795
FXUS65 KBOU 212349
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
549 PM MDT Mon Jul 21 2025

.KEY MESSAGES...

- Isolated/scattered showers and thunderstorms this evening. Main
  threats are brief heavy rain, small hail, and winds to 50 mph.

- Increased moisture and slight cooling expected by midweek
  leading to better chances for showers and thunderstorms Tuesday
  through Thursday.

- Warmer and drier for next weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 210 PM MDT Mon Jul 21 2025

For the rest of today and this evening, scattered showers and
thunderstorms will track eastward across the area. Limited
instability and shear are expected to keep the storms sub-severe
with small hail, brief heavy rain, and wind gusts to 50 mph
possible with the stronger storms. Can`t rule out a couple of
severe storms over the far eastern plains where better instability
(MLCAPE of 1000- 2000 J/kg) will exist. However, shear is still
limited which is expected to continue to limit the severe threat.

Large upper level high over the south central and southeast part
of the country will produce a weak south to southwest flow aloft
across Colorado this upcoming work week. This will transport
subtropical moisture northward into the area. On Tuesday,
precipitable water values increase to 120-150% of normal. In
addition to the increase in moisture, a shortwave trough lift
north-northeast across the region. This is expected to result in
scattered to numerous showers and thunderstorms Tuesday
afternoon/evening. Heavy rainfall and wind gusts to 50 mph will be
the main threats. Shear is very weak for Tuesday afternoon and
evening.

A weak surge (cold front) drops south across the area early
Wednesday ushering slightly cooler temperatures and increasing low
level moisture. North to northeast low level flow continues into
Thursday keeping temperatures somewhat cool (highs in the 80s) and
holding low level moisture over the area. Flow aloft both
Wednesday and Thursday will be weak, resulting in poor shear for
severe weather. However, the slow storm movement will increase the
heavy rainfall threat.

Upper level ridging begins to intensify over the Central and
Southern Rockies Friday. This will bring slightly warmer and drier
air to the region. Enough moisture and instability is expected to
remain in place for isolated/scattered showers and thunderstorms.

For the weekend and next Monday, the upper level high intensifies
over the middle part of the country. On Monday, the models show
the 500mb upper level high peaking at 598-600(dam) high over
Nebraska and Kansas. If this pans out, it will be a hot and mostly
dry period come Saturday through Monday.

&&

.AVIATION /00Z TAFS through 00Z Wednesday/...
Issued at 549 PM MDT Mon Jul 21 2025

Will leave in the PROB30 group for -TSRA and VRB20G35KT for a
couple hours based on reality. Normal drainage winds can be
expected around 06Z later tonight. No ceiling issues. For Tuesday
afternoon`s convection, I will leave the TEMPO group in as models
continue to show better chances of showers and thunderstorms in
the afternoon.

&&

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

&&

$$

DISCUSSION...Meier
AVIATION.....rjk