855
FXUS65 KBOU 100845
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
245 AM MDT Thu Sep 10 2026

.KEY MESSAGES...

- Mainly dry through Friday with warmer temperatures.

- Return to more unsettled pattern this weekend with a chance of
  thunderstorms especially on Sunday. Cooler Saturday, then warmer
  on Sunday.

- Another cold front moves into the area next Monday or Tuesday
  with a chance of showers and thunderstorms.

&&

.DISCUSSION /Through Wednesday/...
Issued at 240 AM MDT Thu Sep 10 2026

The flow aloft will remain WNW today as southerly level flow is
across the plains.  MLCAPE will rise up to 1000 j/kg over portions
of the far ern plains by aftn.  Chances for tstms still look on the
low side as I can`t find a focus for activity.  However, can`t rule
out an isold storm or two mainly across Lincoln county where a weak
convergence zone will exist this aftn.  Meanwhile, temps will begin
to warm as readings reach the upper 80`s to lower 90`s over nern CO.

On Fri, zonal flow aloft will be over the area as a sfc lee trough
develops over the plains.  This will lead to another warm day as
highs rise into the upper 80`s to mid 90`s over the plains.
Meanwhile, models have some mid level moisture embedded in the flow,
which may lead to isold high based showers/tstms over the higher
terrain in the aftn.  Across the plains, MLCAPE is under 500 j/kg so
any threat of showers/tstms will be on the low side.

For Fri night into Sat, zonal flow aloft will continue.  Meanwhile,
a cold front will move across Fri night into Sat morning.  This
front will drop temps back to more seasonal levels across nern CO.
MLCAPE is fcst to be in the 500-800 j/kg across the plains with
lower values across the higher terrain.  For now, have kept in a
slight chc for showers/tstms across the higher terrain and along the
I-25 Corridor for the aftn/evening hours.  Highs over nern CO will
be in the upper 70`s to mid 80`s.

By Sun, an upper level trough will move into the nrn Rockies with
increasing WSW flow aloft across the area.  At the sfc, a lee trough
will intensify east of the mtns with SSE low level flow across the
plains.  MLCAPE is fcst to increase to 1000-1500 j/kg over portions
of the plains east of a pseudo dryline. Thus may see a few
strong/svr storms by late aftn thru the evening hours. Highs on
Sun, will likely rise back to above normal levels.

Looking ahead to Mon, WSW flow aloft will remain over the area.
Models have backed off on the timing of another cold front moving
across as they now show it moving in Mon night into Tue morning.  If
this front does hold off until Mon night, then another day of above
normal temps would occur over the plains.  Meanwhile, may have a
better chc of showers/tstms across the plains Mon night into Tue
morning as position of upper level jet combines with upslope flow
behind the front.

For Tue, differences exist between the ECMWF and GFS with respect to
timing of additional precip and temps.  The ECMWF has a cool and
stable airmass, over the plains, with highs only in the mid 60`s to
lower 70s.  Meanwhile, the GFS isn`t as cool and has far more
precip.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1103 PM MDT Wed Sep 9 2026

VFR conditions will continue. Light SE winds will become southerly
by 08z and then turn more SSW by 12z. By 18z, winds will become
SE and then shift to southerly by 03z Thu evening.

&&

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

&&

$$

DISCUSSION...RPK
AVIATION...RPK

NWS BOU Office Area Forecast Discussion