294
FXUS65 KBOU 202345
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
545 PM MDT Tue Oct 20 2026

.KEY MESSAGES...

- Mild temperatures through Friday. Mostly dry through early
  Wednesday.

- Isolated light rain/snow showers possible over the mountains
  Tuesday afternoon.

- A more organized system late Wednesday through early Friday,
  with rain showers becoming more numerous over the mountains.

- Seasonable temperatures for the weekend into next week.

&&

.DISCUSSION /Through Tuesday/...
Issued at 258 PM MDT Tue Oct 20 2026

Recent radar imagery shows a couple of showers moving off the
northern CO foothills. These showers are being supported by
enhanced vorticity and lift from the weak shortwave moving across
northern CO this afternoon. Temperatures are sitting in the 60s to
70s over the Denver metro and plains, with 50s and low 60s across
the mountains. Isolated showers will continue to be possible over
the high terrain through sunset, although very minimal rainfall
(perhaps just a few hundredths) is expected to reach the ground.
Skies will be mostly clear tonight with morning lows expected to
be slightly warmer than this morning over the plains, with
temperatures in the low 50s for the Denver metro, and some mid 40s
in the usual cold spots out in the northeast CO plains.

An upper level ridge will begin to build over the area tonight,
reinforcing above-average temperatures for the rest of the work week
as temperatures soar into the mid to upper 70s at low elevations.
This upper level ridge will also strengthen southwest flow aloft and
bring an increase in Pacific moisture later in the day ahead of a
strong cutoff low to the west. However, we do not expect any rain
chances to arrive to the mountains of our area until the late
afternoon/early evening. Moisture transport will intensify late
Wednesday night as the cutoff low reaches the California coast, and
a robust subtropical jet channels Pacific moisture towards the Four
Corners in an atmospheric river-like fashion. A first round of
isolated showers will be possible into the overnight hours over the
mountains, and mid level clouds will begin to drift over the plains.

Shower coverage should increase over the high terrain Thursday
afternoon. However, as has been outlined in previous AFDs,
southwesterly flow aloft and limited instability will favor more
modest rainfall amounts for southwest CO, with much lighter amounts
over our CWA. Recent model trends have showed little change in QPF for
the central mountains and Front Range, with amounts generally
ranging from a trace up to 0.50", and perhaps some locally higher
amounts for the mountains of Park County. Given the tropical
nature of this airmass, it will be difficult to get snow
accumulation out of this system, with perhaps only some dustings
above 12,000 ft. For the Denver metro, a few sprinkles up to a
trace of rainfall cannot be ruled out Thursday afternoon if any
showers are able to survive off the foothills. Otherwise, it will
be another warm day for the plains, with temperatures in the mid
70s and partly cloudy skies.

The cutoff low will begin to weaken late Thursday into Friday as the
trough axis drifts over Utah. However, a tight pressure gradient
will encourage breezy south-southwest winds over the east CO plains
throughout the day on Friday. Current model guidance suggests wind
gusts up to 30-40 mph possible over a large portion of the east CO
plains. We also expect temperatures to climb into the upper 70s with
clearing skies, warm air advection, and weak downsloping,
potentially leading to a slight drop in humidities (20%-30%). If
humidities trend any drier, we could be looking at critical fire
weather conditions Friday afternoon over portions of the
CO plains given the overlap of gusty winds and drier air.

A cold front will push through the area Saturday morning, bringing
another period of northerly breezy winds with gusts up to 25-30 mph.
There is still some model disagreement regarding the strength,
and the moisture accompanying this front. Some ensemble members
suggest a moister and cooler scenario, with low clouds and
afternoon temperatures over the Denver metro dipping well below
average. Other model solutions hint at partly sunny skies and
temperatures in the low 60s, which is right at the climatological
average. It is worth noting, however, that models have trended a
bit moister with the front since yesterday, with some light
mountain snow accumulations becoming increasingly likely Saturday
into Sunday. Looking ahead, there is considerable spread in
synoptic ensemble guidance, making next week`s forecast quite
uncertain at this time.

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 540 PM MDT Tue Oct 20 2026

VFR conditions are expected throughout the TAF period. Winds are
rather VRB at this time, but should settle into drainage by
around 3-5z and be under 10 kts. There is a TEMPO until 2z due to
an outflow boundary currently located in Weld County that could
increase wind gusts a touch to around 10 kts. Winds should turn to
the southeast for most of the afternoon tomorrow and be around 10
kts with a slight increase to 10-15 kts by Wednesday evening.
There will be an increase in mid-level cloud cover starting
Wednesday evening and then lasting through most of Thursday.

&&

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

&&

$$

DISCUSSION...AA
AVIATION...MV

NWS BOU Office Area Forecast Discussion