570
FXUS65 KBOU 161146
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
546 AM MDT Sun Aug 16 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms expected this afternoon and
  evening. A few of them could become strong to severe, with
  strong winds, large hail, and heavy rainfall.

- Warming and drying trend for Monday and Tuesday.

&&

.DISCUSSION /Through Saturday/...
Issued at 136 AM MDT Sun Aug 16 2026

As of 1:30AM, we`re starting to see some patchy fog develop over
portions of Larimer and Weld counties, with areas of Laramie
county just to our north down to 1/4 mile visibility. Fog is
expected to develop further south in the next few hours,
potentially impacting the urban corridor, portions of I-25, I-70
and I-76. Visibilities down to 1/4 mile are expected for isolated
areas. A Dense Fog Advisory may be needed if the coverage of the
1/4 mile visibilities are great enough. The most likely timing of
fog near the urban corridor will be between 4AM and 8AM.

The upper level high, that was to our southeast, will start to move
west today. This will put us in more zonal flow aloft, which will
begin our drying trend. Precipitable water values today will
decrease, but will remain around 100% to 125% of normal. A weak
disturbance will move through the flow aloft to our south, providing
the best lift around the Palmer Divide and south. Surface winds will
be more from the southeast today. The SE surface winds will allow
for some weak upslope for our northern counties near the Cheyenne
Ridge. With the slightly lower PWs and less widespread lift,
showers and storms are expected to be lower in coverage today
compared to the past few days. Scattered showers and
thunderstorms will likely form around the Cheyenne ridge and
Palmer Divide areas today, moving east/southeast through the
afternoon and evening. The flash flooding threat will be lower
today, due to the decrease in PWs, decrease in coverage, and
increase in storm motions. However, with all the rain we`ve seen
lately there could still be some localized flooding concerns due
to the more saturated soils and lower flash flood guidance. We do
have a slight risk for severe weather again this afternoon. Low
level lapse rates will be steep today and 0-6km shear will be
sufficient for strong to severe storms to develop (~30 to 35
kts). But there is a potential bust factor with the severe
weather threat, due to the possibility of morning fog and low
clouds sticking around longer than expected and impacting
instability. Stronger storms will have the capability of
producing large hail, strong winds, and heavy rainfall.

A warming and drying trend is forecast for Monday and Tuesday. Upper
level ridging will start to build to our west as the upper level
high shifts more towards the four corners region. Temperatures on
Monday will warm closer to normal with much lower rain chances. On
Tuesday, models are still a bit up in the air, but a few of them are
hinting at a weak cold front Tuesday afternoon and evening moving
in from the north. The timing of this front will impact highs in
our northern plains counties for Tuesday and our precip chances
for Tuesday. We`ll see a brief cooling in the temperatures on
Wednesday behind that front, and an increase in rain chances as we
see increased moisture behind the front and maybe some surface
convergence from the stalled boundary. But then upper level
ridging really starts to build just to the west of our area for
Thursday and Friday, before shifting east over our area for the
weekend. Highs are forecast to sit in the mid 80s to mid 90s for
the plains for the end of next week.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 535 AM MDT Sun Aug 16 2026

Patchy fog is present this morning across the plains. The densest
fog and lowest visiblities are around KDEN, where visibilities
are currently at 1/2 mile. Elsewhere, visibilities are generally
around 3mi to 7mi. Fog and low clouds are expected to stick around
until roughly 14Z. Winds will once again be mostly light and
variable today, with a general northerly component this morning
and SW to SE component this afternoon. Coverage of showers and
storms this afternoon still looks to be on the lower end near the
TAF sites, with higher coverage to the north and south. So, we`ve
left the Prob30 for this afternoon and evening for now. But, we
could see some stronger winds and wind shifts from outflow
boundaries from nearby convection later today. Tonight, winds
should be light drainage winds or light and variable. Ceilings and
visibilities should be clearer tonight.

&&

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

&&

$$

DISCUSSION...AP
AVIATION...AP

NWS BOU Office Area Forecast Discussion