454
FXUS65 KBOU 082330
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
530 PM MDT Sat Aug 8 2026

.KEY MESSAGES...

- Hot this weekend with highs reaching 95 to 105 across northeast
  Colorado. A Heat Advisory is in effect for the northern I-25
  Corridor and Denver metro from 11 AM today to 8 PM Sunday.

- Virga showers possible through early evening across the high
  terrain and plains, with strong outflow winds. Another round of
  virga showers expected Sunday.

- Elevated to locally critical fire weather conditions possible
  across the mountains and high valleys through the weekend.

- Precipitation chances increase and temperatures decrease mid to
  late next week.

&&

.DISCUSSION /Through Saturday/...
Issued at 1243 PM MDT Sat Aug 8 2026

Main concern this weekend will be the heat, as an upper level ridge
of the Desert southwest continues to bring hot temperatures today
and Sunday. Current surface observations already show temperatures
ranging from upper-80s to upper-90s across the plains. With us
reaching 90s before noon today, it looks like we will be on track
for temperatures to reach the upper 90s to low 100s by this
afternoon. The only caveats would be incoming smoke or outflows from
virga showers keeping us just shy of forecasted highs. However, even
if we are a few degrees shy, we will still be reaching Heat Advisory
criteria, and thus will keep it going today. Overnight lows will
be exceptionally warm, with guidance indicating some areas not
reaching below 80 dg until 10/11 PM.

Current satellite imagery shows cumulus developing over the high
terrain and Palmer Divide area, with a few virga showers already
popping up. Expect this to continue into the late afternoon/early
evening across the high terrain and the plains. Given the dry air
mass in place in the lower levels, most precipitation should not
reach the ground. However, a few of the stronger storms could wet
the ground. ACARS profiles show an inverted-V sounding, with DCAPE
values reaching up to 1500-1800 J/kg, so gusty outflows are expected
with these virga showers. Most gusts should be up to 45-50 mph, but
can`t rule out an isolated severe gust.

Elevated fire weather conditions will continue this afternoon for
the high terrain, where relative humidity values have already
dropped to below 20% and winds gusting up to 20 mph so far. Guidance
still indicates the potential for westerly winds gusting up to 25-30
mph, particularly for the northern mountains and North Park.
However, these stronger winds should be short in duration.

Sunday will see temperatures a degree or two cooler from Saturday,
but it will still feel very hot with highs around 98-99 in Denver
and low 100s for most of the eastern plains. The Heat Advisory will
continue into the evening. It looks like we are on track to tie or
break the maximum temperature record for August 9 (98 dg set in
2021), however another round of smoke and/or virga showers could
keep us shy of those temperatures. Modeled Skew-T soundings still
indicate an inverted-V sounding, so don`t expect much, if any,
precipitation to reach the ground. However, with the increase in mid-
level moisture, do expect these virga showers to be a bit more
widespread than Saturday. With any of these storms, strong outflow
winds will be the main concern.

Temperatures in the mid/upper 90s still likely Monday and through
midweek, with daily chances of scattered afternoon virga
showers/thunderstorms. Best precipitation chances will be for the
high terrain, but still can`t rule out a few showers spilling onto
the plains. This slow increase in moisture through the week could
produce localized heavy rainfall in the mountains with the strongest
storms. WPC does have a Marginal Risk for excessive rainfall each
day for this reason.

it is not until the later half of the week that we could see a
significant difference in temperatures and widespread precipitation
chances. Ensemble guidance is honing in on the breakdown of the
upper level ridge by Wednesday/Thursday, where southwest flow aloft
will bring in better monsoonal moisture. Precipitable water
values will soar to ~150% of normal, which will promote more
widespread showers and thunderstorms, with beneficial rainfall
across the region. That does not mean every location will see this
though. Due to this, the threat of excessive rainfall will also
increase, but it is too soon to know exactly where the biggest
threat will be. In terms of temperatures, NBM continues to be a
tad cooler than global ensemble output. However, there is a large
spread of temperatures between the individual solutions of the
GEFS and ECMWF, so will continue to monitor.

&&

.AVIATION /00Z TAFS through 00Z Monday/...
Issued at 525 PM MDT Sat Aug 8 2026

Smoke will continue to affect all three terminals throughout the
TAF period and beyond with slantwise visibility issues at times.
KFTG and TDEN have shown several microbursts this afternoon near
all three terminals causing briefly strong and erratic winds at
all three terminals. A PROB30 remains in place through 2z this
evening for the possibility of virga showers causing at least 40
kt wind gusts and briefly lowering ceilings to 12,000 ft AGL.

Current radar shows an outflow boundary just north of KDEN as well
as several microbursts occurring just northwest and southwest of
KDEN. If the outflow boundary pushes through, there could be a one
to two hour period of a northerly component to the winds. If the
boundary does not make it through, we expect more of a southerly
component to the winds for the next few hours. By about 2z to 4z,
drainage winds should kick in.

Tomorrow will be a similar story as this afternoon with winds
turning to the north/northeast by the early afternoon and virga
showers possible at all three terminals starting as early as 19z and
lasting through the afternoon. Soundings show more moisture for
tomorrow afternoon compared to today, so have gone ahead with a
TEMPO for the possibility of 40 kt wind gusts and briefly lowering
ceilings. A PROB30 is now in place early tomorrow evening for the
continued chances for virga showers to occur. Given the dry
airmass at the lower levels, little to no rainfall is expected
once again.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM MDT Sunday for COZ038>040.

&&

$$

DISCUSSION...MAI
AVIATION...MV

NWS BOU Office Area Forecast Discussion