589
FXUS65 KBOU 280537
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1137 PM MDT Mon Jul 27 2026

.KEY MESSAGES...

- Scattered to numerous showers and storms with locally heavy rain
  Tuesday and Wednesday. Temperatures settle back closer to
  normal.

- Drying out again later in the week. Heat returns for next
  weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 145 PM MDT Mon Jul 27 2026

We had an MCV over the area this morning, which provided some cloud
cover and light rain across a good portion of the area. The cloud
cover and rain has kept temperatures in our area quite a bit cooler
than surrounding areas (as of 1PM a station in northern Weld County
was still at 75 degrees). The cooler temperatures and cloud cover
will limit instability in portions of our area for this afternoon.
The heavier cloud cover is pushing to the northeast, with good
clearing in the urban corridor. Showers and thunderstorms are
expected to form this afternoon across the higher terrain, pushing
east into plains during the evening hours. A few of the storms
this evening could still be strong to marginally severe, but at
this point the main hazard looks to be heavy rainfall leading to
flash flooding, with a secondary hazard of strong winds.

The rain chances and flooding threat will continue into Tuesday and
Wednesday. The upper level set up will remain similar, with a weak
disturbance or two moving through the upper level ridge aloft each
afternoon. At the surface, PWs are forecast to remain around 150%
to 200% of normal. The flooding threat is expected to increase
for tomorrow, as the warm cloud layer depth increase slightly and
rainfall from today makes soils more prone to flooding. The
coverage tomorrow also looks a bit higher, with potential for a
few strong storms with heavier rainfall rates compared to today.
Instability and shear will be decent enough for a few marginally
severe storms as well. The main hazards tomorrow will likely be
strong winds and heavy rain. The one limiting factor for heavy
rain potential will be the cloud layer winds increasing a few
knots for Tuesday, which could help storms move slightly faster.

A similar set up will exist for Wednesday as well. The flooding
potential for Wednesday will depend heavily on how much rain falls
today and tomorrow. Areas that see heavy rain on today and Tuesday
will be more prone to flash flooding on Wednesday. Storm motions
remain on the elevated side for Wednesday, but the high moisture
and previous rainfall will lead to a 3rd day of flash flooding
potential. While precipitation is not guaranteed each day at every
location, there is a high chance (>70%) that over the next 3 days
many locations in our area will see at least 0.25 inches of rain,
with a good chance that a few localized areas see multiple inches
of rain. Right now, the best chance for these higher rain amounts
are in our eastern plains counties.

The upper level ridge will begin to shift more to the west for
Thursday into the weekend, putting us in northwest flow aloft and
decreasing the moisture over the area. This will significantly
reduced our rain chances for the plains, with the potential for some
isolated to scattered activity lingering in the higher terrain. The
thermal ridge will remain off to our west through the work week,
keeping temperatures in the low to mid 90s for much of the plains.
The thermal ridge will start to shift more eastward by the end of
the week as the upper level ridge starts to tilt and push more
northeast.

&&

.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1137 PM MDT Mon Jul 27 2026

Storm threat has exited the area for the night. Winds were
attempting to settle back to fairly normal S-SW winds, although we
will have to watch a potential surge back from the east or
northeast overnight as storms in Nebraska and Kansas send an
outflow back this way. If that occurs, there`s a slight (10-20%
chance) of some stratus development but overall VFR will persist.

On Tuesday, the main concern will shift toward likely occurrence
of thunderstorms, most favored 21Z-24Z and perhaps as early as 20Z
at KBJC. The threat of stronger storms is greater than yesterday
so we`ll have TEMPO G35-40kts, TSRA, and some visibility
restriction to 5-6SM...although if a direct hit occurs visibility
could go down as low as 1SM given potential for heavy rain with
storms. Outside of that, look for mid level ceilings above 8,000
feet AGL and fairly normal diurnal wind patterns

&&

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

&&

$$

DISCUSSION...AP
AVIATION...20

NWS BOU Office Area Forecast Discussion