516
FXUS65 KBOU 291854
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1254 PM MDT Fri Aug 29 2025

.KEY MESSAGES...

- Scattered to numerous storms through Saturday with locally heavy
  rainfall in a few areas. An isolated severe storm possible as
  well.

- Warmer and drier Sunday through Tuesday.

&&

.DISCUSSION /Through Thursday/...
Issued at 224 PM MDT Thu Aug 28 2025

MLCAPE this aftn was up to 1500 j/kg over the plains with mid level
flow in the 20-25 kt range.  Overall low level flow was very weak
across the plains.  With favorable instability, will see sct mainly
outflowed dominant storms from the higher terrain across the plains.
There is a low threat for a marginal svr storm over the plains thru
the evening hours.  Meanwhile, storms will be moving so threat of
flash flooding will be low in most areas. Overnight, as low level
flow begins to increase may see an increase in tstm activity over
the east central plains, especially over Lincoln county.

On Fri, will see another round of sct showers and tstms.  MLCAPE
will range from 1000-1500 j/kg mainly over the far ern plains.  Once
again there could be an isold marginal svr storm where the best
instability exists.  Highs on Fri will remain slightly below
seasonal normals.

By Sat, the flow aloft will become more NWLY as a cool front moves
into nern CO.  There could be a disturbance embedded in the flow
aloft which may increase tstm chances across the area.  Once again
may see locally heavy rain with some of the storms with an isold svr
storm possible.  Highs on Sat will remain below normal.

From Sun thru Tue a drier and somewhat warmer pattern will develop
across the area as an upper level ridge builds from the Great Basin
into the Pacific NW.

The next pattern change may occur by the middle of next week.  The
ECMWF has a strong upper level trough over the Great Lakes and upper
Midwest with NNW flow aloft over the area.  This allows for much
cooler air to move into the area for Wed and Thu.  On the flip side
the GFS has a less amplified trough with the cooler air staying
mainly to the east.  For now it`s hard to say which model may verify
this far out.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1225 PM MDT Fri Aug 29 2025

Scattered thunderstorms will develop this afternoon and may impact
the terminals. Gusty winds, lower ceilings, and lower visibility
may occur during these storms. Worst case scenario is that winds
gust up to 40 knots, ceilings drop to 3,000 feet, and visibility
drops to 2 SM. Having said that, the best instability is to the
south of the terminals so showers and storms will likely be on the
weaker side over the terminals.

With a shortwave trough passing through the area tonight, there
will be a chance for showers and storms that lingers throughout
most of the night. There is also a chance that low ceilings and/or
fog/mist develops in the morning hours due to the high moisture
content in the atmosphere. However, the rain may lower the chance
of fog.

During the day on Saturday, drier air will move across the area.
This will lead to more isolated storms but storms could produce
stronger wind gusts.

&&

.HYDROLOGY...
Issued at 224 PM MDT Thu Aug 28 2025

Scattered showers and thunderstorms will occur through Saturday
with locally heavy rain in some areas, especially on Saturday.
Drier air will move into the area on Sunday and continue through
early next week with only isolated thunderstorms over the higher
terrain.

&&

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

&&

$$

DISCUSSION...RPK
AVIATION...Danielson
HYDROLOGY....RPK