439
FXUS65 KBOU 060021
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
621 PM MDT Sun Oct 5 2025

.KEY MESSAGES...

- Front Range mountain and higher foothills snow tonight, with a
  few inches accumulation expected (80-90% chance).

- Rain showers in the lower foothills and I-25 Corridor, areas of
  drizzle or light rain eastern plains.

- Chilly through Monday and Monday night.

- Above normal temperatures return for mid/late week.

&&

.DISCUSSION /Through Sunday/...
Issued at 248 PM MDT Sun Oct 5 2025

Satellite shows clouds increasing along the Front Range in the
upsloping post-frontal airmass this afternoon. A few showers were
developing in the higher terrain, about as scheduled. KFTG 88D
Vad wind profiler now shows upslope has deepened to 10,000 ft MSL,
and there should be at least a little further deepening this
evening. However, speeds will remain relatively weak at 10-15 kts.
While moisture is relatively limited, there is weak QG lift and
continued upslope to overcome that. Thus, we do expect precipitation
to become more widespread during the evening hours with these
features in place. However, given the moisture limitations we
think this will remain an upslope focused event favoring the Front
Range north of I-70 (drier south). Finally, it should be noted
the right entrance region of a passing jet max and also some weak
frontogenesis could result in a couple of heavier bands, and
models seem intent in focusing on this from western Boulder County
into the Mummy Range - where higher elevations are expected to
see several inches of snow. Snow levels will be lowering with
further cool advection. The northern Front Range Foothills around
Red Feather Lakes should see snow levels drop to 8,000 feet later
this evening, but only to around 9,000 feet farther south toward
the I-70 Corridor. Thus, most impacts will be to the higher passes
including Cameron Pass and Trail Ridge Road in RMNP (the latter
already pre-emptively closed). Also, couldn`t rule out some
slushy roads along higher elevations of the Peak to Peak Highway.

Precipitation intensity is expected to decrease overnight as the
upslope component weakens, but a weak and shallow upslope
environment means we`ll likely see areas of light drizzle linger
into Monday morning. Low clouds and weak upslope will stick around
for the day, resulting in chilly conditions with high temperatures
only reaching the lower to mid 50s on the plains, and a few spots
may see temps not even hitting 50F!

We`ll have another chance of showers redeveloping Monday
afternoon, but overall the forcing seems weaker than tonight.
There is a hint of a jet streak but frontogenesis seems limited.
That said, a few models were showing another banded precipitation
even sneaking out of the foothills and across Denver metro for the
evening hours. We have increased PoPs a bit for this.

The low clouds are likely (70-80% chance) to hold in Monday
night, limiting and frost or Frost Advisory potential. Then slight
warming should occur Tuesday, before a stronger warming trend
still occurs for Wednesday through the end of the week. Overall,
temperatures will be several degrees above normal Wednesday
through next weekend. Chances of precipitation will hold off until
the end of the week (Friday and beyond), and even then most
chances would be confined to the mountains as we`ll be under the
influence of ridging and southwest flow aloft. The confidence of
this decreases toward Sunday as ensembles differ on speed of the
next weather disturbance.

&&

.AVIATION /00Z TAFS through 00Z Tuesday/...
Issued at 618 PM MDT Sun Oct 5 2025

Decent east-northeasterly winds continue at DIA early this
evening, with the models continuing this trend through the
evening. None of models show any hint of normal drainage winds
overnight, keeping the easterly flow going through sunrise, albeit
at speeds under 12 knots. Models also continue to show easterly
winds through most of the day Monday.

Area radars and observations are indicating, light rain showers
over the Greater Denver area and all the Front Range, including
the big airport at this time.  Most models keep the light rain
going through about 06Z later tonight. For ceilings, will go with
BKN-OVC015-030 from 01Z or 02Z this evening, through the
overnight hours well into Monday morning.

&&

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

&&

$$

DISCUSSION...Barjenbruch
AVIATION.....rjk