Castle Rock, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

416
FXUS65 KBOU 220553
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1053 PM MST Sat Dec 21 2024

.KEY MESSAGES...

- Warm and dry today and Sunday.

- Periods of light snow in the mountains Monday, Wednesday, and
  Friday with some travel impacts.

- Slight chance of rain or snow showers at lower elevations on
  Christmas afternoon and evening with minimal impacts.

&&

.UPDATE...
Issued at 810 PM MST Sat Dec 21 2024

Some fine-tuning of winds and temperatures performed this evening,
with a primary focus on the narrow corridor along the lower
foothills and immediately adjacent plains. The latest forecast
soundings are more consistent in depicting robust formation of a
thermal belt below 700mb where there should be some resultant
downslope wind enhancement leading to gusts of 35-45 mph in spots
between midnight and sunrise. As discussed below, this will make
for notably mild conditions in these locations overnight, so have
nudged lows up a couple of degrees.

&&

.SHORT TERM /Through Sunday/...
Issued at 153 PM MST Sat Dec 21 2024

Current observations show widespread 60s across the plains this
afternoon. The record high of 67 hasn`t been reached, but 65 is
still an impressive temperature for this being the Winter
Solstice. Satellite imagery shows clear skies across the forecast
area with the exception of a mountain wave cloud situated over
western Boulder County.

For tonight, a shortwave trough passing across the northern Rockies
will help flatten the upper-level ridge in place over the western
US. With a jet max moving into our north, WNW flow aloft is expected
to increase overnight, bringing increased winds to our highest
mountain elevations and higher foothills of the Front Range
Mountains. Wind gusts up to 50 mph will be possible until early
tomorrow morning. Downsloping winds will keep temperatures mild for
locations in the lower foothills, keeping them in the 40s overnight.
The plains will see the 20s to 30s, and the mountain valleys will be
in the single digits to teens.

WNW flow aloft will continue into Sunday as the shortwave exits the
Rockies. Cross sections show increasing moisture through the
afternoon beginning in the mountains and spilling over the plains in
the evening. Moisture is still expected to be minimal, however,
there should be enough for some light orographic snow flurries to
develop over the northern mountains in the afternoon. But mostly we
will just see increased cloudiness throughout the day across the
forecast area. Winds are expected to mix down along the Wyoming
border leading to breezy conditions through the afternoon. High
temperatures will be similar to today`s with parts of the plains
reaching the mid 60s once again.

&&

.LONG TERM /Sunday night through Saturday/...
Issued at 153 PM MST Sat Dec 21 2024

There will be a progressive wave pattern during the long term
period with troughs moving through our forecast area roughly every
other day. While there will be plenty of troughs that come
through, they will all be rather weak and the plains may struggle
to see much in the way of precipitation.

The first trough in the long term period that will move through
will be later in the day on Monday. This trough will be so weak
that there will not be much of a surface low pressure system
associated with it and temperatures may only come down a couple of
degrees from Sunday. There will be some mid to upper level
moisture that will arrive in the mountains and with the help of
upslope flow and weak PVA, snow is expected on the western slopes.
Models keep the snow amounts rather light with the Park Range
seeing the highest totals of 3-7". The Medicine Bow mountains will
see 1-5" with lower amounts in the I-70 mountain corridor. The
main travel impacts from this snow will be confined mostly to
Rabbit Ears and Cameron Pass.

Tuesday will by dry as a ridge moves overhead. Highs will be well
above normal on the plains with mid to upper 50s expected.

The trough that arrives in the area on Christmas day initially
looks intriguing aloft. A closed low at 500 mb will position
itself over the Four Corners before heading into southeast
Colorado. That is usually a setup that can produce bigger
snowstorms in our area. However, this system lacks a push of cold,
arctic air, so it will struggle to deepen the surface low pressure
system as the temperature gradient will remain rather weak.
Nonetheless, this will bring a healthy shot of snow to the
mountains which may see moderate snow amounts and travel impacts.
As the low wraps up on Christmas evening, a band of mixed
precipitation may develop over the plains. With relatively warm
surface temperatures across the plains, the travel impacts should
be limited from this system as the precipitation may fall as rain
or, if snow does fall, the warm road temperatures could melt some
of it.

Another trough will come from the Pacific Northwest on Friday.
This will primarily bring snow the northwestern slopes in the
mountains. A persistent northwesterly flow aloft may keep the snow
going in the mountains into next weekend. This type of system
favors snow in Steamboat Springs and Winter Park while other areas
in the central mountains see less. The plains will likely remain
dry Thursday through the following weekend with above normal
temperatures. There is a sign in the ensembles that colder air
will arrive around New Year`s Eve.

&&

.AVIATION /06Z TAFS through 06Z Monday/...
Issued at 1051 PM MST Sat Dec 21 2024

Normal drainage winds are in place at DIA currently and they will
continue well into mid morning. Models are showing weak westerly.
then northwesterly winds late this morning and afternoon, with
more drainage winds expected by a couple hours after sunset this
evening. There will be no ceiling issues.

&&

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

&&

$$

UPDATE.......Rodriguez
SHORT TERM...Bonner
LONG TERM....Danielson
AVIATION.....RJK