858
FXUS65 KBOU 292343
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
543 PM MDT Wed Jul 29 2026

.KEY MESSAGES...

- Showers and thunderstorms likely across the high terrain in the
  late morning, shifting to the plains by the afternoon.

- Strong storms could produce localized flash flooding,
  particularly for the burn scar and areas along and east of the
  southern I-25 Corridor.

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

&&

.DISCUSSION /Through Wednesday/...
Issued at 253 PM MDT Wed Jul 29 2026

It is another afternoon of showers and thunderstorms across Colorado
as monsoonal moisture continues to raise precipitable water (PW) for
the region to values (1.0"-1.6") that greatly exceed the 90th
percentile of climatology. Numerous thunderstorms have already
developed over the Front Range and the urban corridor, with radar-
estimated totals with the strongest storms ranging from 1.00" to 2.0"
in one hour. Weak mean cloud layer winds (<10KT) will lead to
slow storm motions and torrential rainfall that may lead to
localized flash flooding, particularly over burn scars and areas
with antecedent soil moisture from Tuesday`s storms.

We have issued a Flood Watch for flash flooding for the Palmer
Divide, where high-res model guidance has been a bit more bullish
with thunderstorm coverage and instability will be more robust
(MLCAPE ~1000 J/kg). However, localized flash flooding may occur
outside of the Watch if storm redevelopment occurs over the same
areas, and with any storms that become anchored to the terrain.
We expect showers and storms to start diminishing in coverage by 9
pm, with perhaps a few decaying thunderstorms lingering over the
mountains and the easternmost Colorado plains.

For tomorrow, the upper level ridge currently over the southwest
U.S. weakens, and westerly winds aloft cuts off the flow of
monsoonal moisture from the southwest. We expect shower coverage to
decrease, although afternoon showers will still be possible (20% to
35% chance) mainly over the highest peaks, northern foothills, and
the Palmer Divide. The northeast Colorado plains will still hold on
to PWs around 1.5" and dewpoints in the low 60s, so this is where
the better chance for a strong isolated thunderstorm will reside. We
are not overly concerned about flash flooding for tomorrow due to
the decreased rainfall coverage as well as faster storm motions,
with cloud layer mean winds around 20KT.

The passage of a shortwave trough will bring another chance for
isolated strong to severe thunderstorms on Friday, although
uncertainty remains regarding the convective setup due to the
mesoscale convective system (MCS) that model guidance has suggested
will track through central Nebraska in the early morning hours,
which could produce an outflow front that greatly alters convective
parameters for Friday. Nevertheless, decent northwest flow aloft (20-
30KT) and the advection of higher dewpoints from the central plains
due to easterly flow at the surface could lead to a few strong
storms that produce erratic gusty outflows up to 50 mph.

Long-range ensembles are in good agreement that the upper level
ridge strengthens to our west on Saturday, the atmosphere dries out,
and temperatures rise above normal once again. Triple digits and
heat concerns are becoming increasingly likely for Sunday and
Monday over the plains, including the Denver metro. Uncertainty
enters the picture halfway through next week due to a series of
shortwaves sliding through the Pacific Northwest, and a weakening
of the ridge over the Four Corners.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 537 PM MDT Wed Jul 29 2026

VFR conditions will prevail through the TAF period. A few SHRA
remain northeast/east of DEN but are not expected to cause any
significant impacts this evening. Winds behind this convection
have been generally out of the southeast and should slowly turn
towards more of a typical drainage pattern over the next few
hours. There is once again a very slight chance of some morning
stratus or fog, but with drainage winds this looks rather
unlikely.

Isolated to widely scattered convection is forecast again for
Thursday afternoon. With limited coverage near the terminals we
opted for a PROB30 with slightly better chances of variable/gusty
outflow winds.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 9 PM MDT this evening for COZ041-046-047.

&&

$$

DISCUSSION...AA
AVIATION...Hiris