760
FXUS65 KBOU 181141
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
541 AM MDT Fri Oct 18 2024

.KEY MESSAGES...

- Much cooler temperatures today and Saturday.

- Likely to widespread precipitation this evening into Saturday
  morning, with snow in the mountains.

- Scattered to likely precipitation Saturday afternoon into
  Sunday...with snow in the mountains.

- A few inches of snow expected in most of the mountains, with
  heavier totals south of I-70.

- Dry and warmer for all the forecast area Monday through
  Thursday.

&&

.SHORT TERM /Through Tonight/...
Issued at 350 AM MDT Fri Oct 18 2024

Currently, radar shows light 20-30 dBZ showers for parts of the high
country this morning. Additionally, a few METARs show winds shifting
north as the cold front enters northeastern Colorado. A cooler
airmass should bring much lower temperatures compared to yesterday.
Breaks in partly cloudy skies for the plains will allow some daytime
heating where afternoon highs between 53-66F are possible across the
plains. Mountains and valleys drop to 38-55 this afternoon. As the
upper level trough digs deeper into western portions of Colorado, a
plume of mid-level moisture will lead to scattered to numerous
showers over northeastern Colorado starting late afternoon. Weak
instability exist in the foothills and plains thus an isolated
thunderstorm or two could occur late afternoon hours through early
evening but majority of areas should receive rainfall this
evening. Temperatures should drop quickly where a few mountain
areas transition to snow. This update includes a slight decrease
to NBM QPF values in the mountains leading to an overall decrease
in snowfall amounts due to a delay in showers this morning.
Snowfall totals through tonight should remain 1-3 inches for areas
above 9 thousand feet. Also NBM QPF falls in agreement with
models for areas east of the Divide could receive 0.10-0.40 inches
of rainfall overnight with highest totals along the Palmer Divide
and Lincoln county. The upper low will stall in the Four Corners
providing consistent moisture and weak synoptic forcing which
keeps showers mainly south and along I-70 after midnight tonight.

&&

.LONG TERM /Saturday through Thursday/...
Issued at 350 AM MDT Fri Oct 18 2024

The stationary upper-level low positioned over Arizona is
expected to remain in place through Saturday. As daytime heating
progresses throughout the morning, snow showers over the southwest
Front Range Mountains, and Mosquito Range are expected to
transition to rain as snow levels raise back up towards 10,000
feet. Temperatures are expected to warm into the mid 50s for
Saturday`s high across the plains and mountain valleys, putting us
roughly 5 to 10 degrees below normal for a change. Due to our
proximity to the low, we will have a chance for light rain showers
throughout the day, with light snow showers possible above
10,000`. By early Sunday morning, snow totals are expected to be
less than 1" below 10,000 feet, with the exception of Park County
where 1-4" will be possible down to 9,500 feet. The greatest
accumulations are expected in the Mosquito Range above 11,000
feet, where close to a foot is expected. Totals will decrease as
you move north across the Front Range Mountains. Sometime Sunday,
the low is expected to lift northeast across Colorado. As it
traverses the area, light precipitation can be expected with
localized areas of heavier rainfall, mainly ahead of the vorticity
max, though exact placement of this feature is unclear at this
time. There will be enough moisture wrapping around the backside
of the low to bring another wave of mountain snow showers, this
time more focused on our northern mountain ranges, with snow
levels expected to stay above 9,000 feet. Light accumulations are
expected with the highest elevations seeing up to 3" of additional
snowfall Sunday through Monday morning.

By Monday afternoon, above normal temperatures will return with 70s
expected across the plains. Warm and dry conditions are expected
through the week as ridging persists over the western CONUS once
again.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 541 AM MDT Fri Oct 18 2024

VFR conditions are possible until 01Z this evening. There is
potential for lower cloud decks this morning but there is low
forecast confidence if those clouds will arrive KDEN and KBJC.
Decided to delay the timing of low clouds instead of removing the
potential chance between 14-18Z. Scattered showers will develop
late this afternoon and cloud coverage shifts from SCT to BKN and
wind speeds increase between 10-13kts. Winds should remain north
through the evening.

By late evening, there is potential for IMC where cloud decks
lower near 8-6k feet. While a few showers may linger, it is
possible for fog north of all terminals if showers decrease in
coverage into Saturday morning.

&&

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

&&

$$

SHORT TERM...AD
LONG TERM...Bonner
AVIATION...AD