831 
FXUS65 KBOU 081111
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
511 AM MDT Tue Sep 8 2026

.KEY MESSAGES...

- Slightly cooler today with a chance of thunderstorms mainly over
  the Palmer Divide and southeast plains. A few strong storms 
  possible with gusty winds, hail and locally heavy rainfall.

- Mainly dry Wednesday through Friday with warmer temperatures for
  Thursday and Friday.

- Return to more unsettled pattern and cooler weather favored for
  next weekend with a chance of thunderstorms mainly on Sunday.

&&

.DISCUSSION /Through Monday/...
Issued at 239 AM MDT Tue Sep 8 2026

The flow aloft will become more WSW today as best monsoon 
moisture shifts mainly across srn portions of the area. Meanwhile,
a secondary surge of drier air in the lower levels will move 
across the plains. By aftn, MLCAPE will range between 500-800 j/kg
and be confined to the srn foothills, Palmer Divide and over sern
portions of the CWA. With decent shear in place, can't rule out a
few stronger storms in this area by late aftn thru the early 
evening hours. PW values will still be around 150 percent of 
normal, in the same general area, so may see locally heavy 
rainfall as well. Over the rest of the area, shower and tstms will
be more isolated in coverage. Highs today will drop back into the
mid to upper 80's across the plains.

For Wed, drier in westerly flow aloft will be over the area as a 
cold front move across.  As a result, expect dry conditions with 
cooler temps as highs finally drop back to more seasonal levels.
By Wed night, low level southeast flow will develop which will lead 
to some return of moisture across the plains.  Meanwhile, a weak 
disturbance embedded in WNW flow aloft may bring some nocturnal 
tstms to portions of the sern plains overnight.  Current data, keeps 
most of this activity over sern CO with srn Lincoln county being on 
the nrn fringe. For now, have kept in chc pops mainly across srn 
portions of Lincoln county.

On Thu, the flow aloft will remain WNW as southerly level flow is 
across the plains.  MLCAPE will rise up to 1000 j/kg over portions 
of the plains by aftn.  For now, chances for tstms look on the low 
side as I can't find a focus for activity, however, that doesn't 
mean there couldn't be an isold storm or two across the plains by 
late aftn. Meanwhile, temps will begin to warm as readings reach 
the upper 80's to lower 90's over nern CO.

Looking ahead to 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 a slight chc of higher based 
showers/tstms over the higer terrain.  Across the plains, MLCAPE is 
rather minimal so chances of precip look low.

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. 
Once again MLCAPE is rather minimal and confined to the higher 
terrain.  Thus will keep in a slight chc for showers/tstms 
mainly across the mtns.

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 southerly low level flow across 
the plains.  MLCAPE is fcst to increase to around 1000 j/kg over the 
plains east of a pseudo dryline.  Thus may see a few stronger storms 
by late aftn thru the evening hours.  Highs on Sun, will likely rise 
back to above normal levels.

Looking ahead to Mon, rather dry WSW flow aloft will be over the 
areas a cool front affects the plains.  Latest data, doesn't show 
much low level moisture behind the front so it may end up dry with 
temps dropping back to seasonal normals.

&&

.AVIATION /12Z TAFS through 12Z Wednesday/...
Issued at 506 AM MDT Tue Sep 8 2026

Light and variable winds early this morning wil become NE by 16z
and then more easterly by 19z.  By 21z, expect a more ESE wind.
There is still a 20-30 percent chance of tstms in the 21z to 01z
time period. However, the best chc of storms will stay south of
BJC and DIA and will likely impact APA. Thus have kept prob30 at 
both BJC and DIA with a tempo at APA. By 01z the threat of storms
will end with winds becoming SE. By 04z winds will have a more 
southerly direction. Late tonight, a cold front will move across 
between 09z and 10z with winds shifting to the north.

&&

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

&&

$$

DISCUSSION...RPK
AVIATION...RPK