617
FXUS65 KBOU 010617
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1117 PM MST Wed Dec 31 2025

.KEY MESSAGES...

- Warm and dry conditions will prevail for the plains and urban
  corridor through at least Monday.

- Light mountain snow returns Thursday, increasing on Friday.
  Heaviest snow will be in the Park Range, with 5-10" and locally
  higher totals expected.

- Expect breezy to windy conditions at times across the high
  country and foothills Friday through early next week, with
  occasional intrusions of gusty winds into the lower elevations.

&&

.DISCUSSION /Through Wednesday/...
Issued at 158 PM MST Wed Dec 31 2025

Our little taste of winter is in the rear view mirror already, with
60-degree readings making a return today in the plains and urban
corridor. At least for our mountains, the warm and dry pattern will
be interrupted Thursday into Friday as our upper-level ridge
flattens and allows for a couple of weak shortwaves to traverse the
state. Synoptic scale forcing still appears limited, and snow ratios
will be lower than average for this time of year given the mild
temperatures and notably weak lapse rates, especially Thursday (when
they could even fall close to 8:1). However, cross-barrier flow and
moisture availability will both be reasonably healthy, especially
for our northern mountain ranges closest to the axis of stronger
winds. Ensembles have shown a fairly consistent upward trend in QPF
Friday for the Park Range, where there`s increasing confidence in
accumulations of 5-10" above 9,000 ft, and locally around 1+ ft
across the higher peaks. Most of this should fall late Thursday
night through Friday, with snow showers being much lighter during
the day Thursday. Winter Weather Advisories have been posted for the
Park Range and northern Front Range mountains where snow will be
heaviest.

Amounts across the I-70 mountain corridor will be considerably lower
given their more shadowed positioning and the weaker orographics,
but a few inches of snow may still snarl traffic over the passes
during this period. Additionally, snowfall accumulations for the
mountain valleys will be quite limited, given it`s primarily an
orographic snow event and snow levels may even be above some valley
floors at times, especially early on.

Meanwhile, much of this elevated moisture will spill over into the
lower elevations Thursday afternoon and night, and may be just
enough to squeeze out some virga and isolated light rain showers for
the urban corridor and Cheyenne Ridge - no more than a few
hundredths at most, and only locally. We`ll be a few degrees cooler,
mainly a result of increased cloud cover, but still with a shot at
breaking 60F. The mild conditions will also transfer into the
overnight periods, with lows expected to remain above freezing the
next several nights near the base of the foothills under persistent
but modest downslope flow. Winds will turn gustier late week,
particularly Friday behind the second shortwave, with gusts 45-60
mph for the higher elevations, and 30-40 mph in our northeast plains
Friday afternoon.

Warmer and drier conditions will dominate the picture over the
weekend as a ridge of high pressure moves east into Colorado. With
subsident flow in place, highs look to peak Sunday, when we may
flirt with daily record highs in spots if the warmer scenarios come
to fruition. Increased southwest flow aloft will also favor
development of breezier conditions into early next week, along with
a return of winter weather potential as early as Monday to our high
country.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1116 PM MST Wed Dec 31 2025

Models have normal drainage winds progged until mid morning and
speeds will be fairly light. Normal diurnal pattens are expected
to continue the rest of the day. Satellite pictures and cross
sections indicate that skies will be BKN-OVC through this evening.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory from 11 AM Thursday to 5 PM MST Friday
for COZ031.

Winter Weather Advisory from midnight Thursday night to 5 PM MST
Friday for COZ033.

&&

$$

DISCUSSION...BRQ
AVIATION...66