Thornton, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

882
FXUS65 KBOU 232058
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
158 PM MST Tue Dec 23 2025

.KEY MESSAGES...

- Warm and dry through Friday, with the mountains seeing breezy
  conditions and a slight chance (20-40%) of light snow and
  rain/snow showers Thursday into Friday.

- Increased fire danger Friday for the foothills and portions o
  the urban corridor, although humidity levels remain uncertain.

- Light mountain snow expected Saturday, favoring the Park Range.

- Cooler starting Saturday, with slim potential for precipitation
  for the lower elevations.

&&

.DISCUSSION /Through Tuesday/...
Issued at 1259 PM MST Tue Dec 23 2025

Another warm afternoon today, though with a relatively pronounced
north/south gradient over the urban corridor thanks to Denver
cyclone-induced northerly flow keeping temperatures cooler to the
north of the Denver metro. Will be much of the same story
tomorrow, with highs 20-25 degrees above normal and continued dry
conditions. Denver will flirt with its record daily high again
(both forecast and record are 70F). The mountains will see slight
cooling with greater cloud cover, but nonetheless will be mild.

The ridge will remain anchored in place over the central plains on
Christmas Day, and enhanced downslope flow will make for another
likely record-breaking warm day with little change in
temperatures. Marginally stronger flow aloft will provide for
breezy conditions in our high country, but these won`t spread into
lower elevations. Guidance has been consistently delaying the
arrival of deeper moisture into the mountains, reducing the chance
of any late-day showers to under 20% outside of the Park Range for
Christmas. In fact, mountain snow potential isn`t overly
impressive for Friday either, with a corridor of dry air at mid-
levels oscillating over Colorado with some discrepancy as far as
its exact positioning. With high country winds expected to peak
Friday and producing leeside gusts 40-60 mph, there`s potential
for near-critical fire weather conditions if the drier air
surfaces in the afternoon. For the lower elevations, temperatures
will relax slightly on Friday, but we`ll still warm into the
60`s.

Models still suggest the upper-level low off the NorCal coast
will push onshore Friday night, this favoring a period of
increased moisture advection into the high country through
Saturday as the trough approaches. The moisture plume does look to
fizzle out slightly as it pushes southeast, lending greater
confidence to a few inches of snow accumulation for the Park
Range, and lower confidence elsewhere. Both GEFS and EC ensemble
suites show quite similar QPF distributions, with a probability of
exceeding 0.10" in 24 hrs of around 90% for the Park range,
lowering to around 50% for the I-70 corridor. Those numbers drop
to around 20% and 5% respectively when assessing probabilities of
exceeding 0.50". All in all, not all that promising with respect
to making more than a minor dent in our trailing snowpack
conditions, however we may see some slick travel conditions for
mountain passes.

Meanwhile, the lower elevations will see a considerable cooldown
Saturday with the passage of a cold front, with the cooler air
being reinforced for Sunday when highs are expected to be near or
even slightly below (yes, below!) normal. Chances for
precipitation east of the mountains late Saturday into Sunday
morning remain slim, with the bulk of guidance keeping a shortwave
too far to our north, but there`s enough potential with the
frontal push to sustain about 20% PoPs for the urban corridor,
foothills and the Palmer Divide.

Milder and dry conditions are favored as we enter into early next
week.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1042 AM MST Tue Dec 23 2025

Models point to weak normal diurnal wind patterns for DIA this
afternoon and tonight.  Weak northeasterlies later this
afternoon, then a return to normal drainage winds by mid evening.
There will be no ceiling issues.

&&

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

&&

$$

DISCUSSION...BRQ
AVIATION.....66