382
FXUS65 KBOU 041745
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1045 AM MST Wed Mar 4 2026

.KEY MESSAGES...

- Rain/snow showers across South Park and Palmer Divide likely
  through Wednesday morning.

- Critical fire weather conditions possible across the plains on
  Thursday due to mild, dry, and breezy conditions.

- Potential for colder storm system with more widespread snow
  Thursday night through Friday, although uncertainty in amounts
  remains.

&&

.DISCUSSION /Through Tuesday/...
Issued at 1043 PM MST Tue Mar 3 2026

Current water vapor imagery shows the upper level shortwave over
eastern Colorado, with rain/snow showers ongoing over South Park and
Palmer Divide. These showers will linger overnight before gradually
ending around sunrise tomorrow as the system exits the region. Hi-
res guidance indicates areas of patchy fog across the northern and eastern
plains early Wednesday morning. However, that should quickly
dissipate by mid-morning with daytime heating.

Wednesday looks to be a quiet day, as upper level ridging will
return to the state, along with warm temperatures and dry
conditions. With subsident flow aloft, clear skies will prevail,
allowing temperatures to reach up to the low 60s across the plains,
and mid 30s to upper 40s/50s for mountains and valleys.

On Thursday, southwest flow aloft will increase ahead of an incoming
shortwave trough. 700-mb temperatures will likely reach up to 4 to 6
dg C by the afternoon, which would help promote temperatures in the
high 60s across the plains. Lee cyclogenesis is favored to develop
at the surface over the plains, which will create breezy winds south
of the low. Those breezy winds combined with low relative humidity
values will promote elevated to critical fire weather conditions
across portions of our southern plains (see Fire Weather Discussion
below).

Guidance continues to be in good agreement of a shortwave trough
breaking into two pieces of energy late Thursday/early Friday, with
one ejecting from Colorado into the northern Great Plains, and the
other one trekking towards the southern California coast and
becoming a closed low. However, models are still struggling with how
the former shortwave evolves. The most recent GEFS run has the
shortwave strengthening into a closed low over northeast Colorado,
while the ECMWF keeps an open shortwave that eventually gets sheared
out from another system in Canada. Regardless of either scenario,
cold air and moisture will be advected into the region as a cold
front arrives sometime overnight Thursday. How much moisture is
still the question (and dependent on the evolution of the system).
The GEFS has consistently been drier than the ECMWF. However,
with the medium range models indicating similar QPF values as the
global ensembles for the plains, will continue to trend QPF
amounts towards the ensemble mean. Mountain snow is expected from
Thursday afternoon through Saturday morning, with the bulk of the
accumulations on Friday. It is still too early to go into details
about exact snowfall amounts, but if models continue to trend the
way they have been these past few runs, we could be looking at
Winter Weather Advisories for the mountains on Friday in the next
forecast updates. For the plains, expect light precipitation (snow
becoming more likely!) to begin by Friday morning before
gradually ending by late Friday evening/early Saturday morning,
favoring areas along the I-25 corridor.

By the weekend, we will likely have weak flow aloft as Colorado
looks to be in between the two systems mentioned above. Dry
conditions and warmer temperatures should prevail for the mountains
and plains.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1044 AM MST Wed Mar 4 2026

Normal diurnal wind patterns are expected today at DIA; with weak
east/southeasterlies this afternoon, then weak drainage winds from
late evening on into Thursday morning. There will be no ceiling
issues.

&&

.FIRE WEATHER...
Issued at 1043 PM MST Tue Mar 3 2026

Critical fire weather conditions are possible on Thursday, as
above normal temperatures and dry conditions return to the plains.
Guidance has continued to indicate RH values below 15% for areas
across the Palmer Divide, Lincoln, and southern Washington
counties. However, the exact location of the strongest winds are
still uncertain at this moment. A cyclone is favored to develop
over the plains, with winds gusting up to 25-30 mph at times.
As of right now, confidence is still high enough to continue the
Fire Weather Watch. However, will be monitoring for any need to
expand the watch to include Washington county or Denver metro.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch Thursday afternoon for COZ241-245>247.

&&

$$

DISCUSSION...MAI
AVIATION...66
FIRE WEATHER...MAI

NWS BOU Office Area Forecast Discussion