586
FXUS65 KBOU 081848
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1248 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 today 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 /18Z TAFS through 18Z Sunday/...
Issued at 1140 AM 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.
GOES-19 satellite imagery shows clouds and smoke starting to
increase at this hour. Winds have been slow to turn to the
northwest/north this afternoon given a small inversion that was
still present on ACARS soundings, but they have started to turn in
the last 30 minutes or so.

For this afternoon starting as early as 19z, virga showers are
possible causing at least 40 kt wind gusts and briefly lowering
ceilings to 12,000 ft AGL. A PROB30 is in place. The latest CAMs
continue to hint at a low (10-20%) chance of wind gusts even
briefly exceeding 45 kts. By 1 or 2z, virga showers will greatly
decrease with winds turning to drainage overnight.

Tomorrow will be a similar story with winds turning to the
north/northeast by the early afternoon and virga showers possible
at all three terminals starting around 20z 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.
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