792
FXUS65 KBOU 041115
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
515 AM MDT Fri Jul 4 2025

.KEY MESSAGES...

- Scattered showers and a few thunderstorms this morning.

- Additional scattered showers and thunderstorms this afternoon,
  diminishing from west to east early this evening.

- A chance of afternoon and evening thunderstorms and above normal
  temperatures are expected for the weekend into early next week.

&&

.UPDATE...
Issued at 240 AM MDT Fri Jul 4 2025

Water vapor satellite imagery showing a shortwave trough over the
Four Corners region rotating around the upper level high over
northern Mexico. Behind the shortwave, drier air can be seen over
Arizona and southern Utah. Ahead of the shortwave trough we are
seeing scattered showers across the higher terrain. Expect
additional showers and a few weak thunderstorms to develop this
morning across the urban corridor and eastern plains. By noon, the
best lift and showers/storms will shift east of Colorado. As
drier air starts to filter into the area, some clearing will take
place. Airmass becomes unstable with SBCAPE of 300-700 J/kg.
Additional isolated/scattered thunderstorms are expected to
develop early this afternoon across the higher terrain, urban
corridor, and nearby plains. This activity shifts eastward and
ends early evening as the airmass continues to dry. Over the far
eastern plains, stronger storms will be possible where better
moisture is expected to hang on through the afternoon. A couple
storms could just reach severe criteria with 60 mph winds and one
inch diameter hail.

&&

.DISCUSSION /Through Thursday/...
Issued at 239 PM MDT Thu Jul 3 2025

Thunderstorms have developed over western Colorado, but are slow
to spread east so far this afternoon as the storm motions are
south to north. This area of convection will creep eastward
through this evening, and eventually most of the mountains should
have some showers. It`s questionable if there will be anything
east of the mountains this evening, however. The main threat will
be gusty winds, though a few spots could get a brief heavy rain.

As the shortwave trough moves eastward, it should interact with
the moisture on the plains later tonight into Friday morning. This
will likely produce another batch of showers and thunderstorms. If
they`re able to develop along the I-25 corridor it would likely be
just before or around sunrise, then the threat out on the
northeast plains is in the morning hours. There may be enough
CAPE/moisture for a few strong storms in the northeast corner if
the timing is slow enough (late morning), but the severe threat
looks low.

For later in the day, the winds aloft will become more
northwesterly with some drying and a little cooling. There will
likely still be some afternoon convection, although it might not
be much. With continued drying into the evening, the activity will
likely be over for the mountains and I-25 corridor by sunset, or
at least pretty minimal coverage.

The models continue with subtle day to day changes with a low
amount of moisture around and temperatures a little above the hot
summer normals. There`s not great confidence on how the details
will affect convective trends, but it looks like there will be
increasing moisture coming into the northeast plains Saturday
afternoon which could be a focus for a few strong to severe
storms. Model soundings suggest 1000-1500 J/kg of CAPE with
sufficient shear for supercell structures.

The theme for the next week will be a gradually strengthening
ridge over the Rockies. But a shortwave passing over the northern
Rockies about Sunday may restrain the warming and force some
convection Sunday and Monday. The ridge is more likely to
strengthen near us by the middle of the week.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 515 AM MDT Fri Jul 4 2025

VFR to continue today and tonight. An upper level system will
bring mid and high clouds through 15Z Friday with scattered
showers. A brief/weak thunderstorm can`t be ruled out (about 10%
chance). Slightly drier air begins to move in after 18Z, but
enough moisture and instability will remain for a 30 percent
chance of a thunderstorm through Friday afternoon (00Z Saturday).
Gusty outflow winds to 35 knots will be possible near and under
the storms. Clouds continue to decrease after 00Z Saturday with
mostly clear skies by 06Z and southerly drainage winds.

&&

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

&&

$$

UPDATE...Meier
DISCUSSION...Gimmestad
AVIATION...Meier