953
FXUS65 KBOU 190750
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
150 AM MDT Wed Aug 19 2026

.KEY MESSAGES...

- Isolated storms again for Wednesday, though chances of stronger
  storms shift to the south.

- Warming and drying trend to end the week, before monsoon
  moisture attempts to return Sunday into early next week.

&&

.DISCUSSION /Through Tuesday/...
Issued at 140 AM MDT Wed Aug 19 2026

As of 1:30AM, storms are moving through our southeastern
counties. The last of our discreet supercells, which likely
produced some large hail tonight, are moving east out of Lincoln
County. Behind these storms, we have a line of weaker storms that
have developed along what I assume is an outflow boundary. The
southern portion of Elbert County and middle/northern portion of
Lincoln county have been worked over by the round of storms prior
to this line, but as the boundary continues to progress southeast
into southern Lincoln county, the storms could start to tap into
some better instability. We do have an isolated storm going up in
southern lincoln currently (1:30AM) and it`s staying below severe
thresholds, so hopefully the line will follow suit and strengthen
slightly, but remain sub severe as it moves southeast. Given the
current storm motion, the line of storms should move out of our
forecast area around 3:30AM.

Near normal temperates are expected this afternoon, with highs in
the mid 80s to around 90 degrees across the plains. Flow aloft will
turn more to the northwest as upper level ridging builds over the
four corners region. There will be a weak shortwave that moves
through the flow aloft, but models are showing it to the south of our
area, giving PUBs forecast area the higher rain coverage for this
afternoon. Some weak upslope from the easterly surface winds could be
enough to trigger some isolated to scattered activity near the higher
terrain, but coverage will be best in Park county and the Palmer
Divide area for our CWA. Shear will be strong once again today,
but MLCAPEs will generally remain less than 800 J/kg this
afternoon, limiting our severe threat. With that being said,
DCAPEs could be in excess of 1000 J/kg today, so we could still an
isolated strong wind threat.

The ridge will continue to build Thursday and Friday, increasing
temperatures to above normal. Highs are forecast to peak on
Friday, with temperatures in the plains getting into the mid to
upper 90s. PWs in the high country are forecast to stay around
100% to 140% of normal during this time frame. So, we could still
see some isolated activity Thursday and Friday afternoon, but
coverage will likely stay confined to the higher terrain.

The upper level ridging will start to push east on Saturday, turning
winds aloft to the southwest. At the surface a weak boundary will
move through, turning winds more easterly for Saturday. Because of
these two things, we`ll see an influx of moisture for Saturday
into Sunday, bringing PWs back into the 130% to 200% range for our
CWA. Temperatures will lower slightly for the weekend, but remain
above normal through the start of next week. Starting Saturday,
models start to diverge on the eastward extent of rain chances.
Moisture will be present, so it really just depends on the timing
of potential lifting mechanisms (disturbances
aloft/upslope/boundaries/etc). Right now, ensemble members are
pretty all over the place for next week, with around 30-40% of
members showing measurable rain making it out of the higher
terrain and onto the plains each afternoon.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 1154 PM MDT Tue Aug 18 2026

There are some isolated to scattered showers and thunderstorms
near or over our 3 TAF sites as of midnight. Coverage of
thunderstorms is higher off to the east. Isolated storms will
exist near KDEN and KAPA for the next hour or two, with lower
chances for storms near KBJC. The main question we have going into
the overnight hours, is if the showers over the higher terrain is
going to survive and push off into the plains, impacting the
airports. Right now, we`re not expecting the showers to make it
to the TAF sites, but if the showers continue to strengthen and
look like they`re going to push off the foothills, there could be
an hour or two of rain as that moves east over the area. The most
likely timing for that activity would be around 07Z-09Z for KBJC
and 08Z to 10Z for KDEN and KAPA.

After the showers and thunderstorms move through, winds should
generally be from the south/southwest. In the mid morning, winds
will turn more westerly, then northerly, before eventually
becoming northeasterly around 17Z to 18Z. Chances for showers and
thunderstorms will be lower tomorrow, with the highest chances at
KAPA around 21Z to 01Z. Coverage will likely be lower than this
evenings convection. Starting around 03Z, breezy SE winds are
forecast to move into KDEN and KAPA, with gusts around 20 to 25
mph. Winds should start to decrease around 06Z and turn more
southerly.

&&

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

&&

$$

DISCUSSION...AP
AVIATION...AP

NWS BOU Office Area Forecast Discussion