300
FXUS65 KBOU 021129
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
529 AM MDT Wed Sep 2 2026

.KEY MESSAGES...

- A chance for showers and thunderstorms in the northern Mountains
  today with gusty winds. A slight chance of showers and a few
  thunderstorms across the plains late this afternoon and evening.

- Warmer Thursday and Friday with mainly dry conditions.

- Return of better moisture by the weekend with an increasing
  chance for showers and thunderstorms across the high country.

&&

.DISCUSSION /Through Tuesday/...
Issued at 233 AM MDT Wed Sep 2 2026

Drier air in SW flow aloft will remain in place across the area
today.  However, there is a decent upper level jet over the area
which will combine with decent lapse rates and lingering moisture,
to produce a chance of showers/tstms over the higher terrain, mainly
north of I-70.  With decent mid level flow, gusty winds will
accompany this activity as well.  Meanwhile, along northern areas of
the I-25 Corridor, will see sct high based showers along with a
possible tstm by late aftn. DCAPE is around 1000 j/kg so brief
gusty outflow winds will occur with this activity as well. For
tonight, the upper level jet will move slowly across the plains
which may lead to an additional chc of higher based showers and a
few tstms thru the evening hours. As for highs today, readings
will rise into the upper 80`s to lower 90s over the plains.

On Thu, SW flow aloft will continue but it appears an even drier
airmass will be in place. Thus don`t expect any shower/tstm
activity. Temps will continue to warm with readings rising into
the lower to mid 90`s across nern CO.

By Fri, the flow aloft will become more SSW.  Some monsoon moisture
could get entrained into the flow.  At this point, still think any
shower/tstm activty in the aftn/evening will be widely sct. Once
again highs will reach the lower to mid 90`s over nern CO.

For the weekend, models still show an upper level trough over the
wrn US with an upper level high extending from the srn Rockies into
the central US.  As a result, this will leave SSW flow aloft across
the area as some monsoon moisture moves across the area.  It`s not
certain how deep this moisture will be initially.  Specific Humidity
is in the 5-6 g/kg range on Sat and then increases to 7-8 g/kg on
Sun. Thus, activity on Sat may be rather high based and more sct
as compared to Sun which may have better coverage. Meanwhile, it
still appears highs will remain above normal both days with more
90`s possible over nern CO.

By Labor Day, the upper level trough over the wrn US is fcst to move
northeast across the nrn Rockies.  As a result, this leaves nrn CO
in SW flow aloft.  Models continue to show monsoon moisture embedded
in the flow with specific humidity from 6-8 g/kg.  Thus will keep in
a good chc of showers/tstms.  Highs still look to remain above
normal across the plains.

For Tue and Wed, there are some disagreements between the ECMWF and
GFS.  The ECMWF has more of a zonal component developing as monsoon
moisture is shifted southward.  Meanwhile, the GFS keeps SW flow
aloft across the area with a continued influx of monsoon moisture.
Thus, the ECMWF would have drier conditions both days while the GFS
would have a chc of showers/tstms.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 523 AM MDT Wed Sep 2 2026

Will see sct hi based showers developing as early as 21z with a
10 percent of -tsra thru 01z. Have gone VCSH with a prob30 for
-tsra. With DCAPE around 1000 j/kg may see some brief gusts up to
 40 mph. After 01z, not sure how much additional shower activity
 there will be so have just gone with prob30 thru 04z.

As far as winds they were SW/SSW early this mornng but should go
more south by 14z. By 19z will switch them to more SE and then
more ESE by 21z. Will likely see a wind shift to the north between
00Z and 01z. By 04z winds will trend to more easterly and then
transition to drainage by 07z.



&&

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

&&

$$

DISCUSSION...RPK
AVIATION...RPK