377
FXUS65 KBOU 081134
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
534 AM MDT Wed Oct 8 2025

.KEY MESSAGES...

- Patchy dense fog possible this morning, mainly across Weld
  county.

- Above normal temperatures return today and continue through
  Saturday.

- Less confidence in the pattern by the end of the weekend into
  early next week.

&&

.UPDATE...
Issued at 313 AM MDT Wed Oct 8 2025

Should be a mild and mostly sunny day across the forecast area.
Only change was to add some fog into the grids this morning.
While the setup is not perfect, some short term guidance insists
on fog developing across Weld county before sunrise, continuing
through the mid morning hours. BUFKIT profiles from the HRRR/RAP
would also support a period of fog, perhaps even drifting into the
northern/northeastern Denver metro. Satellite is quiet so far...
but will need to watch that through the AM hours.

&&

.DISCUSSION /Through Tuesday/...
Issued at 306 PM MDT Tue Oct 7 2025

This morning`s stratus deck has lifted into a higher stratocumulus
deck with drying being offset by convection driven by the heating
of the day. The drying is starting to wind as we`re seeing some
decrease in coverage south of Denver and near the eastern border.
This trend will continue, but we probably won`t see a big decrease
in the cloud cover until the heating turns off with sunset. With
the cool dry air, temperatures should drop a bit more than we had
forecast in the mountain valleys. There could be some patchy fog
in the coldest spots on the plains, but we expect the stratus to
persist over the southern fringe of our area where there is more
moisture, and further north probably enough drying to prevent
widespread fog development.

Wednesday will be warmer with drier air mixing down across most of
the area and southwest flow aloft increasing. We`ll approach
critical fire weather conditions over the mountains for a few
hours. For Thursday into Friday, an upper ridge will move from the
Rockies onto the plains. High clouds will spread over the area
from southwest to northeast on Thursday, with increased humidities
over the mountains, but not much chance of rain yet. On Friday and
Saturday, moisture will continue to increase although the cloud
cover will limit the amount of instability. Scattered showers and
a few thunderstorms can be expected over the mountains, but
rainfall should generally be light. The plains will have the
clouds, but still little or no rain.

On Sunday, a shortwave should pass north of Colorado, with the
tail end enough to provide a better chance of showers for the
plains. It still doesn`t look like much though. There should also
be a front to drop temperatures on the plains 10 degrees or so.

There are discrepancies in the structure of the upstream trough
after that. There`s probably some initial drying behind the Sunday
shortwave, for less or no shower activity. We could have another
shortwave Tuesday, or just increasing southwest flow aloft. NBM
holding lower elevation temperatures in the 70s with only slight
chance PoPs looks good.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 528 AM MDT Wed Oct 8 2025

Satellite shows an area of fog developing across southwestern Weld
county, a little northeast of EIK. While overnight HRRR runs have
been far too bullish with the fog development so far, the shallow
surface moisture underneath a strong inversion would promote at
least some fog potential, especially if drainage winds weaken or
if there`s a wind shift out to the N/NW at DEN. Did introduce a
TEMPO for some modestly reduced visibility, but at this point
still think any dense fog stays off to the northwest of DEN. Any
fog should burn off as the inversion breaks later this morning...
close to 15-16z. Quieter conditions are expected at BJC/APA this
morning.

VFR conditions are expected to prevail through the rest of the TAF
period with a typical diurnal wind pattern with light speeds
(<10kt).


&&

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

&&

$$

UPDATE...Hiris
DISCUSSION...Gimmestad
AVIATION...Hiris