253
FXUS65 KBOU 122035
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
235 PM MDT Sun Oct 12 2025

.KEY MESSAGES...

- Precipitation chances return late Monday across the mountains
  and plains.

- Above normal temperatures expected by mid-week.

- Precipitation chances return late Wednesday into Thursday
  across the mountains and plains.


&&

.DISCUSSION /Through Sunday/...
Issued at 232 PM MDT Sun Oct 12 2025

An upper level low will dive southward along the West Coast
through Monday night. This will allow for SW flow aloft across the
area.  Cross-sections show an increase in mid level moisture across
the area Mon thru Mon night. Weak disturbances embedded in the
flow will bring a chc of rain and snow showers to the higher
terrain with a chc of rain showers over the far nern plains mainly
late Mon aftn and night.

On Tue, an upper level low will move from central California into
wrn portions of the Great Basin by Tue night. As this occurs the
flow aloft will become more SSW. Cross-sections show limited
moisture across most of the area thru Tues night so dry conditions
are expected with seasonal temperatures.

From Wed thru Wed night, an elongated upper level trough will
gradually develop from the nrn Rockies into the Great Basin, as a
significant piece of energy moves northeast from the main upper
level low.  This will allow for mainly dry SSW flow aloft across the
area thru Wed aftn.  Temperatures will be above normal with gusty
south winds across the plains.

By late Wed night into Thu, the srn portion of the elongated upper
level trough will move across nrn CO.  This will allow for a better
chc of rain and snow showers across the higher terrain.  Over the
plains a cold front will move in by Thu morning bringing in cooler
temperatures.  QG fields show some ascent thru the aftn which may
allow for a chc of rain showers over the plains.

For Fri thru Sat, there are some differences between the ECMWF and
GFS. Sat The GFS has the upper level trough move east of the area
with dry conditions and seasonal temperatures.  Meanwhile, the ECMWF
has another piece of energy moving into the Great Basin Fri night
and then across the area on Sat.  As a result, this would bring a
chc of precipitation to the area along with cooler temperatures.  At
this time will go with the blended solution which is mainly dry with
seasonal temperatures.

&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1151 AM MDT Sun Oct 12 2025

VFR conditions expected through the TAF period. Gusty westerly
winds have finally set in across KDEN and KBJC late this morning.
With the gusty NW winds in place off the Cheyenne Ridge, an
anticyclonic wind pattern has developed across the plains which
is keeping KAPA winds light and northeasterly. Expecting gusty WNW
winds to persist at KBJC/KDEN through the afternoon before
gradually diminishing through the evening. Winds at KDEN are
expected to settle into the SSE for the overnight hours and
continuing through the TAF period, with increasing gusts beginning
around 14/15Z Monday morning.

There is low confidence in the winds at KAPA for this afternoon,
as there is potential for a shear zone to move across the field
keeping the northeasterly winds in place on its northern edge, and
bring WSW winds in on its southern edge. If the boundary stays to
the south, winds will likely stay northeasterly, but if it moves
more north, we can expect winds to become WSW. Have introduced a
TEMPO to account for this between 21-24Z. There is far more
agreement in guidance and higher confidence in winds past 0Z, with
an easterly turn expected before settling into the SSE for the
overnight through the rest of the TAF period.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM MDT Monday for COZ038-042-043.

&&

$$

DISCUSSION...63
AVIATION...999