212
FXUS65 KBOU 302025
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
225 PM MDT Wed Jul 30 2025

.KEY MESSAGES...

- Cooler and more active weather pattern with scattered
  thunderstorms and locally heavy rain through Friday,
  particularly east of the Continental Divide.

- Drier and warmer weather pattern begins this weekend and lasts
  through early next week.

&&

.DISCUSSION /Through Wednesday/...
Issued at 225 PM MDT Wed Jul 30 2025

The cold front that pushed through the area last night brought
cooler and drier air to eastern Colorado, including the Front
Range. Thunderstorms already formed late this morning and early
afternoon over the mountains. The storms that progressed eastward
over the cooler and more stable air quickly dissipated. ACARS
soundings show a strong cap between 600-700mb. Models have been
persistent showing it warms enough and the cap erodes enough for
scattered/numerous showers and thunderstorms later today. The
timing of the convection off the higher terrain will be slightly
delayed, late this afternoon and evening. Temperatures around 80F
and dew points in the lower 50s yield around a 1000 J/kg. Even
with the drying, precipitable water values will be at or over an
inch (110-130% of normal) across the plains. Storm movement will
be slow, around 10 mph, so localized heavy rain will be a threat.
Because of the delayed start to the storms across the lower
elevations, storms may linger a little past midnight over the
plains.

For Thursday, additional scattered to numerous showers and
thunderstorms are expected during the afternoon and evening.
Precipitable water values will be close today. Instability may a
little better with 1000-2000 J/kg expected, highest over the
eastern plains. Southeast winds will be 10-20 mph across the
plains, which may help with shear. However, winds aloft are
forecasted to decrease leading to limited shear and slow storm
movement. Heavy rain possibly leading to localized flooding will
be the main threat. A couple severe storms can`t be ruled out as
well given the higher CAPE values.

The atmosphere begins to dry Friday, with precipitable water
values falling below 100% of normal over the higher terrain and
Front Range. Low level moisture hangs on over the eastern plains
with dew points in the 50s to lower 60s. MLCAPE climbs to
1500-2500 J/kg, leading to a couple strong to severe
thunderstorms. Shear will again be limited, keeping the severe
threat on the low side. Temperatures warm, but stay a little below
normal with highs in the mid to upper 80s.

For the weekend, the upper level high settles over the Desert
Southwest and northern Mexico. This will result in a westerly flow
aloft across Colorado. Airmass slowly dries with precipitable
water values falling below normal Saturday over much of the area,
and dries a little more for Sunday. High-based showers and storms
will be possible over the higher terrain and urban corridor. Over
the eastern plains, southeast low level flow will help hold
moisture over eastern Colorado where there will be a better chance
for afternoon and evening showers and thunderstorms. With the
main high off to the south, temperatures won`t be too hot. There`s
a slight difference between the ECMWF ensembles and the GFS
ensembles with ECMWF ensembles showings highs about 5 degrees
cooler (upper 80s over northeast Colorado) than the GFS ensembles
(lower 90s over northeast Colorado).

For next week, an upper level trough sets up over the northwest
part of the country. This nudges the ridging northeastward and it
intensifies. This is expected to push highs into the 90s for
Monday- Wednesday of next week. With the subtropical moisture
(monsoon moisture) cut off by the high, chances for showers and
thunderstorms will be on the lower side.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 225 PM MDT Wed Jul 30 2025

Stratocumulus clouds with ceilings of 5000-6000 feet at DEN will
continue to rise as temperatures warm. Thunderstorms have formed
over the higher terrain earlier than expected. Across the Denver
area, a cold front moved through last night bringing cooler and
drier air to the area. ACARS soundings show the airmass is
strongly capped at this time. So these first storms are expected
to dissipate as they move off the higher terrain. Eventually, the
cap is expected to erode with scattered thunderstorms moving
across the Denver area. Because of the capped airmass, pushed back
the beginning time of the thunderstorm tempo until 22Z. The
threat for storms lingers into the evening hours 02-03Z.

Southerly winds develop overnight and continue into Thursday.
There will be a chance for low clouds overnight, but the southerly
wind direction should help keep the low clouds from forming.
Another round of afternoon thunderstorms is expected Thursday,
beginning around 21Z.

&&

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

&&

$$

DISCUSSION...Meier
AVIATION...Meier