BJC are expected to be dry and not be impacted by storms. APA
may receive an outflow boundary from storms over the southern
foothills.

&&

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

&&

$$

DISCUSSION...Danielson
AVIATION...Danielson